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C Lecomte

Publications and source records attributed to C Lecomte.

At least 55 records · Page 3Linked to original sources
PubMed1998

Antigenic diversity of bovine viral diarrhoea viral isolates contradicts the concept of herd specific strain.

In the epidemiology of bovine viral diarrhoea (BVD), immunotolerant - persistently infected animals (IPI) appear to be major sources of contamination. These animals produce large quantities of replicating virus and have therefore been proposed as being responsible for generating antigenic variability. However, limited studies have failed to detect antigenic or genetic changes in viruses isolated at different times from IPI. An hypothesis is that the immunotolerance of IPI against their homologous strain is accompanied by immune elimination of antigenic variants. The presence of an IPI in a herd could therefore limit antigenic variation, eventually leading to the existence of herd specific strains. To verify this hypothesis we characterized, against a panel of monoclonal antibodies, 37 BVD virus strains isolated from IPI of 12 herds in Eastern Belgium. Intra-herd antigenic variation was compared to inter-herd variation. Antigenic variation within herds was found to be surprisingly high but, nevertheless, significantly lower than variation between herds.

Animals↗
PubMed1998

Primary HIV-1 infection: diagnosis and prognostic impact.

Acute infection with HIV is symptomatic in approximately two thirds to three-fourths of patients. This stage is defined as primary HIV infection or acute HIV illness. The diagnosis is crucial for public health because counseling can be provided to reduce the risk of transmission and for individual because early antiretroviral treatment could improve the prognosis, slowing the rate of disease progression. Physicians should be aware of the broad clinical spectrum representative of primary HIV infection, which ranges from mild symptoms resembling classic mononucleosis infection to highly severe presentations. Progression to AIDS and to death has been associated with the severity of the acute HIV infection. Clinical trials with combined antiretroviral drugs are needed to identify the best drug combinations as well as the optimal duration of treatment.

AIDS Serodiagnosis↗
PubMed1998

Bovine viral diarrhoea virus induces apoptosis in blood mononuclear cells by a mechanism largely dependent on monocytes.

The induction of apoptosis by bovine viral diarrhoea virus (BVDV) was examined in bovine peripheral blood mononuclear cells (PBMC) incubated with an antigenically homologous pair of non-cytopathic and cytopathic BVDV. Our results show that the cytopathic biotype, in contrast to the non-cytopathic counterpart, induces apoptosis in PBMC. Flow cytometry analysis of cells undergoing apoptosis revealed that: (1) monocytes constitute the major cell population undergoing apoptosis; (2) cytopathic virus also induces apoptosis in BoCD4+, BoCD8+ and BoWC1+ T cells in whole PBMC cultures but not in purified T cell suspensions; (3) the degree of apoptosis of BoCD4+ and BoCD8+ T cells incubated with the cytopathic virus was significantly enhanced by the presence of monocytes. Taken together, these results suggest that bovine monocytes play an important role in apoptosis induced by cytopathic BVDV.

Animals↗
PubMed1998

[Female fertility prognosis and diethylstilbestrol. Personal data and review of the literature].

Diethylstilbestrol (DES) exposure in utero in females is a cause of clear-cell adenocarcinoma of the cervix and of several anatomical and functional disorders of the genital tract. DES exposure must be evoked whenever counselling women for reproductive disorders. In France around 80,000 women have had in utero DES exposure. The cases of 4 young women who consulted our Reproduction Center for reproductive disorders illustrate the usual difficulties faced by these patients. In spite of their difficult past reproductive history (uterine malformations, repeated miscarriages, ectopic pregnancies) and low fertility rate, all four women conceived successfully, either after spontaneous or induced ovulation. We stress the need for adapted psychological and medical care which can lead to successful childbearing in the vast majority of these high-risk patients.

Adult↗
PubMed1997

Solution structure of TsKapa, a charybdotoxin-like scorpion toxin from Tityus serrulatus with high affinity for apamin-sensitive Ca(2+)-activated K+ channels.

TsKapa (TsK), purified from the Buthidae Tityus serrulatus is a very high potent ligand for small-conductance apamin-sensitive calcium-activated potassium channels (SK). It is able to efficiently compete with apamin for binding on this channel (K0.5 = 0.3 nM) [Legros, C. et al., FEBS Lett. 390:81-84, 1996]. The solution structure of TsK has been determined by 2D-NMR techniques, which led to the full description of its 3D conformation: a short alpha helix from residues 14 to 20 and a three-stranded antiparallel beta sheet (residues 2-3, 27-29, and 32-34). The interaction of TsK with the SK potassium channel has been modeled according to the charge anisotropy of the ligand. The resulting dipole moment orientates TsK so that it presents toward the receptor, a surface, mainly basic, encompassing residues K18 and K19 on one side and R9 and Y8 on the other. Despite its three-dimensional structure that is related with scorpion toxins active on voltage-gated potassium channels such as charybdotoxin, the pharmacological activity and specificity of TsK is related with shorter scorpion toxins (i.e., possessing an only two-stranded beta sheet) such as scyllatoxin (also named leiurotoxin I) or P05.

Amino Acid Sequence↗
PubMed1997

Pregnancy after intravenous pulsatile gonadotropin-releasing hormone in a hyperprolactinaemic woman resistant to treatment with dopamine agonists.

It is difficult to achieve pregnancy in hyperprolactinaemic patients in whom prolactin inhibiting agents are ineffective. Medical treatment with bromocriptine, lisuride and the new agent CV 205-502 (quinagolide) was unsuccessful in normalizing hyperprolactinaemia in a 28 year-old woman to treat anovulatory infertility. Repeated Magnetic Resonance Imaging (MRI) was normal, with no images suggestive of prolactin adenoma. A live child was born after pulsatile GnRH treatment despite persistently elevated prolactin levels; normal MRI and decreased prolactin levels were observed after pregnancy. In summary, successful pregnancy can be obtained with pulsatile GnRH treatment in women resistant to old and new medical treatments of hyperprolactinaemia.

Adult↗
PubMed1997

Whipple disease. Clinical review of 52 cases. The SNFMI Research Group on Whipple Disease. Société Nationale Française de Médecine Interne.

Whipple disease is a rare, multiorgan disease with prominent intestinal manifestations. We report a retrospective clinical study of 52 patients recruited in various parts of France from 1967 to 1994. Seventy-three percent of the patients were male. Clinical manifestations preceding the diagnosis were articular for 35 patients (67%), digestive for 8 patients (15%), general for 7 patients (14%), and neurologic for 2 patients (4%). At a later stage of the disease, 44 patients (85%) presented diarrhea, weight loss, and malabsorption, while 8 patients (15%) did not show any gastrointestinal symptom throughout the development of the disease. Forty-three patients (83%) presented arthralgia or arthritis, and 11 (21%) had prominent neurologic symptoms. In addition, cardiovascular symptoms were present in 9 patients (17%); mucocutaneous symptoms, in 9 patients (17%); pleuropulmonary symptoms, in 7 patients (13%); and ophthalmologic symptoms, in 5 patients (10%). All patients but 1 were given a positive diagnosis on histopathologic criteria: jejunal biopsy for 46 patients (90%), lymph node biopsy for 3 patients (6%), brain biopsy for 1 patient (2%), postmortem jejunal and cerebral biopsy for 1 patient (2%). With treatment, the disease evolved favorably in 47 patients (90%), while 5 patients (10%) had unfavorable outcomes (2 deaths from neurologic involvement, 1 patient with chronic dementia, and 2 patients with digestive symptoms insensitive to antimicrobial therapy). Of the 41 patients initially treated successfully and whose treatment has been completed, clinical evolution after discontinuation of treatment was favorable in 34 cases (83%). Clinical relapses occurred in 7 patients. No relapse was observed after treatment by trimethoprim-sulfamethoxazole, alone or following a combination of penicillin and streptomycin, or after the combination of penicillin and streptomycin, whatever the oral follow-up treatment prescribed. The evolution of patients showing a relapse was favorable in all cases after reintroduction of antibiotic therapy. These results are discussed in the light of previously published series and case reports of Whipple disease. The diagnosis of the disease remains difficult at an early phase or when digestive symptoms are absent. It is noteworthy that proximal enteroscopy is sometimes misleading, considered normal on macroscopic examination and nonspecific on pathologic grounds. A normal erythrocyte sedimentation rate represents another pitfall. Histopathology is the key for positive and differential diagnosis, and may require multiple and repeated biopsies. Findings from molecular biology confirm the central role of an uncultured Gram-positive bacillus which was named in 1992 Tropheryma whippelii. A recent report suggests that polymerase chain reaction (PCR) analysis of peripheral blood might allow the diagnosis of Whipple disease in some cases. However, immunologic or cellular parameters such as macrophagic function may play an important, although not clearly elucidated, role in the pathogeny of the disease. Trimethoprim-sulfamethoxazole should be considered the antimicrobial agent of choice in the treatment of Whipple disease, minimizing the risk of cerebral involvement and relapses.

Adult↗
PubMed1997

Differential involvement of disulfide bridges on the folding of a scorpion toxin.

Leiurotoxin I is a neurotoxin, blocker of Ca(2+)-activated apamin-sensitive K+ channel, purified from the venom of the scorpion Leiurus quinquestriatus hebraeus. It is a 31-residue polypeptide reticulated by three disulfide bridges, i.e. Cys3-Cys21, Cys8-Cys26 and Cys12-Cys28. To investigate the role of these disulfide bridges in the folding of this toxin, analogs lacking one disulfide bridge were synthesized. The structures of two analogs in which two half-cystines were placed by alpha-aminobutyrate residues to suppress one disulfide bridge, were analyzed by 1H NMR. The NMR studies reveal a three-dimensional structure identical with the native toxin for the analog lacking disulfide bridge Cys3-Cys21 and a loss of organized structure for another analog lacking disulfide bridge Cys12-Cys28. These analogs are, respectively, fully active and weakly active (2% of the residual activity) when tested in vitro for their ability to interact with their receptor channel and in vivo for their neurotoxic activity in mice. This suggest that disulfide bridge Cys12-Cys28 is essential for the folding process. In contrast, the lack of disulfide bridge Cys3-Cys21 does not affect the folding and the maintenance of bioactive conformation of Leiurotoxin I.

Amino Acid Sequence↗
PubMed1997

Efficacy and safety of desensitization with sulfamethoxazole and trimethoprim in 48 previously hypersensitive patients infected with human immunodeficiency virus.

OBJECTIVE: To study the safety and efficacy of desensitization with the use of a combination product of sulfamethoxazole and trimethoprim in previously hypersensitive patients infected with the human immunodeficiency virus. DESIGN: Prospective survey, with a median follow-up of 16 months (range, 5-24 months). SETTING: Day-care hospital in a referral center. PATIENTS: All human immunodeficiency virus-infected patients who had a history of allergic reactions (eg, rash) to sulfamethoxazole-trimethoprim and who required sulfamethoxazole-trimethoprim prophylaxis. INTERVENTION: The desensitization procedure took 2 days. The full dose (sulfamethoxazole-trimethoprim, 400-80 mg) was reached on the third day according to the following schedule: day 1--4-0.8 mg at 9 AM, 8-1.6 mg at 11 AM, 20-4 mg at 1 PM, and 40-8 mg at 5 PM; day 2--80-16 mg at 9 AM, 160-32 mg at 3 PM, and 200-40 mg at 9 PM; and day 3--400-80 mg at 9 AM. MAIN OUTCOME MEASURE: The onset of cutaneous adverse effects attributable to sulfamethoxazole-trimethoprim therapy within 3 months after desensitization. RESULTS: Of the 48 evaluable patients, 37 (77%) tolerated sulfamethoxazole-trimethoprim desensitization without toxic effects and continued to take sulfamethoxazole-trimethoprim daily. Desensitization failed in 11 cases (5 on day 1, 3 on day 2, and 1 each on days 9, 11, and 90). Acute hypotension and a nonfatal myocardial infarction developed in 1 of these patients. The factors that were predictive of failure were a relatively high CD4+ cell percentage (11% vs 8%; P = .008) and a relatively high CD4+/CD8+ ratio (0.27 vs 0.12; P = .02). CONCLUSIONS: The efficacy of desensitization with sulfamethoxazole-trimethoprim was confirmed; this desensitization procedure was more often successful in patients with lower CD4+ cell percentages and CD4+/CD8+ ratios. However, sulfamethoxazole-trimethoprim therapy should be reintroduced carefully.

Adult↗
PubMed1997

[Cutaneous tuberculosis. A study of 4 cases].

INTRODUCTION: The recent increase in the incidence of tuberculosis has led to the return of cutaneous forms of this disease. In addition, diagnosis can now be made rapidly using genoma amplification. CASE REPORT: Four cases of cutaneous tuberculosis are described in nonimmunosuppressed patients: two cases of lupus vulgaris, including one due to Mycobacterium africanum, and two others of gummas, including one associated with tuberculosis verrucosa. The diagnosis was suggested by epidemiological, clinical, histological and immunological findings and confirmed by culture of the bacilli in 3 cases and by genoma amplification in 1. DISCUSSION: These observations illustrate the difficulties encountered in determining the tuberculosis nature of skin lesions. The clinical presentation, differential diagnosis, the pathophysiology of this disease and the new interest in genoma amplification are discussed.

Adult↗
PubMed1996

Synthesis and characterization of leiurotoxin I analogs lacking one disulfide bridge: evidence that disulfide pairing 3-21 is not required for full toxin activity.

Leiurotoxin I (Lei-NH2), a toxin isolated from the venom of the scorpion Leiurus quinquestriatus hebraeus, is a blocker of the apamin-sensitive Ca(2+)-activated K+ channels. It is a 31-residue polypeptide cross-linked by three disulfide bridges which are presumably between Cys3-Cys21, Cys8-Cys26, and Cys12-Cys28. To investigate the role of these disulfides, analogs of Lei-NH2 lacking one disulfide bridge (i.e., [Abu3,21]Lei-NH2, [Abu8,26]Lei-NH2, and [Abu12,28]Lei-NH2) were chemically synthesized by selective replacement of each pair of half-cystines forming a bridge by two alpha-aminobutyrate (Abu) residues. The two disulfide pairings of the main folded form of the synthetic analogs were established by enzymatic proteolysis. They were as expected between Cys8-Cys26 and Cys12-Cys28 for [Abu3,21]Lei-NH2 but were unexpectedly between Cys3-Cys12 and Cys21-Cys28 for [Abu8,26]Lei-NH2 and between Cys3-Cys8 and Cys21-Cys26 for [Abu12,28]Lei-NH2. The synthetic peptides were tested in vitro for their capacity to compete with the binding of [125I]apamin to rat brain synaptosomes and in vivo for their neurotoxicity in mice. In both assays, [Abu3,21]Lei-NH2 exhibited full Lei-NH2-like activity whereas [Abu8,26]Lei-NH2 and [Abu12,28]-Lei-NH2 possessed only residual activities (< 2% native toxin activity). This suggests that disulfide bridge Cys3-Cys21 is not essential per se for high toxin activity. Circular dichroism (CD) spectroscopy of the three analogs showed that only [Abu3,21]Lei-NH2 exhibited a CD spectrum similar to that of Lei-NH2, suggesting they both adopt closely related conformations, in agreement with the pharmacological data. Structural models of the analogs were constructed on the basis of the disulfide pairing assignment and compared with that of Lei-NH2.

Amino Acid Sequence↗
PubMed1996

The attenuated V60 strain of channel catfish virus possesses a deletion in ORF50 coding for a potentially secreted glycoprotein.

A wild-type strain of channel catfish virus was compared at the genomic level with the attenuated strain V60. In addition to several minor differences, restriction mapping revealed one major deletion (approximately 1200 bp) in ORF50 of the V60 strain. Cloning and sequencing of part of this ORF confirmed the presence of a 1164-bp deletion. It should result in a protein of 282 amino acids instead of 670. The predicted truncated protein lacks most of a threonine-rich, highly repetitive region in its central part. Since the protein encoded by ORF50 possesses a hydrophobic N-terminal leader sequence and no membrane anchor sequence, we suggest that it could be a secreted glycoprotein. This protein might be N-glycosylated (35 potential sites) and, given the repetitive arrangement of its residues (mainly threonines), also heavily O-glycosylated like the mucin-type glycoproteins. The deletion observed in ORF50 of the V60 strain implies the loss of 24 potential N-glycosylation sites and should considerably reduce the extent of O-glycosylation.

Amino Acid Sequence↗
PubMed1996

[Preimplantation assessment: experimental data on animals and humans].

Assessing and/or improving the implantation prognostic remain a major goal for research studies as well as for teams doing embryo transfer in many species. Criteria for such a goal were focussed ten years ago and combined theoretically: -sensitivity for applying to one embryo; -clear cut-off for individual decision; -fastness to be suitable for embryo transfer in due time; -no toxicity or invasiveness for embryo; -finally some simple technical approach in order to be applies by a large number of teams. Moreover whatever may be qualitative or quantitative criteria, they should be relied to the final result as alive newborn. The more ancient way to appreciate embryo quality deal with the simple observation of morphological and kinetic criteria about embryo, but such non invasive approach was obviously limited, in spite of the positive influence of regular blastomers, absence of fragmentation and synchronization with time of transfer on implantation rate. The major transcriptional activity of human embryo developing between 6 and 8 cells stage, of course, were unassessed by transfer to day 2. Moreover the apparent quality of the embryo better reflected oocyte quality than embryo quality. Coculture development encompassed only partially such limitation. Using fluorescent probes, it was possible to evaluate some metabolic activity as well as membrane integrity, but such criteria revealed to be both invasive and uneasily reliable with developmental ability of the embryo. Methods dealing with glucidic, protidic or lipidic metabolisms are developed elsewhere, but revealed uneasy to apply, due both to their invasiveness or technical difficulties and their large inter-individual variability. Some hope has raised by the finding of growth factors or cytokines which are expressed by the embryo and/or embryotrophic but a lot of works remain to be down before an easy practical application.

Animals↗
PubMed1995

Computational studies of crystalline H3PO4.

A polarized split-valence wavefunction was computed for the H3PO4 molecule at its neutron crystallographic valence geometry, and the wavefunction was used to map the molecular electron-density distribution and to simulate X-ray crystal structure factors for both static, at-rest and dynamic thermally averaged structures. The thermal vibrational averaging was approximated using anisotropic mean-square atomic displacements from approximately 300 K neutron diffraction data. The simulated X-ray data were used to test pseudoatom multipole modeling of the valence electron-density distribution, in particular, radial modeling of the M valence shell of the P atom, and deconvolution of the nonspherical density features from anisotropic vibrational smearing.

Crystallography, X-Ray↗
PubMed1995

Experimental electron density in crystalline H3PO4.

X-ray diffraction data for H3PO4 crystals have been measured to dmin = 0.46 A resolution, and used to model the electron-density distribution with the hydrogen structure of the crystals adopted from an earlier neutron diffraction analysis. The molecule is asymmetric in the crystal with site symmetry 1 (C1), but the local symmetries of the pseudoatomic densities are, within experimental error, equivalent as they would be under idealized 3m (C3v) molecular symmetry. Although the experimental analysis entailed substantial problems with absorption and extinction corrections, the static deformation density from the experiment agrees very well with that from a polarized split-valence molecular orbital wavefunction for an isolated molecule with the crystallographic molecular geometry. Hydrogen bonding in the crystal polarizes the molecule's P==O acceptor group towards P(+)--O-, and appears to relocalize the lone-pair density of the P--OH donor groups. Crystal data: anhydrous orthophosphoric acid, H3PO4, M(r) = 98.00, room temperature, P2(1)/c, a = 5.7572 (13), b = 4.8310 (17), c = 11.5743 (21) A, beta = 95.274 (12) degrees, V = 320.55 (25) A3, Z = 4, dx = 2.030 mg mm-3, mu = 0.660 mm-1 for lambda(Mo K alpha) = 0.7107 A, F(000) = 200 e-, R(parallel F) = 0.026 for 3512 unique reflections.

Crystallography, X-Ray↗
PubMed1993

Expression of the bovine viral diarrhoea virus Osloss p80 protein: its use as ELISA antigen for cattle serum antibody detection.

The putative gene encoding the cytopathic bovine viral diarrhoea virus (BVDV) Osloss strain p80 protein was amplified by PCR and inserted into a T7 promoter-based vector for expression in Escherichia coli. Bacterial expression led to cytoplasmic insoluble inclusion bodies which were denatured by urea treatment and renatured by dialysis. Rabbit antisera were raised against this p80 recombinant antigen and assayed for the immunoprecipitation of either p120 or p80 protein from cytopathic or non-cytopathic BVDV biotype-infected bovine cells. The p80 gene sequence was also integrated into a baculovirus genome for its expression in Spodoptera frugiperda insect cells. The recombinant proteins isolated from bacteria or insect cells showed distinct antigenic properties when analysed by ELISA. Their ability to detect anti-BVDV specific antibodies was examined in a monoclonal antibody-based competitive ELISA performed on a series of field cattle sera. This comparative assay revealed the superiority of the insect cell-mediated expression to mimic the natural BVDV antigen produced by cell culture. The baculovirus/insect cell recombinant antigen gave the highest correlation between the ELISA-detected antibodies and the corresponding virus neutralization data.

Animals↗