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Biomedical subjects

H Gérard

Publications and source records attributed to H Gérard.

At least 19 recordsLinked to original sources
PubMed2005

Immunolocalization of sex hormone-binding globulin (SHBG) in human ovarian follicles and corpus luteum.

Sex hormone-binding globulin (SHBG), a hepatic carrier protein for sex steroids is expressed in different steroid-sensitive tissues, including Sertoli cells of the testis. It has been suggested that this protein may be one of the local regulators of spermatogenesis. The expression of SHBG in the ovary is currently unknown. We have previously demonstrated the synthesis of SHBG in granulosa-lutein cells from patients undergoing in vitro fertilization. In this study, the presence of SHBG in human ovarian follicles and corpora lutea is investigated, using immunohistochemistry on adult and fetal ovarian tissue sections. SHBG is localized in the whole granulosa layer at all stages of folliculogenesis, whereas, only isolated theca cells are immunostained. In primordial and primary follicles, the oocyte cytoplasm shows an intense immunostaining, which disappears after the secondary stage. In the microenvironment of the mature oocytes, SHBG is present in the surrounding cumulus cells, the perivitelline space, and nearby the oolemma. In the corpus luteum, SHBG is localized in large luteal cells, whereas, small luteal cells do not show any significant staining. By analogy with the testis, these results raise the question of an involvement of SHBG in the regulation of follicular maturation as well as in luteal function.

Adult↗
PubMed2005

Age-dependence of urinary normal and modified nucleosides in childhood as determined by reversed-phase high-performance liquid chromatography.

Modified nucleosides have been characterized as tumor markers for a number of malignant diseases. In order to use these markers in children, the age-dependence of the nucleoside levels in healthy children has to be established and taken into account in diagnostic decisions. In this study, the levels of 12 normal and modified nucleosides in urine of 166 healthy children and adolescents with an age between 1 day and 19 years are determined by reversed-phase HPLC, and age-dependent reference ranges are defined. The urinary nucleoside concentrations are related to the creatinine concentrations, which allows the use of randomly collected urine samples. All nucleoside levels in urine of children decrease with age, most pronounced during the first 4 years of life, and the age-dependence of the reference values of the individual nucleosides can be approximated by a mathematical function y = b(0) + b(1) (1/x) with the regression coefficients b(0) and b(1,) the nucleoside levels y and the age x between 1 year and 19 years. In the very young children, the shifts in the nucleoside concentrations are more differentiated. Starting with low levels on the first day of life, the concentrations of all studied nucleosides rise up to an age of 1-2 months, when they reach their absolute maximum for all age periods, and then decrease.

Adolescent↗
PubMed2004

Expression of sex hormone-binding globulin (SHBG) in human granulosa-lutein cells.

Sex hormone-binding globulin (SHBG) was classically thought to be a plasma steroid-carrying protein of hepatic origin, but recently, locally produced, membrane-bound SHBG has been shown to influence cell functions in several steroid-responsive tissues. In the ovary, SHBG is known to be present in the follicular fluid, but information about a possible intracellular presence of SHBG in this organ is still very scarce. In this study the presence of SHBG was assessed by immunohistochemistry in human granulosa-lutein cells (GLC) collected by follicle puncture for in vitro fertilization. SHBG was detected in the cytoplasm of GLC before and after in vitro culture for up to 96 h. The presence of full-length SHBG messenger RNA was demonstrated in GLC by reverse transcription-polymerase chain reaction (RT-PCR) in both cultured and uncultured cells. These results demonstrate a local synthesis of SHBG in GLC and raise the question of the physiological significance of these findings in follicular physiology.

Alternative Splicing↗
PubMed2004

Histological study of the human temporo-mandibular joint and its surrounding muscles.

This is a histological study of the human temporo-mandibular joint and its surrounding muscles. Using a microscopic study of serial sections from anatomical specimens from six subjects, the detailed anatomy of the joint is presented with particular regard to the histology. This study has allowed, in particular, the description of the ligaments and capsule as well as the insertions of the masticatory muscles (temporalis, masseter, lateral pterygoid) on this joint. These observations are then compared with the anatomical and histological data already reported on this subject. This study shows that the bulk of the muscular fibres of the lateral pterygoid passes under the foot of the disc is attached over the whole height of the condylar, unite and extend as far as the medial pole of the joint under the insertion of the articular disc. An insertion of the temporo-masseter musculo-tendinous complex on the anterior and lateral capsulo-discal structures was observed. The lateral pterygoid is composed of a succession of tendinous and fleshy fibres. This study confirms the thickening of the lateral capsule that corresponds to a lateral collateral ligament, and the absence of a medial collateral ligament. Medial stability is conferred by the lateral ligament of the contralateral joint.

Aged↗
PubMed2001

Facile C(sp(2))/OR bond cleavage by Ru or Os.

Os(H)(3)ClL(2) (L = P(i)Pr(3) or P(t)Bu(2)Me) are shown to be useful "precursors" to "OsHClL(2)", which react with vinyl ethers to form first an eta(2)-olefin adduct and then isomerize to the carbenes, OsHCl[CMe(OR)]L(2). Subsequent R- and L-dependent reactions involve C(sp(2))-OR bond cleavage, to make either carbyne or vinylidene complexes. The mechanisms of these reactions are explored, and the thermodynamic disparity of Ru versus Os and the influence of the OR group and the spectator phosphine ligands are discussed based on DFT (B3PW91) calculations.

Journal Article↗
PubMed2001

Frequency and genome load of Epstein-Barr virus in 509 breast cancers from different geographical areas.

Since the few data exploring a possible association between Epstein-Barr virus (EBV) and breast cancer are conflicting, we investigated this association together with the influences of geographical areas. 509 breast cancers were sampled from areas with varying risks of nasopharynx carcinoma (NPC) such as North Africa (Algeria and Tunisia, high-risk area); southern France (Marseille, intermediate-risk area); and northern Europe (northern France, the Netherlands and Denmark; low-risk areas). Polymerase chain reaction (PCR) of a subregion of EBV BamHIC encoding the EBERs demonstrated that 31.8% of the tumours contained the viral genome. No significant differences were observed among the geographical areas. However, positive samples showed higher loads of the EBV genome in the NPC high- and intermediate-risk areas than in the low-risk areas. EBV type 1 was the dominant strain. In situ hybridization studies using a(35)S-labelled riboprobe for EBER1 and a laser capture microdissection, combined with quantitative PCR, showed that EBV localization was restricted to some tumour epithelial cell clusters. EBV could not be detected in the stroma. Considering the whole population covered, the presence of the EBV genome was not correlated with age, menopausal status, tumour, size, nodal status or histological grade.

Adult↗
PubMed2000

Unsaturated Ru(0) species with a constrained bis-phosphine ligand: [Ru(CO)2(tBu2PCH2CH2PtBu2)]2. Comparison to [Ru(CO)2(PtBu2Me)2].

The synthesis of Ru(C2H4)(CO)2(dtbpe) (dtbpe = tBu2PC2H4PtBu2), then green [Ru(CO)2(dtbpe)]n is described. In solution, n = 1, while in the solid state, n = 2; the dimer has two carbonyl bridges. DFTPW91, MP2, and CCSD(T) calculations show that the potential energy surface for bending one carbonyl out of the RuP2C(O) plane is essentially flat. Ru(CO)2(dtbpe) reacts rapidly in benzene solution to oxidatively add the H-E bond of H2, HCl, HCCR (R = H, Ph), [HOEt2]BF4, and HSiEt3. The H-C bond of C6HF5 oxidatively adds at 80 degrees C. CO adds, as does the C=C bond of H2C=CHX (X = H, F, Me). The following do not add: N2, THF, acetone, H3COH, and H2O.

Journal Article↗
PubMed2000

Fetal target organs of graft-versus-host reaction induced in utero by injection of maternal cells in a pig model.

The target organs of graft-versus-host reaction (GVHR) in adult or neonates are the site of multifocal lymphocytic infiltrates. GVHR can also be acquired in utero by maternal cells crossing the placenta, but the fetal target organs are unknown. The aim of this study was to determine these target fetal organs. The distribution pathway of infused labeled lymphocytes within cryostat sections of fetal organs was analyzed, and fetal target organs of infused lymphocytes were investigated in both isogenic and semiallogenic situations. Isogenic cells were observed in less organs and semiallogenic cells were localized in a more restricted number of organs than isogenic cells. Furthermore, the liver, the thyroid, and the spleen were the fetal target organs in the two studied gestations. GALT, thymus, and kidney were also lymphocyte targets in isogenic gestation. In conclusion, isogenic cells induced GVHR in more fetal organs than semiallogenic cells.

Animals↗
PubMed2000

[Factors limiting in utero lymphocyte transplantation and cell therapy].

To evaluate factors of cell transplantation in utero in human, we have injected into rat fetuses of varied stage (n=61) several doses of non labeling lymphocytes mixed with FITC labeled latex beads. The ratio of fetal death and the histopathological effect longer after birth were assessed. Our results showed that the elevated fetal death ratio were observed after the injections of a high doses in young fetuses. Low doses provoked the same effect when injected to old fetuses. In living fetuses, histopathological lesions mimicking a graft versus host reaction were noticed throughout several organes six week after birth. We concluded that lymphocyte transplantation in utero depends on the dose of injected cells and stage of fetal development.

Animals↗
PubMed1999

Differences in steroid 5alpha-reductase iso-enzymes expression between normal and pathological human prostate tissue.

We studied the expression level and cell-specific expression patterns of 5alpha-reductase (5alpha-R) types 1 and 2 iso-enzymes in human hyperplastic and malignant prostate tissue by semi-quantitative RT-PCR and in situ hybridisation analyses. In situ hybridisation established that 5alpha-R1 mRNA is preferentially expressed by epithelial cells and little expressed by stromal cells whereas 5alpha-R2 mRNA is expressed by both epithelium and stroma. Semi-quantitative RT-PCR has been performed on total RNA from different zones of normal prostate, BPH tissues and liver. We found that 5alpha-R1 and 5alpha-R2 mRNAs expression was near the same in all zones of normal prostate. In BPH tissue, 5alpha-R1 and 5alpha-R2 mRNAs expression was slightly but significantly increased, when it was compared to the levels recorded for normal prostate. In cancer samples, 5alpha-R1 mRNA expression was higher than in normal and hyperplastic prostate but the level of 5alpha-R2 mRNA was not statistically different from that observed in the different zones of normal prostate. In liver, 5alpha-R2 mRNA level was similar to that measured in BPH but 5alpha-R1 mRNA expression was ten times higher. The increase observed in 5alpha-R isoenzymes expression in BPH tissue could play an important role in the pathogenesis and/or maintenance of the disease.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1999

[The chondrocranium of an 18 mm human embryo. A 3-dimensional computer-assisted reconstruction].

INTRODUCTION: Three-dimensional reconstruction of histologic structures is still a real challenge. This is the reason why very few specimens are published, especially for the head. MATERIAL AND METHODS: The chondrocranium of an 18-mm human embryo was reconstructed from serial histologic sections. The three-dimensional reconstruction was based on a software used in geology and adapted to medical applications. This software was able to smooth the reconstructed model, i.e. to correct the distortions due to the histologic preparation. RESULTS: The chondrocranium model is presented. To facilitate spatial orientation, we added the reconstruction of Merkel cartilage, of Reichert cartilage, of the vertebrae, and of the cerebrum. The different portions of the chondrocranium are described. DISCUSSION: The three-dimensional result is described and advantageously compared to the rare wax models available. The morphological differences are detailed. CONCLUSION: This technique of three-dimensional reconstruction with its smoothing procedure is a very well adapted method for reconstruction of histologic structures. The results presented confirm the educational value of this tool, which is otherwise a powerful instrument of morphogenic study.

Anatomy, Cross-Sectional↗
PubMed1998

3D reconstruction of the mouse's mesonephros.

The present work reports on the three-dimensional reconstruction of the segmented mesonephros during the embryonic development of the mouse. With a light microscope and an automatic reconstruction of surfaces, aspects of the mesonephros are described. These surfaces are obtained by using digitized contour lines. A new interpolation method called DSI (Discrete Smooth Interpolation) enables correction of the distortion induced by microtomy in paraffin sections. After a triangulation step, this method uses a smoothing algorithm, which implies a spatial redistribution of the vertices of the triangles to correct the rotational and translational misalignment. The use of this 3D program improves the understanding of the development patterns and helps us to appreciate changes in the rebuilt mesonephros. By 10.5 embryonic days, tubules emerge from the Wolffian body and begin their formation, then between 11.5 and 13.5 embryonic days, tortuous mesonephric tubules bound to the Wolffian duct form small curls, which grow and finally unwind. At the same time, mesonephric tubules unbound to the Wolffian duct appear, and on 13.5 embryonic days, the Müllerian duct is visible. After 14.5 embryonic days, the segmented mesonephros keeps its general aspect but decreases in size. At this time, each gonad is provided with both Wolffian and Müllerian ducts. Later, the Wolffian duct differentiates into the definitive male duct system, whilst the Müllerian duct regresses. Conversely, the paramesonephric duct differentiates into the definitive female duct system, whilst the mesonephric duct in turn degenerates. By this time degeneration has begun in the cranial portion of the mesonephros and this process progresses caudally. The spatial organization of the mesonephric tubules and the precise organization of all connections between these elements and the ducts may be well defined. Such approach can allow for a high definition of the normal pattern of mesonephros differentiation.

Animals↗
PubMed1998

Differentiated aspect of female and male mouse mesonephroi.

In the mouse, Sryis expressed by somatic cells in the genital ridge and leads to initiate the transformation of the indifferent gonad into a testis. Here, we have examined the segmented female and male mesonephroi over the developmental period when the initiation of seminiferous cord formation takes place. We have generated three-dimensional models which reveal structural differences between male and female mesonephric tubules at 11.5, 13.5 and 14.5 days post coitum. We evaluate, following structural parameters, that form and orientation of the tubules could evolve differently in both sexes. We propose that the structural organization of the mesonephric tubules presents an early dimorphism.

Animals↗
PubMed1997

Sertoli cell-specific expression of rat androgen-binding protein in transgenic mice: effects on somatic cell lineages.

The Sertoli cells of many species produce an androgen binding protein (ABP) which carries testicular androgens to the epididymis and is thought to play a role in sperm maturation. In the present report we analyzed the morphological modifications present in Leydig, Sertoli, and peritubular cells of the testis of young adult male mice transgenic for ABP gene, which overproduce ABP in testis. By in situ hybridization we demonstrated that ABP is specifically produced by Sertoli cells. Using light and electron microscopy, we detected scattered alterations of the seminiferous tubule cells which include cell degeneration and vacuolization. Leydig and Sertoli cells present morphological signs of hyperfunctioning compensatory mechanisms which include increased amounts of lipid droplets probably due to the existence of a stimulated steroid synthesis that in turn could be a consequence of the decreased unbound testosterone and/or a direct paracrine effect of ABP. Peritubular cells also present numerous signs of hyperstimulation.

Androgen-Binding Protein↗
PubMed1997

Retinol free and retinol complexed beta-lactoglobulin binding sites in bovine germ cells.

A high affinity specific binding site for bovine beta-lactoglobulin (BLG) was identified in bovine germ cell plasma membrane enriched fractions. Binding was found to be reversible and pH-dependent with maximum binding occurring at pH 5. The on-rate and off-rate constants were 2.26 +/- 0.8 x 10(5) M(-1) min(-1) (n = 3) and 0.016 +/- 0.004 min(-1) (n = 3), respectively. Scatchard analysis showed a single class of binding sites, with 12.38 +/- 4.62 x 10(12) sites per mg of membrane protein (n = 3) and a dissociation constant (K(D)) estimated at 26.43 +/- 2.68 nM. There was inhibition of iodinated-BLG (variant A) (125I-BLGA) binding to germ cell plasma membrane enriched fractions in the presence of unlabelled BLG variant A, BLG variant B, retinol complexed BLGA and human retinol-binding protein. Inhibition was observed neither with BSA nor with lactoferrin. 125I-BLGA incubated with a Triton X-100 solubilized plasma membrane fraction formed a high molecular mass complex in Superose 12B gel filtration. This receptor complex disappeared in the presence of unlabelled BLGA and in the presence of 10 mM EDTA. The results suggest that germ cell plasma membrane may contain a receptor which is capable of binding either retinol free or retinol complexed BLGA.

Animals↗
PubMed1997

[Unusual facial clefts].

After briefly review facial morphogenesis, the authors define facial clefts, distinguishing primary clefts, secondary clefts, and residual clefts. They discuss the uncertainties surrounding the embryology and clinical features of palpebral colobomas. The various pathogenetic concepts are analysed: amniotic hypothesis, vascular hypothesis, fusion defect. The various classifications of rare facial clefts are reviewed, with particular emphasis on Tessier's classification and the so-called Milan classification. The general principles of surgical treatment are described together with the various skeletal and soft tissues procedures.

Craniofacial Abnormalities↗