Biomedical subjects
Publications and source records attributed to A Bernard.
Meeting the patient care needs after the regular work day requires agencies to have a well-planned, comprehensive extended-hours program. This description of a large agency's approach to providing this service can be helpful to all agencies, regardless of size and location.
Human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent involved in the disease HTLV-1-associated myelopathy, or tropical spastic paraparesis (HAM/TSP). The pathogenesis of HAM/TSP is poorly understood, but it is probable that viral infection has an indirect, deleterious effect on neural function. In this regard, dysfunction in astrocytes may be severely detrimental, as they supply neurons with metabolic precursors, control the extracellular levels of ion and excitatory neurotransmitters, and are electrically coupled with oligodendrocytes. In a model in vitro, we demonstrate that HTLV-1 induces an imbalance in the expression of two astrocyte enzymes, at both the transcriptional and translational levels. In both human astrocyte precursors and rat glial cells, the levels of expression of glutamine synthetase (GS) and glutamate dehydrogenase (GDH) were increased and decreased, respectively, after coculture with HTLV-1 T cells. The enhancement of GS expression may result from the action of the protein Tax, which is demonstrated to transactivate the GS gene promoter, while the decreased expression of GDH seems to reflect some compensatory mechanism in response to GS induction. GS and GDH are involved in the conversion of glutamate into glutamine or alpha-ketoglutarate, which then acts as a precursor for glutamatergic and gamma-aminobutyric acid (GABA)-ergic neurons. Metabolism in astrocytes altered by Tax protein may lead to deleterious effects if it modifies the extracellular levels of glutamine, glutamate, and GABA and thus modulates neuronal excitability and osmotic equilibrium in the central nervous system of HTLV-1-infected patients.
The X-linked lymphoproliferative syndrome (XLP) is an inherited immuno-deficiency to Epstein-Barr virus infection that has been mapped to chromosome Xq25. Molecular analysis of XLP patients from ten different families identified a small interstitial constitutional deletion in 1 patient (XLP-D). This deletion, initially defined by a single marker, DF83, known to map to interval Xq24-q26.1, is nested within a previously reported and much larger deletion in another XLP patient (XLP-739). A cosmid minilibrary was constructed from a single mega-YAC and used to establish a contig encompassing the whole XLP-D deletion and a portion of the XLP-739 deletion. Based on this contig, the size of the XLP-D deletion can be estimated at 130 kb. The identification of this minimal deletion, within which at least a portion of the XLP gene is likely to reside, should greatly facilitate efforts in isolating the gene.
The Clara cell protein, the human counterpart of rabbit uteroglobin, exerts an anti-inflammatory action by interfering in different ways with the cytokine-network. Firstly, CC16 behaves like an anti-cytokine by downregulating the production of IFN-gamma, IL-1 and TNF-alpha by stimulated leukocytes. The extent of inhibition depends on the inducing agent (being maximal when IL-2 is used as inducer) and varies with the applied concentration of CC16. Secondly, the protein reduces the antiviral activity and the augmentation of phagocytosis induced by IFN-gamma. In both cases (inhibition of production and biologic activity) there is a 50% reduction in the presence of 10 ng/ml CC16. The natural and IFN-gamma-enduced cytotoxicity of NK-cells however, are enhanced by the presence of CC16, indicating a more complex interaction of CC16 with the immune-system. The immunosuppressive properties make CC16 a promising agent for the treatment of inflammatory reactions and auto-immune diseases.
Two low molecular weight MAP2 variants have been described, MAP2c and MAP2d. These variants are produced from a single gene by alternative splicing, and in their C-terminal regions contain, respectively, 3 and 4 tandem repeats, some of which are known to be involved in binding to microtubules. Substantial differences in the developmental expression pattern of MAP2c and MAP2d suggest they have different functions in neural cells. In order to investigate the respective roles of these MAP2 variants, we have analyzed the effects of MAP2c and MAP2d expression on microtubule and microfilament organization in transiently transfected cells. Our results show that both variants stabilize microtubules, but only MAP2d stabilizes microfilaments.
In the last two years intracytoplasmic sperm injection (ICSI) has become frequently employed as an assisted reproductive technique primarily to treat male factor infertility.' In order to achieve high pregnancy rates, all assisted reproductive technologies including ICSI require sufficient number and quality oocytes. In our practice we use three different ovulation induction regimens (CC/hMG, GnRH-a/hMG, and GnRH-a/FSH) to maximize the number of oocytes available for fertilization. In this present report, we retrospectively com- pared pregnancy rates with ICSI following the use of these protocols.
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The aim of this study was to determine what factors beyond age affect post-operative mortality. We included 971 patients (mean age 61 +/- 10 years; 882 men, 89 women). There were 61 patients (6%) 75 years of age and over. Post-operative death rate was 15% in patients 75 and over versus 6% in patients under 75 (p = 0.01). Other variables significantly correlated with post-operative death after univariate analysis were: heart failure, Karnofsky score, VEMS, CV, PaCO2, tumor size, right side resection, pneumonectomy and large exeresis. Multivariate analysis retained 6 independent variables affecting post-operative mortality: age > or = 75 years (p = 0.019), Karnofsky score (p = 0.0001), right side resection (p = 0.0002, pneumonectomy (p = 0.04, large resection (p = 0.029) and hypocapnia (p = 0.01). If these parameters are considered when deciding on surgery, pulmonary exeresis may be proposed in elderly patients.
A 60-year-old man was admitted to hospital with threatened anterior myocardial infarction due to double tight stenosis in the 1st and 2nd segments of the left anterior descending artery. This double stenosis was successfully treated, without any complications, by two Palmatz-Schatz 15.4 mm (PS 154 A) coronary stents. He was readmitted to hospital six months later for another episode of threatened anterior infarction, due to restenosis involving the 2 coronary stents. Balloon angioplasty of this restenosis was attempted, but the poor result led us to insert 2 contiguous articulated Palmatz-Schatz 154 mm stents (PS 154 A) inside the previous two stents. The result was excellent with no complications apart from distal dissection induced by the guide, requiring insertion of an AVE Stent, 8 mm long and 3 mm in diameter. An exercising myocardial scintigraphy performed one month after the procedure was normal. The patient is still asymptomatic with a follow-up of 6 months. The feasibility and low risk of complication of balloon angioplasty in the case of restenosis, after insertion of an intracoronary stent have been demonstrated by several studies. To our knowledge, no case of restenosis of an intracoronary stent, treated by insertion of a new stent, have been reported. We report a case of restenosis on two Palmatz-Schatz stents successfully treated by insertion of two contiguous PS 154 A stents.
Examination of legislative and reglementary framework where genic and cellular therapy take place: in a French and US context. Actual evolution. Comparison of difficulties in development and valorisation of project treatments in France and the US.
Within the framework of an European Commission-funded project, groups of industrial workers exposed to heavy metals (cadmium, mercury and lead) or solvents were studied together with corresponding control groups. Eighty-one measurements were carried out on urine and serum samples and the scientific results together with individual questionnaire information were entered into a central database. Data obtained was assessed centrally and individually in subsidiary studies. The measurable contributions were assessed either singly or in combination, of smoking, gender, metal exposure and site, to nephrotoxicity. The potential value of each test as an indicator of nephrotoxicity was then assessed on the basis of sensitivity and specificity. A number of new tests including prostaglandins and for extracellular matrix components were investigated as well as established tests for renal damage and dysfunction. The data obtained from this comprehensive study emphasises the value of noninvasive biomarkers for the early detection of nephrotoxicity due to environmental toxins. The urinary profile varied with the type of environmental/occupational toxin. By careful selection of a small panel of markers they can be used to indicate the presence of renal damage, the principal region affected, and to monitor the progress of disease and damage. Biomarkers were also used to confirm and tentatively establish safe exposure levels to nephrotoxins.
Expression of the liver fatty acid binding protein (L-FABP) has been studied in the liver of pregnant and lactating rats. The L-FABP concentration found in the cytosol by immuno-enzymatic assay (ELISA) was consistently higher in the dams during the pregnancy and the lactation than in the age-matched virgin females. Paradoxically, a decrease in the L-FABP mRNA level occurred in the maternal liver during the last days of the gestation. This level remained low on days 7 and 14 of the lactation. Since the transcription rate of the L-FABP gene was unchanged in the maternal liver, these data suggest a post-transcriptional regulation of the L-FABP during pregnancy and lactation in the rat. The nutritional adaptations occurring during pregnancy and lactation are not involved in this regulation since a chronic maternal food-restriction failed to correct these modifications. The mechanism of this regulation is presently unknown, but possibilities include hormonally mediated effects.
Interleukin-5 (IL-5) is a cytokine that plays a major role in the differentiation and activation of eosinophils. In order to identify which charged residues of human IL-5 are important in binding to its receptor and subsequent cellular activation, we have systematically replaced all of the clusters of charged amino acids with alanine residues. The mutants have been expressed in Escherichia coli, renatured, and purified. They were assayed for ability to cause proliferation of the erythroleukaemic cell line TF-1 and the up-regulation of eosinophil adhesion to ICAM-1. In addition, we studied receptor binding using either immobilized recombinant IL-5 receptor alpha-chain or the alpha/beta-receptor complex expressed on TF-1 cells. The key charged residue involved in binding to the beta-chain of the receptor is Glu-12. This residue is in an identical position to those previously identified in IL-3 and granulocyte-macrophage colony-stimulating factor (GM-CSF) involved in binding to the receptor beta-chain. The alpha-chain binding site is shown to involve the side chains Arg-90 and Glu-109, located in the second beta sheet and after the end of the fourth helix, respectively. It is unique to IL-5 and does not occur in IL-3 or GM-CSF. Understanding the topology of the interaction of IL-5 with its receptor chains will help in the search for rationally designed antagonists of IL-5 function.
Real-time monitoring of intermolecular interactions can provide a direct and rapid estimate of the affinity and kinetics of interactions between biomolecules. Optical methods based on the measurement of changes of refractive index in the immediate vicinity of a liquid-solid interface are particularly convenient because they require no radioactive, fluorescent or other labelling of the molecules under study. In the present work we have followed the specific interaction of protein molecules on a SiO2/TiO2 surface with the help of the optical grating coupler sensor instrument BIOS-1. This instrument allows the determination of the absolute mass of protein adsorbed to the sensor surface and, therefore, the calculation of the molar ratio of the components partaking in an intermolecular interaction. For example, about 3 ng avidin/mm2 surface area could be adsorbed. This amount closely corresponds to a monolayer composed of densely packed globular avidin molecules. A dimeric, biotinylated leucine zipper peptide was bound to this avidin layer at a molar ratio of 1:1 (1 peptide molecule/4 biotin binding sites of tetrameric avidin). An average of 1/2.6 peptides was recognized by a peptide-specific monoclonal antibody. Even though avidin was not covalently bound to the sensor surface, the avidin-coated chip could be used repeatedly to measure the time course of antibody binding as a function of the concentration of the antibody. From such measurements it was possible to calculate the association and dissociation rate constants assuming that the interaction of the antibody with the surface-bound antigen can be described by a simple Langmuir binding model. The limits of the Langmuir model are discussed. The same antigen-antibody reaction was also analyzed by a surface plasmon resonance biosensor (BIAcoreTM, Pharmacia). The results obtained with the two instruments, which register different optical phenomena and employ different surface chemistry, were in good agreement.
Matrix-degrading proteases, including metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs), are involved in modulation of the extracellular matrix, which participates in neural cell differentiation, brain morphogenesis and tissue integrity. Metalloproteinases and TIMPs are associated with inflammatory and degenerative processes in the central nervous system and are regulated by cytokines. Human retroviral infections are frequently associated with neurological disturbances. In the present paper, we have studied the changes occurring in human primitive neuroectodermal cells following infection with human T cell lymphotropic virus type 1 (HTLV-I), a retrovirus responsible for HTLV-I-associated myelopathy. Infected neural cells were found to have high metalloproteinase 9 (MMP9-92 kDa gelatinase) activity. MMP9 induction is dependent on HTLV-I infection of neural cells. In addition, soluble factors, especially tumour necrosis factor alpha, secreted by infected cells, act as mediators of induction. HTLV-I infection also induces expression of RNA coding for tissue inhibitor of metalloproteinase 2. These observations indicate that HTLV-I infection selectively modulates the expression of molecules involved in the dynamic equilibrium between the synthesis and degradation of the neural cell matrix and leads to its remodelling, which modifies cell-cell interactions and cellular function.
Calmodulin (CaM) antagonists chlorpromazine, trifluoperazine, and N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide HCl inhibit Jurkat T cell activation, as monitored by measuring interleukin-2 synthesis in cells treated by a combination of CD3 monoclonal antibody and phorbol myristate acetate. T cell activation with CD3 monoclonal antibody is accompanied by a decreased synthesis of phosphatidylserine due to the release of Ca2+ from the endoplasmic reticulum. CaM antagonists reverse the phosphatidylserine (PtdSer) inhibition induced by CD3. This increase of PtdSer synthesis was observed in the absence of any modification of CD3-induced Ca2+ movements. Both in intact cells and in an acellular system, the increase of PtdSer synthesis induced by CaM antagonists was abolished in the presence of EGTA, indicating that the base exchange enzyme system responsible for PtdSer synthesis is regulated by CaM provided that Ca2+ is present. By contrast, cyclosporin A that inhibits T cell activation through the interaction of cyclophilin-cyclosporin A complexes with the calmodulin-activated phosphatase, calcineurin, had no effect on PtdSer synthesis. Calmodulin thus appears as a junction leading to at least two independent pathways of regulation of T cell activation, one involving the calcineurin phosphatase and the other the base exchange enzyme system responsible for PtdSer synthesis.
CD40 ligand (CD40L) is expressed on the surface of activated CD4+ T cells, basophils, and mast cells. Binding of C40L to its receptor, CD40, on the surface of B cells stimulates B cell proliferation, adhesion and differentiation. A preparation of soluble, recombinant CD40L (Tyr-45 to Leu-261), containing the full-length 29-kDa protein and two smaller fragments of 18 and 14 kDa, has been shown to induce differentiation of B cells derived either from normal donors or from patients with X-linked hyper-IgM syndrome (Durandy, A., Schiff, C., Bonnefoy, J.-Y., Forveille, M., Rousset, F., Mazzei, G., Milili, M., and Fischer, A. (1993) Eur. J. Immunol. 23, 2294-2299). We have now purified each of these fragments to homogeneity and show that only the 18-kDa fragment (identified as Glu-108 to Leu-261) is biologically active. When expressed in recombinant form, the 18-kDa protein exhibited full activity in B cell proliferation and differentiation assays, was able to rescue of B cells from apoptosis, and bound soluble CD40. Sucrose gradient sedimentation shows that the 18-kDa protein sediments as an apparent homotrimer, a result consistent with the proposed trimeric structure of CD40L. This demonstrates that a soluble CD40L can stimulate CD40 in a manner indistinguishable from the membrane-bound form of the protein.