Biomedical subjects

M Billard

Publications and source records attributed to M Billard.

At least 19 recordsLinked to original sources

PubMed2005

[Local guidelines and quality of antibiotic treatment in urinary tract infections: a clinical audit in two departments of a university hospital].

AIM: To assess the effect of local guidelines implemented at the Nantes University Hospital regarding antibiotic therapy for urinary tract infections. DESIGN: Before/after study of one medical ward and one urologic surgery ward. Quality was measured by two principal criteria: compliance with guidelines and medical justification in the specific clinical situation. Both criteria considered simultaneously the choice of drug, dose and duration of treatment. Deviations from the guidelines were described. RESULTS: 1086 UTI cases were identified over two 12-month periods, before and after the dissemination of guidelines (for prostatitis, pyelonephritis, indwelling catheter-associated UTIs, and other undefined UTIs). The guidelines were applicable in 313 (30%) cases. Overall, after implementation of the guidelines, the percentage of justified prescriptions did not change significantly (41.8% compared with 38.7%, p=0.299), but the percentage of correct (conforming) prescriptions fell (from 30.4% to 15.7%, p=0.0022). The percentages of correct and justified prescriptions differed in the medical (respectively 45.0% and 46.6%,) and surgical units (13.1% and 36.5%). CONCLUSIONS: Issuing guidelines does not necessarily improve the quality of antibiotic therapy for UTIs in hospitals.

Anti-Bacterial Agents↗

PubMed2005

[Adequate prescription of antibiotic therapy for urinary tract infections in hospital: identifying and correcting non-observance of guidelines].

OBJECTIVE: We analyzed the adequacy of antibiotic therapy prescribed for urinary tract infections (UTI): prostatitis, pyelonephritis, indwelling catheter-associated UTIs, or other undefined UTIs. DESIGN: The adequacy of prescriptions to local guidelines was assessed retrospectively in two wards (Internal Medicine and Surgical Urology) of the Nantes University Hospital. The principal criteria involved simultaneously: choice of the molecule, dose, and treatment duration. Non-observances of guidelines were major (non-adequacy of the molecule, prescription of a non-active molecule according to in vitro susceptibility tests, non-appropriate treatment abstention), or minor (non-justified treatment, non-justified bitherapy, no prescription of bitherapy when requested, no treatment adaptation when requested, too short or too long treatment length, dosage mistakes). RESULTS: One thousand eighty-six infections were collected over a 24-month period. The overall rate of adequate prescriptions was 40.1% (46.6% in Internal Medicine and 36.5% in Surgical Urology). In Internal Medicine (226 non observance among 389 prescriptions), the ratio of major non-observance of guidelines was 9.8%. Among them, 44.7% were non-appropriate treatment abstentions. In Surgical Urology (539 non observance out of 695 prescriptions), non-observance related to treatment length were the most frequent. The ratio of major non-observance was 19.9%. Among them, non-adequacy of the molecule reached 60.7%. Non-justified treatment and non-appropriate bitherapies were frequent. CONCLUSIONS: For both units, indwelling catheter-related UTIs and other UTIs accounted for more than 50% of the infections although not detailed in the local guidelines. Identifying and analyzing Non observance may lead to targeted correcting actions to improve prescription quality.

Adult↗

PubMed2001

The major CD9 and CD81 molecular partner. Identification and characterization of the complexes.

By associating with specific partner molecules and with each other, the tetraspanins are thought to assemble multimolecular complexes that may be especially relevant with respect to metastasis. We have previously identified a 135-kDa molecule (CD9P-1) as a major molecular partner of CD9 in cancer cell lines. This molecule was identified, after immunoaffinity purification and mass spectrometry analysis, as the protein encoded by the KIAA1436 gene and the human ortholog of a rat protein known as FPRP. Cross-linking experiments detected a complex of the size of CD9 plus CD9P-1, showing that these glycoproteins directly associate with each other, probably in the absence of any other molecule. The use of chimeric CD9/CD82 molecules revealed the role of the second half of CD9, comprising the large extracellular loop and the fourth transmembrane domain. CD9P-1 was also shown to form separate complexes with CD81 and with an unidentified 175-kDa molecule. It also associated with other tetraspanins under conditions maintaining tetraspanin/tetraspanin interactions. The identification of a protein strongly linked to the tetraspanin web and the production of a specific monoclonal antibody will help to further characterize the role of this "web" under physiological and pathological conditions.

Animals↗

PubMed2000

CD46 (membrane cofactor protein) associates with multiple beta1 integrins and tetraspans.

The tetraspans associate with a large number of surface molecules, including a subset of beta1 integrins and, indirectly through CD19, with the complement receptor CD21. To further characterize the tetraspan complexes we have raised and selected monoclonal antibodies (mAb) for their ability to immunoprecipitate a molecule associated with CD9. A unique mAb was identified which recognizes the complement regulator CD46 (membrane cofactor protein). CD46 associated in part with several tetranspans and with all beta1 integrins that were tested (CD29/CD49a, CD29/CD49b, CD29/CD49c, CD29/CD49e, CD29/CD49f) but not with beta4 integrins. These data, together with cross-linking experiments showing the existence in living cells of CD46/integrin complexes, suggest that CD46 associates directly with beta1 integrins and indirectly with tetraspans. CD46 also acts as a receptor for measles virus; however, mAb to various integrins and tetraspans did not modify the virus fusion entry step.

Animals↗

PubMed1999

Selective tetraspan-integrin complexes (CD81/alpha4beta1, CD151/alpha3beta1, CD151/alpha6beta1) under conditions disrupting tetraspan interactions.

The tetraspans are molecules with four transmembrane domains which are engaged in multimolecular complexes (the tetraspan web) containing a subset of beta1 integrins (in particular alpha3beta1, alpha4beta1 and alpha6beta1), MHC antigens and several unidentified molecules. The molecules associated with tetraspans are readily detected after immunoprecipitation performed in mild detergents such as Brij 97 or CHAPS. In this study we show that another classical mild detergent, digitonin, dissociated most of these associated molecules, including integrins, from the tetraspans CD9, CD37, CD53, CD63, CD82, Co-029, Talla-1 and NAG-2. In contrast, reciprocal immunoprecipitations from various cell lines demonstrated that two other tetraspans, CD81 and CD151, formed complexes with integrins not disrupted by digitonin. These complexes were CD81/alpha4beta1, CD151/alpha3beta1 and CD151/alpha6beta1. Furthermore, a new anti-CD151 monoclonal antibody (mAb), TS151r, was shown to have a restricted pattern of expression, inversely related to the sum of the levels of expression of alpha6beta1 and alpha3beta1. This mAb was unable to co-precipitate integrins in digitonin, suggesting that its epitope is blocked by the association with integrins. Indeed, the binding of TS151r to the cell surface was quantitatively diminished following alpha3beta1 overexpression. Altogether, these data suggest that, among tetraspans, CD81 interacts directly with the integrin alpha4beta1, and CD151 interacts directly with integrins alpha3beta1 and alpha6beta1. Because all tetraspan-tetraspan associations are disrupted by digitonin, it is likely that the other tetraspans interact indirectly with integrins, through interactions with CD81 or CD151.

Animals↗

PubMed1999

Are prescribed medications effective in the treatment of insomnia complaints?

Although frequently investigated in the general population, the epidemiology of insomnia complaints and their treatment have received little attention in general practice. This study recruited patients > or =15 years of age, consecutively, from 127 general practitioners in France. The physicians collected data from 11,810 of their patients, of whom 55.5% were women. Insomnia complaints were reported by 26.2% (25.4% to 27%) of the sample and use of sleep-promoting medication by 10.1% (9.7% to 10.7%). About 47% of the prescribed drugs used were anxiolytics and 45% hypnotics. Most consumers took sleep-enhancing drugs on a daily and long-term basis and most reported that the medication improved their quality of sleep. However, few distinctions emerged between elderly drug-taking insomniacs and elderly nontreated insomniacs with respect to the various dimensions of sleep. Results underscore the persistent general tendency among French general practitioners to overprescribe anxiolytics for the treatment of insomnia complaints and that they do so on a long-term basis, despite the findings of numerous studies showing that benzodiazepines are ineffective in the treatment of sleep complaints over the long term.

Adolescent↗

PubMed1998

CD19 is linked to the integrin-associated tetraspans CD9, CD81, and CD82.

The CD19-CD21-CD81 complex regulates signal transduction events critical for B lymphocyte development and humoral immunity. CD81, a molecule with 4 transmembrane domains, member of the tetraspan superfamily, is engaged, together with other tetraspans such as CD9, CD53, CD63, and CD82, in multimolecular complexes containing beta1 integrins and major histocompatibility complex antigens. Here we demonstrate that two other tetraspans, CD82 and the early B cell marker CD9, are coimmunoprecipitated with CD19 from Brij97 lysates of B cell lines. Moreover, CD9 was coprecipitated from lysates of purified CD10(+) early B cells. These associations were confirmed by the cocapping of CD19 with CD9 or CD82. The CD9/CD19 association was disrupted in the presence of digitonin, contrary to the CD81/CD19 association, indicating that CD9 and CD81 interact with CD19 in different ways. The CD9/CD81 association is also disrupted in the presence of digitonin, suggesting that CD9 associates with CD19 only through CD81. To characterize the regions involved in the CD81/CD19 association, two reciprocal CD9/CD81 chimeric molecules were tested for the association with CD19, but none of them could be coprecipitated with CD19 in digitonin, indicating that the domain of CD81 responsible for its association with CD19 is complex. Finally, engagement of CD9 could induce the tyrosine phosphorylation of different proteins, including CD19 itself, suggesting that the CD9/CD19 association is functionally relevant. Thus, a physical and functional link is formed between the CD19-CD21-CD81 complex and the integrin-tetraspan complexes, which is dynamically modulated in the process of B cell differentiation.

Animals↗

PubMed1997

Functional analysis of four tetraspans, CD9, CD53, CD81, and CD82, suggests a common role in costimulation, cell adhesion, and migration: only CD9 upregulates HB-EGF activity.

Molecules of the tetraspan superfamily are engaged in multimolecular complexes containing other proteins such as beta 1 integrins and MHC antigens. Although their functions are not clear, they have been suggested to play a role in cell adhesion and migration, signal transduction, and costimulation. We have in this paper directly compared the functional properties of four tetraspans, CD9, CD53, CD81, and CD82. mAbs to any of these molecules were able to deliver a costimulatory signal for CD3-mediated activation of the T cell line Jurkat. CD82 mAbs were the most efficient in triggering this effect. Moreover, engagement of CD9, CD81, and CD82 induced the homotypic aggregation of the megakaryocytic cell line HEL, and inhibited the migration of this cell line. Similar results were obtained with the preB cell line NALM-6 using the CD9 and CD81 mAbs. The CD81 mAb 5A6 produced the strongest effects. Therefore, the tetraspans are recognized by mAbs which produce similar effects on the same cell lines. This is consistent with the tetraspans being included in large molecular complexes and possibly forming a tetraspan network (the tetraspan web). We also demonstrate that the tetraspans are likely to keep specific functional properties inside this network. Indeed, we have demonstrated that the human CD9 is able, like the monkey molecule, to upregulate the activity of the transmembrane precursor of heparin-binding EGF as a receptor for the diphtheria toxin when cotransfected in murine LM cells. Neither CD81, nor CD82 had such activity. By using chimeric CD9/CD81 molecules we demonstrate that this activity requires the second half of CD9, which contains the large extracellular loop, the fourth transmembrane region, and the last short cytoplasmic domain.

Animals↗

PubMed1997

CD9, but not other tetraspans, associates with the beta1 integrin precursor.

The molecules of the tetraspan superfamily have two unequal extracellular domains separated by four transmembrane (TM) domains. These molecules are associated on the cell surface with each other and with other partner molecules, in particular beta1 integrins. We now show that CD9 associates with the precursor of the beta1 integrin (pre beta1). This association is detected as early as 15 min after metabolic labeling, and the use of Brefeldin A demonstrates that it does not require Golgi modifications of either CD9 or integrin beta1. The specificity of this interaction is demonstrated by the fact that other tetraspans, CD63, CD81, and CD82, do not associate with pre beta1, and CD9 does not associate with immature human histocompatibility leukocyte antigen class I. In order to localize the region of CD9 responsible for the association with the beta1 integrin, we have generated two reciprocal chimeric CD9/CD82 molecules with the junction localized just after the third TM region. The large extracellular loop of CD9 or the fourth TM domain, or both, appear to be sufficient to mediate an association with the mature integrin with a high efficiency, compared to CD82. By contrast, association with pre beta1 requires at least two regions of the molecule. Mutation of CD9 at the consensus site of the tetraspan superfamily, localized between the second and the third TM domain, did not impair the co-precipitation of pre beta1. Finally, because pre beta1 associates with calnexin, we have investigated a possible association of CD9 with this chaperone molecule. CD9 associates with calnexin independently of its association with the beta1 integrin, suggesting that calnexin could be involved in the processing of CD9.

Animals↗

PubMed1996

CD9, CD63, CD81, and CD82 are components of a surface tetraspan network connected to HLA-DR and VLA integrins.

CD9, CD63, CD81, and CD82 are glycoproteins of unknown function which belong to the tetraspan superfamily. These molecules have short cytoplasmic sequences, four transmembrane domains and two unequal extracellular regions. Here, we show that these molecules are associated with each other on cell surface and with other glycoproteins such as very late antigen (VLA) integrins and HLA-DR antigens. Moreover, the VLA integrins and HLA-DR antigens were also found to be associated. The interactions of these molecules were analyzed by transfection experiments. It is demonstrated that overexpression of CD9 antigen in Raji cells leads to a lower efficiency of precipitation of CD81 and CD82, suggesting a direct interaction between these molecules. In these cells, the co-precipitation of CD81 and CD82 was not modified, suggesting that these tetraspans did not compete for association. However, in COS-7 cells, transfection of both CD81 and CD82 led to a marked reduction of the number of CD9/CD81 or CD9/CD82 complexes compared to single-transfected cells, and this was associated with the appearance of CD81/CD82 complexes. Therefore, in this cellular system, CD9 competes with CD81 and CD82 for association with the other tetraspan proteins. Finally, the tetraspans do not compete for the association with integrins or HLA-DR. Indeed, when CD9 was expressed in Raji cells, it was incorporated into the pre-existing complexes of these molecules with CD81 and CD82. These data suggest the existence of a tetraspan network which, by connecting several molecules, may organize the positioning of cell surface proteins and play a role in signal transduction, cell adhesion, and motility.

Animals↗

PubMed1995

Characterization of the 5' region of the CD10/neutral endopeptidase 24.11 gene.

We have characterized the 5' region of the CALLA/CD10 gene which has been shown to be identical to the membrane-associated enzyme neutral endopeptidase 24.11 (NEP). There is no CAAT or TATA box in the 5' flanking region, upstream of exon 1, but a GC rich region with several Sp1 binding sites. We have detected several putative initiation transcription sites by primer extension and by nuclease S1 analysis. Moreover by reverse transcriptase-polymerase chain reaction, we demonstrated the existence of a new exon: exon 1bis. This exon can be alternatively spliced as has already been described for exon 1 and exon 2.

Base Sequence↗

PubMed1994

CD9 antigen is an accessory subunit of the VLA integrin complexes.

The CD9 antigen is a cell surface glycoprotein of unknown function which belongs to the tetraspans family. We demonstrate here, by precipitation, Western blotting and co-capping experiments, that this molecule is associated with a large fraction of beta 1 integrins in two cell lines, the pre-B cell line NALM-6 and the megakaryocytic cell line HEL. In HEL cells, CD9 antigen is only associated with VLA-4. In contrast, in NALM-6 cells, CD9 antigen is associated with both VLA-4 and VLA-5. On the other hand, only the beta 1 chain is co-precipitated with the CD9 antigen in transfected L cells. These data show that the CD9 antigen is associated with the beta 1 chain rather than with a particular integrin. CD9 monoclonal antibodies (mAb) did not modify the binding of HEL and NALM-6 cells to fibronectin, laminin or collagen. The association of CD9 antigen to VLA integrins is strengthened by the fact that both CD9 and anti-VLA mAb induce aggregation of the two cell lines and inhibit their migration in Transwell chambers. Because the aggregating effect, but not the inhibition of migration, is observed in CEM or CD9-transfected CEM cells, these two effects are likely to be mediated by different mechanisms.

Amino Acid Sequence↗

PubMed1994

Evaluation of canines for accelerant detection at fire scenes.

In recent years, canines have been successfully used in fire investigations to detect accelerant residues. We set out to determine the lower limits at which canines could reliably detect potential accelerants. Measured amounts ranging from 10 to as little as 0.01 microL of gasoline, kerosene, and isopars were applied to preselected spots along a continuous sample path (25 to 40 feet long) made out of burned and unburned wood or nylon carpeting strips at the testing site. Two canines were led past this sample path at least three times and positive alerts and negative responses were recorded. Both dogs were generally able to alert on spots containing 0.01 microL or more of all three accelerants, at or beyond the purge and trap recovery and gas chromatographic detection method employed. The canines did alert occasionally on background, especially that containing traces of styrene residues, either purposely added in specific amounts or formed upon partial pyrolysis of carpeting material. The dogs alerted on sites containing 0.1 to 1.0 microL of freshly applied gasoline or kerosene placed at actual heavily damaged fire scenes, but were less successful on samples containing smaller amounts.

Animals↗

PubMed1994

A new cytokine (IK) down-regulating HLA class II: monoclonal antibodies, cloning and chromosome localization.

The role of HLA class II Antigens in the control of the immune response is determined not only by the genetic polymorphism of these molecules, but also by their density on the cell surface. It is therefore essential to identify the signals that modulate HLA Class II gene activity in normal and neoplastic cells. We have purified a cytokine (IK factor, 19 kDa) secreted by the leukemic cell line K562 and several cancer cells, which inhibits HLA Class II antigen induction by IFN-gamma. We produced specific mAbs which antagonize the biological effect of IK in colon carcinoma Colo 205 cells induced to express HLA-DR molecules by IFN-gamma. Moreover, in Colo 205, HLA-DR can also be induced by the protein synthesis inhibitor Cycloheximide (0.1 micrograms ml-1); and addition of IK factor almost completely abolishes HLA class II expression. We have also performed the cloning and the sequencing of a specific cDNA. This probe recognizes a 2.1 Kb mRNA in different cell types. The nucleotide sequence exhibits no homologies with known cytokines. IK gene localization shows that it maps on chromosome 2p15-p14. The transient transfection of the cDNA in COS cells induces the secretion of a biologically active 19 kDa protein which is recognized in Western blot by 1C5B11 blocking mAb. This paper reports the characterization of a new cytokine down-regulating HLA class II Antigens, whose analysis will help to better understand HLA class II gene regulation and the mechanism of escape from immunorecognition in cancer cells.

Amino Acid Sequence↗

PubMed1993

Molecular cloning of the mouse equivalent of CD9 antigen.

The CD9 antigen was originally described as a 24 kDa molecule present on B lineage-derived acute lymphoblastic leukemia cells and developing B-lymphocytes. However, platelets express a large amount of CD9 antigen and can be activated by CD9 antibodies. We report here the cloning and sequencing of a cDNA coding for the mouse CD9 antigen. There is 89% homology at amino acid level between the human and mouse CD9 molecules. Most of the differences (19 out of 24) are located in the large putative extracellular domain encoded by exons 5 and 6. CD9 antigen belongs to a new cell surface protein family which includes TAPA1 and the platelet activation antigen CD63. These proteins share common structural features with the CD9 antigen and a similar distribution of the evolutionarily variable region.

Amino Acid Sequence↗

PubMed1993

Organization of the human CD9 gene.

The CD9 antigen was originally described as a 24-kDa molecule present on B-lineage-derived acute lymphoblastic leukemia cells and developing B lymphocytes. Platelets also express a large amount of CD9 antigen and can be activated by CD9 antibodies. We report here the structure of the CD9 gene, which is composed of 8 exons spanning more than 20 kb. There is no TATA or CAAT box in the 5'-flanking domain of the CD9 gene, but a 120-bp region extremely rich in C and G (88%) contains several Sp 1 binding sites and a consensus site for the binding of zinc-finger proteins of the Krox/EGR family. The CD9 antigen belongs to a new cell surface protein family. The organization of its gene closely resembles the organization of the genes for two other members of this protein family, TAPA1 and CD63, which share with CD9 respectively 45 and 25% identity at the amino acid level.

Amino Acid Sequence↗

PubMed1991

Molecular cloning of the CD9 antigen. A new family of cell surface proteins.

The CD9 antigen was described originally as a 24-kDa surface protein of non-T acute lymphoblastic leukemia cells and developing B-lymphocytes. It is also strongly expressed on platelets, among other cells, where it shows the property of mediating platelet activation and aggregation upon binding with mAbs. The primary structure has been elucidated by cloning the cDNA from a lambda gt11 expression vector library constructed with megakaryocytic mRNA. Monoclonal antibodies were used as probes with an APAAP amplification of the signal. The 5' region was further cloned in a lambda gt10 randomly primed cDNA library. The initiation codon was immediately followed by a sequence coding for the tetrapeptide corresponding to the NH2-terminal sequence identified in a microsequencing procedure. Only one species of mRNA was found with an estimated size of 1.4 kilobase. CD9 antigen appears to be a 227-amino acid molecule with four hydrophobic domains and one N-glycosylation site. Sequence and structural comparisons showed extensive similarity of the CD9 antigen with a 237-amino acid molecule described previously as the human melanoma-associated antigen ME491 and a Schistosoma mansoni membrane protein of 218 amino acids. These three proteins identify a new family of cell-surface proteins.

Amino Acid Sequence↗

PubMed1989

Acquisition of tumorigenic potential in the human myoepithelial HBL100 cell line is associated with decreased expression of HLA class I, class II and integrin beta 3 and increased expression of c-myc.

The human breast cell line HBL100 acquires the capacity to invade normal tissues and to replace them by proliferation in vitro only at high passage levels (HPL). These cells therefore are a useful model for studying tumor progression in vitro. We have analyzed the expression of cell-surface markers supposed to be involved in the control of the neoplastic process. Quantitative flow cytometry has revealed that: (1) spontaneous expression of HLA class-I antigens strongly decreases in HPL HBL100 cells vs. LPL cells, which parallels amplification and over-expression of c-myc oncogene; (2) HLA DR antigens can be induced by IFN-gamma in LPL but not in HPL HBL100 cells; (3) HBL100 cells secrete a soluble protein factor which specifically inhibits HLA DR induction by IFN-gamma even in heterologous cell systems; (4) 50% of LPL HBL100 cells express integrin beta 3, whereas HPL HBL100 cells lose this antigen; (5) this cell line is myoepithelial in origin, since 100% of HBL100 cells exhibit the CD10 antigen. Our data stress a role of HLA antigens, of some integrins and of c-myc in the acquisition of malignant potential by myoepithelial mammary cells of the HBL100 line.

Biomarkers, Tumor↗