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Biomedical subjects

Thomas Bardin

Publications and source records attributed to Thomas Bardin.

At least 19 recordsLinked to original sources
PubMed2007

Paget's disease of bone in the French population: novel SQSTM1 mutations, functional analysis, and genotype-phenotype correlations.

UNLABELLED: Mutation screening of the SQSTM1 gene in 94 French patients with PDB revealed two novel point-mutations (A381V and L413F) and two new compound heterozygous genotypes (P392L/A381V and P392L/A390X). Functional analysis showed an increased level of SQSTM1/p62 protein in PDB patients and truncated forms of the protein encoded by the A390X allele. Clinical data indicate that PDB patients with SQSTM1 mutation are younger at PDB diagnosis and have more extensive bone lesions. INTRODUCTION: Paget's disease of bone (PDB) is a common chronic disease of the skeleton, with a strong genetic component. A recurrent mutation (P392L) was first identified on chromosome 5, in the Sequestosome 1 (SQSTM1) gene. Several other mutations of the SQSTM1 gene have been described in PDB patients, affecting the ubiquitin-associated domain (UBA) of the SQSTM1/p62 protein. The objectives of this study were to evaluate the frequency of the SQSTM1 mutations in French PBD patients, to study the expression of the SQSTM1/p62 protein, and to search for genotype-phenotype correlations. MATERIALS AND METHODS: Blood was obtained from 94 unrelated French PDB patients and 100 controls for mutation screening of exons 7 and 8, encoding for the UBA domain of SQSTM1. Epstein-Barr virus (EBV)-immortalized B-cell lymphocytes were established from 13 patients, giving access to functional analysis of the gene and the SQSTM1/p62 expressions using real-time PCR and Western blot. RESULTS: Mutations of the SQSTM1 gene were identified in 12 of the 94 PDB patients (13%). Eight patients carried P392L. Two novel missense mutations were identified: L413F and A381V. This A381V mutation and A390X were found in distinct patients already carriers of P392L. The SQSTM1/p62 protein expression in PDB patients increased when zero, one, or two mutations were present, and SQSTM1 truncated forms were associated with the A390X mutation. The mean age of PDB diagnosis was younger in patients with the SQSTM1 mutation. PDB was more extensive in patients who carried a SQSTM1 mutation. CONCLUSIONS: Mutations of SQSTM1 are present in the French population. PDB patients with and without the SQSTM1 mutation have an increased level of SQSTM1/p62, caused by overproduction of the protein, probably involved in the pathophysiology of PDB. The presence of the SQSTM1 mutation may be a worsening factor for PDB.

Adaptor Proteins, Signal Transducing↗
PubMed2006

IRF5 rs2004640-T allele, the new genetic factor for systemic lupus erythematosus, is not associated with rheumatoid arthritis.

BACKGROUND: Recently, a new genetic factor within the interferon regulatory factor 5 (IRF5) gene was demonstrated for systemic lupus erythematosus (SLE) through linkage and association: the rs2004640-T allele. IRF5 is involved in the production of rheumatoid arthritis (RA) cytokines, and SLE already shares with RA one genetic factor within the tyrosine phosphatase PTPN22 gene. AIM: To test the hypothesis that the SLE IRF5 genetic factor could also be shared with RA. PATIENTS AND METHODS: 100 French Caucasian trio families with RA were genotyped and analysed with the transmission disequilibrium test, the frequency comparison of the transmitted and untransmitted alleles, and the genotype relative risk. 97% power was available to detect at least a trend in favour of a factor similar to that reported for SLE. RESULTS: The analysis showed the absence of linkage and association globally and in "autoimmune" RA subsets, with a weak non-significant trend against the IRF5 rs20046470-T allele. Given the robustness of familial-based analysis, this slight negative trend provided strong evidence against even a weaker factor than that reported for SLE. CONCLUSION: Our results exclude the IRF5 rs2004640-T allele as a major genetic factor for RA in this French Caucasian population.

Adult↗
PubMed2006

Validation of the reshaped shared epitope HLA-DRB1 classification in rheumatoid arthritis.

Recently, we proposed a classification of HLA-DRB1 alleles that reshapes the shared epitope hypothesis in rheumatoid arthritis (RA); according to this model, RA is associated with the RAA shared epitope sequence (72-74 positions) and the association is modulated by the amino acids at positions 70 and 71, resulting in six genotypes with different RA risks. This was the first model to take into account the association between the HLA-DRB1 gene and RA, and linkage data for that gene. In the present study we tested this classification for validity in an independent sample. A new sample of the same size and population (100 RA French Caucasian families) was genotyped for the HLA-DRB1 gene. The alleles were grouped as proposed in the new classification: S1 alleles for the sequences A-RAA or E-RAA; S2 for Q or D-K-RAA; S3D for D-R-RAA; S3P for Q or R-R-RAA; and X alleles for no RAA sequence. Transmission of the alleles was investigated. Genotype odds ratio (OR) calculations were performed through conditional logistic regression, and we tested the homogeneity of these ORs with those of the 100 first trio families (one case and both parents) previously reported. As previously observed, the S2 and S3P alleles were significantly over-transmitted and the S1, S3D and X alleles were under-transmitted. The latter were grouped as L alleles, resulting in the same three-allele classification. The risk hierarchy of the six derived genotypes was the same: (by decreasing OR and with L/L being the reference genotype) S2/S3P, S2/S2, S3P/S3P, S2/L and S3P/L. The homogeneity test between the ORs of the initial and the replication samples revealed no significant differences. The new classification was therefore considered validated, and both samples were pooled to provide improved estimates of RA risk genotypes from the highest (S2/S3P [OR 22.2, 95% confidence interval 9.9-49.7]) to the lowest (S3P/L [OR 4.4, 95% confidence interval 2.3-8.4]).

Arthritis, Rheumatoid↗
PubMed2006

Successful treatment with rasburicase of a tophaceous gout in a patient allergic to allopurinol.

BACKGROUND: A 56-year-old white woman was referred to our institution with a 16-month history of severe, gouty, recurrent, acute polyarthritis involving the finger joints. She also had numerous small subcutaneous tophi in her hands. The patient was intolerant to allopurinol and had mild renal insufficiency attributed to uric-acid nephrolithiasis and interstitial nephropathy. INVESTIGATIONS: Physical examination, laboratory testing, X-rays of the hands, feet and pelvis, CT of the pelvis, microscopic analysis of an aspirate from a finger tophus. DIAGNOSIS: Tophaceous gout associated with urate nephropathy in a patient intolerant to allopurinol. MANAGEMENT: Acute polyarthritis was successfully managed by intravenous bolus methylprednisolone combined with codeine, diclofenac and low-dose colchicine. Rasburicase infusions combined with fenofibrate and sodium bicarbonate achieved to maintain serum acid uric below 360 micromol/l.

Allopurinol↗
PubMed2006

Muscle involvement in sarcoidosis: a retrospective and followup studies.

OBJECTIVE: Muscle involvement is a frequent histopathologic feature of sarcoidosis, but its clinical presentation has been rarely reported and its longterm outcome is unclear. We describe the features and outcome of 5 patients with muscle sarcoidosis. METHODS: A retrospective study from hospital charts over the period 1985-2001 in 2 academic rheumatology centers. RESULTS: Muscle involvement was identified in 5 patients (3 women, 2 men) aged 37 to 61 years, out of a cohort of 45 patients with sarcoidosis. No symptomatic muscle involvement was observed in the 20 patients with Lofgren syndrome of our series. Muscle involvement was the initial feature of the disease in 2 patients. Three patients had nodular type and the 2 others the myositic type. Chronic myopathy was not observed. Followup of patients with muscle disease ranged from 30 to 144 months (mean 72.6). Prednisone was used at a starting dose from about 0.33 to 1 mg/kg/day in all patients, then progressively tapered, and was associated with use of hydroxychloroquine (HCQ) in 2 cases. One poorly compliant patient was persistently prescribed 40 mg/day prednisone and HCQ by his general practitioner and was still complaining of diffuse myalgia at the last 30-month followup visit. One patient also receiving HCQ experienced cardiac and renal relapse, leading to transient increase in steroid dosage, but remained symptom-free 3 years after steroid discontinuation. Muscle relapses occurred in the 3 other patients. Muscle symptoms disappeared after readministration of corticosteroids or increase of prednisone dosage. The first patient was symptom-free without any treatment at the last followup visit. The second was still taking 10 mg/day 144 months after disease onset because of steroid-dependent myalgia. The last patient was asymptomatic with 10 mg/day prednisone at the last evaluation. CONCLUSION: Symptomatic muscle involvement may be an initial feature of chronic, and usually the systemic form of, sarcoidosis. It responds to corticosteroid therapy, but relapse seems to be frequent.

Adult↗
PubMed2005

Rheumatoid arthritis seropositive for the rheumatoid factor is linked to the protein tyrosine phosphatase nonreceptor 22-620W allele.

The protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene encodes for lymphoid tyrosine phosphatase LYP, involved in the negative regulation of early T-cell activation. An association has recently been reported between the PTPN22-620W functional allele and rheumatoid factor-positive (RF+) rheumatoid arthritis (RA), among other autoimmune diseases. Expected linkage proof for consistency cannot be definitely produced by an affected sib-pair (ASP) analysis. Our aim was therefore to search for linkage evidence with the transmission disequilibrium test. DNA from the French Caucasian population was available for two samples of 100 families with one RA patient and both parents, and for 88 RA index cases from RA ASP families. Genotyping was carried out by PCR-restriction fragment length polymorphism. The analysis was performed using the transmission disequilibrium test, genotype relative risk and ASP-based analysis. The transmission disequilibrium test of the PTPN22-620W allele revealed linkage and association for RF+ RA (61% of transmission, P = 0.037). The genotype relative risk showed the risk allele in 34% of RF+ RA patients and in 24% of controls derived from nontransmitted parental chromosomes (P = 0.047, odds ratio = 1.69, 95% confidence interval = 1.03-2.78). The ASP investigation showed no enriched risk allele in RA multiplex families, resulting in a lack of power of ASP analysis, explaining the published negative results. This study is the first to show linkage of PTPN22 to RF+ RA, consistent with PTPN22 as a new RA gene.

Arthritis, Rheumatoid↗
PubMed2005

New classification of HLA-DRB1 alleles supports the shared epitope hypothesis of rheumatoid arthritis susceptibility.

OBJECTIVE: The shared epitope hypothesis was formulated to explain the involvement of HLA-DRB1 in rheumatoid arthritis (RA). However, several studies, which considered only the HLA-DRB1 alleles shown to be associated with RA risk, rejected this hypothesis. In this report, we propose that a different classification of HLA-DRB1 alleles be considered, based on the amino acid sequence at position 70-74. METHODS: The fit of both HLA-DRB1 classifications was tested in 2 groups of RA patients. All subjects were recruited through the European Consortium on Rheumatoid Arthritis Families, and included 100 patients with isolated RA and 132 patients with at least 1 affected sibling. RESULTS: The new classification produced risk estimates that fit all of the observed data, i.e., the distribution of the HLA-DRB1 genotype in the 2 patient groups, and the distribution of parental alleles shared by affected sibpairs. The risk of developing RA under this new classification depends on whether the RAA sequence occupies position 72-74 but is modulated by the amino acid at position 71 (K confers the highest risk, R an intermediate risk, A and E a lower risk) and by the amino acid at position 70 (Q or R confers a higher risk than D). CONCLUSION: A new classification based on amino acid sequence allows us to show that the shared epitope RAA sequence at position 72-74 explains the data, with the risk of developing RA modulated by the amino acids at positions 70 and 71.

Alleles↗
PubMed2005

Hypomagnesemia and chondrocalcinosis in short bowel syndrome.

Chondrocalcinosis is a result of deposition of calcium pyrophosphate dihydrate (CPPD) crystals in cartilage and fibrocartilage. Chondrocalcinosis is usually sporadic but has also been associated with a variety of metabolic diseases including hypomagnesemia. Reported cases of hypomagnesemia associated chondrocalcinosis were mostly due to renal genetic disorders such as Bartter's or Gitelman's syndrome. We describe 3 patients with chronic hypomagnesemia induced by short bowel syndrome who developed symptomatic chondrocalcinosis. CPPD crystals were identified by polarizing light microscopy in one patient. The underlying intestinal pathology was radiation enteritis in 2 patients and mesenteric arterial thrombosis in the third. Our observations strengthen the hypothesis of a role for magnesium in CPPD crystal deposition disease.

Aged↗
PubMed2004

[Psoriatic rheumatism].

Five to 7% of patients with cutaneous psoriasis suffer from inflammatory rheumatism that is sero-negative for rheumatoid factor, and is often erosive. The inflammation is predominant to the entheses and can affect the axial or peripheral skeleton, often in an associated manner. The most common peripheral signs are those of an asymmetrical oligo-arthritis type, and the most evocative are arthritis of the distal inter-phalangeal joints. A symmetrical polyarthritis can also be observed. The severe mutilating forms are fortunately very rare. Axial signs include sacro-iliitis that is more often bilateral and spinal involvement of an ankylosing spondyloarthitic type, predominating in the cervical and thoracic spine. The treatment usually calls for a non-steroidal anti-inflammatory and local injection of cortisone. Steroids must be used with care and reserved for the severe forms. DMARDS include Salazopyrin, methotrexate, and in the severe and resistant forms, the inhibitors of TNFalpha.

Adult↗
PubMed2004

A TNFR1 genotype with a protective role in familial rheumatoid arthritis.

OBJECTIVE: Results of genome scans in rheumatoid arthritis (RA) have suggested that the tumor necrosis factor receptor I (TNFRI) and TNFRII loci (TNFR1 and TNFR2) are susceptibility loci. A TNFR2 polymorphism was found to be associated with familial RA. TNFR1 is mutated in TNFR-associated periodic syndrome (TRAPS). We undertook this study to test the TNFR1 exonic polymorphism closest to the TRAPS mutations site (+36 A/G) for association with RA. METHODS: DNA samples were available from two groups of the French Caucasian population: 1) 100 families with 1 RA patient and both parents and 2) 86 RA index patients from families with at least 2 siblings with RA (affected sibpairs [ASPs]). The +36 A/G polymorphism of TNFR1 was genotyped by polymerase chain reaction-restriction fragment length polymorphism. The analysis was performed using the transmission disequilibrium test, the genotype relative risk, and a linkage-based test previously described. RESULTS: A negative association between RA and the +36 A/A genotype, suggested in the first sample (P = 0.084), was demonstrated in the second (ASP RA) sample (odds ratio [OR] 0.465; P = 0.012) and confirmed by the linkage-based test (OR 0.17; P = 0.008). The protective genotype, present in 41% of controls, was less frequent in RA patients: 33% in the first sample, 24% in the ASP RA sample, and 11% in the linkage-derived subgroup. Distribution of both TNFR2 196 R/R and TNFR1 +36 A/A genotypes in the ASP RA sample showed that both suspected genotypes were exclusive. CONCLUSION: We found evidence for an association between RA and a TNFR1 protective genotype, restricted to familial RA. Distribution of the TNFR2 196 R/R and TNFR1 +36 A/A genotypes in familial RA could suggest an interaction between TNFR1 and TNFR2 in the genetic susceptibility for RA.

Adult↗
PubMed2004

Dense genome-wide linkage analysis of rheumatoid arthritis, including covariates.

OBJECTIVE: Rheumatoid arthritis (RA) is a heterogeneous disease that exhibits a complex genetic component. Previous RA genome scans confirmed the involvement of the HLA region and generated data on suggestive signals at non-HLA regions, albeit with few overlaps in findings between studies. The present study was undertaken to detect potential RA gene regions and to estimate the number of true RA gene regions, taking into account the heterogeneity of RA, through performance of a dense genome scan. METHODS: In a study of 88 French Caucasian families (105 RA sibpairs), 1,088 microsatellite markers were genotyped (3.3-cM genome scan), and a multipoint model-free linkage analysis was performed. The statistical assessment of the results relied on 10,000 computer simulations. A covariate-based multipoint model-free linkage analysis was performed on the locations of regions with suggestive evidence for linkage. RESULTS: Involvement of the HLA region was strongly confirmed (P = 6 x 10(-5)), and 19 non-HLA regions showed suggestive evidence for linkage (P < 0.05); 9 of these overlapped with regions suggested in other published RA genome scans. A routine 12-cM genome scan with the same families would have detected only 7 of the 19 regions, including only 4 of the 9 overlapping regions. From the 10,000 computer simulations, we estimated that 8 +/- 4 regions (mean +/- SD) were true-positives. RA covariate-based analysis provided additional linkage evidence for 3 regions, with age at disease onset, erosions, and HLA-DRB1 shared epitope as covariates. CONCLUSION: The results of this study provide evidence of 19 non-HLA RA gene regions, with an estimate of 8 +/- 4 as true-positives, and provide additional evidence for 3 regions from covariate-based analysis.

Arthritis, Rheumatoid↗
PubMed2004

The ANKH gene and familial calcium pyrophosphate dihydrate deposition disease.

Familial calcium pyrophosphate dihydrate deposition (CPPD) disease is a chronic condition in which CPPD microcrystals deposit in the joint fluid, cartilage, and periarticular tissues. Two forms of familial CPPD disease have been identified: CCAL1 and CCAL2. The CCAL1 locus is located on the long arm of chromosome 8 and is associated with CPPD and severe osteoarthritis. The CCAL2 locus has been mapped to the short arm of chromosome 5 and identified in families from the Alsace region of France and the United Kingdom. The ANKH protein is involved in pyrophosphate metabolism and, more specifically, in pyrophosphate transport from the intracellular to the extracellular compartment. Numerous ANKH gene mutations cause familial CCAL2; they enhance ANKH protein activity, thereby elevating extracellular pyrophosphate levels and promoting the formation of pyrophosphate crystals, which produce the manifestations of the disease. Recent studies show that growth factors and cytokines can modify the expression of the normal ANKH protein. These results suggest a role for ANKH in sporadic CPPD disease and in CPPD associated with degenerative disease.

Animals↗
PubMed2004

Current management of gout in patients unresponsive or allergic to allopurinol.

The manifestations of gout can be abolished permanently by lifelong urate-lowering therapy maintaining serum urate levels under 360 mmol/l, as this ensures dissolution of pathogenic crystals of monosodium urate monohydrate. Benzbromarone has been withdrawn from the market, leaving allopurinol as the only urate-lowering drug readily available in France. Allopurinol may induce unacceptable side effects, and in patients with dose-limiting renal failure it may not be sufficiently effective. Because allopurinol can induce serious side effects when given concomitantly with purine antimetabolites, it is contraindicated in organ transplant recipients. In patients who cannot tolerate allopurinol, dietary treatment, discontinuation of diuretic agents, and use of losartan or fenofibrate to treat concomitant hypertension or dyslipidemia, respectively, may ensure adequate control of serum urate levels. Desensitization to allopurinol can be attempted in patients with mild cutaneous hypersensitivity reactions but is difficult to perform and rarely used. Uricosuric agents may be helpful in patients with normal or diminished urate excretion. Probenecid is available in France from hospital pharmacies, and benzbromarone can be prescribed via a time-limited authorization procedure. Rasburicase, an Aspergillus urate oxidase produced by genetic engineering, is indicated to prevent acute hyperuricemia induced by chemotherapy for hematological malignancies. Factors that limit the use of rasburicase include the absence of a marketing authorization, the need for parenteral administration, and the absence of validated treatment schedules. Patients with renal failure precluding the use of effective allopurinol dosages are good candidates for benzbromarone therapy. Organ transplant recipients can be given benzbromarone, within the current restrictions to its use; alternatively, mycophenolate mofetil can be substituted for calcineurin inhibitors, which elevate serum urate levels, or for azathioprine, which contraindicates the use of allopurinol.

Allopurinol↗
PubMed2004

Structure-modifying agents for osteoarthritis: an update.

The terms "chondroprotective" and "structure-modifying" were coined to identify a class of drugs capable of preventing, stabilizing, or repairing joint damage caused by osteoarthritis. The method of reference for evaluating structure-modifying effects in knee or hip osteoarthritis is the measurement of joint space loss on serial plain radiographs. Joint space width can be measured manually or by a computer. Several radiological techniques have been described for measuring joint space width in the medial femorotibial compartment of the knee and the superolateral part of the hip. Most studies of potentially structure-modifying effects evaluated slow-acting drugs for osteoarthritis, which are currently used for their delayed symptomatic effect in osteoarthritis. Although most of these agents have shown promising effects in vitro, none has been proven to produce clinically meaningful structure-modifying effects in humans with osteoarthritis.

Animals↗
PubMed2004

Musculoskeletal features of disorders of lipid metabolism and multicentric reticulohistiocytosis.

PURPOSE OF REVIEW: Musculoskeletal features of hyperlipidemia are well known, although rarely encountered by rheumatologists. New data have been collected on the beneficial and adverse effects of lipid-lowering drugs, which are of interest to rheumatologists. Multicentric reticulohistiocytosis is a rare systemic disorder of which joint involvement is an important and frequent feature. Recent advances in its pathophysiology and management have been made. RECENT FINDINGS: Little has been added to the knowledge about the musculoskeletal features of hyperlipidemia in the recent literature. In contrast, the interest in fenofibrate for treating hyperuricemia in patients with lipid disorders or in those intolerant of allopurinol has been further supported. Muscle toxicity of statins continue to retain attention, and the ability of these drugs to induce low-grade myopathy, without increasing serum creatine kinase, has been defended. Multicentric reticulohistiocytosis has been the subject of a number of articles, including reports on the efficacy of cyclosporine and of etanercept in one patient each. SUMMARY: Several issues of therapeutic importance are discussed in this brief review.

Fenofibrate↗
PubMed2003

Prognostic value of early computed tomography in radiculopathy due to lumbar intervertebral disk herniation. A prospective study.

OBJECTIVE: To prospectively evaluate the relationship between the early computerized tomography (CT) features of disk herniation and the clinical outcome in patients with recent-onset sciatic or femoral neuralgia treated conservatively. Early CT is often used, despite the absence of data on usefulness for predicting outcomes. METHODS: Of 78 patients with sciatica or femoral neuralgia of less than 1 month's duration, presumably due to a disk herniation, 75 were found by CT to have a disk herniation at the expected level. All patients were treated conservatively. The 60 patients who were reassessed clinically after 3 months were included in the study. Based on the results of the clinical assessment, the patients were classified as having a good outcome (complete or partial recovery) or a poor outcome. CT findings were compared in these two groups. RESULTS: None of the features of disk herniation studied on the CT scans were significantly correlated with the clinical outcome. A larger herniation or presence of a free fragment was more common in the good outcome group, but the differences were not statistically significant (P= 0.07). CONCLUSION: In this study, early CT scan did not predict the clinical outcome of patients with nerve root pain from lumbar disk herniation. None of the CT criteria was associated with a poor clinical outcome. Early CT scan has no prognostic value in this setting.

Adolescent↗