HLA-DPB1 gene polymorphism and multiple sclerosis: a large case-control study in the southwest of France

The polymorphism at the HLA-DPB1 locus has been characterized in a large number of patients with multiple sclerosis (n = 112) and in healthy controls (n = 115). Both patients and controls lived in the southwest of France (in the Pyrénées Atlantiques) and had similar ethnic background. The typing procedure involved the selective amplification of the second exon of the DPB1 locus by polymerase chain reaction, followed by hybridization of the amplified DNA with 14 sequence-specific oligonucleotide probes. Individual alleles were identified by the pattern of hybridization of the different probes. The distribution of the DPB1 alleles was not significantly different in multiple sclerosis patients and controls (p = 0.11). This does not corroborate the reported association of multiple sclerosis with the primed lymphocyte typing (PLT)-defined DPw4 specificity and is not in favour of a role played by polymorphic residues of the DP molecule in susceptibility to multiple sclerosis.     

Three highly polymorphic microsatellites at the human myelin oligodendrocyte glycoprotein locus, 100 kb telomeric to HLA-F : Characterization and relation to HLA haplotypes

The MOG locus, located on chromosomal bands 6p21.3-p22 and mapped about 100 kb telomeric to HLA-F, was isolated from cosmid ICRFcl09A2434 and shown to contain three microsatellites. These CA-repeat polymorphic markers were characterized in a sample of 173 healthy unrelated individuals and 84 DNAs from the HLA Workshop reference panel, by a method combining fluorescence labeling of PCR products and use of an automated DNA sequencer. For the three markers, frequencies of heterozygotes are well predicted from allele frequencies by the Hardy—Weinberg rule, which suggests that problems of allele nonamplification are unlikely. Typing of cell lines homozygous in the HLA region allowed unambiguous definition of 81 HLA-MOG haplotypes and showed that several HLA ancestral haplotypes extended to the MOG region. The high degree of polymorphism (59%, 51%, and 81% at the three loci, respectively, and 87% at the haplotype level) makes these new markers informative for association or linkage studies with diseases such as hemochromatosis or multiple sclerosis, and for studies aimed at precisely delineating the site of crossover in chromosomes in which recombination occurred in the distal part of the HLA class I region.     

Neurectodermal differentiation of extraskeletal myxoid chondrosarcoma: a classical feature?

Extraskeletal myxoid chondrosarcoma (EMC) is a phenotypically and genotypically distinct entity with a protracted course. A documented case of an extraskeletal myxoid chondrosarcoma characterized by a t(9; 17) (q22; q11) translocation with a neuroendocrine and neural differentiation is reported.     

Recombination pattern of the TCR γ locus in human peripheral T-cell lymphomas

The recombination events of the γ and β T-cell receptor (TCR) loci were analysed in a series of 39 peripheral T-cell lymphomas (PTCLs) in association with the expression of TCR chains. In TCR αβ PTCLs, 22/23 cases showed a γ-gene rearrangement while only 18/23 showed a concomitant β-gene rearrangement. The germline configuration of the β locus was found in angioimmunoblastic lymphadenopathy and lymphoepithelioid lymphomas. Three γδ PTCLs rearranged both γ and β genes. TCR silent PTCLs showed three different patterns of γ- and β-gene rearrangements. Three cases were in germline configuration for both loci; five cases had a rearranged γ and a germline β locus; and five cases had the two loci rearranged. Regarding the variable genes in the γ-rearranged alleles, members of the VγI subgroup were the most frequently presented (39/50), followed by VγII, VγIII, and VγIV (9/50, 1/50, and 1/50, respectively). Joining segment usage was as follows: J1 or J2 (32/50), JP1 or JP2 (17/50), and JP (1/50). Taken together, these data demonstrate that the γ locus is more frequently rearranged whatever the TCR expression. The γ-locus analysis provides a better diagnostic yield than the β locus in the study of PTCL clonality.     

Mycoplasma pneumoniae-associated nephritis in children

 Mycoplasma pneumoniae infection is a rare cause of acute nephritis. Six children (2 girls) aged 5–10 years, admitted for nephritis, had serological tests showing recent Mycoplasma pneumoniae infection. The diagnosis of Mycoplasma pneumoniae infection was based on the presence of serum IgM, detected either by immunofluorescence (IF) (n=1) or enzyme-linked immunosorbent assay (n=5). Four children had a renal biospy, with analysis of parenchymal Mycoplasma pneumoniae components by indirect IF and polymerase chain reaction. Extrarenal symptoms were: respiratory (n=3), ear, nose, and throat (n=2), gastrointestinal (n=3), hepatic (n=1), neurological (n=1), articular (n=1), and hematological (n=3). The patients presented with acute nephritis (1 had a nephrotic syndrome) or with acute renal failure and proteinuria. Pathological findings included type 1 membranoproliferative glomerulonephritis (MPGN, n=1), proliferative endocapillary glomerulonephritis (n=2), and minimal change disease (n=1). The patient with type 1 MPGN progressed rapidly towards end-stage renal failure because of a congenital solitary kidney. Among the patients with endocapillary glomerulonephritis, 1 relapsed 6 months later and remained proteinuric, while the other recovered, as did the child with minimal change disease. The search for Mycoplasma pneumoniae antigens and nucleic acids in renal tissue was negative. However, the absence of the microorganism in the kidney is a common feature of post-streptococcal glomerulonephritis. We conclude that Mycoplasma pneumoniae is a rare yet potential cause of acute glomerulonephritis. Received: 13 September 1996 / Revised: 16 June 1998 / Accepted: 18 June 1998     

Fish Dentitions as Paradigms for Odontogenic Questions

Bony fish, and in particular teleosts, represent a morphologically extremely diverse group of vertebrates, well suited to study certain problems in odontogenesis. In this article we address some questions that can benefit much from the use of fish dentitions as paradigms, such as endodermal participation in tooth formation and epithelial primacy in initiation events. Next, we highlight some results recently obtained in our laboratory with respect to two models, the zebrafish (Cyprinidae), and selected species of cichlids (Cichlidae). Finally, we pinpoint some questions that lend themselves admirably to be examined using fish models, such as the factors that control renewed initiation of teeth, and the relationship (or absence thereof) between Hox genes and tooth formation.     

Advanced glycosylation end products (AGE): new toxins?

Advanced glycation end-products (AGEs) are found in excess during diabetes mellitus, uremia and aging. Non enzymatique glycation, glycoxidation with glucose auto-oxidation and the polyol pathway are involved in the production of AGEs. Tissue accumulation of AGEs and their binding to cell receptors are critical steps in the deleterious consequences of AGE excess. AGE-receptor interaction altered endothelial cells, macrophages, mesangial and mesothelial cell functions. AGEs appear to be involved in the genesis of diabetic micro but also macro-angiopathy. Reduction of AGE clearance and permanent oxidative stress are responsible for AGE excess during uremia. High-flux hemodialysis and peritoneal dialysis reduce AGE level but kidney transplantation is the best treatment to restore homeostasis. New drugs are tested to reduce AGEs or AGE deleterious effects but the best treatment remains the prevention of AGE formation by a strict glycemic control.     

Leka, a New Platelet Antigen Absent in Glanzmann''s Thrombasthenia

The serum of a patient who developed a posttransfusion purpura contained antibodies directed against a previously undescribed platelet antigen Lek a. The antiplatelet activity was present in the IgG fraction and was detected by immunofluorescence, 51Cr lysis and 14C-serotonin release. The frequency of the Lek a phenotype in the French population is 98.18%. Lek a does not appear to be sex-linked and seems to be closely related to the Bak a antigen. The Lek a antigen is not expressed on thrombasthenic platelets but is found on platelets from patients with the Bernard-Soulier syndrome which suggests that this antigen is carried by platelet glycoproteins IIb and/or IIIa.     

Activation of receptor for advanced glycation end products: a mechanism for chronic vascular dysfunction in diabetic vasculopathy and atherosclerosis

Receptor for advanced glycation end products (RAGE) is a member of the immunoglobulin superfamily of cell surface molecules and engages diverse ligands relevant to distinct pathological processes. One class of RAGE ligands includes glycoxidation products, termed advanced glycation end products, which occur in diabetes, at sites of oxidant stress in tissues, and in renal failure and amyloidoses. RAGE also functions as a signal transduction receptor for amyloid beta peptide, known to accumulate in Alzheimer disease in both affected brain parenchyma and cerebral vasculature. Interaction of RAGE with these ligands enhances receptor expression and initiates a positive feedback loop whereby receptor occupancy triggers increased RAGE expression, thereby perpetuating another wave of cellular activation. Sustained expression of RAGE by critical target cells, including endothelium, smooth muscle cells, mononuclear phagocytes, and neurons, in proximity to these ligands, sets the stage for chronic cellular activation and tissue damage. In a model of accelerated atherosclerosis associated with diabetes in genetically manipulated mice, blockade of cell surface RAGE by infusion of a soluble, truncated form of the receptor completely suppressed enhanced formation of vascular lesions. Amelioration of atherosclerosis in these diabetic/atherosclerotic animals by soluble RAGE occurred in the absence of changes in plasma lipids or glycemia, emphasizing the contribution of a lipid- and glycemia-independent mechanism(s) to atherogenesis, which we postulate to be interaction of RAGE with its ligands. Future studies using mice in which RAGE expression has been genetically manipulated and with selective low molecular weight RAGE inhibitors will be required to definitively assign a critical role for RAGE activation in diabetic vasculopathy. However, sustained receptor expression in a microenvironment with a plethora of ligand makes possible prolonged receptor stimulation, suggesting that interaction of cellular RAGE with its ligands could be a factor contributing to a range of important chronic disorders.