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Biomedical subjects

D Gilbert

Publications and source records attributed to D Gilbert.

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

Overlap of the anti-cardiolipin and anti-nucleosome responses of the (NZW X BXSB)F1 mouse strain: a new pattern of cross-reactivity for lupus-related autoantibodies.

The association of anti-nuclear antigen (ANA) and anti-cardiolipin (CL) antibodies is often observed during systemic lupus erythematosus (SLE) or the primary anti-phospholipid syndrome, thereby raising the possibility of a relationship between these two autoantibody populations. To determine whether ANA and anti-CL antibodies can overlap, we derived, from a male (NZW x BXSB)F1 mouse, 14 hybridomas selected based on their capacities to react with CL and to label HEp-2 cell nuclei. Four of these anti-CL were IgG and bound to CL and phosphatidylserine in a cofactor-dependent manner and reacted strongly with nucleosomes. Variable region sequence analysis indicated that these four monoclonal antibodies (mAb) were derived from three independent B cell clones that used recurrent heavy and/or light chain immunoglobulin rearrangements, as assessed by comparison with each other and prototypic anti-CL mAb previously derived from different lupus mouse strains. These results indicate that anti-CL mAb can have overlapping cross-reactivities with nucleosomes, thereby defining a new category of SLE-related autoantibodies characterized by their capacities to recognize distinct supramolecular complexes, formed by the association of an anionic structure and a protein, that exert a strong selective pressure on autoreactive B cell clones.

Amino Acid Sequence↗
PubMed2000

Two-dimensional electrophoresis and mass spectrometry identification of proteins bound by a murine monoclonal anti-cardiolipin antibody: a powerful technique to characterize the cross-reactivity of a single autoantibody.

Antigenic cross-reactivity, i.e., the capacity of a single antibody to react with apparently dissimilar structures, is a common characteristic of autoantibodies produced during systemic lupus erythematosus (SLE), an autoimmune disease developed by humans and certain strains of mice. Characterization of the extent of cross-reactivity of SLE-related autoantibodies may help identify the immunogenic stimulus, or stimuli, of autoantibody-secreting B-lymphocytes. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) was combined with mass spectrometry (MS) to identify cell proteins recognized by a single monoclonal autoantibody (mAb 4B7), derived from an (NZW x BXSB)F1 mouse and selected based on its capacity to react with cardiolipin, that binds to elements in the cytoplasm and nucleoli of HEp-2 cells as assessed by indirect immunofluorescence assay. Proteins from HL-60 extract were separated by 1-D and 2-D PAGE. Western blotting with mAb 4B7 after SDS-PAGE revealed four bands, two intensely labeled at 35 and 32 kDa, and two weaker ones at 20 and 60 kDa; three spots were detected after 2-D PAGE. After trypsin in-gel digestion of the three protein spots, MS yielded representative matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) Reflector or quadrupole-time of flight (Q-TOF) spectra. The three corresponding proteins were identified as the nucleolar phosphoprotein B23 (nucleophosmin), heterogeneous nuclear ribonucleoprotein A2 (hnRNP A2) and the 60 kDa Ro/SS-A RNP. Thus, these results showed that 2-D PAGE combined with MS constitutes a sensitive and powerful technique to characterize the full extent of cross-reactivity of a single mAb and may constitute a new approach to further characterize the immunogenic cellular components involved in the breakage of B-cell tolerance observed in SLE.

Amino Acid Sequence↗
PubMed2000

The living cell: a complex autodynamic multi-oscillator system?

Life cannot be simply defined in biochemical terms but it is associated with autodynamic behaviour. This fact implies that all aspects of cell biology should be viewed in terms of the resultant temporal features. Theoretical arguments indicate that the dynamic state can be explained only by the existence of periodicity. In accordance with this view, experimental evidence indicates the existence of multiple oscillators and at least some are highly complex, implying that failure to understand aspects of cell biology can stem from inadequate concepts.

Animals↗
PubMed2000

Association of KM genotype with bullous pemphigoid.

Association of kappa light chain immunoglobulin allotypes with bullous pemphigoid was examined in 101 Caucasian patients. Km alleles were determined by polymerase chain reaction amplification followed by restriction enzyme digestion. The frequency of Km(3)/Km(1,2)kappa light-chain genotype was found to be significantly associated with the disease, while that of the Km(3)homozygous genotype was significantly higher in patients with both anti-BPAG1 and anti-BPAG2 autoantibodies.

Autoantigens↗
PubMed2000

A paraneoplastic mixed bullous skin disease: breakdown in tolerance to multiple epidermal antigens.

We report a new type of paraneoplastic mixed bullous skin disease in a patient with a B-cell lymphoma associated with monoclonal IgM kappa paraproteinaemia. The patient's clinical and histological features were reminiscent of bullous pemphigoid. Characterization of antiepidermal antibodies by immunoblotting and indirect immunoelectron microscopy demonstrated a novel pattern of reactivity: IgG antibodies were directed against desmoplakins I-II and BPAG2, and were associated with antidesmoglein 3 polyclonal IgM antibodies. Such an autoreactive pattern involving antidesmoplakins, anti-BPAG2 and antidesmoglein 3 antibodies has not been previously reported. It reflects the breakdown of tolerance to multiple epidermal antigens observed in some patients with malignancy.

Autoantibodies↗
PubMed2000

Sensitivity and specificity of clinical, histologic, and immunologic features in the diagnosis of paraneoplastic pemphigus.

BACKGROUND: Paraneoplastic pemphigus (PNP) is an autoimmune blistering disease characterized by the production of autoantibodies mainly directed against proteins of the plakin family. An overlapping distribution of autoantibody specificities has been recently reported between PNP, pemphigus vulgaris (PV), and pemphigus foliaceus (PF), which suggests a relationship between the different types of pemphigus. OBJECTIVE: Our purpose was to evaluate the sensitivity and the specificity of clinical, histologic, and immunologic features in the diagnosis of PNP. METHODS: The clinical, histologic, and immunologic features of 22 PNP patients were retrospectively reviewed and compared with those of 81 PV and PF patients without neoplasia and of 8 PV and 4 PF patients with various neoplasms. RESULTS: One clinical and 2 biologic features had both high sensitivity (82%-86%) and high specificity (83%-100%) whatever the control group considered: (1) association with a lymphoproliferative disorder, (2) indirect immunofluorescence (IIF) labeling of rat bladder, and (3) recognition of the envoplakin and/or periplakin bands in immunoblotting. Two clinicopathologic and two biologic features had high specificity (87%-100%) but poor sensitivity (27%-59%): (1) clinical presentation associating erosive oral lesions with erythema multiforme-like, bullous pemphigoid-like, or lichen planus-like cutaneous lesions; (2) histologic picture of suprabasal acantholysis with keratinocyte necrosis, interface changes, or lichenoid infiltrate; (3) presence of both anti-epithelial cell surface and anti-basement membrane zone antibodies by IIF; and (4) recognition of the desmoplakin I and/or BPAG1 bands in immunoblotting. Interestingly, 45% of patients with PNP presented initially with isolated oral erosions that were undistinguishable from those seen in PV patients, and 27% had histologic findings of only suprabasal acantholysis, which was in accordance with the frequent detection of anti-desmoglein 3 antibodies in PNP sera. CONCLUSION: The association with a lymphoproliferative disorder, the IIF labeling of rat bladder, and the immunoblotting recognition of envoplakin and/or periplakin are both sensitive and specific features in the diagnosis of PNP.

Humans↗
PubMed2000

Prospective evaluation of the frequency and clinical significance of antineutrophil cytoplasmic and anticardiolipin antibodies in community cases of patients with rheumatoid arthritis.

OBJECTIVES: To evaluate the frequencies of antineutrophil cytoplasmic (ANCA), anticardiolipin (aCLA) and anti-beta(2)-glycoprotein 1 antibodies (abeta(2)-GP1A) in rheumatoid arthritis (RA) of limited duration in patients recruited primarily from private practitioners (80%), and to attempt to correlate the presence of these antibodies with certain clinical and/or biological criteria. Patients and methods. Patients (n = 102) with RA evolving for <5 yr (mean 2.2 yr) were recruited. A home evaluation collected clinical data [Ritchie articular index, Health Assessment Questionnaire (HAQ) index, extra-articular manifestations] and blood for biological analyses [C-reactive protein (CRP), rheumatoid factor, ANCA, aCLA, abeta(2)-GP1A]. ANCA were detected by indirect immunofluorescence on neutrophils and their specificity was determined by enzyme-linked immunosorbent assay (ELISA) and confirmed by immunoblotting; aCLA and abeta(2)-GP1A were detected by ELISA. RESULTS: Patients had mild RA (Ritchie = 11/78 +/- 9.6; HAQ = 0.79/3 +/- 0.7), probably due to the recruitment procedure. ANCA, aCLA and abeta(2)-GP1A frequencies were 18.5, 7 and 0%, respectively. Titres of ANCA and aCLA were low. A perinuclear ANCA staining pattern was exclusively observed and lactoferrin was shown to be the major antigen recognized. No relationship was found between ANCA and aCLA and/or rheumatoid factor, or any clinical manifestations. ANCA were more common in RA of longer duration (cut-off: 4 yr; P = 0.05) and aCLA were correlated with the CRP level (P = 0.05). CONCLUSIONS: In RA of recent onset, ANCA and aCLA were detected at low titres and frequencies, and were not associated with any clinical manifestations. A longitudinal study is needed to determine whether their early appearance is predictive of subsequent disease severity.

Adult↗
PubMed2000

Comparative activities of ciprofloxacin and levofloxacin against Streptococcus pneumoniae in an In vitro dynamic model.

The activities of levofloxacin (500 mg every 24 h) and ciprofloxacin (750 mg every 12 h) against six pneumococcal isolates in an in vitro dynamic model were compared. For one strain, levofloxacin reduced the inoculum by over 4 log CFU/ml and ciprofloxacin reduced the inoculum by over 2 log CFU/ml. For four isolates, both drugs reduced inocula by 4 log CFU/ml within 6 h, suggesting that this dose of ciprofloxacin should be as effective as levofloxacin against these pneumococci.

Anti-Infective Agents↗
PubMed2000

Horizontal Distribution Patterns of Testate Amoebae (Protozoa) in a Sphagnum magellanicum Carpet.

The distribution of soil microorganisms is generally believed to be patchy and to reflect habitat heterogeneity. Despite this general rule, the amount of existing data on species distribution patterns is scarce. Testate amoebae (Protozoa; Rhizopoda) are an important component of soil microbial communities and are increasingly used in ecological and paleoecological studies of Sphagnum-dominated peatlands, but data on the spatial structure of communities are completely lacking. This is an important aspect since quantitative models used for paleoecological reconstruction and monitoring are based on species assemblages. We explored the distribution patterns of testate amoebae distribution in a macroscopically homogeneous Sphagnum carpet, down to a scale of several centimeters. Distributions maps of the species and spatially constrained sample groups were produced. Multivariate and individual spatial autocorrelations were calculated. The importance of spatial structure was quantified by canonical correspondence analysis. Our ultimate goal is to find the finest resolution of environmental monitoring using testate amoebae. The distribution patterns differed among species, resulting in a complex spatial structure of the species assemblage in a whole. Spatial structure accounted for 36% of the total variation of species abundance in a canonical correspondence analysis constrained by spatial variables. This structure was partly correlated to altitude (microtopography) at a very fine scale. These results confirmed the existence of significant broad- and fine-scale spatial structures within testate amoebae communities that could in part be interpreted as effects of ecological gradients. This shows that, on a surface area of 0.25 m(2), ecological conditions which look uniform from a macroscopic point of view are not perceived as such by Sphagnum-inhabiting organisms. Therefore, testate amoebae could prove very useful to monitor fine-scale ecological processes or disturbances. Studies of the species' spatial distribution patterns in combination with autoecological studies are needed and should be included in the toolbox of biomonitoring itself.

Journal Article↗
PubMed2000

[Evaluation of histological criteria for bullous pemphigoid. Correlation with antigens recognized by immunoblotting of anti-epidermal autoantibodies].

The aim of this study was to evaluate the histological findings observed in patients with bullous pemphigoid in whom the diagnosis of bullous pemphigoid could be confirmed by direct immunofluorescence and immunoblot serum analysis. Seven histological criteria were considered for selection of skin biopsy specimens: 1) cleavage of dermal epidermal junction; 2) migration of eosinophils along dermal epidermal junction; 3) presence of intra epidermal eosinophils (with or without associated spongiosis); 4) absence of keratinocyte necrosis; 5) absence of acantholysis; 6) absence of dermal fibrosis; 7) absence of vasculitis. Depending on the number of criteria observed the histological picture was considered as: highly suggestive, suggestive or poorly suggestive of bullous pemphigoid. The histological picture was considered as highly suggestive in 50% of cases, suggestive or poorly suggestive in 37% and 13% of cases respectively. Migration of eosinophils along dermal epidermal junction was observed in 23 biopsy specimens (50%). Histological findings considered as poorly suggestive of bullous pemphigoid consisted of a prurigo-like or an eczematous-like or a drug induced-like picture or no specific cutaneous erosions. An histological picture highly suggestive of bullous pemphigoid was observed in 67% of patients whose serum contained anti-BPAG2 antibodies and in only 36% patients of without anti-BPAG2 antibodies (p=0,04). On the contrary, only one bullous pemphigoid patient (4%) with circulating anti-BPAG2 antibodies had a histological picture poorly suggestive of bullous pemphigoid. These findings are in accordance with the pathogenic properties of anti-BPAG2 antibodies demonstrated in animal models. This study showed that: 1) typical histological findings of bullous pemphigoid are only observed in 50% of skin biopsy specimens. 2) The diagnosis of bullous pemphigoid should be considered in elderly patients even when a poorly specific prurigo-like or eczematous-like histological picture is observed. Moreover, it underlines the usefulness of direct immunofluorescence of skin biopsy specimens and indirect immunofluorescence and immunoblot analysis of serum in such atypical cases of bullous pemphigoid.

Autoantibodies↗
PubMed1999

Expansion of circulating V gamma 9/V delta 1 T cells in a patient with a syndrome of recurrent fever: evidence for an unusual antigen-driven process leading to selection of recurrent motifs within TCR junctional loops of diverse lengths.

Polyclonal expansions of human Vdelta1 T cells have been described in diverse physiopathological situations without strong TCR structural data for an antigen-driven selection. Here, we have analyzed the phenotype and TCR repertoire of gamma delta T cells obtained from the peripheral blood of a 19-year-old patient with a syndrome of recurrent fever, which accounted for up to 40% of CD3(+) T cells and expressed predominantly Vgamma9 and Vdelta1 TCR regions and a memory phenotype. Sequence analysis of Vdelta1-Jdelta1 transcripts derived from peripheral blood lymphocytes (PBL) indicated that, while Vdelta1-Jdelta1 junctional sequences were diverse in length, all but one contained several recurrent motifs at conserved positions from both the 5'- and 3'-ends of the complementarity-determining region (CDR)3 loop. Analysis of gamma delta T cell clones derived from patient PBL demonstrated that Vgamma9(+) but not Vgamma9(-) T cell clones frequently expressed Vdelta1 chains with these characteristics and unveiled a hierarchy between the constraints imposed on the 5'- vs. the 3' motifs of the Vdelta1 CDR3 loops. These results constitute the first strong evidence for a nominal antigen-driven selection of Vdelta1 T cells in vivo and also suggest that the hierarchy of the constraints imposed by antigens respectively on the length and amino acid composition of TCR CDR3 loops differs between alpha beta and gamma delta T cells.

Amino Acid Sequence↗
PubMed1999

Solution structure of the hRPABC14.4 subunit of human RNA polymerases.

The protein hRPABC14.4 is an essential subunit of human RNA polymerases I, II, and III and is required for the transcription of all human nuclear genes. The structure of hRPABC14.4 was determined by nuclear magnetic resonance spectroscopy. The protein fold comprises a highly conserved central domain forming two antiparallel alpha-helices flanked by the less conserved N- and C-terminal regions forming a five-stranded beta-sandwich. Amino acids from the two helices participate in the generation of a hydrophobic surface area which is conserved in all eukaryotic and archaeal homologous subunits, and likely constitutes a critical macromolecular interaction interface. The hRPABC14.4 structure accounts for mutagenesis results in Saccharomyces cerevisiae and provides a structural working model for elucidating the role of this subunit in the molecular architecture and function of the human nuclear RNA polymerases.

Amino Acid Sequence↗
PubMed1999

Immunoblot and immunoelectronmicroscopic analysis of endemic Tunisian pemphigus.

Tunisian pemphigus is a newly described form of endemic pemphigus whose clinical, histological and epidemiological characteristics have recently been detailed. The objective of this study was to analyse the binding properties of autoantibodies present in sera from patients with endemic Tunisian pemphigus using immunoblotting and indirect immunoelectron microscopy (IEM). Thirty patients with pemphigus foliaceus (PF) and six with pemphigus vulgaris (PV) seen in the dermatology department of Tunis Hospital between 1992 and 1994 were selected for this study. Seven of 30 (23%) and six of 12 (50%) PF sera tested bound to the 160 kDa band of desmoglein 1 when tested on bovine tongue and human epidermal extracts, respectively. Two of six and two of three PV sera tested bound to the 130 kDa desmoglein 3 in these two extracts. Immunoblot and indirect IEM showed that 24 of 30 (80%) PF sera contained IgG1, IgG3 or IgG4 antibodies that bound to a 185-kDa polypeptide localized on the desmosomal plaque. This immunological analysis showed that most endemic Tunisian pemphigus sera correspond to PF sera and are characterized by a high frequency of autoantibodies directed against a recently identified 185-kDa antigen of the desmosomal plaque.

Adult↗