Publications by authors named "Isabelle Leduc"

Older adults with acute myeloid leukemia (AML) have a poor prognosis because frailty and the characteristics of the disease limit the use of intensive chemotherapy (ICT). Treatment with 5-azacitidine (5-AZA) or low-dose cytarabine (Cytarabine) (LDAC) - with or without venetoclax - is currently recommended in this setting. However, we lack real-life data on response rates and treatment outcomes.

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  • Familial forms of monoclonal gammopathy, including multiple myeloma (MM) and Monoclonal Gammopathy of Undetermined Significance (MGUS), are rare, with MGUS being more commonly observed and sometimes advancing to MM.
  • A study identified 318 families with multiple cases of monoclonal gammopathy, highlighting potential genetic links and family clusters with parent-child and sibling cases.
  • Despite some genetic similarities, familial cases generally present similarly to sporadic cases but show a better prognosis, with longer median survival rates for those with familial MM.
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There is a pressing need for a gonorrhea vaccine due to the high disease burden associated with gonococcal infections globally and the rapid evolution of antibiotic resistance in Neisseria gonorrhoeae (Ng). Current gonorrhea vaccine research is in the stages of antigen discovery and the identification of protective immune responses, and no vaccine has been tested in clinical trials in over 30 years. Recently, however, it was reported in a retrospective case-control study that vaccination of humans with a serogroup B Neisseria meningitidis (Nm) outer membrane vesicle (OMV) vaccine (MeNZB) was associated with reduced rates of gonorrhea.

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  • - The study investigates the virulence of two strains of *Haemophilus ducreyi*, specifically comparing a class I strain (35000HP) and a derivative class II strain (FX548) to assess their potential for vaccine testing against chancroid and cutaneous ulcers in children.
  • - Results showed that the rate of papule formation was significantly higher for 35000HP compared to FX548 (95.8% vs. 62.5%), indicating that FX548 is less virulent in humans.
  • - Despite both strains expressing similar amounts of the hemoglobin receptor (HgbA) and showing comparable growth patterns, FX548's reduced pathogenicity suggests it may not be suitable for evaluating the efficacy of H
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The Ducreyi serum resistance A (DsrA) protein of Haemophilus ducreyi belongs to a large family of multifunctional outer membrane proteins termed trimeric autotransporter adhesins responsible for resistance to the bactericidal activity of human complement (serum resistance), agglutination and adhesion. The ability of DsrA to confer serum resistance and bind extracellular matrix proteins lies in its N-terminal passenger domain. We have previously reported that immunization with a recombinant form of the passenger domain of DsrA, rNT-DsrA, in complete/incomplete Freund's adjuvant, protects against a homologous challenge in swine.

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Haemophilus ducreyi is the causative agent of the sexually transmitted genital ulcer disease chancroid. Strains of H. ducreyi are grouped in two classes (I and II) based on genotypic and phenotypic differences, including those found in DsrA, an outer membrane protein belonging to the family of multifunctional trimeric autotransporter adhesins.

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  • Pathogens need to adhere to cells to cause infections, making strategies to block this adhesion crucial for preventing diseases.
  • The DsrA adhesin from H. ducreyi, a Gram-negative bacterium, is a potential vaccine target since it sticks to host cells and proteins.
  • In testing the rNT-DsrAI vaccine in pigs, those that received it developed strong antibody responses and showed no signs of infection, while control pigs did, suggesting the vaccine may help clear infections by disrupting pathogen adhesion.
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Haemophilus ducreyi is the etiologic agent of the sexually transmitted genital ulcer disease chancroid. In both natural and experimental chancroid, H. ducreyi colocalizes with fibrin at the base of the ulcer.

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  • Haemophilus ducreyi requires heme from human hosts for infection, utilizing TonB-dependent transporters, with HgbA being essential for early infection stages.
  • Active immunization with the HgbA protein provides complete protection in pig models of chancroid, indicating its potential as a vaccine.
  • Passive immunization using anti-nHgbA serum offers some protection against related strains, showing that antibodies can block heme acquisition but do not kill the bacteria directly.
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  • Haemophilus ducreyi causes chancroid and relies on humans for heme, with a vaccine using the hemoglobin receptor HgbA showing effectiveness against a specific strain.
  • The study tested a new vaccine formulation (nHgbAI/MPL) and found it protected pigs from a homologous strain but not from a different strain, indicating a limit to its efficacy.
  • Despite lower antibody levels compared to the previous vaccine, the nHgbAI/MPL vaccine could block binding to the target, implying a need for a broader vaccine approach.
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HgbA is the sole TonB-dependent receptor for hemoglobin (Hb) acquisition of Haemophilus ducreyi. Binding of Hb to HgbA is the initial step in heme acquisition from Hb. To better understand this step, we mutagenized hgbA by deletion of each of the 11 putative surface-exposed loops and expressed each of the mutant proteins in trans in host strain H.

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Resisting the bactericidal activity of naturally occurring antibodies and complement of normal human serum is an important element in the evasion of innate immunity by bacteria. In the gram-negative mucosal pathogen Haemophilus ducreyi, serum resistance is mediated primarily by the trimeric autotransporter DsrA. DsrA also functions as an adhesin for the extracellular matrix proteins fibronectin and vitronectin and mediates attachment of H.

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Haemophilus ducreyi contains 3 TonB-dependent receptors: the hemoglobin receptor HgbA, which is required for virulence in humans; the heme receptor TdhA; and an uncharacterized conserved hypothetical protein TdX (HD0646). A double tdX/tdhA mutant (FX527) was constructed on the background of a human-passaged variant of strain 35000 (35000HP). Six volunteers were infected with 35000HP at 3 sites on one arm and with FX527 at 3 sites on the other.

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The ability to bind extracellular matrix proteins is a critical virulence determinant for skin pathogens. Haemophilus ducreyi, the etiological agent of the genital ulcer disease chancroid, binds extracellular matrix components, including fibronectin (FN). We investigated H.

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The etiologic agent of chancroid is Haemophilus ducreyi. To fulfill its obligate requirement for heme, H. ducreyi uses two TonB-dependent receptors: the hemoglobin receptor (HgbA) and a receptor for free heme (TdhA).

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Haemophilus ducreyi produces two outer membrane proteins, called DltA (H. ducreyi lectin A) and DsrA (H. ducreyi serum resistance A), that contribute to the ability of the organism to evade complement-mediated serum killing.

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Oral live Salmonella vaccine vectors expressing recombinant guest antigens help stimulate systemic, mucosal, humoral, and cell-mediated immune responses against Salmonella and recombinant antigens. It may be possible to use them effectively against Haemophilus ducreyi, the bacterium that causes chancroid, a sexually transmitted genital ulcer disease. This study aimed to test the feasibility of using oral Salmonella vaccine vectors for the evaluation of chancroid vaccine candidates in the temperature-dependent rabbit model of H.

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The Haemophilus ducreyi outer membrane component DsrA (for ducreyi serum resistance A) is necessary for complete resistance to normal human serum (NHS). When DsrA expression in 19 temporally and geographically diverse clinical isolates of H. ducreyi was examined by Western blotting, 5 of the strains expressed a different immunotype of the DsrA protein (DsrA(II)) than the well-characterized prototypical strain 35000HP (DsrA(I)).

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Haemophilus ducreyi, the causative agent of chancroid, is highly resistant to the complement-mediated bactericidal activity of normal human serum (NHS). Previously, we identified DsrA (for ducreyi serum resistance A), a major factor required for expression of the serum resistance phenotype in H. ducreyi.

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