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D Gilbert

Publications and source records attributed to D Gilbert.

At least 73 records · Page 4Linked to original sources
PubMed1997

A complementarity-determining region peptide of an anti-desmosome autoantibody may interact with the desmosomal plaque through molecular mimicry with a cytoplasmic desmoglein 1 sequence.

The sera of patients with pemphigus, a group of autoimmune blistering skin diseases, contain autoantibodies directed against components of adhering junctions termed desmosomes. F12, a human monoclonal antibody derived from a pemphigus patient, recognizes an unknown polypeptide of the desmosomal and hemidesmosomal plaques. The third complementarity-determining region of the F12 heavy chain (VH-CDR3) was shown to share a four-amino-acid sequence (GSSG) with the intracellular domains of desmoglein 1 and bullous pemphigoid antigen 2 which interact with components of, respectively, the desmosomal and hemidesmosomal plaques. Computer modeling of F12 showed that the GSSG sequence protudes inside the antigen-combining site and thus might be involved in antigen interactions. The GSSG sequence is essential to F12 function, since a peptide containing the VH-CDR3 inhibited its binding to target antigens while VH-CDR3 peptides with specific modifications of the GSSG sequence did not. These data allow us to hypothesize that certain autoantibodies produced during the course of an autoimmune disease can behave as adhesion molecules, through the molecular mimicry of the motif involved in protein/protein adhesion, and to propose a new self-antigen binding mechanism for some autoantibodies.

Amino Acid Sequence↗
PubMed1997

Idiotypic analysis of anti-nucleosome monoclonal antibodies derived from lupus mice.

3F6 and 2E1 are anti-(H2A-H2B) monoclonal antibodies derived from a 12-month-old (NZBxNZW)F1 mouse that diverged from the same clonal precursor by somatic mutations. Rabbit anti-idiotypic antisera were prepared against these two monoclonal antibodies and used as probes to analyse the properties and expression of 3F6 and 2E1 idiotypes. Both idiotypes were conformational, distant from the antigen binding site and did not correlate with a VH- or VL-chain usage. 3F6 was preferentially bound by anti-3F6 idiotype but was weakly recognized by anti-2E1 idiotype suggesting, since 3F6 derives from 2E1, that 3F6 bore idiotypic determinants generated by somatic mutations. While none of the murine anti-DNA monoclonal antibodies tested expressed 2E1 or 3F6 idiotypes, 3F6 idiotype could be detected on approximately one-third of anti-(H2A-H2B) monoclonal antibodies derived from other lupus strains of mice, demonstrating the presence of cross-reactive idiotypes on autoantibodies directed against a nucleosome that could result from somatic mutations.

Animals↗
PubMed1997

Human and murine PTX1/Ptx1 gene maps to the region for Treacher Collins syndrome.

Ptx1 belongs to an expanding family of bicoid-related vertebrate homeobox genes. These genes, like their Drosophila homolog, seem to play a role in the development of anterior structures and, in particular, the brain and facies. We report the chromosomal localization of mouse Ptx1, and the cloning, sequencing, and chromosomal localization of the human homolog PTX1. The putative encoded proteins share 100% homology in the homeodomain and are 88% and 97% conserved in the N- and C-termini respectively. Intron/exon boundaries are also conserved. Murine Ptx1 was localized, by interspecific backcrossing, to Chr 13 within 2.6 cM of Caml. The gene resides centrally on Chromosome (Chr) 13 in a region syntenic with human Chr 5q. Subsequent analysis by fluorescent in situ hybridization places the human gene, PTX1, on 5q31, a region associated with Treacher Collins Franceschetti Syndrome. Taken together with the craniofacial expression pattern of Ptx1 during early development, the localization of the gene in this chromosomal area is consistent with an involvement in Treacher Collins Franceschetti Syndrome.

Amino Acid Sequence↗
PubMed1997

Modeling of anti-nucleosome immunoglobulin Fv domains: analysis of electrostatic interactions.

Three-dimensional structural models of six murine anti-(H2A-H2B) monoclonal autoantibody variable fragments were built by comparative molecular modeling using the COMPOSER software. Analysis of the antibody combining sites is based on the hypothesis that ionic and/or electrostatic interactions predominate in antigen antibody binding, as suggested by the cationic nature of histones and the amino acid sequences of the antibody hypervariable regions. The study of the electrostatic potentials of their combining site surfaces, computed with the MOLCAD software, and the comparison with the electrostatic potentials of 13 selected control mAbs show the lack of a unique electrostatic pattern. One group of three mAbs expresses a strong and large electronegative area, supporting the hypothesis that ionic interactions predominate in antigen recognition. The second group, containing the other three mAbs, exhibits an alternation of electropositive and electronegative areas. All, however, present a localized electronegative area in the vicinity of H-CDR1 and H-CDR2 loops that is generated by the presence of at least one acidic residue. The model suggesting that the binding activity may depend on charged residues at the same site is reminiscent of what was previously reported in anti-DNA mAbs. In addition, the alternation of electropositive areas and electronegative areas in second group mAbs is also frequently observed in certain anti-DNA mAbs. These data argue for the existence of relationships between these two autoantibody populations and suggest that they share a common immunogenic particle formed by anionic and cationic components, such as a nucleosome.

Amino Acid Sequence↗
PubMed1997

Estimating progression of visual field loss in glaucoma.

PURPOSE: The authors estimated the prevalence and rates of progressive visual field loss in glaucoma patients followed annually for a median of 6.3 years. METHODS: Linear regression was used to estimate rates of progression of mean deviation, corrected pattern standard deviation (CPSD), clusters of locations based on the Glaucoma Hemifield Test (GHT), and location specific changes in C-30-2 fields of the Humphrey Analyzer. RESULTS: Sixty-seven eyes of 56 patients whose first two consecutive fields were abnormal on GHT were included. Almost all patients were under treatment or had undergone surgery for glaucoma. Visual field deteriorated in 19 (28%) eyes based on worsening of one or more CPSD, GHT clusters, or individual test locations (regression slopes significantly different from zero). Corrected pattern standard deviation deteriorated in 5 eyes, at least one GHT cluster deteriorated in 17 eyes, and one or more individual test locations deteriorated in 15 eyes. For those whose visual field deteriorated, CPSD increased by 0.9 dB/year. Glaucoma Hemifield Test clusters declined by between 1.4 and 2.4 dB/year. Deterioration at individual locations ranged from 1.0 to 5.0 dB/year. Age, but not baseline visual field severity, was predictive of further visual field loss. The odds ratio for the association between progressive visual field loss and thinning of the nerve fiber layer was 1.81 (95% confidence interval: 0.52, 6.33), and 3.78 (95% confidence interval: 0.80, 18.16) for the association between progressive visual field loss and optic disc changes during follow-up based on masked photograph readings. CONCLUSIONS: Less than one in three eyes of patients with glaucoma had any progressive field loss. Average changes in threshold sensitivities of less than 1 dB/year could not be detected with seven fields done over 6 years. Larger changes or increased frequency of visual field testing would need to occur before smaller changes could be detected statistically.

Disease Progression↗
PubMed1997

Identification of a new antibody population directed against a desmosomal plaque antigen in pemphigus vulgaris and pemphigus foliaceus.

Pemphigus vulgaris and pemphigus foliaceus are characterized by autoantibodies directed against transmembrane glycoproteins of desmosomes. F12, a human monoclonal autoantibody that binds to the desmosomal plaque, recognizes a 180-190-kDa doublet when immunoblotted against bovine tongue epithelium. Because F12 was derived from the peripheral blood lymphocytes of a patient with pemphigus vulgaris, we looked for the presence of anti-180-190-kDa antibodies in pemphigus vulgaris and pemphigus foliaceus serum. By immunoblot analysis, a third of the pemphigus serum contained anti-180-190-kDa antibodies that belonged to IgG subclass 1 or 3, unlike those that recognized desmogleins 1 and 3 (IgG4). By immunoelectron microscopy analysis on human oral mucosa and human skin with mAb to human IgG3, pemphigus serum containing anti-180-190 kDa antibodies recognized desmosomal plaques. The presence of antibodies with F12 properties in pemphigus serum was further demonstrated by a rabbit anti-F12 idiotype antiserum that allowed detection of F12 idiotype in serum with anti-180-190-kDa antibodies. These results indicate that some pemphigus vulgaris and pemphigus foliaceus serums contain antibodies that react with both intra- and extracellular structures of desmosomes and further demonstrate the heterogeneity of the autoimmune response in both types of pemphigus.

Antibodies, Monoclonal↗
PubMed1997

Net effect of inoculum size on antimicrobial action of ampicillin-sulbactam: studies using an in vitro dynamic model.

To examine the predictable effect of inoculum size on the kinetics of the antimicrobial action of ampicillin-sulbactam, five TEM-1 beta-lactamase-producing Escherichia coli strains were studied in an in vitro dynamic model at two different initial inocula (N0S). All bacteria were exposed to ampicillin-sulbactam in a simulated system reflecting the pharmacokinetic profiles in human tissue after the administration of a single intravenous dose of ampicillin (2 g) plus sulbactam (1 g). Each strain was studied at low (4.0 to 5.2 log CFU/ml) and high (5.0 to 7.1 log CFU/ml) N0S. Despite pronounced differences in susceptibilities, the patterns of the killing curves observed with a given strain at different N0S were similar. As expected, viable bacterial counts increased with inoculum size. Striking visual contrasts in the respective curves for each organism were reflected by the area under the bacterial count-time curve (AUBC) but not by the difference between the N0 and the lowest bacterial counts (Nmin) at the nadir of the killing curve: the N0-associated changes in the AUBC on average were 75%, versus 2.5% for log N0--logNmin. To examine qualitative differences in antimicrobial effects at different N0S (i.e., the net effect of the inoculum), the difference in the high and low N0S was subtracted from each point on the killing curve obtained at the higher N0 for each strain. These adjusted curves were virtually superimposable on the observed killing curves obtained at the lower N0. Moreover, by using adjusted data, the AUBC values were similar at the two inocula, although slight (average, 11%) but systematic increases in the AUBC occurred at high N0S. Thus, there was only a weak net effect of inoculum size on the antibacterial effect of ampicillin-sulbactam. Due to similar slopes of the AUBC-log N0 plots, the antibacterial action at different N0S may be easily predicted by an approximate equation; the predicted AUBCs were unbiased and well correlated with the observed AUBCs (r = 0.997). Compiled data obtained with normalized AUBCs for different strains at different N0S yielded a positive correlation (r = 0.963) between the N0-normalized AUBC and the MIC of ampicillin-sulbactam. The adjustment and normalization procedure described might be a useful tool for revealing the net effect of the inoculum and to predict the inoculum effect if there are no qualitative differences in antimicrobial action at different inocula.

Ampicillin↗
PubMed1997

Relationship between the in vivo localization and the immunoblotting pattern of anti-basement membrane zone antibodies in patients with bullous pemphigoid.

OBJECTIVE: To compare the localization of anti-basement membrane zone (BMZ) antibodies bound in vivo with the antigenic specificities of circulating anti-BMZ antibodies in patients with bullous pemphigoid (BP). DESIGN: Comparison of the results of an examination of the skin specimens of the patients using direct immunoelectron microscopy and direct immunofluorescence on 1-mol/L sodium chloride-split skin with the results of an analysis of the corresponding serum samples using the immunoblot technique. SETTING: Immunodermatology department in a teaching hospital. PATIENTS: Thirty-six patients with typical BP and circulating anti-BMZ antibodies. RESULTS: Serum samples from 22 patients with BP indicated only BP antigen 1 in the results of immunoblot analysis. Using direct immunofluorescence, an analysis of the peribullous skin samples obtained from these 22 patients showed deposits of IgG exclusively located along the epidermal side of sodium chloride-split skin; the results of direct immunoelectron microscopic examination showed deposits of IgG located on the intracellular portion of hemidesmosomes in 18 (82%) of these 22 specimens, whereas 4 biopsy specimens had linear IgG deposits located both intracellularly and extracellularly along the keratinocyte plasma membrane. The results of immunoblot analysis of the serum samples from 5 patients with BP indicated BP antigen 2 alone; the results of direct immunoelectron microscopic examination of peribullous skin samples from these 5 patients showed linear intracellular and extracellular deposits along the keratinocyte membrane, corresponding to an epidermal fluorescence labeling pattern of peribullous sodium chloride-split skin in 2 patients and a combined (dermal and epidermal) pattern in 3 patients. CONCLUSION: The 2 different patterns of reactivity of anti-BMZ antibody deposits bound in vivo closely corresponded to the antigenic specificities indicated in the corresponding serum samples of the patients. These results are in accordance with those previously obtained in vitro and argue for identical binding profiles of circulating antibodies that are bound in vivo in BP.

Autoantibodies↗
PubMed1997

Autoantibody formation against a 190-kDa antigen of the desmosomal plaque in pemphigus foliaceus.

We report changes in the antigen recognition pattern of sera from two pemphigus foliaceus patients with a long-term follow-up. The patients' sera were analysed by immunoblotting using different antigenic sources: cultured human keratinocytes, bovine tongue epithelium and a recombinant protein corresponding to the C-terminal end of the 230-kDa bullous pemphigoid antigen. While initial serum samples reacted exclusively with the 160-kDa desmoglein 1, the later sera reacted both with desmoglein 1 and a 190-kDa antigen immunolocalized to the desmosomal plaque, previously demonstrated to be recognized by sera of some patients with paraneoplastic pemphigus. IgG subclass analysis further showed that antidesmoglein 1 antibodies were of IgG1 and/or IgG4 subclasses, while anti-190-kDa antibodies were IgG3. The patients were free of malignancy.

Aged↗
PubMed1996

The human tumour suppressor gene p53 is alternatively spliced in normal cells.

Alternative splicing affecting the p53 carboxy-terminus has previously been described in mouse but not in normal human cells. We report here the detection in normal human lymphocytes of an alternatively spliced form of human p53 mRNA containing an additional 133 bp exon derived from intron 9. This splice variant encodes a truncated protein of 341 amino-acids including 10 new amino-acids derived from the novel exon. The truncated protein, which lacks part of the p53 tetramerization domain, fails to bind DNA in vitro and has a transcriptional defect in vivo in both yeast and mammalian cells. Quantitative RT-PCR experiments suggest that the alternatively spliced form is only present in significant amounts in quiescent cells. Considering the numerous functions ascribed to the carboxy-terminus of the p53 protein, this splice variant may have important implications for the biological role of p53 in normal cells.

Alternative Splicing↗
PubMed1996

Structural properties and mutation patterns of anti-nucleosome monoclonal antibodies are similar to those of anti-DNA antibodies.

Four monoclonal antibodies (mAb) derived from an (NZB x NZW)F1 mouse bound to nucleosomes, total histones and to the H2A-H2B dimers but not to individual histones or DNA. Sequencing of their heavy (H)- and light (L)-chain variable region genes showed that they derived by somatic mutations from the same B cell precursor. The distribution of negatively and positively charged amino acids in the H-chain complementarity-determining regions was very similar to that observed not only in anti-H2A-H2B mAb derived from different lupus-prone mouse strains but also in anti-DNA mAb. Combined analysis of the mAb structures and their interactions with immobilized H2A-H2B dimer or total histones by plasmon resonance allowed us to assign the H-chain mutations a major role in the binding profiles of these anti-nucleosome mAb. Interestingly, four of the five H-chain mutations that distinguished mAb 3F6 from 2E1 generated negatively or positively charged amino acid residues, and two of them occurred at positions 56 and 76, which are frequently involved in the maturation process of anti-DNA antibodies. A modeling study of the 3F6 variable fragment (Fv) predicted that acidic residues occupy the cleft of the Ab combining site and have the potential to participate in electrostatic interactions. Thus, the demonstration that (NZB x NZW)F1-derived anti-H2A-H2B antibodies share certain structural features and mutation patterns with anti-DNA mAb suggest that common selection and maturation processes account for the production of these lupus-related autoantibodies.

Amino Acid Sequence↗
PubMed1996

Similarity of expression of activation markers and CD28 on gamma delta and alpha beta-receptor T cells in HIV infection.

During human immunodeficiency virus (HIV) infection, phenotypic analysis of circulating gamma delta+ T cells showed a downregulation of the CD28 surface antigen, as recently demonstrated for CD4+ and CD8+ alpha beta+ T cells. The downregulation of the CD28 molecule predominated on CD8+ gamma delta+ T cells. Moreover, an increased expression of CD38 and/or HLA-DR molecules was found on gamma delta T cells as reported for alpha beta T cells indicating that all categories of circulating T lymphocytes share similar phenotypic abnormalities in HIV-infected patients. These unique changes in the different T-cell subsets might be induced by sustained activation of the immune system or by the rapid turnover of T cells and argue for a global dysregulation of T lymphocytes during HIV infection.

ADP-ribosyl Cyclase↗
PubMed1996

Do naturally occurring autoantibodies participate in the constitution of the pathological B-cell repertoire in systemic lupus erythematosus?

Systemic lupus erythematosus (SLE) is the prototype of systemic autoimmune diseases. In both human and mouse SLE diseases, the autoimmune response targets a restricted set of autoantigens. Many of them are nucleic acids and proteins involved in the synthesis and processing of DNA or RNA, a characteristic which should be taken into consideration to elucidate the origins of non organ-specific autoantibodies. Several observations, in particular those obtained from experimental models of SLE induced in normal mice, suggest that the breakdown of B-cell tolerance occurs in the periphery. Herewith, we present data further supporting the proposition that SLE-associated autoantibodies originate from natural autoantibody-secreting B cells activated in the internal environment of lupus mice. Thus, one may hypothesize that certain clones of the expanded primary B-cell repertoire are selected to differentiate into harmful IgG autoantibody-secreting clones, thereby raising the question of the nature of immunogenic structures involved in SLE. Our analysis of the immunochemical and structural properties of anti-nucleosome and anti-myeoloperoxidase monoclonal antibodies derived from (NZB x NZW)F1 mice leads us to propose that complexes formed by the association of DNA and DNA-binding proteins and, more generally, by anionic molecules associated with proteins, possess a selective advantage over other autoantigens to induce the differentiation of certain B-cell clones and the very special profile of the SLE-autoimmune response. These DNA/DNA-protein complexes could also play a role in the activation of the T-cell compartment in SLE.

Animals↗
PubMed1996

The other side of affirmative action: reactions of nonbeneficiaries to sex-based preferential selection.

Researchers studied 162 male undergraduates in an experiment designed to investigate how the experience of unfair treatment affects the reactions of nonbeneficiaries of sex-based preferential selection in terms of responses to the work task, characterizations of the woman beneficiary, and prosocial orientation to the work setting. The basis of selection (merit or preference), the comparative ability of the participant and the selectee (superior, inferior, equal, or unknown) and the presence or absence of one type of explanatory justification for the selection decision (an ideological account) were systematically varied. Results indicated that preferential selection can produce negative reactions on the part of nonbeneficiaries. However, reactions to preferential selection were not always uniform, and procedural and distributive aspects of unfairness concerns were found to have consequences for different types of nonbeneficiary reactions. In addition, the mitigating effects of the ideological account were found to be limited to situations in which the beneficiary and nonbeneficiary were believed to be equally qualified.

Decision Making, Organizational↗
PubMed1996

Severe autosomal dominant hypertension and brachydactyly in a unique Turkish kindred maps to human chromosome 12.

Finding genes that cause human hypertension is not straightforward, since the determinants of blood pressure in primary hypertension are multifactorial. One approach to identifying relevant genes is to elucidate rare forms of monogenic hypertension. A relevant mutation may provide a rational starting point from which to analyse the pathophysiology of a condition affecting 20% of the world's population. In 1973 a family with autosomal dominantly inherited brachydactyly and severe hypertension, where the two traits cosegregated completely, was described. We have now re-examined this kindred, and localized the hypertension and brachydactyly locus to chromosome 12p in a region defined by markers D12S364 and D12S87. As the renin-angiotensin-system and sympathetic nervous system respond normally in this form of hypertension, the condition resembles essential hypertension. This feature distinguishes this form of hypertension from glucocorticoid remediable aldosteronism and Liddle's syndrome, which are salt-sensitive forms of monogenic hypertension with very low plasma renin activity. We suggest that identification of the gene involved in hypertension and brachydactyly and its mutation will be of great relevance in elucidating new mechanisms leading to blood pressure elevation.

Adult↗
PubMed1996

Predictors of effect of ampicillin-sulbactam against TEM-1 beta-lactamase-producing Escherichia coli in an in vitro dynamic model: enzyme activity versus MIC.

The clinical outcome in patients treated with ampicillin-sulbactam may not always be predictable by disc susceptibility testing or with the MIC as determined with a constant level (4 micrograms/ml) of the beta-lactamase inhibitor (MIC1). The enzyme activities (EA) and the MICs estimated at a constant ratio of ampicillin to sulbactam of 2:1 (MIC2) for 15 TEM-1 beta-lactamase-producing strains of Escherichia coli were examined as alternatives to MIC1 as predictors of the antibacterial effects of this combined drug as studied in an in vitro model which simulates ampicillin-sulbactam pharmacokinetic profiles observed in human peripheral tissues. Integral parameters describing the area under the bacterial count-time curve (AUBC), the area between the normal growth curve, and the killing curve of bacteria exposed to antibiotic (ABBC), and the second parameter expressed as a percentage of its maximal hypothetical value (ABBC/ABBCmax) were calculated. All three parameters correlated well with EA (AUBC, r = 0.93; ABBC, r = -0.88; ABBC/ABBCmax, r = -0.91) and with MIC2 (r = 0.94, -0.94, and -0.95, respectively) but not with MIC1. Both EA and MIC2 can be considered reliable predictors of the antibacterial effect of ampicillin-sulbactam in an in vitro model. These correlations suggest that in vitro kinetic-dynamic models might be useful to reexamine established susceptibility breakpoints obtained with data based on the MIC1 (MICs obtained with constant levels of beta-lactamase inhibitors). These data also suggest that quantitative determinations of bacterial beta-lactamase production and MICs based on the component concentration ratio observed in vivo might be useful predictors of the effect of ampicillin-sulbactam and other beta-lactam-inhibitor combinations.

Ampicillin↗