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Biomedical subjects

C Bourgeois

Publications and source records attributed to C Bourgeois.

At least 19 recordsLinked to original sources
PubMed2002

(68)(28)Ni(40): Magicity versus superfluidity.

The neutron-rich (66,68)Ni have been produced at GANIL via interactions of a 65.9A MeV 70Zn beam with a 58Ni target. Their reduced transition probability B(E2;0(+)(1)-->2+) has been measured for the first time by Coulomb excitation in a (208)Pb target at intermediate energy. The B(E2) value for (68)Ni(40) is unexpectedly small. An analysis in terms of large scale shell model calculations stresses the importance of proton core excitations to reproduce the B(E2) values and indicates the erosion of the N = 40 harmonic-oscillator subshell by neutron-pair scattering.

Journal Article↗
PubMed2000

Centrifugation and addition of glycerol at 22 degres C instead of 4 degrees C improve post-thaw motility and fertility of stallion spermatozoa.

The aims of this study were to evaluate the effects of cooling rate to 4 degrees C and temperature at the time of centrifugation/glycerol-addition (freezing extender: INRA82 + 2% egg yolk + 2.5% glycerol) on postcentrifugation recovery rate, post-thaw motility and per-cycle fertility. When centrifugation/glycerol-addition was performed at 4 degrees C (14 ejaculates), a moderate cooling rate (37 degrees C to 4 degrees C in I h) resulted in higher post-thaw motility (45%) than when using a slow cooling rate (37 degrees C to 4 degrees C in 4 h) (39%; P<0.05). When centrifugation/glycerol-addition was performed at 22 degrees C (37 degrees C to 22 degrees C in 10 min) (10 ejaculates), post-thaw motility was lower when spermatozoa were frozen directly from 22 degrees C (23%) than when spermatozoa were cooled to 4 degrees C (22 degrees C to 4 degrees C in 1 h) before freezing (47%; P<0.0001). When centrifugation/glycerol-addition was performed at 22 degrees C (before cooling at a moderate rate), as opposed to 4 degrees C (after cooling at a moderate rate), a significant improvement of 1) recovery of spermatozoa after centrifugation (P<0,0001), 2) post-thaw motility of spermatozoa at thawing (40% vs 36% (n < or = 291 ejaculates/group), P<0.0001) and 3) per-cycle fertility (56% vs 42% (n > or = 190 cycles/group), P<0.01) was observed. In conclusion, centrifugation/glycerol-addition at 22 degrees C followed by cooling to 4 degrees C at a moderate rate results in an improvement of post-thaw motility, spermatozoa recovery rate and per cycle fertility.

Animals↗
PubMed2000

Response of naïve and memory CD8+ T cells to antigen stimulation in vivo.

We studied the influence of memory T cell properties on the efficiency of secondary immune responses by comparing the in vivo immune response of the same numbers of T cell receptor (TCR) transgenic (Tg) naïve and memory T cells. Compared to naïve Tg cells, memory cells divided after a shorter lag time; had an increased division rate; a lower loss rate; and showed more rapid and efficient differentiation to effector functions. We found that initial naïve T cell priming resulted in cells expressing mutually exclusive effector functions, whereas memory T cells were multifunctional after reactivation, with each individual cell expressing two to three different effector functions simultaneously. These special properties of memory T cells ensure the immediate control of reinfection.

Animals↗
PubMed2000

A CpG-rich RNA and an RNA helicase tightly associated with the DNA demethylation complex are present mainly in dividing chick embryo cells.

In the developing chicken embryo, active DNA demethylation requires both RNA and proteins (Nucleic Acids Res. 25, 2375-2380, 1997; ibid. 25, 4545-4550, 1997, FEBS Lett. 449, 251-254, 1999a). In vitro assays indicate that in the 5- and 12-day-old embryos the highest specific activity of 5-methylcytosine DNA glycosylase is found in the brain, the eyes and the skin. In situ hybridization with antisense CpG-rich RNA tightly associated to the DNA demethylation complex shows a restricted expression pattern only in proliferating tissues such as the neuroepithelia of the brain in 5-day-old embryos. The RNA is absent in differentiated tissues like the skeletal and heart muscle, liver and the crystallin-producing cells in the lens. The CpG-rich RNA is transcribed in a developmental stage-specific rather than in a cell-specific manner. In contrast transcripts of DNA methyltransferase are found in dividing and quiescent cells. In situ hybridization with a probe of a RNA helicase which is also associated with the DNA demethylation complex shows a very similar localization in mitotically active tissues as the CpG-rich RNA. The content of 5-methylcytosine in individual cells was determined with a specific monoclonal antibody and cytometric analysis on tissue sections. The results indicate that proliferating cells have on the average 15% more methylated cytosines than non-dividing cells. This represents roughly 3x10(6) more methylation sites per haploid genome.

Animals↗
PubMed1999

Embryo-maternal interactions at the implantation site: a delicate equilibrium.

Blastocyst implantation and successful establishment of pregnancy require delicate interactions between the embryo and the maternal environment. During preimplantation, maternal/embryo communication is mediated by the trophectoderm. In the late luteal phase, physiological changes occur in the endometrium to allow blastocyst implantation. The "window of implantation" represents the period of maximum uterine receptivity for implantation. In response to signals from the embryo, pregnancy-specific proteins are released in maternal serum and a series of morphological, biochemical and immunological changes occur in the uterine environment. These systemic and local modifications can be considered to constitute "the maternal recognition of pregnancy". The human hemochorial placenta arises primarily through proliferation, migration and invasion of the endometrium and its vasculature by the embryonic trophoblast. The complex invasive processes accompanying implantation of the embryo are controlled at the embryo-maternal interface by factors from decidualized endometrium and the trophoblast itself. An inflammatory reaction and a proper maternal immune response allow survival and development of the feto-placental unit. In this review, we focus on interactions between trophoblast and uterine tissues and on cellular mechanisms and molecular signals involved in the closely regulated process of implantation.

Cytokines↗
PubMed1999

Identification and expression of Go1 and Go2 alpha-subunit transcripts in human myometrium in relation to pregnancy.

The 39-kDa Goalpha protein, the alpha subunit of a major heterotrimeric G protein of brain and neuroendocrine cells, was found to be present in human myometrium. Using three different antisera, we showed its strong expression in myometrium from pregnant patients as compared to nonpregnant ones. This is in agreement with the high expression level of its two isoforms (alphao1 and alphao2), previously described in late pregnancy. To better ascertain the nature of these immunoreactive isoforms, we investigated transcripts of the Goalpha gene in myometrium from pregnant and nonpregnant patients by reverse transcription-polymerase chain reaction (RT-PCR). In this tissue, the amplified cDNA product of a region common to both Go1alpha and Go2alpha mRNA variants was recognized as the Goalpha nucleotide sequence. Transcripts of Go1alpha and Go2alpha were identified by sequencing. A partial cDNA Go2alpha sequence was described, which differed from the Goalpha gene by two nucleotides in exon 8B. Levels of Go1alpha and Go2alpha transcripts analyzed by semi-quantitative RT-PCR were significantly higher in myometrium from pregnant than from nonpregnant patients. It is suggested that Goalpha gene expression in this tissue may contribute to modifications seen in the signaling pathways observed at the end of pregnancy.

Amino Acid Sequence↗
PubMed1999

Alterations of DNA methylation patterns in germ cells and Sertoli cells from developing mouse testis.

In situ alterations of DNA methylation were studied between 14 d postcoitum and 4 d postpartum in Sertoli cells and germ cells from mouse testis, using anti-5-methylcytosine antibodies. Compared to cultured fibroblasts, Sertoli cells display strongly methylated juxtacentromeric heterochromatin, but hypomethylated chromatids. Germ cells always possess hypomethylated heterochromatin, whereas their euchromatin passes from a demethylated to a strongly methylated status between days 16 and 17 postcoitum. This hypermethylation occurs in the absence of DNA replication, germ cells being blocked in the G(0)-G(1) phase from day 15 postcoitum to birth. The DNA hypermethylation of germ cells is maintained until birth and could be visualized on both chromatids of metaphase chromosomes at the first postpartum cell division. Subsequently, the DNA hypermethylation is lost semiconservatively, being replaced by a methylation pattern recalling the typical fibroblast pattern. These alterations of DNA methylation follow a strict chronology, are chromosome structure and cell-type dependent, and may underlie profound changes of genome function.

Animals↗
PubMed1998

Immune response to baculovirus expressed protein fragment amino acids 190-289 of respiratory syncytial virus (RSV) fusion protein.

At least two neutralizing epitopes have been identified in the amino acid (aa) sequence 190-289 of the RSV fusion protein. The authors expressed this region in insect cells (bF190-289) and compared the immune response to bF190-289 with that induced by baculovirus expressed full-length fusion protein (bF). As with bF, mice primed with bF190-289 produced exclusively antibodies of IgG1 isotype, generated neutralizing antibodies, reduced significantly the virus titer (about a half log10 reduction) after RSV challenge and induced a Helper T (Th) 2 cell response in mediastinal lymph node cells (MLNC) restimulated in vitro. Thus, the aa sequence 190-289 represents a major immunogenic region of the RSV fusion protein.

Amino Acid Sequence↗
PubMed1998

Modifications of CD8+ T cell function during in vivo memory or tolerance induction.

Naive monoclonal T cells specific for the male antigen can be stimulated in vivo to eliminate male cells and become memory cells or to permit survival of male cells and become tolerant. Memory cells responded to TCR ligation by cyclic oscillations of calcium levels and immediate secretion of very high levels of IL-2 and interferon-gamma. Tolerant cells did not proliferate in response to ionomycin and phorbol myristate acetate, failing to mobilize calcium to produce IL-2 or express IL-2R, but survived for long time periods in vivo and secreted IL-10. These results emphasize that tolerance is not an absence of all functional activity and may be associated with modifications of behavior conferring important regulatory functions on tolerant T cells.

Animals↗
PubMed1998

Prophylactic administration of a complementarity-determining region derived from a neutralizing monoclonal antibody is effective against respiratory syncytial virus infection in BALB/c mice.

Immunotherapy with antibodies against respiratory syncytial virus (RSV) is a treatment option given the absence of any vaccine or other available satisfactory treatment. We selected one of our monoclonal antibodies, RS-348, that is highly neutralizing. We showed that a single peptide (PEP3H) derived from complementarity-determining region 3 (CDR3) of its heavy chain was capable of neutralizing the virus in vitro. When intranasally administered 24 h before challenge, this peptide protected BALB/c mice against RSV lung infection. These results indicate that a single CDR can be effective against RSV infection.

Amino Acid Sequence↗
PubMed1998

Heparin-like structures on respiratory syncytial virus are involved in its infectivity in vitro.

Addition of heparin to the virus culture inhibited syncytial plaque formation due to respiratory syncytial virus (RSV). Moreover, pretreatment of the virus with heparinase or an inhibitor of heparin, protamine, greatly reduced virus infectivity. Two anti-heparan sulfate antibodies stained RSV-infected cells, but not noninfected cells, by immunofluorescence. One of the antibodies was capable of neutralizing RSV infection in vitro. These results prove that heparin-like structures identified on RSV play a major role in early stages of infection. The RSV G protein is the attachment protein. Both anti-heparan sulfate antibodies specifically bound to this protein. Enzymatic digestion of polysaccharides in the G protein reduced the binding, which indicates that heparin-like structures are on the G protein. Such oligosaccharides may therefore participate in the attachment of the virus.

Antibodies, Monoclonal↗
PubMed1997

Cross-reactive and group-specific immune responses to a neutralizing epitope of the human respiratory syncytial virus fusion protein.

Immune responses to a synthetic peptide corresponding to amino-acids 205-225 of the fusion protein from group B respiratory syncytial (RS) virus, were studied in mice and rabbits, and compared to a similar peptide from group A RS virus. Peptide 205-225 (B) was recognized by monoclonal antibody RS-348, and was immunogenic in both mice and rabbits, as was peptide 205-225 from the fusion protein of a group A strain. Peptide 205-225 (B) induced a proliferative T-cell response, demonstrating the existence of a T-cell epitope in this region of the fusion protein of group B viruses. Both peptides were able to induce a T-cell cross-reactive proliferation when mice were primed with either the homologous or the heterologous peptide. ELISA were performed using synthetic peptides or whole virus (from group A and B) as antigens. Mice anti-peptide sera recognized both homologous and heterologous peptides. A similar pattern was observed with RS virus strains. In indirect immunofluorescence assays, both anti-peptide rabbit sera recognized human nasal epithelial cells infected with A or B strains of RS virus. In contrast, while anti-peptide 205-225 rabbit serum from group A neutralized group A and B strains of RS virus, anti-peptide 205-225 rabbit serum from group B was unable to neutralize a group A virus, although it neutralized a group B strain. These results are similar to the immune response observed in children following primary RS virus infection.

Amino Acid Sequence↗
PubMed1997

AIDS-related primary brain lymphomas: histopathologic and immunohistochemical study of 51 cases. The French Study Group for HIV-Associated Tumors.

Fifty-one cases of acquired immunodeficiency syndrome (AIDS)-related primary brain lymphomas (AR-PBL) were investigated for clinical characteristics; human immunodeficiency virus (HIV)-associated disorders; histopathologic features; immunophenotype; Epstein-Barr virus (EBV) infection; and, when frozen tissue was available, oncogene rearrangements. AR-PBL occurred late in the course of AIDS and were usually associated with other systemic or cerebral disorders and with a low level of CD4 lymphocytes. All cases were high grade lymphomas according to the Working Formulation or updated Kiel classification, and often displayed a multifocal pattern. Thirty cases were classified as immunoblastic with plasmacytic differentiation, 18 cases were large cell lymphomas with an immunoblastic component or centroblastic polymorphic lymphomas, and 2 were small noncleaved non-Burkitt lymphomas (Working Formulation). This latter category is classified as Burkitt's-like lymphoma in the REAL nomenclature. One case could not be classified because of necrosis. AR-PBL showed a high level expression of activation and adhesion molecules. The presence of EBV was detected in most cases, and, when PCR was used, this was a constant finding. bcl-2 oncoprotein and latent membrane protein-1 (LMP-1) were strongly expressed. None of the tested cases expressed p53, or were rearranged for bcl-2 or c-myc oncogenes. This study confirms the immunophenotypic specificity of AR-PBL, which may reflect the special immune status of the brain.

Adult↗
PubMed1997

Value of a ligase chain reaction assay for detection of ganciclovir resistance-related mutation 594 in UL97 gene of human cytomegalovirus.

Human cytomegalovirus (HCMV) isolates resistant to ganciclovir were found in patients undergoing therapy. Therefore, we have developed a new specific and sensitive method--a ligase chain reaction (LCR) assay--for detection of frequently encountered 594 mutated codon in ganciclovir (GCV) resistant virus. Previous studies characterized an alanine to valine change on codon 594 in resistant strains. A novel substitution in 594, alanine to glycine, is described which is also capable of conferring ganciclovir resistance. LCR products were analyzed on polyacrylamide gel- and the mutant was detected using a non radioactive method. The LCR product detection was then adapted to a microtitre plate format with a colorimetric detection. This method allowed the distinction of mutated GCV-resistant strains from sensitive strains with a high sensitivity, and the detection of a low percentage of mutated DNA in virus load. This assay could be useful in following the evolution of mutated DNA compared to viral infection.

Alanine↗
PubMed1997

Endothelin-1 and ETA receptor expression in vascular smooth muscle cells from human placenta: a new ETA receptor messenger ribonucleic acid is generated by alternative splicing of exon 3.

Endothelin-1 (ET-1) is a potent vasoactive peptide in stem villi vessels, which are considered to be the major sites of placental vascular resistance. To investigate the influence of pregnancy-specific hormonal environment on ET and ET receptor (ET-R) expression, we first developed and characterized a culture of vascular smooth muscle cells from stem villi vessels. Secondly, we investigated whether the muscular layer of stem villi vessels could be a site of the ET expression described in the placenta, and we examined this expression in placental vascular smooth muscle cells (PVSMCs). Prepro-ET-1 and prepro-ET-3 messenger ribonucleic acid (mRNA) were identified in stem villi vessels, whereas only prepro-ET-1 mRNA was observed in PVSMCs. Third, with the goal of using PVSMCs as ET target cells, we characterized the ET-R expressed by these cells in comparison with the muscular layer of stem villi vessels. Whereas both ETA-R and ETB-R are present in stem villi vessels, we found that PVSMCs express exclusively ETA-R. In addition to the previously reported ETA-R spliced transcripts, we described a new ETA-R transcript, ETA-R delta 3, generated by exclusion of exon 3 in stem villi vessels and PVSMCs. Alternative splicing mechanisms of ETA-R mRNA could constitute a control of the abundance of active ETA-R in terms of contractility. PVSMCs will be a useful model to study the environmental stimuli involved in the regulation of ET and ET-R expression in the muscular layer of feto-placental vasculature.

Alternative Splicing↗
PubMed1997

Malignant melanoma and granulomatosis.

Sarcoidosis or granulomatous reactions have rarely been reported in association with malignant melanoma (MM). We describe seven patients who presented with both granulomatous disease and MM, and discuss the physiopathological and prognostic significance of this association. In three patients, the granulomatosis was diagnosed as true sarcoidosis and in one patient, as tumour-associated granuloma. In three cases, designated here as atypical tumour-associated granulomatoses, the presence of clear-cut pulmonary granulomatous nodules was typical neither for sarcoidosis nor for tumour-associated granuloma and was highly suggestive of melanoma metastases. Mediastinal lymphadenopathy was present in every patient. In all seven patients, the question of mediastinal or pulmonary involvement or relapse of the MM was raised, but could be confirmed in only one patient. MM can be associated with granulomatous disease. Knowledge of this association has implications in the management of patients with MM.

Adult↗
PubMed1997

Effects of trace element and/or vitamin supplementation on vitamin and mineral status, free radical metabolism and immunological markers in elderly long term-hospitalized subjects. Geriatric Network MIN. VIT. AOX.

A randomized double-blind trial was performed in order to assess the efficacity of differing combinations of antioxidant nutrients on biochemical parameters of vitamin and trace element status, immunological parameters and free radical metabolism in elderly long term hospitalized subjects. A total of 756 institutionalized elderly subjects were recruited in 26 nursing homes in different areas of France. Four groups were constituted, receiving daily, for 1 year, either vitamins (beta-carotene, 6 mg; vitamin C, 120 mg; and vitamin E, 15 mg), trace elements (zinc, 20 mg and selenium, 100 micrograms), trace elements associated with vitamins, or a placebo. Biochemical indicators of trace elements and vitamin status and free radical parameters were measured before and after 6 months and 1 year of supplementation. Some immunological markers were investigated initially and after 6 months of supplementation on a subsample of 134 subjects. Mean plasma levels of alpha-tocopherol, gamma-tocopherol, vitamin C, alpha-carotene, beta-carotene and copper increased significantly after 6 months of supplementation in groups receiving vitamins alone or associated with trace elements. Serum selenium concentrations were significantly increased at 6 months of supplementation, and serum zinc only after one year in the trace element groups. Serum lycopene levels were significantly decreased by trace element supplementation. A significant increase in Se-glutathione peroxidase (GPx) levels was observed in groups receiving trace elements alone or associated with vitamins. No effect was noted on superoxide dismutase (SOD) activity or TBARs production. No effect of supplementation was found for in vitro lymphocyte proliferative responses or most lymphocyte subsets, except for a significantly lower percentage of CD2 subsets observed in groups receiving mineral supplementation either alone or associated with vitamins. A significant difference in CD19 subsets was found in groups receiving trace elements. Mean IL-1 production was significantly higher after 6 months of supplementation in the vitamin groups.

Aged↗