PubMed Health⌕ Search

Biomedical subjects

F Plénat

Publications and source records attributed to F Plénat.

18 recordsLinked to original sources
PubMed2006

Quantitative analysis of the elastic fibres in the human temporomandibular articular disc and its attachments.

A quantitative study of the elastic fibres found in the human temporomandibular disc and its attachments was performed. Seven left discs from 57- to 82-year-old subjects, without macroscopic evidence of a TMJ disorder, were analysed and prepared in parasagittal sections. The surface amount was measured, thresholded and expressed from 0 to 1, using microscopic digitized views after Weigert's resorcin-fuchsin staining of elastic fibres. Fibre density rates ranged from 0 to 0.687. The mean density was 0.1532 (sigma=0.1150) in the upper bilaminary zone, 0.1097 (sigma=0.1159) in the lower bilaminary zone, 0.0474 (sigma=0.0782) in the anterior band, 0.0180 (sigma=0.0603) in the posterior band and null in the intermediate zone. The difference in density rate between the structures was significant, except for the posterior band and the intermediate zone. The elastic fibre density rates in central and medial locations of the upper and lower bilaminary zones were twice as big as in the lateral locations. In the anterior band, the elastic fibre density was less abundant medially than in its lateral part. These quantitative results support the current elastic fibre distribution scheme, and confirm the necessity of studying their orientation, taking into account age and temporomandibular joint health parameters.

Age Factors↗
PubMed2001

Morphologic and functional development of whole human fetal stomachs grafted into nude mice.

To study in vivo the cellular differentiation and secretion of human developing fetal stomach, ethically and technically impossible to perform in utero, 256 fetal stomachs were xenografted. Human stomachs from 6- to 10-week-old fetuses were grafted for 1-273 days into nude mice. Biopsies for immunohistochemistry, hybridization and electron microscopy were taken and a catheter introduced into the human stomach. Macroscopic growth was fast and cells in S phase were numerous during the first 9 weeks, then the stomach size was stable and the gastric mucosa, of adult type, remained normal. In situ hybridization detected only a minute mouse mesenchymal chimerism in the graft. Chromogranin A, intrinsic factor and H+/K+ adenosine triphosphatase were immunohistolocally detected in epithelial cells 20 days after grafting, gastrin was detected after 30 days and pepsinogen after 60 days. The pH in gastric juice, which was at 8.0 +/- 0.1 from days 10-25, dropped from 4.39 +/- 1.80 at 30 days to 1.58 +/- 0.29 at 90 days. Intrinsic factor was stable and pepsin ranged from 6.8 +/- 7.8 to 134 +/- 51 units at 90 days. The differentiation of the epithelial cells in xenografts was very accelerated in comparison to that in utero.

Animals↗
PubMed2001

Increased expression of the vascular endothelial growth factor is a pejorative prognosis marker in papillary thyroid carcinoma.

Vascular endothelial growth factor (VEGF) is a potent stimulator of endothelial cell proliferation. It has been implicated in tumor growth of human thyroid carcinomas. Using the VEGF immunohistochemistry staining score, we correlated the level of VEGF expression with the metastatic spread of 19 cases of thyroid papillary carcinoma. The VEGF immunostaining score, ranging from 0-9, was determined as the multiplication of a percentage of labeled thyrocytes score (0, no labeling; 1, <30%; 2, 31--60%; 3, >61% of labeled thyrocytes) and an intensity score (0, no staining; 1, weak; 2, mild; 3, strong staining). The mean score +/- SD was 5.74 +/- 2.59 for all carcinomas. The mean score for metastatic papillary carcinoma was 8.25 +/- 1.13 vs. 3.91 +/- 1.5 for nonmetastatic papillary cancers (P < 0.001). By discriminant analysis, we found a threshold value of 6.0, with a sensitivity of 100% and a specificity of 87.5%. There were no statistical differences between metastatic and nonmetastatic carcinomas when age, tumor size, or thyroglobulin levels were considered. The VEGF immunostaining score seems to be a helpful marker for metastasis spread in differentiated thyroid cancers. An increased production of VEGF could assess an aggressive disease and be the hallmark of a trend to produce metastasis. We propose the VEGF immunostaining score as a marker for the prognosis in differentiated thyroid cancers. A value of 6 or more, should be considered as at high risk for metastasis threat, prompting the physician to institute a tight follow up of the patient.

Adolescent↗
PubMed2001

[Formaldehyde fixation in the third millennium].

This review deals with the general principles and problems of formaldehyde fixation. After a short description of 1) formaldehyde methods of production, 2) chemical properties of formaldehyde solution, and 3) kinetic of formaldehyde binding in tissue, formaldehyde reactivity with the tissue biopolymers, proteins and cucleic acids mainly, are described. How formaldehyde fixation of tissues adversely affects the reactivity of cellular proteins with their respective specific antibody and the ways the most commonly used retrieval techniques in immunohistochemistry act are, thereafter, discussed. Finally, concerns that need to be dealt with when formalin-fixed specimens are used for genomic analysis and studies of DNA expression are highlighted.

DNA↗
PubMed1999

[Paraneoplastic opsoclonus-myoclonus syndrome revealing T-cell lymphoma].

BACKGROUND: Nonrhythmic involuntary ocular oscillations and axial and segmentary myoclonia are associated in the opsoclonus-myoclonus syndrome. In adults, a paraneoplastic origin is generally found. We report the first of opsoclonus-myoclonus associated with non-Hodgkin's lymphoma. CASE REPORT: A 66-year-old woman rapidly developed a typical opsoclonus-myoclonus syndrome within a few hours, presenting vertigo, cerebellous ataxia, multidirectional involuntary ocular movements and non-rhythmic axial and segmentary myoclonia. Brain computed tomography and magnetic resonance imaging demonstrated discrete diffuse anomalies of the white substance predominating in the pons. The cerebrospinal fluid showed discrete lymphocytosis. Antineuron antibodies were negative. No cause could be identified until the development 11 months later of pleomorphic T-cell mediastino-cervical lymphoma. The patient responded moderately to a CHOP regimen which had no effect on the opsoclonus-myoclonus syndrome. Death occurred after a 16-month course due to pulmonary complications. DISCUSSION: Neuroblastoma and infectious causes predominate in opsoclonus-myoclonus syndromes observed in children; in adults, the predominant cause is cancer. Antineuron, anti-Ri and anti-Hu antibodies can be evidenced in some cases, arguing in favor of a paraneoplastic mechanism. Recent reports have evidenced MRI anomalies in the pons and the cerebellum, anatomically well correlated with the opsoclonus-myoclonus syndrome. Besides small-cell bronchogenic anaplastic cancer, the possibility of cancer of the breast and uterus, and both non-Hodgkin and Hodgkin lymphoma should be explored, knowing the cancer develops several month after the opsoclonus-myoclonus syndrome.

Aged↗
PubMed1998

Evaluation of coupling of cobalamin to antisense oligonucleotides by thin-layer and reversed-phase liquid chromatography.

We have evaluated by chromatography two strategies of oligonucleotide binding to vitamin B12 (cobalamin). The first one was based on a covalent linkage of aminooligonucleotide to carboxycobalamin in presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). Carboxycobalamin and EDC-cobalamin were eluted with a retention time of 16.5 and 21.6 min, respectively, in RP-HPLC, while aminooligonucleotide and oligonucleotide-cobalamin were coeluted at 19.4 and 19.8 min. In the second strategy, avidin was coupled to both biotinylated oligonucleotide and vitamin B12. Aminocobalamin and biotinylated cobalamin had respective retention times of 13 and 15.7 min in RP-HPLC and respective Rf values of 0.3 and 0.8 in thin-layer chromatography. Incubation of avidin with biotinylated cobalamin produced, in Superose 12 gel permeation, a peak with a retention time of 28 min, which corresponded to avidin-biotinylated cobalamin as it disappeared with an excess of either biotin or biotinylated oligonucleotide. In conclusion, we have prepared and purified by RP-HPLC and gel permeation chromatography an oligonucleotide-avidin-cobalamin complex which will be used as a vector complex of antisense oligonucleotides.

Avidin↗
PubMed1997

Human immunodeficiency virus type 1 in an unusual cystic lymphoepithelial lesion of the lung.

AIMS: We present the clinical and histopathological findings of an unusual pulmonary cystic lymphoepithelial lesion in an HIV sero-positive patient. METHODS AND RESULTS: The 32-year-old female patient developed two nodules in the vicinity of the right and left hila. Left upper lobectomy showed a 40-mm wide cystic lesion. The cyst wall was lined by a squamous epithelium and lymphoid tissue with a marked follicular hyperplasia and a prominent follicular cell dendritic network expressing HIV major core protein p24. CONCLUSIONS: The absence of an Epstein-Barr virus infected lymphoid population and monoclonal immunoglobulin gene rearrangement supported the benign nature of the lesion.

Adult↗
PubMed1997

Prospective evaluation of protein bound vitamin B12 (cobalamin) malabsorption in the elderly using trout flesh labelled in vivo with 57Co-cobalamin.

BACKGROUND: The frequency of dietary protein bound vitamin B12 malabsorption in elderly patients remains controversial. AIMS: To evaluate this malabsorption in elderly hospitalised patients using a modified Schilling test. PATIENTS: Fourteen elderly patients with low B12 blood levels were prospectively selected from 394 hospitalised patients. METHODS: The modified Schilling test was performed with trout labelled in vivo. RESULTS: The test was normal in five healthy elderly subjects, in 7/8 patients with pancreatic insufficiency, and in nine non-elderly patients with antral gastritis. The low decision limit was established at 3.3% (median 4.8%). From the 14 elderly patients with low B12 prospectively selected from 394 hospitalised patients, seven had a real deficiency with anaemia and an increased homocysteine and/or methylmalonate serum level. The modified Schilling test showed malabsorption in five of these patients, including two in which the standard Schilling test was normal, and three in which the standard Schilling test was partially corrected by an intrinsic factor. CONCLUSIONS: Protein bound vitamin B12 malabsorption was detected in at least 0.5% of elderly hospitalised patients, using the labelled trout flesh absorption test.

Adult↗
PubMed1997

[The PRINS technique. Aplication to the detection of X and Y chromosomes for follow-up of bone marrow allografts performed with an opposite sex donor].

The PRimed IN Situ synthesis is a method for rapid identification of chromosomes in metaphase or interphase on cytological preparations and frozen tissue sections, using oligonucleotide primers derived from chromosome specific subsets of repeated DNA families. PRINS technique is an alternative to fluorescence in situ hybridization, as sensitive as FISH but faster and more specific. This technique is potentially of great interest for pathologists involved in transplantation pathology or cytogenetic interphasic oncology.

Adult↗
PubMed1997

Autoantibodies in pernicious anemia type I patients recognize sequence 251-256 in human intrinsic factor.

Pernicious anemia is an organ-specific autoimmune disease characterized by cobalamin deficiency, megaloblastic anemia, neuropathy, and autoimmune gastritis with anti-intrinsic factor autoantibodies. Type 1 anti-intrinsic factor autoantibodies block the cobalamin binding site of the intrinsic factor, a gastric protein required for the assimilation of cobalamin. The aim of our study was to identify the epitope domain of type 1 antibodies. Different series of peptides derived from the intrinsic factor sequence were synthesized and tested for antibody binding in enzyme-linked immunosorbent assay, radioisotope assay, gel filtration, and SDS-PAGE autoradiography. One of these peptides, named IF-R7 (the intrinsic factor aminoacid sequence 251-265), showed a type 1 antibody binding activity and inhibited, in vitro, their blocking activity with Ki at 2.3 microM. The cross-linking of IF-R7 to beta-lactoglobulin produced type 1 anti-intrinsic factor antibodies in immunized sheep. In vivo Schilling tests performed on guinea pigs also revealed IF-R7 peptide inhibition of type 1 antibody blocking activity. 256Ser, 258Lys, 262Tyr and 265Val of the IF-R7 were essential for the epitope recognition. Reactivity with type 1 antibodies was found in IF-R7 homologous peptides from herpesvirus Saimiri and from pathogenic Escherichia coli. In conclusion, the epitope of type 1 anti-intrinsic factor autoantibodies is located in the 251-265 amino acid sequence of the protein. The identification of this epitope will enable the definition of an experimental animal model of anti-IF autoimmunity in order to study the pathogenesis of pernicious anemia.

Amino Acid Sequence↗
PubMed1997

[An exceptional variety of medulloblastoma: melanotic medulloblastoma].

We report a new case of melanotic medulloblastoma of the vermis in a 3 1/2 year old boy. This tumor showed a typical histological appearance with pseudoepithelial pigmented structures immunoreactive for S100 protein and vimentin. The tumor did not recur after total surgical removal and post operative radiation. However, after a 10 year follow-up, imaging demonstrated that a second tumor occurred in the left cerebellar hemisphere, which, on histological examination, was a typical glioblastoma. Hypothesis concerning the histogenesis of the second tumor, as well as a causal association with radiation therapy and possible contribution of growth hormone therapy are discussed.

Cerebellar Neoplasms↗
PubMed1997

[Extra-cardiac rhabdomyoma of the fetal type].

Rhabdomyomas are benign tumors of striated muscle. They are distinguished by topographic data: cardiac or genital and by histological criteria: foetal or adult type. The foetal type is the most heterogeneous, with either a majority of immature cells or a mixture of maturing elements. This diversity has led to distinguish immature (or standard) foetal Rhabdomyomas from intermediate foetal Rhabdomyomas. One observation of this last type is reported. The authors highlight the essential characteristics of foetal Rhabdomyomas, however the exact meaning remains unclear: an anomaly in the differentiation of the striated muscle? or a true tumoral process through genetic anomaly?

Fetal Diseases↗
PubMed1994

The role of platelet-derived growth factor production by tumor-associated macrophages in tumor stroma formation in lung cancer.

Lung cancer is the most common cause of death by cancer in developed countries. Since a tumor cannot develop without the parallel expansion of a tumor stroma, a better understanding of its formation could lead to new therapeutical approaches. In this respect, since platelet-derived growth-factor (PDGF) is a chemotactic and growth factor for mesenchymal and endothelial cells, lung tumors of patients undergoing surgery for non-small cell lung cancer were evaluated for their replication rate using iododeoxyuridine incorporation, and for the expression of PDGF genes and the presence of PDGF A and B chains and of PDGF receptor alpha and beta subunits. This observation demonstrates that: (a) tumor cells and stroma mesenchymal cells, but not tumor-associated macrophages, display a high replication rate; (b) 1 of 3 tumors are characterized by cancer cells expressing the genes for PDGF A and/or B chains, while 1 of 2 tumors are composed of tumor cells presenting PDGF receptors alpha and beta subunits on their surface, and in only 1 of 6 tumors, tumor cells coexpress PDGF and its receptor; (c) in almost all tumors, tumor-associated macrophages express PDGF A and/or B chain genes; (d) mesenchymal cells, as well as endothelial cells, do not express PDGF A and B chain genes but do express PDGF receptor alpha and beta subunits; and (e) an ongoing active process was suggested in the periphery of the tumor by the simultaneous strong expression of PDGF A and B chain genes by tumor-associated macrophages and the high replication rate of mesenchymal and endothelial cells in the same area. Thus, PDGF is likely to have a limited autocrine role in tumor cell replication but is a potential player, in a paracrine fashion, in tumor stroma development.

Carcinoma, Non-Small-Cell Lung↗
PubMed1985

[Prenatal diagnosis of triploidy. I. Echographic, clinical and anatomic studies].

Three cases of triploidy have been diagnosed prenatally on ultrasonography and clinical features. A morphological and histological study of both foetus and placenta is made. The cases and a review of live-born triploid infants published in the literature allow a description of some characteristic malformations. Possibilities of triploïd pregnancy recognition are discussed.

Adult↗