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M Lemaire

Publications and source records attributed to M Lemaire.

At least 37 records · Page 2Linked to original sources
PubMed2000

Specific passive immunity reduces the excretion of glycoprotein E-negative bovine herpesvirus type 1 vaccine strain in calves.

We investigated the excretion of either a glycoprotein E (gE)-negative bovine herpesvirus type 1 (BHV1) vaccine strain or a conventional modified-live vaccine strain in both naïve and passively immunised calves. The replication of gE-negative strain was considerably reduced in the maternally immunised calves, in comparison with the non-immune calves. On the other hand, the excretion of the gE-positive conventional vaccine strain was not reduced and even seemed to be prolonged in the presence of maternal antibodies. These results suggest that BHV1 gE may play a role in virus survival in the presence of antibodies.

Animals↗
PubMed2000

The TATA-binding protein-associated factor yTafII19p functionally interacts with components of the global transcriptional regulator Ccr4-Not complex and physically interacts with the Not5 subunit.

The Saccharomyces cerevisiae HIS3 gene is a model system to characterize transcription initiation from different types of core promoters. The NOT genes were identified by mutations that preferentially increased transcription of the HIS3 promoter lacking a canonical TATA sequence. They encode proteins associated in a complex that also contains the Caf1 and Ccr4 proteins. It has been suggested that the Ccr4-Not complex represses transcription by inhibiting factors more specifically required for promoters lacking a TATA sequence. A potential target is the yTaf(II)19 subunit of TFIID, which, when depleted, leads to a preferential decrease of HIS3 TATA-less transcription. We isolated conditional taf19 alleles that display synthetic growth phenotypes when combined with not4 or specific not5 alleles. Inactivation of yTaf(II)19p by shifting these mutants to the restrictive temperature led to a more rapid and striking decrease in transcription from promoters that do not contain a canonical TATA sequence. We demonstrated by the two-hybrid assay and directly in vitro that yTaf(II)19p and Not5p could interact. Finally, we found by the two-hybrid assay that yTaf(II)19p also interacted with many components of the Ccr4-Not complex. Taken together, our results provide evidence that interactions between Not5p and yTaf(II)19p may be involved in transcriptional regulation by the Ccr4-Not complex.

Alleles↗
PubMed2000

A single point mutation in TFIIA suppresses NC2 requirement in vivo.

Negative cofactor 2 (NC2) is a dimeric histone-fold complex that represses RNA polymerase II transcription through binding to TATA-box-binding protein (TBP) and inhibition of the general transcription factors TFIIA and TFIIB. Here we study molecular mechanisms of repression by human NC2 in vivo in yeast. Yeast NC2 genes are essential and can be exchanged with human NC2. The physiologically relevant regions of NC2 have been determined and shown to match the histone-fold dimerization motif. A suppressor screen based upon limiting concentrations of NC2beta yielded a cold-sensitive mutant in the yeast TFIIA subunit Toa1. The single point mutation in Toa1 alleviates the requirement for both subunits of NC2. Biochemical characterization indicated that mutant (mt)-Toa1 dimerizes well with Toa2; it supports specific recognition of the TATA box by TBP but forms less stable TBP-TFIIA-DNA complexes. Wild-type but not the mt-Toa1 can relieve NC2 effects in purified transcription systems. These data provide evidence for a dimeric NC2 complex that is in an equilibrium with TFIIA after the initial binding of TBP to promoter TATA boxes.

Base Sequence↗
PubMed2000

Isolation and characterization of human orthologs of yeast CCR4-NOT complex subunits.

The yeast CCR4-NOT protein complex is a global regulator of RNA polymerase II transcription. It is comprised of yeast NOT1 to NOT5, yeast CCR4 and additional proteins like yeast CAF1. Here we report the isolation of cDNAs encoding human NOT2, NOT3, NOT4 and a CAF1-like factor, CALIF. Analysis of their mRNA levels in different human tissues reveals a common ubiquitous expression pattern. A multitude of two-hybrid interactions among the human cDNAs suggest that their encoded proteins also form a complex in mammalian cells. Functional conservation of these proteins throughout evolution is supported by the observation that the isolated human NOT3 and NOT4 cDNAs can partially com-plement corresponding not mutations in yeast. Interestingly, human CALIF is highly homologous to, although clearly different from, a recently described human CAF1 protein. Conserved interactions of this factor with both NOT and CCR4 proteins and co-immunoprecipitation experiments suggest that CALIF is a bona fide component of the human CCR4-NOT complex.

Amino Acid Sequence↗
PubMed2000

The NC2 repressor is dispensable in yeast mutated for the Sin4p component of the holoenzyme and plays roles similar to Mot1p in vivo.

NC2 (Dr1/DRAP1) and Mot1p are global repressors of transcription that have been isolated in both Saccharomyces cerevisiae and humans. NC2 is a dimeric histone-fold complex that represses RNA polymerase II transcription through binding to TBP and inhibition of TFIIA and TFIIB. Mot1p is an ATPase that removes DNA-bound TBP upon ATP hydrolysis. In this work, we studied the core promoter specificity of NC2 in vivo using a strain that carries mutated NC2beta activity. We show that NC2, like Mot1p, is required for transcription of the HIS3 and HIS4 TATA-less core promoters. Furthermore, whereas neither Mot1p nor NC2 appear to function as repressors of the HIS3 gene in cells growing exponentially in glucose, we find that both are required for repression of the HIS3 TATA promoter when cells go through the diauxic shift. Thus, the activity of these factors is similarly regulated depending upon the physiological conditions, and it appears that core promoters activated or repressed by them in vivo might be distinguishable by whether or not they contain a canonical TATA sequence. Finally, although NC2 is an essential factor for yeast viability, we isolated a mutation in a non-essential component of the holoenzyme, Sin4p, that bypasses the requirement for NC2.

Adenosine Triphosphatases↗
PubMed2000

Production of bovine herpesvirus type 1-seronegative latent carriers by administration of a live-attenuated vaccine in passively immunized calves.

The consequences of the vaccination of neonatal calves with the widely used live-attenuated temperature-sensitive (ts) bovine herpesvirus type 1 (BHV-1) were investigated. The ts strain established acute and latent infections in all vaccinated calves either with or without passive immunity. Four of seven calves vaccinated under passive immunity became clearly BHV-1 seronegative by different serological tests, as did uninfected control calves after the disappearance of maternal antibodies, and they remained so for long periods. A cell-mediated immune response was detected by a BHV-1 gamma interferon assay, but this test failed to detect the seronegative latent carriers (SNLCs). While they are not detected, SNLCs represent a threat for BHV-1-free herds or countries. This study demonstrates that SNLCs can be easily obtained by inoculation with a live-attenuated BHV-1 under passive immunity and that latent carrier animals without any antibody do exist. Consequently, this situation could represent a good model to experimentally produce SNLCs.

Animals↗
PubMed2000

Effects of bovine herpesvirus type 1 infection in calves with maternal antibodies on immune response and virus latency.

The presence of maternally derived antibodies can interfere with the development of an active antibody response to antigen. Infection of seven passively immunized young calves with a virulent strain of bovine herpesvirus type 1 (BHV-1) was performed to determine whether they could become seronegative after the disappearance of maternal antibodies while latently infected with BHV-1. Four uninfected calves were controls. All calves were monitored serologically for 13 to 18 months. In addition, the development of a cell-mediated immune response was assessed by an in vitro antigen-specific gamma interferon (IFN-gamma) production assay. All calves had positive IFN-gamma responses as early as 7 days until at least 10 weeks after infection. However, no antibody rise was observed after infection in the three calves with the highest titers of maternal antibodies. One of the three became seronegative by virus neutralization test at 7 months of age like the control animals. This calf presented negative IFN-gamma results at the same time and was classified seronegative by enzyme-linked immunosorbent assay at around 10 months of age. This calf was latently infected, as proven by virus reexcretion after dexamethasone treatment at the end of the experiment. In conclusion, this study demonstrated that BHV-1-seronegative latent carriers can be obtained experimentally. In addition, the IFN-gamma assay was able to discriminate calves possessing only passively acquired antibodies from those latently infected by BHV-1, but it could not detect seronegative latent carriers. The failure to easily detect such animals presents an epidemiological threat for the control of BHV-1 infection.

Aging↗
PubMed2000

[Percutaneous osteosynthesis of pelvic fractures with CT control].

Pelvis fractures, most often multiple, are frequently unstable. Orthopedic treatment is hardly bearable (traction in bed sometimes up to 45 days), the open reduction and internal fixation (ORIF) is heavy. Percutaneous fluoroscopy guided fixation lacks precision in depth. Percutaneous screw fixation with CT scan control answers these drawbacks and represents a quick solution, with few hazard when performed by a trained team and allows a very early resumption of standing.

Adolescent↗
PubMed1999

A specific PCR to differentiate between gE negative vaccine and wildtype bovine herpesvirus type 1 strains.

In the context of infectious bovine rhinotracheitis (IBR) control programmes using glycoprotein E (gE) deleted marker vaccines, a PCR assay was developed to allow the genotypic differentiation between wildtype bovine herpesvirus type 1 (BoHV-1) and gE negative strains. This assay is based on the PCR amplification of a 281 bp DNA fragment within the gE gene. The specificity of the amplification was confirmed by restriction endonuclease analysis and nucleotide sequencing of the PCR product. Its ability to determine the gE genotype of BoHV-1 strains was demonstrated on isolates coming from 20 experimental calves infected with four different BoHV-1 strains. This PCR assay may be a useful tool for monitoring the spread of live marker vaccine and the gE genotype of viral field isolates.

Animals↗
PubMed1999

Antibody response to glycoprotein E after bovine herpesvirus type 1 infection in passively immunised, glycoprotein E-negative calves.

This study was conducted to determine whether young calves with maternal antibodies against bovine herpesvirus type 1 (BHV-1) but without antibodies against glycoprotein E (gE) can produce an active antibody response to gE after a BHV-1 infection. Five calves received at birth colostrum from gE-seronegative cows which had been vaccinated two or three times with an inactivated BHV-1, gE-deleted marker vaccine. After inoculation with a wild-type virulent strain of BHV-1, all the passively immunised gE-negative calves shed virus in large amounts in their nasal secretions. All the calves seroconverted to gE within two to four weeks after inoculation and then had high levels of gE antibodies for at least four months. The development of an active cell-mediated immune response was also detected by in vitro BHV-1-specific interferon-gamma assays. All the calves were latently infected, because one of them re-excreted the virus spontaneously and the other four did so after being treated with dexamethasone. The results showed that under the conditions of this work the gE-negative marker could also distinguish between passively immunised and latently infected calves.

Animals↗
PubMed1999

Hereditary paraganglioma.

Head and neck paraganglioma is a rare tumour, especially in its familial form. We report a case of a multifocal head and neck paraganglioma in a young man with a family history of cervical tumours. At the age of 24, exploration of a left cervical swelling disclosed jugulotympanic and carotid body paragangliomas. Surgical removal of both tumours was performed. Two years later, a right carotid body as well as vagal paragangliomas were discovered. Follow-up at age 30 demonstrated relapse of the bilateral cervical paragangliomas, but also aortopulmonary and mesogastric paragangliomas. Cervical paragangliomas were also detected in the patient's sister and daughter, but not in his father. Furthermore, the proband's paternal grandmother and a maternal great-uncle had a history of 'neck scar'. This family history is suggestive of an autosomal dominant pattern of inheritance with maternal genomic imprinting. Genetic analysis of paraganglioma kindreds showed linkage with two different loci: 11q13.1 and 11q22.3-q23. Further knowledge of the genes involved could provide early diagnosis and accurate genetic counselling in affected families. Thorough familial investigation is consequently mandatory in all head and neck paragangliomas, especially in younger patients with multiple localizations, as surgical removal is safer at an early stage.

Adult↗
PubMed1999

Absorption and intestinal metabolism of SDZ-RAD and rapamycin in rats.

The new immunosuppressive agent, SDZ-RAD, and its analog rapamycin were examined for intestinal absorption, metabolism, and bioavailability in Wistar rats. Intestinal first-pass metabolism studies from rat jejunum showed that at 0.5 mg of SDZ-RAD/kg rat, 50% of the parent compound was metabolized in the intestinal mucosa, and this decreased to around 30% when SDZ-RAD was increased to 5.0 mg/kg rat. Results for rapamycin at the low dose were similar to those for SDZ-RAD, but at the higher dose only 1 to 14% of the total rapamycin absorbed was metabolized by the intestine. After i.v. administration of 1 mg/kg SDZ-RAD or rapamycin, the area under the concentration curve (AUC) for rapamycin was twice that of SDZ-RAD, resulting in a systemic clearance of 6.2 ml/min and 3.0 ml/min for SDZ-RAD and rapamycin, respectively. However, the AUC for oral absorption was similar for the two compounds: 140 and 172 ng*h/ml for SDZ-RAD and rapamycin, respectively. Because blood clearance was faster for SDZ-RAD after i.v. administration, the absolute oral bioavailability for SDZ-RAD was 16% compared with 10% for rapamycin. Overall, the data suggest that intestinal first pass is a major site of metabolism for SDZ-RAD and rapamycin and that intestinal absorption of SDZ-RAD was much faster than that of rapamycin. This allowed it to counteract the combined actions of faster systemic clearance and increased intestinal metabolism, resulting in comparable absolute exposure when given orally. Also, the coadministration of cyclosporin A with SDZ-RAD was shown to dramatically increase blood AUCs for SDZ-RAD, probably through saturating intestinal metabolism mechanisms.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1999

[Plea for accelerated rehabilitation after ligament plasty of the knee by a bone-patellar tendon-bone graft].

Knee rehabilitation after ACL repair with bone-tendon-bone graft is still controversial. While there was a tendency to protect the graft and the donor site in the eighties, actual tendency is to propose more aggressive, so called accelerated rehabilitation protocol. An extensive analysis of the literature shows that this accelerated rehabilitation is justified because of histologic, biomechanic, surgical and clinical arguments. This accelerated rehabilitation is based on seven reasons, at least: 1) the necrosis of the graft, initially observed in animals, does not seem to be as important in humans as demonstrated by histological studies after in vivo biopsies; 2) the use of solid bone-tendon-bone graft, whose resistance is maximum in the early post-operative period and is superior to the resistance of the ACL; 3) the more precise positioning (more "isometric") because of optic magnification allowed by arthroscopy; 4) the absence of graft impingement, routinely controlled, because of a more posterior tibial placement of the graft and the eventual notch-plasty; 5) the solid and confident fixation of the graft because of interference screws; 6) anterior knee pain are less important when early constraints are applied on the knee; 7) finally, undisciplined and demanding patients who refuse all protection for the graft and the donor site, have good and stable results regarding stability of the knees. Early constraints on the knee after bone-tendon-bone graft and interference fixation give better tolerance on the extension mechanism without compromising integrity of the graft and knee stability. Appropriate level of constraints on the ACL graft and the donor site guides the collagenic reorganisation process. Early restoration of normal hyperextension, decreased knee pain and maintenance of muscular trophicity, allowing patients to go back to sport at 4 months, are the most evident benefits of this accelerated rehabilitation. These considerations cannot be applied to the other grafts (fascia lata, semi-tendinous, allografts ...) and to other ways of fixation (sutures, staples, ...).

Animals↗
PubMed1998

Pyrazole bioisosteres of leflunomide as B-cell immunosuppressants for xenotransplantation and chronic rejection: scope and limitations.

T-cell immunosuppressant-based therapies efficiently control early graft rejection in allotransplantation settings. They fail, however, to prevent those rejection events which are mediated by transplant-induced antibody (Ab) responses such as those involved in xenograft and chronic allograft rejection. This is mainly due to their inability to block T-cell-independent Ab production against the transplanted organs. The bioactive metabolite 2(Z) of leflunomide (1) inhibits the formation of such Ab, but the drug has pharmacokinetic properties and a therapeutic window incompatible with transplantation indications. Pyrazole 3, a constrained analogue of 2(Z), was designed and shown to be conformationally and biologically similar to 2(Z). Further investigations with derivatives of 3 demonstrated that the pyrazoles had very tight structure-activity relationships, the only equipotent compound being 3o. However, in contrast to 2(Z), both 3 and 3o were inactive in vivo due to short half-life and drug concentrations lower than the in vitro obtained IC50 values. Compound 3o inhibits T-cell-independent Ab production by a different biochemical mechanism from that of 2(Z) and 3 and may therefore represent a valuable tool for the identification of new targets for B-cell inhibition.

Administration, Oral↗
PubMed1998

2-Nitrophenylcarbamoyl-(S)-prolyl-(S)-3-(2-naphthyl)alanyl-N-benzyl-N - methylamide (SDZ NKT 343), a potent human NK1 tachykinin receptor antagonist with good oral analgesic activity in chronic pain models.

A lead compound which had sub-micromolar affinity for the rabbit NK1 receptor but negligible affinity for rat NK1 receptors, 3a, was discovered by directed screening. 2-Substitution in the ring of the benzylthiourea substituent in the initial lead was found to be important, and halogens (Cl, Br) in this position were found to improve affinity for the human receptor. The activity of a series of 2-halo-substituted benzylthioureas was then optimized by modification of the proline diphenylmethyl amide, guided by a simple conceptual model based on structural overlay between these early antagonists and NK1 selective peptides. In this way, aromatic amino acid amides were identified which had improved affinity with respect to the starting diphenylmethyl (DPM) amides. The first sub-nanomolar ligand for the human NK1 receptor which arose from this series, 4af, combined a 2-chlorobenzylthiourea unit with a 2-naphthylalanine amide. Contemporaneously it was discovered that the benzylthiourea unit could be simplified to a phenylthiourea providing that an appropriate 2-substituent was also incorporated. Combination of these two series gave 2-NO2 phenylthiourea analogues which led directly to the analogous urea, 5f (2-nitrophenylcarbamoyl-(S)-prolyl-(S)-3-(2-naphthyl)alanyl-N-benz yl- N-methylamide, SDZ NKT 343), a highly potent ligand for the human NK1 receptor (Ki = 0.16 nM). In addition to its high in vitro potency, 5f proved to be a potent orally active analgesic in guinea pig models of chronic inflammatory and neuropathic pain. The nature of the 2-aryl substituent was found to be critical for oral activity in this series. Clinical evaluation of 5f as a novel analgesic agent is currently underway.

Analgesics↗