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Biomedical subjects

F Blanchard

Publications and source records attributed to F Blanchard.

At least 37 records · Page 2Linked to original sources
PubMed2002

Health-care use by rheumatoid arthritis patients compared with non-arthritic subjects.

OBJECTIVE: To compare the use of health-care by rheumatoid arthritis (RA) patients and non-arthritic subjects (NA) and to look for factors determining their patterns of health-care use. METHODS: A multicentre cohort of 223 RA and 446 NA subjects matched for age, gender, period of data collection and residence were questioned about their use of health-care services. Patterns of health-care use were identified by principal components analysis. Factors determining the use of health-care services were assessed by multiple linear and logistic regression analysis. RESULTS: The proportions of RA subjects who declared having had at least one contact with the health-care system in the previous 12 months and in the previous 4 weeks were higher than those for NA subjects for all health and social professionals except dentists and homeopaths. Types of health-care use explored were hospital, prescribed, general ambulatory and specialized ambulatory care. Factors determining health-care use were disease status, administrative area, employment status and age. CONCLUSIONS: RA subjects use health-care services more widely than NA subjects. Variation in recourse behaviour is related to differences within administrative areas.

Ambulatory Care↗
PubMed2001

Identification of agonistic and antagonistic antibodies against gp190, the leukemia inhibitory factor receptor, reveals distinct roles for its two cytokine-binding domains.

The receptor for the cytokine leukemia inhibitory factor (LIF) associates the low affinity binding component gp190 and the high affinity converter gp130, both of which are members of the family of hematopoietic receptors characterized by the cytokine receptor homology (CRH) domain. The gp190 is among the very few members of this large family to contain two CRH domains. The membrane-distal one (herein called D1) is followed by an Ig-like domain, a membrane-proximal CRH domain called D2, and three type III fibronectin repeats. We raised a series of monoclonal antibodies specific for the human gp190. Among them was the blocking antibody 1C7, which was directed against the D1Ig region and which impaired the binding of LIF to gp190. Another blocking antibody, called 12D3, was directed against domain D2 and interfered with the reconstitution of the high affinity receptor complex, independently of the interaction between LIF and gp190. The blocking effect of these two antibodies concerned four cytokines known to use gp190, i.e. LIF, oncostatin M, ciliary neurotrophic factor, and cardiotrophin-1. Among 23 antibodies tested alone or in combination (two anti-D2 and 21 anti-D1Ig), only the mixture of the two anti-D2 antibodies displayed agonistic activity in the absence of the cytokine. Taken together, these results demonstrate that the two CRH domains of gp190 play different functions in ligand binding and receptor activation.

Animals↗
PubMed2001

Oncostatin M regulates the synthesis and turnover of gp130, leukemia inhibitory factor receptor alpha, and oncostatin M receptor beta by distinct mechanisms.

The cytokine receptor subunits gp130, leukemia inhibitory factor receptor alpha (LIFRalpha), and oncostatin M receptor beta (OSMRbeta) transduce OSM signals that regulate gene expression and cell proliferation. After ligand binding and activation of the Janus protein-tyrosine kinase/STAT and mitogen-activated protein kinase signal transduction pathways, negative feedback processes are recruited. These processes attenuate receptor action by suppression of cytokine signaling and by down-regulation of receptor protein expression. This study demonstrates that in human fibroblasts or epithelial cells, OSM first decreases the level of gp130, LIFRalpha, and OSMRbeta by ligand-induced receptor degradation and then increases the level of the receptors by enhanced synthesis. The transcriptional induction of gp130 gene by OSM involves STAT3. Various cell lines expressing receptor subunits to the different interleukin-6 class cytokines revealed that only LIFRalpha degradation is promoted by activated ERK and that degradation of gp130, OSMRbeta, and a fraction of LIFRalpha involves mechanisms that are separate from signal transduction. These mechanisms include ligand-mediated dimerization, internalization, and endosomal/lysosomal degradation. Proteosomal degradation appears to involve a fraction of receptor subunit proteins that are ubiquitinated independently of ligand binding.

3T3 Cells↗
PubMed2001

Measuring general health status in dementia: practical and methodological issues in using the SF-36.

The objective of this study was to examine the measurement properties of the Medical Outcomes Study (MOS) 36-Item Short-Form health survey (SF-36) in a representative sample of dementia patients. A total of 138 subjects with dementia were evaluated with the SF-36. They were recruited from 16 centers, including 7 university hospital centers. Dementia severity, demographic variables, co-morbidity and functional limitations were also measured. The measurements obtained were compared by source of information (patient, family proxy, and care provider proxy). Thirteen patients refused to complete this questionnaire. Help from the interviewer was necessary in 72.8% of the cases. The average completion time was 18.8 minutes. Missing data exist in only 5.6% of the cases on average, except among patients with severe dementia (Mini Mental State Examination <10). With regard to reliability, internal consistency was acceptable to good; Cronbach's a ranged from a low of 0.59 to a high of 0.92 across subscales (median 0.75). Test-retest intraclass correlation coefficients were moderate to good (range 0.51-0.81) except for Role emotional (0.17), Bodily pain (0.49) and Mental health (0.45). For patients with MMSE > or = 15, test-retest coefficients were better (range 0.53-0.90). Intraclass correlation coefficient suggests that proxies are a poor substitute for obtaining a patient's perspective of his/her health status. In conclusion, the SF-36 is unsuitable for severe dementia, because severity of disease mainly affected the feasibility, acceptability, and reproducibility of the instrument. This study, however, confirms that it is possible to question subjects with mild to moderate dementia on their health status.

Aged↗
PubMed2001

The effect of supplementation by different nitrogen sources on the production of lactic acid from date juice by Lactobacillus casei subsp. rhamnosus.

Production of lactic acid from date juice by fermentation has been studied using Lactobacillus casei subsp. rhamnosus as the producer organism. The optimum substrate concentration, expressed in its glucose content, was 60 g l(-1). Various nitrogen sources were compared with yeast extract in terms of their efficiency for lactic acid production. None of these nitrogen sources gave lactic acid concentrations as high as that obtained with yeast extract. As yeast extract supplementation was not economically attractive, different proportions of (NH4)2SO4 and yeast extract were used. When the elemental nitrogen ratio of(NH4)2SO4 to yeast extract was 4:1, the substrate use and efficiency of lactic acid production were the same as in date juice supplemented with 20 g l(-1) yeast extract (0:5).

Ammonium Sulfate↗
PubMed2001

Agreement between patients' and proxies' reports of quality of life in Alzheimer's disease.

Agreement between self reports and proxy reports of health-related quality of life (H RQoL) was examined in a sample of 76 patients with mild to moderate Alzheimer's disease and their proxies. Patients and proxies completed an '17-item Duke health profile'. The items were rephrased for the proxy. The proportion of exact agreement between patients and proxies on the 17 items ranged from 26.3 to 52.6%. Results reveal poor to moderate agreement (intraclass correlation coefficients (ICCs) from 0.00 to 0.61 for 10 subscales) between patients' and proxies' reports. Agreement was higher for measures of function that are directly observable (physical health, disability) and relatively poor for more subjective measures. Proxy reliability varied according to the relationship of the proxy to the index subject. Spouses and nurses agreed more closely with index subjects than did children or nurses' aides. Agreement decreased with increasing severity of dementia. Statistically significant differences in mean scores were noted for several dimensions, with proxies tending to rate the patients as having a lower quality of life than the patients themselves. This study indicates the importance of considering the information source of a patient's HRQoL. However, assessments by proxies should be used with caution.

Aged↗
PubMed2000

Stimulation of leukemia inhibitory factor receptor degradation by extracellular signal-regulated kinase.

Leukemia inhibitory factor (LIF) signals via the heterodimeric receptor complex comprising the LIF receptor alpha subunit (LIFRalpha) and the common signal transducing subunit for interleukin-6 cytokine receptors, gp130. This study demonstrates that in different cell types, the level of LIFRalpha decreases during treatment with LIF or the closely related cytokine oncostatin M (OSM). Moreover, insulin and epidermal growth factor induce a similar LIFRalpha down-regulation. The regulated loss of LIFRalpha is specific since neither gp130 nor OSM receptor beta shows a comparable change in turnover. LIFRalpha down-regulation correlates with reduced cell responsiveness to LIF. Using protein kinase inhibitors and point mutations in LIFRalpha, we demonstrate that LIFRalpha down-regulation depends on activation of extracellular signal-regulated kinase 1/2 and phosphorylation of the cytoplasmic domain of LIFRalpha at serine 185. This modification appears to promote the endosomal/lysosomal pathway of the LIFRalpha. These results suggest that extracellular signal-regulated kinase-activating factors like OSM and growth factors have the potential to lower specifically LIF responsiveness in vivo by regulating LIFRalpha half-life.

3T3 Cells↗
PubMed2000

Receptor subunit-specific action of oncostatin M in hepatic cells and its modulation by leukemia inhibitory factor.

The related cytokines, interleukin-6 (IL-6), oncostatin M (OSM), and leukemia inhibitory factor (LIF) direct the formation of specific heteromeric receptor complexes to achieve signaling. Each complex includes the common signal-transducing subunit gp130. OSM and LIF also recruit the signaling competent, but structurally distinct OSMRbeta and LIFRalpha subunits, respectively. To test the hypothesis that the particularly prominent cell regulation by OSM is due to signals contributed by OSMRbeta, we introduced stable expression of human or mouse OSMRbeta in rat hepatoma cells which have endogenous receptors for IL-6 and LIF, but not OSM. Both mouse and human OSM engaged gp130 with their respective OSMRbeta subunits, but only human OSM also acted through LIFR. Signaling by OSMRbeta-containing receptors was characterized by highest activation of STAT5 and ERK, recruitment of the insulin receptor substrate and Jun-N-terminal kinase pathways, and induction of a characteristic pattern of acute phase proteins. Since LIF together with LIFRalpha appear to form a more stable complex with gp130 than OSM with gp130 and OSMRbeta, co-activation of LIFR and OSMR resulted in a predominant LIF-like response. These results suggest that signaling by IL-6 cytokines is not identical, and that a hierarchical order of cytokine receptor action exists in which LIFR ranks as dominant member.

Acute-Phase Proteins↗
PubMed2000

[Diagnosis of malnutrition in the elderly by dual energy absorptiometry].

OBJECTIVES: Denutrition is a frequent condition in elderly persons and may have major consequences. A noninvasive investigation, whole body dual energy X-ray absorptiometry, should allow, by direct measurement of body composition, early and reliable diagnosis of denutrition. This study was conducted to elaborate a diagnostic tool using this exam and to test its validity. PATIENTS AND METHODS: A global index of denutrition was proposed combining anthropometric, biological criteria, and the Mini Nutritional Assessment scale. Two agreement analyses were made between classical diagnostic criteria of nutritional status and body fat and fat free mass assessed by anthropometry and absorptiometry. An association between nutritional status and body absorptiometric composition were studied with univariate analysis followed by a multivariate logistic regression model. This model allowed an elaboration of a nutritional absorptiometric index (NAI). RESULTS: One hundred one elderly subjects were included. Twenty-three were considered to be in a state of denutrition. Agreement was poor between anthropometric and biological diagnostic criteria of denutrition. It was good between the different masses assess by anthropometry and absorptiometry. Subjects in a state of denutrition had significantly lower body fat and lower fat free mass. The fat free mass index (fat free mass divided by the square height) and body fat were entered into a logistic model and composed the NAI, which showed good diagnostic validity in terms of specificity and sensitivity. DISCUSSION: Absorptiometry appears to be a simple reliable diagnostic tool for assessing denutrition in elderly persons in routine practice. Further studies are required and should lead to a confirmation of the interest of these absorptiometric indexes.

Absorptiometry, Photon↗
PubMed2000

High production of 1,3-propanediol from industrial glycerol by a newly isolated Clostridium butyricum strain.

Batch and continuous cultures of a newly isolated Clostridium butyricum strain were carried out on industrial glycerol, the major by-product of the bio-diesel production process. For both types of cultures, the conversion yield obtained was around 0.55 g of 1,3-propanediol formed per 1 g of glycerol consumed whereas the highest 1,3-propanediol concentration, achieved during the single-stage continuous cultures was 35-48 g l-1. Moreover, the strain presented a strong tolerance at the inhibitory effect of the 1,3-propanediol, even at high concentrations of this substance at the chemostat (e.g. 80 g l-1). 1,3-Propanediol was associated with cell growth whereas acetate and butyrate seemed non growth-associated products. At low and medium dilution rates (until 0.1 h-1), butyrate production was favoured, whereas at higher rates acetate production increased. The maximum 1,3-propanediol volumetric productivity obtained was 5.5 g l-1 h-1. A two-stage continuous fermentation was also carried out. The first stage presented high 1,3-propanediol volumetric productivity, whereas the second stage (with a lower dilution rate) served to further increase the final product concentration. High 1,3-propanediol concentrations were achieved (41-46 g l-1), with a maximum volumetric productivity of 3.4 g l-1 h-1. A cell concentration decrease was reported between the second and the first fermentor.

Bioreactors↗
PubMed1999

Mannose 6-Phosphate/Insulin-like growth factor II receptor mediates internalization and degradation of leukemia inhibitory factor but not signal transduction.

Leukemia inhibitory factor (LIF) is a multifunctional cytokine belonging to the interleukin-6 subfamily of helical cytokines, all of which use the glycoprotein (gp) 130 subunit for signal transduction. The specific receptor for LIF, gp190, binds this cytokine with low affinity and is also required for signal transduction. We have recently reported that glycosylated LIF produced by transfected Chinese hamster ovary cells also binds to a lectin-like receptor, mannose 6-phosphate/insulin-like growth factor II receptor (Man-6-P/IGFII-R) (Blanchard, F., Raher, S., Duplomb, L., Vusio, P., Pitard, V., Taupin, J. L., Moreau, J. F., Hoflack, B., Minvielle, S., Jacques, Y., and Godard, A. (1998) J. Biol. Chem. 273, 20886-20893). The present study shows that (i) mannose 6-phosphate-containing LIF is naturally produced by a number of normal and tumor cell lines; (ii) other cytokines in the interleukin-6 family do not bind to Man-6-P/IGFII-R; and (iii) another unrelated cytokine, macrophage-colony-stimulating factor, is also able to bind to Man-6-P/IGFII-R in a mannose 6-phosphate-sensitive manner. No functional effects or signal transductions mediated by this lectin-like receptor were observed in various biological assays after LIF binding, and mannose 6-phosphate-containing LIF was as active as non-glycosylated LIF. However, mannose 6-phosphate-sensitive LIF binding resulted in rapid internalization and degradation of the cytokine on numerous cell lines, which suggests that Man-6-P/IGFII-R plays an important role in regulating the amounts of LIF available in vivo.

3T3 Cells↗
PubMed1999

Binding of leukemia inhibitory factor (LIF) to mutants of its low affinity receptor, gp190, reveals a LIF binding site outside and interactions between the two cytokine binding domains.

The gp190 transmembrane protein, the low affinity receptor for the leukemia inhibitory factor (LIF), belongs to the hematopoietin family of receptors characterized by the cytokine binding domain (CBD). gp190 is one of the very few members of this family to contain two such domains. The membrane-proximal CBD (herein called D2) is separated from the membrane-distal one (called D1) by an immunoglobulin-like (Ig) domain and is followed by three fibronectin type III repeats. We used truncated gp190 mutants and a blocking anti-gp190 monoclonal antibody to study the role of these repeats in low affinity receptor function. Our results showed that the D1Ig region was involved in LIF binding, while D2 appeared to be crucial for the proper folding of D1, suggesting functionally important interactions between the two CBDs in the wild-type protein. In addition, a point mutation in the carboxyl terminus of the Ig region strongly impaired ligand binding. These findings suggest that at least two distinct sites, both located within the D1Ig region, are involved in LIF binding to gp190, and more generally, that ligand binding sites on these receptors may well be located outside the canonical CBDs.

Animals↗
PubMed1998

The mannose 6-phosphate/insulin-like growth factor II receptor is a nanomolar affinity receptor for glycosylated human leukemia inhibitory factor.

Comparison of the binding properties of non-glycosylated, glycosylated human leukemia inhibitory factor (LIF) and monoclonal antibodies (mAbs) directed at gp190/LIF-receptor beta subunit showed that most of the low affinity (nanomolar) receptors expressed by a variety of cell lines are not due to gp190. These receptors bind glycosylated LIF produced in Chinese hamster ovary cells (CHO LIF) (Kd = 6.9 nM) but not Escherichia coli-derived LIF or CHO LIF treated with endoglycosidase F. CHO LIF binding to these receptors is neither affected by anti-gp190 mAbs nor by anti-gp130 mAbs and is specifically inhibited by low concentrations of mannose 6-phosphate (Man-6-P) (IC50 = 40 microM), suggesting that they could be related to Man-6-P receptors. The identity of this LIF binding component with the Man-6-P/insulin-like growth factor-II receptor (Man-6-P/IGFII-R) was supported by several findings. (i) It has a molecular mass very similar to that of the Man-6-P/IGFII-R (270 kDa); (ii) the complex of LIF cross-linked to this receptor is immunoprecipitated by a polyclonal anti-Man-6-P/IGFII-R antibody; (iii) this antibody inhibits LIF and IGFII binding to the receptor with comparable efficiencies; (iv) soluble Man-6-P/IGFII-R purified from serum binds glycosylated LIF (Kd = 4.3 nM) but not E. coli LIF. The potential role of Man-6-P/IGFII-R in LIF processing and biological activity is discussed.

Animals↗
PubMed1997

Production and characterization of monoclonal antibodies against the leukemia inhibitory factor low affinity receptor, gp190.

Leukemia inhibitory factor (LIF), oncostatin-M (OSM), ciliary neurotrophic factor (CNTF) and cardiotrophin-1 (CT1) act through transmembrane receptors which share the gp190 glycoprotein chain. The understanding of its involvement in the biology of these cytokines is of importance since these systems have recently been shown to participate in major inflammatory and neoplastic processes such as myelomatosis (Rose-John, S., Heinrich, P.C., 1994. Soluble receptors for cytokines and growth factors: generation and biological function. Biochem. J. 300, 281). In addition, this family of receptors also shares the gp130 transducing chain, with the IL6 and IL11 receptors. Because IL6 and gp130 were the first members to be discovered, most of the available reagents are directed at them. In this respect, monoclonal antibodies have played a major role in elucidating these receptor/ligand interactions and exploring the pathophysiological aspects of their biology. So far, no such reagents have been described for the gp190. We now report the production and characterization of 16 monoclonal antibodies directed against human gp190. They were obtained using recombinant chimeric or truncated proteins produced in a eukaryotic CHO cell line. One was able to block the biological activity of LIF. Because gp190 comprises two hematopoietin binding domains, crude epitope mapping was possible using the same reagents. While more of these antibodies are required, the present set validate the technological approach used for their preparation and should improve our understanding of this class of cytokines.

Animals↗
PubMed1997

Close phenotypic and functional similarities between human and murine alphabeta T cells expressing invariant TCR alpha-chains.

Several studies have demonstrated the existence of a murine NK1.1+ alphabeta T cell subset expressing V alpha14+ TCR alpha-chains with highly conserved invariant junctional sequences and able to secrete Th2 cytokines when exposed to CD1+ stimulator cells. In humans, alphabeta T cells carrying invariant V alpha24+ TCR alpha-chains highly homologous to those expressed by murine NK1.1 cells have been recently described. Here we show that these cells (referred to as V alpha24inv T cells) and murine NK1.1+ alphabeta T cells resemble each other in several ways. First, like their murine counterparts, T cells expressing high levels of V alpha24inv TCRs can be either CD4- CD8- double negative (DN) or CD4+, but they never express heterodimeric CD8 molecules. Second, most V alpha24inv T cells are brightly stained by NKRP1-specific mAb but not by mAb directed against other type II transmembrane proteins of the NK complex. Third, DN and particularly CD4+ V alpha24inv T cells are greatly enriched for IL-4 producers. The concomitant expression of highly conserved TCRs of a particular set of NK markers and of Th2 cytokines in human and murine alphabeta T cells suggests a coordinate acquisition of these phenotypic and functional properties. Furthermore, the relatively high frequency of human V alpha24inv T cells, which are presently shown to represent on average 1/500 PBL, and the high interindividual variations of the size of this cell subset under physiologic conditions go for a major role played by alphabeta T cells carrying invariant TCR in a large array of immune responses.

Animals↗