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Biomedical subjects

F Bienvenu

Publications and source records attributed to F Bienvenu.

At least 19 recordsLinked to original sources
PubMed2001

Cyclin D1 represses STAT3 activation through a Cdk4-independent mechanism.

STAT3 transcription factors are cytoplasmic proteins that induce gene activation in response to cytokine receptor stimulation. Following tyrosine phosphorylation, STAT3 proteins dimerize, translocate into the nucleus, and activate specific target genes. Activation is transient, and down-regulation of STAT3 signaling occurs within a few hours. In this study, we show that cyclin D1 inhibits STAT3 activation. In co-immunoprecipitation and pull-down assays, cyclin D1 was found to associate with the activation domain of STAT3 upon interleukin-6 stimulation. Overexpression of cyclin D1 inhibited transcriptional activation by STAT3 proteins. This effect was not shared by cyclin E, was independent of association with Cdk4, and was unaffected by inhibitors of Cdk4. Whereas cyclin D1 had no effect on the steady-state level of STAT3 proteins in the cytoplasm, it was found to reduce the STAT3 nuclear level in HepG2 cells. These results suggest a model by which cyclin D1 is part of a feedback network controlling the down-regulation of STAT3 activity and highlight a new activity for this cell cycle regulatory protein.

Animals↗
PubMed1997

Procalcitonin and C-reactive protein levels in neonatal infections.

In order to assess the potential fo procalcitonin measurement in the management of neonatal sepsis, daily variations in serum procalcitonin (measured by an immunoluminometric assay) were evaluated in 94 control and infected newborn infants in comparison to C-reactive protein (measured by an immunonephelometric method). High levels of procalcitonin correlated with bacterial invasion and showed no discrepancies with C-reactive protein. procalcitonin increased (up to 400 micrograms l-1 and returned to the normal range (< 0.1 microgram l-1) more quickly than C-reactive protein, suggesting that procalcitonin may be an early marker of favourable outcome. Another finding is a significant procalcitonin peak on the first day of life in the control group, independent of any infectious stimulus. In conclusion, procalcitonin seems to be an interesting marker of neonatal sepsis but additional investigations are needed to understand better its mechanism of synthesis in order to determine its clinical usefulness.

Bacterial Infections↗
PubMed1994

Interleukin 10 induces B lymphocytes from IgA-deficient patients to secrete IgA.

We have previously shown that human B lymphocytes cultured in the CD40 system, composed of an anti-CD40 mAb presented by a CD32-transfected fibroblastic cell line, proliferate but do not secrete antibodies. However, the addition of particles of Staphylococcus aureus Cowan (SAC) induces B cell differentiation even in the absence of exogenous cytokines (CD40/SAC system). Additionally, B lymphocytes cultured in the CD40 system in the presence of human IL-10, produce IgM, IgG, and IgA, and Ig levels are further increased by SAC. Here, we have studied the capacity of peripheral blood lymphocytes from patients with IgA deficiency (IgA-D) to secrete Igs, particularly IgA after CD40 triggering. Peripheral blood mononuclear cells (PBMNC) from IgA-D patients cultured in the CD40/SAC system produced IgM and IgG, but not IgA. The addition of IL-10 to the cultures, enhanced the production of IgM and IgG and most strikingly induced the production of high amounts of IgA. The addition of IL-10 to PBMNC from IgA-D patients activated through CD40 alone resulted in the production of IgA. Thus, SAC and anti-CD40 mAb stimulate B cells to differentiate into cells secreting IgG and IgM whereas IL-10 plays a central role in inducing B cells from IgA-D patients to differentiate into IgA secreting cells.

Adolescent↗
PubMed1994

[Multicenter study of commercial kits for the determination of human IgG subclasses, using the ELISA technique].

We evaluated two commercially available sandwich type Elisa procedures for the measurement of IgG subclasses in human serum. Assay kits from The Binding Site and the Central Laboratory of the Netherlands Red Cross Blood Transfusion Service were tested in six laboratories. The performance of spectrophotometers, pipettes and dilutors were assessed at each center. Within-run precision was estimated according to the Valtec method (Société Française de Biologie Clinique). The overall coefficient of variation ranged from 4 to 50% depending on subclass and kit. We also evaluated the IgG2 and IgG4 specificity using four sera containing a monoclonal IgG2 or IgG4 (kappa or lambda type). Using total IgG and immunoelectrophoresis as a comparative technique, IgG2 kappa and IgG4 kappa were both underestimated, IgG2 lambda was overestimated while IgG4 lambda compared favorably. Polyclonal IgG subclasses were frequently overestimated in these sera suggesting cross-reactions with either monoclonal IgG or other polyclonal IgG. Antigen excess was investigated and not encountered with either kit. Our results demonstrate that these procedures are insufficiently accurate or precise for routine clinical use.

Enzyme-Linked Immunosorbent Assay↗
PubMed1993

Comparison of serum copper determination by colorimetric and atomic absorption spectrometric methods in seven different laboratories. The S.F.B.C. (Société Française de Biologie Clinique) Trace Element Group.

An interlaboratory collaborative trial was conducted on the determination of serum copper using two different methods, based on colorimetry (test combination Copper, Boehringer Mannheim, Mannheim, Germany) and flame atomic absorption spectrometry (FAAS). The general performance of the colorimetric method was below that of FAAS, except for sensitivity and linear range, as assessed by detection limit (0.44 versus 1.32 mumol/L) and upper limit of linearity (150 versus 50 mumol/L). The range of the between-run CVs and the recovery of standard additions were, respectively, 2.3-11.9% and 92-127% for the colorimetric method and 1.1-6.0% and 93-101% for the FAAS method. Interferences were minimal with both methods. The two techniques correlated satisfactorily (the correlation coefficients ranged from 0.945-0.970 among laboratories) but the colorimetric assay exhibited slightly higher results than the FAAS method. Each method was transferable among laboratories.

Analysis of Variance↗
PubMed1986

[Methods of determination of selenium in biological matter].

Main techniques used: graphite furnace atomic absorption direct or after preliminary treatment of the sample, graphite furnace atomic absorption by generation of hydrides, fluorometry, gaz chromatography, differential pulse voltammetry. The various quality criteria of these methods are compared as well as the usual values in the different biological fluids (whole blood, plasma, serum, erythrocytes, urine).

Chromatography, Gas↗
PubMed1986

[Value of plasma fibronectin in pediatric intensive care].

This work was undertaken to demonstrate the pathophysiologic and prognostic value of plasma fibronectin measurement in critically ill children. Fibronectin was measured by laser-nephelometry in 25 children (group 1) whose ages ranged from 1 month to 12 years (mean: 13.8 months). All presented with severe infections. The control group consisted of 16 children with various benign disorders, whose ages ranged from 3 months to 13 years (mean: 3.6 years). Fibronectin plasma levels in group 1 (mean: 0.16 g/l +/- 0.08) and in the control group (mean: 0.28 +/- 0.10) were significantly different (alpha less than 0.001). The initial concentration and the kinetics of this protein during evolution seem to have a good diagnostic and prognostic value in severe infections in children.

Bacterial Infections↗
PubMed1984

Evolution of serum prealbumin, C-reactive protein, and orosomucoid in neonates with bacterial infection.

The simultaneous changes in serum prealbumin, orosomucoid (alpha-acidglycoprotein, AGP), and C-reactive protein (CRP) were evaluated in 36 newborn infants with septicemia (n = 20), meningitis (n = 10), arthritis (n = 5), and peritonitis (n = 1). In 29 patients with a favorable outcome the values for serum prealbumin and CRP showed a rapid return toward normal: in 2 to 3 days serum prealbumin increased by 84% from the basal value and remained at (mean +/- 1 SD) 0.11 +/- 0.02 gm/L. Serum CRP decreased from 85 +/- 75 mg/L (range 0.15 to 206 mg/L) to 49 +/- 64 mg/L (2 to 210 mg/L) at 3 to 4 days of evolution and to normal values at day 13 to 16. The changes in serum orosomucoid values were slower, from 1.33 +/- 0.75 gm/L to 1.16 +/- 0.75 gm/L at day 13 to 16, with normalization after 20 to 30 days. Serum orosomucoid values returned to the normal range with the clinical improvement. In some patients the orosomucoid/prealbumin ratio decreased earlier than the serum orosomucoid concentration. Seven patients died, and in four of these in whom at least three values could be determined serum CRP and orosomucoid remained very high, whereas serum prealbumin did not increase or subsequently decreased. These data show an inverse change in serum CRP and prealbumin concentrations in infected neonates. The immediate decrease in CRP reflects the effect of treatment, whereas the later decrease in serum AGP parallels the clinical course of the infection. Thus the determination of these proteins can help to guide the treatment of infection in newborn infants.

Acute-Phase Proteins↗
PubMed1983

[Humoral factors of immunity in maternal milk. Comparison of their levels in the breast milk of mothers with premature and at-term delivery].

Eight proteins (Immunoglobulin A, G, M, C3 and C4 fractions of complement, alpha 1-glycoprotein, lactoferrin and alpha 1- antitrypsin) were measured by immuno-diffusion or laser nephelometry in 50 milk samples. Thirty nine were heated thrice at 62 degrees C for 20 minutes. Twenty six came from mothers who delivered prematurely (less than 37 weeks) and 13 from mothers who delivered at term. Eleven samples were, used to determine the effect of the heating process. There was no significative difference of the concentrations of the eight proteins between the breast milk obtained at term or prematurely, even when the comparisons were made between colostral milks or transitional milks. The heating process reduced the concentration by 47 % for IgA, more than 88 % for IgG and IgM, 41 to 74 % for the other proteins; only orosomucoid seemed little affected (-16 %). These data suggest that the heating process impairs the immunologic effect of breast milk. This effect must be particularly considered in regard to the absence of any significant difference between the milks obtained at term or prematurely.

Blood Proteins↗
PubMed1983

[Serum ferritin in premature infants].

This study was carried out in twenty-two newborn of birthweight lower than 2 000 g at four and six weeks to determine normal values of serum ferritin in preterm infants and pathological factors who influenced this evolution. Serum ferritin was measured by a kit using a sandwich radioimmunometric method. Elevated values are found in the series of fifteen preterm infants without pathology, with a decreasing evolution. There is no difference in median values at four (266 +/- 91 ng/ml) and six (279 +/- 162) weeks. There is no correlation between serum ferritin values and gestational age nor with hemoglobin values. Serum ferritin values are elevated by inflammatory pathology, blood transfusions and in this case no represent stain pool.

Ferritins↗
PubMed1982

Enzyme-linked immunoadsorbent assay for serum IgE: evaluation in four centres.

We report an evaluation of a commercially available kit, the Biomérieux IgE-kit, for determination of total IgE in serum by the EIA double antibody sandwich method. Results by this procedure and PRIST (Pharmacia) show a degree of association (r) of 0.98 and a regression equation of log Y = 0.79 log PRIST + log 3.31. Correlation between the IgE kit and RIST shows a degree of association of 1.00 and a regression equation of log Y = 1.01 log RIST--log 1.05. Between-laboratory standard deviations are 3%, 3%, and 15% for the IgE concentrations of, respectively, 83, 285, and 900 IU/ml. Similarly, intra- and inter-assay correlations were performed on 60 lyophilised serum samples tested in the four centres. No protein interference was found except for cryoprecipitates. The favourable correlation with existing procedures and the feasibility of this kit offer a new way of measuring IgE levels.

Alkaline Phosphatase↗