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Biomedical subjects

V Dubois

Publications and source records attributed to V Dubois.

At least 19 recordsLinked to original sources
PubMed2006

Thimet oligopeptidase (EC 3.4.24.15) activates CPI-0004Na, an extracellularly tumour-activated prodrug of doxorubicin.

CPI-0004Na is a tetrapeptidic extracellularly tumour-activated prodrug of doxorubicin. The tetrapeptide structure ensures blood stability and selective cleavage by unidentified peptidase(s) released by tumour cells. The purpose of this work was to identify the enzyme responsible for the first rate-limiting step of CPI-0004Na activation, initially attributed to a 70 kDa acidic (pI=5.2) metallopeptidase active at neutral pH that was subsequently purified from HeLa cell homogenates. Two electrophoretic bands were isolated and identified by matrix-assisted laser desorption ionisation-time of flight (MALDI-tof) and electrospray ionisation-quadrupole-time of flight (ESI-Q-tof) mass spectrometry as thimet oligopeptidase (TOP). The identity of the CPI-0004Na activating enzyme and TOP was further supported by the similar substrate specificity of the purified enzyme and recombinant TOP, by thiol stimulation of CPI-0004Na cleavage by cancer cell conditioned media (unique characteristic of TOP) and by the inhibition of CPI-0004Na activation by specific inhibitors or immunoprecipitation. Although other enzymes can be involved, TOP clearly appears to be a likely candidate for extracellular activation of the CPI-0004Na prodrug.

Antineoplastic Agents↗
PubMed2006

Methodology of management of dredging operations I. Conceptual developments.

This article presents a new methodology for the management of dredging operations. Partly derived from existing methodologies (OECD, UNEP, AIPCN), its aim is to be more complete, by integrating the qualities and complementarities of former methodologies. Moreover, it was carried out in a context of sustainable development. Indeed, it supports, according to a framework of industrial ecology, the development and the implementation of solutions of waste improvement of dredged materials, in order to minimize the environmental impact of dredging. It also uses a tool of MultiCriteria Decision-Making Aid (M.C.D.M.A.), in order to integrate local characteristics. In addition, this tool, called DRAGSED, allows to a dialogue to be established between all the parties concerned with a dredging project (harbour's authorities, industrialists, municipalities, administrations, populations, associations,...). Thus, the implementation of this methodology enables consensus to be reached for the dredging solution retained. It also proposes an environmental follow-up, which will allow an evaluation during its application.

Algorithms↗
PubMed2006

Methodology of management of dredging operations II. Applications.

This paper presents the new methodology of management of dredging operations. Derived partly from existing methodologies (OECD, PNUE, AIPCN), it aims to be more comprehensive, mixing the qualities and the complementarities of previous methodologies. The application of the methodology has been carried out on the site of the Port of Dunkirk (FRANCE). Thus, a characterization of the sediments of this site has allowed a zoning of the Port to be established in to zones of probable homogeneity of sediments. Moreover, sources of pollution have been identified, with an aim of prevention. Ways of waste improvement have also been developed, to answer regional needs, from a point of view of competitive and territorial intelligence. Their development has required a mutualisation of resources between professionals, research centres and local communities, according to principles of industrial ecology. Lastly, a tool of MultiCriteria Decision-Making Aid (M.C.D.M.A.) has been used to determine the most relevant scenario (or alternative, or action) for a dredging operation intended by the Port of Dunkirk. These applications have confirmed the relevance of this methodology for the management of dredging operations.

Algorithms↗
PubMed2006

A deletion in exon 3 results in a new HLA-A*01 null allele (A*0115N) in a Martinican woman.

We report the identification of a new HLA-A null allele, HLA-A*0115N. This null allele has been identified within the A*01 group by a combination of serological and molecular typing [Polymerase chain reaction (PCR) sequence-specific primers, PCR sequence-specific oligoprobes and sequence-based typing (SBT)] in a potential intrafamilial bone marrow donor from Martinique (French West Indies). To characterize this A*01 null allele, we performed DNA typing by PCR-SBT on genomic DNA from the beginning of exon 2 (position 84) through the end of the exon 4 (position 895) and revealed a nucleotide deletion at the end of the exon 3. This sole difference between the new allele and the HLA-A*0101 generates a premature stop codon (TGA) in the beginning of exon 4. This deletion most likely explains the lack of cell surface expression of the encoded protein despite the presence of A*01 allele. The absence of correct expression of the antigen on the cell surface was confirmed by one-dimensional isoelectric focusing (1D-IEF). To date, this is the fourth null allele described within the A*01 group.

Alleles↗
PubMed2005

Outcome and long-term follow-up of alloreactive donor lymphocyte infusions given for relapse after myeloablative allogeneic hematopoietic stem cell transplantations (HSCT).

In order to study efficacy, toxicity and the long-term results of donor lymphocyte infusions (DLI), we retrospectively analyzed DLI given for relapse after conventional allogeneic hematopoietic stem cell transplantation (HSCT) in 30 patients with a median delay of 107.5 months after transplant and 58 months after DLI. After DLI, 15 patients established full donor chimerism, three patients developed grade III and one grade IV acute GVHD. A total of 15 patients achieved a disease response. Among the 14 patients with chronic myeloid leukemia (CML), 11 are alive at the last follow-up: five are in complete molecular response (CMR) and two in complete cytogenetic response (CCR) with no other intervention after DLI, three in CMR after imatinib mesylate given after DLI and one in complete hematological response after imatinib mesylate and reduced-intensity conditioning allogeneic SCT performed after DLI. At the time of the last follow-up, 19 (63%) patients died and 11 (37%) remain alive. The 3-year probability of survival for the entire population, CML patients and non-CML patients, was 60, 93, 62% after transplantation, and 48, 80 and 48% after DLI, respectively. A multivariate analysis demonstrated a significantly worse survival rate after transplantation for female recipients, advanced disease and acute leukemia before transplantation.

Adolescent↗
PubMed2005

Influence of pH on the appearance of active peptides in the course of peptic hydrolysis of bovine haemoglobin.

Influence of pH on the appearance of active peptides in peptic hydrolysis of bovine haemoglobin was studied in a homogenous phase system. Six active peptides were studied: three hemorphins: LVVH-7 (beta 31-40), VVH-7 (beta 32-40), VVH-4 (beta 32-37), one bradykinin-potentiating peptide (alpha 110-125), one antibacterial peptide (alpha 1-23), and neokyotorphin (alpha 137-141). The influence of pH was investigated in the course of the hydrolysis of haemoglobin by pepsin at 23 degrees C in acetate buffer at pH 3.5, pH 4.5, and pH 5.5. The hydrolysis of haemoglobin was studied in the presence or absence of urea. The haemoglobin hydrolysis at pH 4.5 is taken as a reference. Two different mechanisms of hydrolysis were observed: "one by one" for native haemoglobin hydrolysis at pH 4.5 and 5.5, and "zipper" for denatured haemoglobin at pH 3.5, pH 4.5, and pH 5.5, and native haemoglobin at pH 3.5. Whatever the pH and medium, a selectivity change by the pepsin was noticed. In the presence of urea, there are two phenomena: some peptides are preferentially produced at pH 3.5 and other peptides at pH 5.5, which seems to favour one particular site of pepsin that is cut. In the absence of urea, these active peptides reached a higher concentration at pH 3.5. In order to prepare these six active peptides, it is suitable to hydrolyse haemoglobin in the absence of urea at pH 3.5 (this pH denatures haemoglobin) where a "zipper" mechanism is obtained, and the peptide quantity is more significant at pH 3.5 than at pH 4.5.

Animals↗
PubMed2004

Antibiotic resistance rates and phenotypes among isolates of Enterobacteriaceae in French extra-hospital practice.

Antibiotic resistance among members of the family Enterobacteriaceae was prospectively surveyed by eight French private laboratories over a 5-month period in 1999. A total of 2,599 consecutive and nonduplicate strains were collected, mainly (60.9%) from patients in the community. Most strains (82.9%) derived from urine. Escherichia coli was the predominant (73.9%) organism isolated. The overall rates of antibiotic resistance were as follows: amoxicillin, 53.4%; amoxicillin-clavulanic acid, 27.3%; ticarcillin, 44.2%; piperacillin-tazobactam, 3.2%; cephalothin, 29.2%; cefuroxime, 14.7%; cefoxitin, 11.5%; ceftazidime, 3.6%; cefotaxime, 2.8%; cefepime, 0.3%; imipenem, 0.1%; gentamicin (G), 3.8%; tobramycin (T), 5.0%; netilmicin (Nt), 3.7%; amikacin (A), 0.7%; nalidixic acid, 14.3%; ofloxacin, 10.4%; cotrimoxazole, 21.1%; nitrofurantoin, 12.7%; fosfomycin, 5.2%; tetracycline, 50.1%; and colistin, 12.5%. Beta-lactam resistance phenotypes essentially comprised penicillinase production (33.9%), overexpression of chromosomal cephalosporinase (4.6%), and synthesis of inhibitor-resistant TEM/OXA enzymes (1.5%) or extended-spectrum beta-lactamases (1.5%). Aminoglycoside resistance phenotypes consisted of GTNt (93 strains), TNtA (68 strains), GTNtA (14 strains), T (4 strains), GT (3 strains), G (1 strain), and reduced uptake/permeability (3 strains). Most of the nalidixic acid-resistant strains were resistant to ofloxacin (72.8%). Antibiotic resistance rates and phenotypes varied widely according to the bacterial group and the source of the strains. Significantly higher rates were observed in private healthcare centers than in the community, due to a higher proportion of both resistant species and resistant strains. However, multidrug-resistant isolates, including five extended-spectrum beta-lactamase-producing strains, were also recovered from the community.

Ambulatory Care↗
PubMed2004

A new HLA-B44 allele (B*44020102S) with a splicing mutation leading to a complete deletion of exon 5.

Using a combination of serology and polymerase chain reaction with sequence-specific primer (PCR-SSP), we have identified in a volunteer bone marrow donor a new HLA class I antigen within the B44 serotype. This human leukocyte antigen (HLA)-B44 variant was typed as 'blank' by microlymphocytotoxicity, whereas the B*44020101 allele was identified by PCR-SSP. A family study confirmed the Mendelian segregation of this blank antigen identified on one of the maternal haplotype transmitted to her child. The DNA sequence of B*44new, now referred to as B*44020102S, performed from the promoter region to the 3' untranslated region revealed a single nucleotide difference (A/G) compared to B*44020101 at the end of intron 4 in the acceptor-splicing site. This mutation leads to an incorrect splicing characterized by the deletion of exon 5 that encodes the transmembrane domain of the HLA antigen. Indeed, full-length complementary DNA sequencing revealed a complete absence of exon 5. Fluorescence-activated cell sorter analysis confirmed the absence of expression of HLA-B44 on the cell surface in the donor, compared to the HLA-B44 positive control. The isoelectric focusing analysis failed to reveal the presence of an HLA-B44 antigen in the donor, showing that no normal HLA-B*44020101 allele was synthesized. The new B*440201010102S allele is a soluble form of B44 without any detectable cell-surface expression. It can thus be considered as a soluble antigen, a form apparently inactive and unfit for antigen presentation.

3' Untranslated Regions↗
PubMed2004

Three new DRB alleles routinely identified by sequence-based typing: DRB1*010103, DRB1*0326 and DRB3*0219.

We describe here two additional DRB1 alleles found in two Caucasoid recipient candidates for organ transplant and a new DRB3 allele found in a Caucasoid unrelated bone marrow donor from the German file. HLA-DRB generic and allele typing were performed using commercial kits, subsequently exon 2 was sequenced. We found a DRB1*010101 with a silent mutation at codon 68 and a DRB1*0306 with a mutation at codon 38 (T-C) which causes an amino acid substitution from Val to Ala. DRB3*0219 differs from DRB3*020201 by two-point mutations at codons 60 and 74 (A/C and A/G, respectively). These mutations at positions 266 and 308 were responsible for two amino acid substitutions (Tyr to Ser and Gln to Arg).

Base Sequence↗
PubMed2004

HLA antibodies and neonatal alloimmune thrombocytopenia.

A female baby with a severe thrombocytopenia at 18 x 10(9)/l was born to a 29-year-old (gestation 2/partum 2) mother. Scattered petechiae were present on her legs, arms, chest and face, but there was no bleeding, infection, fever or hepatosplenomegaly. A platelet antibody screening immunocapture test was positive, which was performed on the mother's serum 3, 12 and 38 days after delivery, but no platelet-specific antibodies were found by the monoclonal-antibody-specific immobilization of platelet antigen assay. The baby's platelets and lymphocytes and the father's platelets reacted strongly with the HLA antibodies present in the mother's serum. The neonate was treated with intravenous human immunoglobulin (Tegeline), 1 g/kg per day) 1, 2 and 3 days after delivery. The platelet count rose from 18 x 10(9)/l on day 0 to 37 x 10(9)/l on day 3 and to 227 x 10(9)/l on day 12. No platelet transfusion was needed. Several factors which developed hereafter lead us to think that this neonatal alloimmune thrombocytopenia is due to the transplacental passage of maternal HLA antibodies to the baby.

Adult↗
PubMed2002

Fibroblasts capture cathepsin D secreted by breast cancer cells: possible role in the regulation of the invasive process.

Breast cancer cells oversecrete the lysosomal peptidase cathepsin D as a pro-enzyme. In this study, we assessed the effect of media conditioned by MRC-5 fibroblasts or MCF-7/6 breast cancer cells on cathepsin D (CD) production and secretion by these two cell types. We also considered the influence of estrogens and matrix components (type I or type IV collagen, or Matrigel) on the expression and activity of CD produced by breast cancer cells of different invasive potentials (MCF-7/AZ, MCF-7/6, MDA-MB-231). In our system, fibroblasts conditioned medium does not significantly affect CD levels produced and secreted by the MCF-7/6 cells. However, we found that fibroblasts are able to capture the pro-CD secreted by these tumor cells by a mannose 6-phosphate-dependent process. We also found a positive correlation between the proportion of extracellular CD levels and the invasive potentials of the tumor cell types considered. If estrogens are able to upregulate CD production and secretion by receptor-positive cells, it is not the case of extracellular matrix components. On the other hand, our results indicate that matrix components are able to influence the distribution of the different CD forms in and out of the cells. Our data suggest that tumor fibroblasts, by enhancing their intracellular CD levels, could assist cancer cells in the digestion of extracellular matrix during the invasion of tissues.

Blotting, Western↗
PubMed2001

Dimer stabilization upon activation of the transcriptional antiterminator LicT.

LicT belongs to the BglG/SacY family of transcriptional antiterminators that induce the expression of sugar metabolizing operons in Gram positive and Gram negative bacteria. These proteins contain a N-terminal RNA-binding domain and a regulatory domain called PRD which is phosphorylated on conserved histidine residues by components of the phosphoenolpyruvate:sugar phosphotransferase system (PTS). Although it is now well established that phosphorylation of PRD-containing transcriptional regulators tunes their functional response, the molecular and structural basis of the regulation mechanism remain largely unknown.A constitutively active LicT variant has been obtained by introducing aspartic acid in replacement of His207 and His269, the two phosphorylatable residues of the PRD2 regulatory sub-domain. Here, the functional and structural consequences of these activating mutations have been evaluated in vitro using various techniques including surface plasmon resonance, limited proteolysis, analytical centrifugation and X-ray scattering. Comparison with the native, unphosphorylated form shows that the activating mutations enhance the RNA-binding activity and induce tertiary and quaternary structural changes. Both mutant and native LicT form dimers in solution but the native dimer exhibits a less stable and more open conformation than the activated mutant form. Examination of the recently determined crystal structure of mutant LicT regulatory domain suggests that dimer stabilization is accomplished through salt-bridge formation at the PRD2:PRD2 interface, resulting in domain motion and dimer closure propagating the stabilizing effect from the protein C-terminal end to the N-terminal effector domain. These results suggest that LicT activation arises from a conformational switch inducing long range rearrangement of the dimer interaction surface, rather than from an oligomerization switch converting an inactive monomer into an active dimer.

Bacillus subtilis↗
PubMed2001

N-Succinyl-(beta-alanyl-L-leucyl-L-alanyl-L-leucyl)doxorubicin: an extracellularly tumor-activated prodrug devoid of intravenous acute toxicity.

Intravenous administration of N-(beta-alanyl-L-leucyl-L-alanyl-L-leucyl)doxorubicin (4) induces an acute toxic reaction, killing animals in a few minutes. This results from its positive charge at physiological pH combined with its propensity to form large aggregates in aqueous solutions. Negatively charged N-capped versions of 4 such as the succinyl derivative 5 can be administered by the iv route at more than 10 times the LD(50) of doxorubicin without inducing the acute toxic reaction, and they are active in vivo.

Animals↗
PubMed2001

Extracellularly tumor-activated prodrugs for the selective chemotherapy of cancer: application to doxorubicin and preliminary in vitro and in vivo studies.

Oligopeptidic derivatives of anthracyclines unable to penetrate cells were prepared and screened for their stability in human blood and their reactivation by peptidases secreted by cancer cells. N-beta-alanyl-L-leucyl-L-alanyl-L-leucyl-doxorubicin was selected as a new candidate prodrug. The NH2-terminal beta-alanine allows a very good blood stability. A two-step activation by peptidases found in conditioned media of cancer cells ultimately yields N-L-leucyl-doxorubicin. In vitro, when MCF-7/6 cancer cells are exposed to the prodrug, they accumulate about 14 times more doxorubicin than MRC-5 normal fibroblasts, whereas when exposed to doxorubicin the uptake is slightly higher in fibroblasts than in MCF-7/6 cells. This increased specificity of the prodrug over doxorubicin was confirmed in cytotoxicity assays using the same cell types. In vivo, the prodrug proved about nine times less toxic than doxorubicin in the normal mouse and also much more efficient in two different experimental chemotherapy models of human breast tumors.

Animals↗
PubMed2001

Qualitative and quantitative molecular detection of enteroviruses in water from bathing areas and from a sewage treatment plant.

Pathogenic enteric viruses can be introduced into the environment as a result of human activities. Enteroviruses are regularly detected in environmental waters or shellfish and can provoke potentially serious diseases. Some authors believe that enteroviruses could represent an interesting indicator of viral contamination in the environment. Since molecular approaches seem to be promising for the detection of these viruses, we developed a simple qualitative RT-PCR procedure for enteroviruses, together with a quantitative RT-PCR assay using RNA internal standard. After one-tube-RT-PCR, this standard and wild enterovirus RNA were detected by differential hybridization with specific probes and a fluorimetric reaction. The quantification of enteroviruses, conducted in a sewage treatment plant, showed a decreasing number of genomic copies from the entrance to the exit (from 3.8 x 10(5) to 5.4 x 10(4) RNA copies/mL) but indicated the presence of enterovirus RNA in the neighboring river (2.2 x 10(3) RNA copies/mL). In bathing areas, enterovirus RNA was detected in 16 out of 226 samples, with copies numbers ranging from 3.7 x 10(2) RNA copies/mL to 7 x 10(4) RNA copies/mL.

Bathing Beaches↗
PubMed2001

Crisis intervention models in the French-speaking countries.

The article presents the crisis intervention model devised by Andreoli (Geneva) which is currently being developed in most crisis units and emergency services in the French-speaking countries of Europe. Two clinical examples are presented: the Short Therapy Centre (Geneva, Switzerland) and the crisis unit of the Saint-Luc Clinic (Brussels, Belgium). The following aspects of these approaches are discussed: (a) the need for crisis intervention rather than a simple answer to emergency, (b) the need for crisis intervention in all acute psychiatric disorders and not only in psychosocial problems, (c) the need to integrate psychiatric hospitalization into a coherent mental health policy, (d) the need for well-trained and round-the-clock teams, (e) the need for continuity of care.

Belgium↗