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P Bertin

Publications and source records attributed to P Bertin.

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

Characterization of polyamine synthesis pathway in Bacillus subtilis 168.

The ubiquitous polyamines fulfil a variety of functions in all three kingdoms of life. However, little is known about the biosynthesis of these compounds in Gram-positive bacteria. We show that, in Bacillus subtilis, there is a single pathway to polyamines, starting from arginine, with agmatine as an intermediate. We first identified the structural gene of arginine decarboxylase, speA (formerly cad), and then described the speE speB operon, directing synthesis of spermidine synthase and agmatinase. This operon is transcribed into two messenger RNAs, a major one for the speE gene and a minor one for both speEand speB. The promoter of the operon was identified upstream from the speE gene by primer extension analysis. Transcription of this operon indicated that the level of agmatinase synthesis is very low, thus allowing a stringent control on the synthesis of putrescine and, therefore, of all polyamines. This is consistent with the level of polyamines measured in the cell.

Aspartate Carbamoyltransferase↗
PubMed1998

Aminoglycoside 6'-N-acetyltransferase variants of the Ib type with altered substrate profile in clinical isolates of Enterobacter cloacae and Citrobacter freundii.

Three clinical isolates, Enterobacter cloacae EC1562 and EC1563 and Citrobacter freundii CFr564, displayed an aminoglycoside resistance profile evocative of low-level 6'-N acetyltransferase type II [AAC(6')-II] production, which conferred reduced susceptibility to gentamicin but not to amikacin or isepamicin. Aminoglycoside acetyltransferase assays suggested the synthesis in the three strains of an AAC(6') which acetylated amikacin practically as well as it acetylated gentamicin in vitro. Both compounds, however, as well as isepamicin, retained good bactericidal activity against the three strains. The aac genes were borne by conjugative plasmids (pLMM562 and pLMM564 of ca. 100 kb and pLMM563 of ca. 20 kb). By PCR mapping and nucleotide sequence analysis, an aac(6')-Ib gene was found in each strain upstream of an ant(3")-I gene in a sulI-type integron. The size of the AAC(6')-Ib variant encoded by pLMM562 and pLMM564, AAC(6')-Ib7, was deduced to be 184 (or 177) amino acids long, whereas in pLMM563 a 21-bp duplication allowing the recruitment of a start codon resulted in the translation of a variant, AAC(6')-Ib8, of 196 amino acids, in agreement with size estimates obtained by Western blot analysis. Both variants had at position 119 a serine instead of the leucine typical for the AAC(6')-Ib variants conferring resistance to amikacin. By using methods that predict the secondary structure, these two amino acids appear to condition an alpha-helical structure within a putative aminoglycoside binding domain of AAC(6')-Ib variants.

Acetyltransferases↗
PubMed1998

Methotrexate and cyclooxygenase metabolism in cultured human rheumatoid synoviocytes.

OBJECTIVE: Our objective was to characterize the effect of methotrexate (MTX) on prostaglandin E2 (PGE2) synthesis in cultured human rheumatoid synovial cells. Prostaglandins (PG) are important mediators of inflammation and joint destruction in rheumatoid arthritis (RA). Two isoforms of cyclooxygenase (COX), the key enzyme in PG synthesis, have been characterized: a constitutively expressed form, COX-1, and an inducible form, COX-2. The mechanisms of action of low dose MTX in RA treatment are still poorly understood. As the clinical effects are often first noticed within a month of starting MTX therapy, an antiinflammatory action has been proposed. METHODS: Adherent synovial cells were obtained by collagenase digestion of rheumatoid synovium, isolated from patients with RA undergoing synovectomy. Between passages 3 and 6, cultured synovial cells were incubated with or without MTX for 54 h, at various concentrations. Interleukin (IL)-1beta (1 ng/ml) was added or not for the last 6 h of incubation. Supernatants were harvested and assayed for PGE2 by enzyme immunoassay (EIA). Exogenous [1-14C]arachidonic acid metabolism of synoviocytes was analyzed by reverse phase high performance liquid chromatography (RP-HPLC). COX-1 and COX-2 mRNA expression was determined by total RNA extraction and reverse transcription polymerase chain reaction. RESULTS: Cellular viability was not affected by MTX. EIA showed that MTX decreased IL-1beta induced PGE2 production by synoviocytes in a dose dependent manner. RP-HPLC analysis confirmed the inhibition of PGE2 and (12S)-12-hydroxy-5,8,10-heptadecatrienoic acid production. COX-1 and IL-1beta induced COX-2 mRNA expression were not inhibited by MTX. CONCLUSION: MTX has an inhibitory effect on IL-1beta stimulated production of PGE2 by cultured human rheumatoid synoviocytes, without affecting either COX mRNA expression. Among various biochemical and immunologic events, MTX could have an antiinflammatory action by decreasing PGE2 release.

Antirheumatic Agents↗
PubMed1998

Influence of biological variables upon pharmacokinetic parameters of intramuscular methotrexate in rheumatoid arthritis.

The pharmacokinetics of methotrexate were studied in 22 patients receiving 5-15 mg per week in a single i.m. administration for rheumatoid arthritis. The data consisted of 3 plasma levels per patient, taken at 2, 6, and 12 hours after the administration. The concentration of methotrexate was determined by fluorescence polarization immunoassay. The pharmacokinetic parameters of a 2-compartment model were determined by Bayesian estimation using the population values of Bressolle et al. [1996]. The fitted parameters were: total plasma clearance of methotrexate (CL), first-order absorption constant (ka), volume of central compartment (V1), and transfer constants between the 2 compartments (k12 and k21). Additional parameters were derived from the fitted ones: maximal concentration (Cmax), time to maximum (tmax), volume of distribution at steady-state (Vss), and terminal half-life (t1/2). Twenty-one biological covariates were considered to explain the interpatient variability. The relationships between these covariates and the pharmacokinetic parameters were investigated by principal component analysis and multiple regression analysis. About 90% of the variability of CL were explained by 4 variables (sex, age, height and serum creatinine). About 50%-70% of the variability of the other pharmacokinetic parameters were explained by a set of covariates including age, height, creatinine, creatinine clearance, and dose. The effect of dose was noticed mainly on k12, Vss, and t1/2, thus suggesting that the transfer of the drug from plasma to tissues may be nonlinear. The possibility of predicting CL with a good precision would facilitate the computation of dosage regimens in these patients.

Adult↗
PubMed1998

Is there an optimal time to administer methotrexate in the treatment of rheumatoid arthritis?

OBJECTIVE: To determine the optimal time to administer methotrexate (MTX) in rheumatoid arthritis (RA). METHODS: In a crossover study 23 patients were administered MTX intramuscularly at either 10 AM or 6 PM. A 2 week interval separated the 2 injections. MTX concentrations were measured using a fluorescence polarization immunoassay. Pharmacokinetic variables were estimated using a Bayesian approach. The morning and evening schedules were compared using analysis of variance to determine the optimal time of injection. RESULTS: No statistical difference was found in the pharmacokinetics of MTX according to hour of injection. A difference in the creatinine clearance, however, was observed in the samples obtained at noon and 8 PM, but clearance of MTX was unchanged. CONCLUSION: Pharmacokinetic variables suggest that MTX can be administered either in the morning (10 AM) or evening (6 PM) in the treatment of RA.

Adult↗
PubMed1998

A randomized, double blind, placebo controlled multicenter trial of murine anti-CD4 monoclonal antibody therapy in rheumatoid arthritis.

OBJECTIVE: To assess safety and efficacy of a murine anti-CD4 monoclonal antibody (Mab) in a population of patients with rheumatoid arthritis (RA) compared to treatment with placebo. METHODS: Fifty-eight patients with defined RA were included in this placebo controlled, randomized, double blind, multicenter study. Of the 48 women and 10 men (mean age 54.5 years), 25 were functional class II and 31 were class III, with 9 years' disease duration; the mean of previous disease modifying antirheumatic drugs was 4; 49 were taking steroids (mean dosage 11 mg/day of prednisone). Eighty percent were rheumatoid factor positive. All were in an active state of the disease with: pain > 4 (mean at inclusion 6.6), tender joints > 4 (mean 12), swollen joint count > 3 (mean 9), morning stiffness > 45 min (mean 185), erythrocyte sedimentation rate > 30 mm (mean 59) or C-reactive protein (CRP) > 30 mg/l (mean 63). Treatment was randomized between murine anti-CD4 Mab (B-F5, Diaclone, 20 mg/day) or placebo intravenously for 10 consecutive days. Efficacy was assessed with a composite index (Paulus), with evaluation of number of patients with 20 or 50% improvement in each group. Changes in measures of single clinical or biological variables were also evaluated. RESULTS: The 2 groups were comparable at inclusion. Treatment was well tolerated. Mild side effects (chills, fever, rash) were seen in both groups. Percentage of patients with global 20 or 50% response did not differ between placebo and Mab groups at Day 10 or at Day 30. Evaluation of single variables showed reduced CRP, swollen joint count, and Ritchie index in some B-F5 patients at Day 10, although in the B-F5 group as a whole only CRP was significant. CONCLUSION: No significant improvement in RA after murine anti-CD4 Mab was observed.

Adult↗
PubMed1997

Role of Escherichia coli histone-like nucleoid-structuring protein in bacterial metabolism and stress response--identification of targets by two-dimensional electrophoresis.

The histone-like nucleoid-structuring protein, H-NS, is a major bacterial chromatin component which influences DNA structure and gene expression. Mutations in hns, the structural gene of H-NS protein, have been shown to result in highly pleiotropic effects in Escherichia coli cells. In this study, we have initiated an index of the proteins whose synthesis is, directly or indirectly regulated by H-NS. Using two-dimensional gel electrophoresis, we have examined the global changes in gene expression which occured in an hns background compared with its wild-type parent. In addition, we analysed the effects of mutations in two other genes i.e. lrp and pta, which are also involved in global regulatory pathways. Although these comparative analyses revealed several common differences, thus suggesting possible interactions between these regulatory mechanisms, i.e. H-NS, Lrp (leucine-responsive regulatory protein) and acetylphosphate, the most extensive modifications occurred in an hns mutant. Among the polypeptides whose level of synthesis was specifically altered in an hns mutant, several corresponded to H-NS targets previously identified by classical selection methods. Moreover, the present study allows us to characterize several H-NS targets, which were identified either by comparison with the E. coli two-dimensional reference maps or by microsequencing procedure. Many of these newly identified polypeptides are involved in adaptation of E. coli cells to environmental challenges, and one of them could be involved in bacterial virulence. Finally, synthesis of several proteins belonging to the heat-shock regulon, more particularly molecular chaperones, was induced in an hns mutant.

Amino Acid Sequence↗
PubMed1997

Characterization of BpH3, an H-NS-like protein in Bordetella pertussis.

This study describes the characterization of BpH3, a Bordetella pertussis DNA-binding protein. Sequence analysis reveals significant homology with the H-NS sequence of Escherichia coli and Haemophilus influenzae, particularly in the C-terminal part of the proteins. Our results provide evidence that H-NS and BpH3 display functional homology. First, expression of BpH3 in an hns mutant results in restoration of motility, an H-NS-dependent phenotype. This effect is dependent on the level of BpH3 expression and results from transcriptional activation of the flagellar master operon. Second, the high level of beta-glucosidase associated with hns mutations is reversed to the low wild-type level in the presence of BpH3. Third, BpH3 is able, like H-NS, to preferentially bind in vitro to curved DNA fragments, such as flhDC and bla promoter regions. Our results are the first demonstration that proteins homologous to H-NS exist in bacteria phylogenetically distant from H. influenzae and enterobacteria.

Amino Acid Sequence↗
PubMed1996

[Medical treatment of osteoarthritis].

Immediate symptom relief, long-term symptom relief and chondroprotection comprise the basis of medical treatment of degenerative joint disease. Nonsteroid anti-inflammatory agents, antalgics and intra-articular infiltrations with corticosteroids provide rapid relief. A more delayed long-term effect can be obtained with a large number of drugs. Chondroprotectors are currently the focus of therapeutic research. Advances in our knowledge of the pathophysiological processes involved in the development of the degenerative process, a critical analysis of current medical therapies and rigorous methodology in clinical trials will soon provide a better range of treatments for patients suffering from degenerative joint disease.

Humans↗
PubMed1996

t(1;5)(q23;q33) in a patient with high-risk B-lineage acute lymphoblastic leukemia.

The t(1;5)(q23;q33) is a rare genetic anomaly that was reported previously in two infants with a myeloproliferative disorder and eosinophilia and in one adult patient with acute nonlymphocytic leukemia (ANLL). A 13-year-old boy with high-risk early pre-B acute lymphoblastic leukemia (ALL) who presented to our institution carried the t(1;5)(q23;q33). He had an initial blast count of 230 X 10(9)/L and responded poorly to prednisone. Complete remission (CR) was achieved, and he had a bone marrow (BM) relapse 3 months after despite intensive consolidation therapy. He underwent allogeneic BM transplantation (BMT) from a human leukocyte antigen (HLA)-identical siblings in early relapse with total body irradiation (TBI) and cyclophosphamide conditioning. He had a short second CR with a central nervous system (CNS) relapse on day + 106 after BMT. Two of the previously reported patients also did not respond to chemotherapy. The t(1;5)(q23;q33) appears to be a rare lineage nonspecific anomaly related to hematologic malignancies that are resistant to current therapy.

Adolescent↗
PubMed1996

Selective engraftment of the granulocyte compartment after allogeneic bone marrow transplantation in a patient with severe aplastic anemia.

PURPOSE: We present a patient with severe aplastic anemia who had partial engraftment with full chimerism after allogeneic bone marrow transplantation from an HLA identical sibling. PATIENTS AND METHODS: A 3-year-old girl with severe aplastic anemia (SAA) received a bone marrow transplantation (BMT) from an HLA identical brother 9 months after her diagnosis. Before BMT she was red blood cell tranfusion dependent, had an absolute neutrophil count (ANC) of 1,000-1,500 x 10(9)/1 and a platelet count of 15-19,000 x 10(9)/1. She was conditioned with 800 cGy total body irradiation (TBI) and cyclophosphamide and received 3X10(8) nucleated cells/kg. RESULTS: She reached an ANC of 1500 x 10(9)/1 on day +35 but her reticulocyte and platelet counts did not recover. A bone marrow aspirate and biopsy post BMT showed hypoplasia with marked decrease in megakaryocyte and red blood cell precursors. The granulocyte compartment showed a left shift with predominance of promyelocytes and myelocytes. The karyotype showed full chimerism (46,XY) with no 46,XX metaphases. CONCLUSION: This case illustrates the possibility of a bone marrow microenvironment defect as the cause of SAA.

Anemia, Aplastic↗
PubMed1996

Fluoroquinolone induced tendinopathy: report of 6 cases.

We describe 6 cases of fluoroquinolone induced Achilles tendinitis in 4 women and 2 men, mean age 68.6 years. Patients presented with pain and swelling of sudden onset, which was most often bilateral. Tendon rupture was frequent, accompanied by nodules and ecchymoses. The diagnosis was clinical, occasionally ultrasonography was helpful; the role of magnetic resonance imaging has yet to be defined. Certain risk factors were found, particularly association with longterm steroid therapy, and close surveillance of high risk subjects is mandatory. Although proper dosage and duration of treatment were respected, the principal fluoroquinolones were clearly incriminated. We found no correlation between treatment duration and the degree of involvement. Nevertheless, immediate discontinuation of the antibiotic and placement of both Achilles tendons at rest is essential. Early and appropriate management did not prevent prolonged recovery times and there was always a risk of functional sequelae. This side effect is class related and rare. Its physiopathologic mechanism is poorly understood.

Adult↗
PubMed1996

Bovine collagen induced systemic symptoms: antibody formation against bovine and human collagen.

We describe the first case of systemic symptoms after injection of bovine collagen and silicone polymers associated with antibodies to both native type I and II bovine and human collagen that varied with clinical features. Joint inflammation, edema at the injection site of bovine collagen implant and fever appeared 6 months after injection. Our patients history raises the question of whether the injection of animal derived collagen, particularly combined with silicone, induces or exacerbates autoimmune disease.

Adult↗
PubMed1996

Synovial cyst at the C1-C2 junction and spondyloarthropathy.

A spinal synovial cyst is a rare extradural benign tumor generally located at the lumbar spine, arising at the facet joint capsule, and usually associated with degenerative changes. We describe a 64-year-old woman with a synovial cyst involving the quadrate ligament of the odontoid process, which caused neurologic signs. Her family history was positive for spondyloarthropathy. The radiologic investigations, preoperative differential diagnosis, and association of spondyloarthropathy with this rare benign foramen magnum tumor are of particular interest.

Cervical Vertebrae↗