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T Lehner

Publications and source records attributed to T Lehner.

At least 127 records · Page 7Linked to original sources
PubMed1991

Association between the 65-kilodalton heat shock protein, Streptococcus sanguis, and the corresponding antibodies in Behçet's syndrome.

The etiology of Behcet's syndrome (BS) is unknown, but a number of streptococcal species have been implicated. A hypothesis was postulated that a shared antigen, such as a stress protein, might account for some of these findings. Indeed, a rabbit antiserum against a 65-kDa heat shock protein of Mycobacterium tuberculosis revealed a corresponding 65-kDa band with all six Streptococcus sanguis strains examined and S. pyogenes but not with S. salivarius. By applying a panel of nine monoclonal antibodies to the mycobacterial 65-kDa heat shock protein, an approximately 65-kDa antigen was identified in the uncommon serotypes of S. sanguis ST3 and H.83 and one with a different Mr was identified in KTH-1 and S. pyogenes. Monoclonal antibodies Y1.2, C1.1, II H9, and ML30, which reacted with these streptococci, recognize residues 11 to 27, 88 to 123, 107 to 122, and 276 to 297 of the 65-kDa heat shock protein, respectively, suggesting that these residues are conserved among some uncommon serotypes of S. sanguis and S. pyogenes. Immunoblot analyses of sera from patients with BS for immunoglobulin A (IgA) and IgG antibodies revealed bands of 65 to 70 kDa with the mycobacterial heat shock protein, S. sanguis strains, and S. pyogenes, although these reactivities were also found to a lesser extent in controls. A 65- to 70-kDa band was found more frequently with S. sanguis KTH-2 or KTH-3 and IgA in serum from patients with BS than with serum from controls (P less than 0.02). Antibodies in serum were then studied by a radioimmunoassay, and in patients with BS this revealed significantly raised IgA antibodies to the recombinant 65-kDa mycobacterial heat shock protein and to soluble protein extracts of S. sanguis ST3, KTH-1, KTH-2, and KTH-3. Whereas significant anti-65-kDa heat shock protein and anti-S. sanguis ST3 antibodies were also found in sera from patients with rheumatoid arthritis and recurrent oral ulcers, the anti-S. sanguis KTH-1, KTH-2, and KTH-3 antibodies were confined to BS. The results are consistent with the hypothesis that some of the streptococcal antigens are associated with heat shock or stress proteins, which will need to be formally established by isolating heat shock proteins from streptococci.

Amino Acid Sequence↗
PubMed1991

Restriction fragment length polymorphisms and sequence variation within the spaP gene of Streptococcus mutans serotype c isolates.

A restriction fragment length polymorphism study was undertaken to determine the extent and location of heterogeneity within spaP encoding the Mr 185,000 cell surface protein P1 (antigen I/II) of Streptococcus mutans serotype c isolates. The gene was found to be highly conserved except for a central variable (V) region predicted to encode less than 150 amino acids. Sequence analysis identified two V-region variants. These differences were independent of the geographic source of the isolates. Southern analysis using synthetic oligonucleotide probes indicated that nonretention of P1 (I/II) by some isolates is not due to a deletion of the 3'-terminal DNA necessary to encode an intact carboxy terminus.

Antigens, Bacterial↗
PubMed1991

Sequence and structural analysis of surface protein antigen I/II (SpaA) of Streptococcus sobrinus.

Streptococcal antigen I/II or the surface protein antigen A (SpaA) of Streptococcus sobrinus is an adhesin which mediates binding of the organism to tooth surfaces. The complete sequence of the gene which encodes SpaA has been determined. The gene consists of 4,584 bp and encodes a protein of 1,528 amino acid residues. The deduced amino acid sequence shows extensive homology with those of the cell surface adhesins from Streptococcus mutans serotypes c and f and from Streptococcus sanguis. Structural analysis of the N-terminal region (residues 50 to 550), which is rich in alanine and includes four tandem repeats of an 82-residue sequence, suggests that it adopts an alpha-helical coiled-coil conformation. Cell surface hydrophobicity may be associated with this region. The C-terminal region is more conserved and includes two tandem repeats of a 39-residue proline-rich sequence. A further proline-rich sequence in this region is predicted to span the cell wall. Although a hydrophobic sequence is present in the C-terminal region, it appears to be too short to span the cell membrane. Anchoring of SpaA in the cell membrane may therefore require some form of posttranslational modification or association with another membrane protein.

Adhesins, Bacterial↗
PubMed1991

Conservation of the gene encoding streptococcal antigen I/II in oral streptococci.

The spaP gene of Streptococcus mutans serotype c encodes a major cell surface protein, streptococcal antigen (SA) I/II, with an Mr of 185,000, that is thought to be involved in bacterial adhesion to teeth. Proteins with significant amino acid sequence homology to SA I/II have also been found in S. sobrinus and S. sanguis. The objectives of this study were to investigate the conservation of the spaP gene in the mutans groups of streptococci and to determine whether homologous genes were present in other species of alpha-hemolytic streptococci. DNA extracted from representative strains of 19 streptococcal species was examined by Southern hybridization and partial DNA sequence analysis. A series of five overlapping DNA probes from the spaP gene were amplified by the polymerase chain reaction and used in the Southern hybridizations. The entire gene was found to be well conserved in all strains of S. mutans serotypes c, e, and f investigated. A probe from the 3' region of the gene, which encodes residues 857 to 1207 of the SA I/II protein, hybridized with DNA from a number of mutans streptococci, as well as with DNA from nonmutans alpha-hemolytic streptococci. Conservation within this region was further demonstrated by sequencing gene fragments of two strains of S. intermedius and S. oralis. The results show that some regions of the spaP gene are highly conserved not only in the mutans group of streptococci but also in other nonmutans alpha-hemolytic streptococci. This suggests that a family of cell surface proteins which, by analogy with the 185,000-Mr SA I/II of S. mutans, could be involved in bacterial adhesion might exist.

Amino Acid Sequence↗
PubMed1991

Late onset autosomal dominant cerebellar ataxia. A family description and linkage analysis with the HLA system.

A family suffering an autosomal dominant form of late onset hereditary cerebellar ataxia is described. Eight affected family members were personally studied, and data from another four were obtained through anamnesis. The mean age of onset was 37.1 +/- 5.4 years (27-47 years). The clinical picture consisted basically of a pure ataxic cerebellar syndrome. CT-scan disclosed diffuse cerebellar atrophy with relative sparing of the brainstem and no involvement of supratentorial structures. Neurophysiological studies (nerve conduction, VEP and BAEP) were normal. Twenty-six individuals were typed for HLA histocompatibility antigens. Lod scores were calculated with the computer program LINKMAP. Close linkage of the ataxia gene with the HLA system in this family could be excluded--0 = 0.02, z = (-2.17)--and the overall analysis of the lod scores suggest another chromosomal location than chromosome 6.

Adult↗
PubMed1990

An investigation of the T cell requirements of in vitro antibody forming B cells detected by the ELISPOT assay and a comparison with antibody synthesis.

We have studied the primate cellular requirements in the antibody forming cell (AFC) assay, using a 185,000 molecular mass streptococcal antigen. Cultures of B cells alone stimulated with the antigen were unable to develop into AFC. Reconstitution of B cells with T cells resulted in a significant increase in the number of AFC. However, CD4 cells were more efficient than T cells in helping the antibody response and CD8 cells failed to induce B cells to synthesise antibody. A comparison between the specific IgG antibody synthesis and the number of AFC detected by the ELISPOT method showed a highly significant correlation between the number of AFC and the amount of specific IgG antibody. We suggest that the AFC (ELISPOT) assay can be readily used to investigate B cell interactions with T cell subsets.

Animals↗
PubMed1990

Genetic homogeneity between acute and chronic forms of spinal muscular atrophy.

The childhood-onset spinal muscular atrophies (SMAs) describe a heterogeneous group of disorders that selectively affect the alpha motoneuron. We have shown that chronic childhood-onset SMA (SMA II and III) maps to a single locus on chromosome 5q. Acute SMA (SMA Type I/Werdnig-Hoffmann/severe/infantile) is the main cause of heritable infant mortality. Mapping the acute SMA locus by conventional methods is complicated by the rapidly fatal course of the disease and its recessive mode of inheritance. We present here the typing of four inbred acute-SMA families with DNA markers on chromosome 5q and analysis of these together with acute families from our previous study to demonstrate genetic homogeneity between the acute and chronic forms of SMA. The data indicate that the acute SMA locus maps to chromosome 5q11.2-13.3. Two families seem unlinked to 5q markers, raising the possibility of genetic heterogeneity or disease misclassification within the acute and chronic family sets.

Acute Disease↗
PubMed1990

Genetic mapping of chronic childhood-onset spinal muscular atrophy to chromosome 5q11.2-13.3.

SPINAL muscular atrophy (SMA) describes a group of heritable degenerative diseases that selectively affect the alpha-motor neuron. Childhood-onset SMAs rank second in frequency to cystic fibrosis among autosomal recessive disorders, and are the leading cause of heritable infant mortality. Predictions that genetic heterogeneity underlies the differences between types of SMA, together with the aggressive nature of the most-severe infantile form, make linkage analysis of SMA potentially complex. We have now analysed 13 clinically heterogeneous SMA families. We find that 'chronic' childhood-onset SMA (including intermediate SMA or SMA type II, and Kugelberg-Welander or SMA type III) is genetically homogeneous, mapping to chromosomal region 5q11.2-13.3.

Adolescent↗
PubMed1990

Measuring the inflation of the lod score due to its maximization over model parameter values in human linkage analysis.

A computer-simulation method is presented for determining and correcting for the effect of maximizing the lod score over disease definitions, penetrance values, and perhaps other model parameters. The method consists of simulating the complete analysis using marker genotypes randomly generated under the assumption of free recombination. It is applicable as a "post-treatment" to linkage analyses of any trait with an uncertain mode of inheritance and/or disease definition. When the method is applied to a linkage analysis of schizophrenia versus chromosome 5 markers, we find that, in this specific case, the P-value associated with a maximum lod score of 3 is equal to 0.0003. We also find that a lod score of 3.0 should be "deflated" by approximately 0.3 to 1 units, and, by tentative extrapolation, the observed lod score of 6.5 should be "deflated" by 0.7 to 1.5 units.

Chromosomes, Human, Pair 5↗
PubMed1990

Sequencing and characterization of the 185 kDa cell surface antigen of Streptococcus mutans.

The gene spa P (formerly designated as spa P1) encoding the Mr 185,000 surface antigen I/II of Streptococcus mutans, serotype c (strain NG5) has been sequenced. The deduced amino acid sequence of antigen I/II (1561 residues) includes a putative signal peptide (residues 1-38), as well as a transmembrane region (residues 1537-1556). The N-terminal part of the protein (residues 39-550) is particularly rich in alanine and includes three tandem repeats of a sequence of 82 residues. This region is predicted to be alpha-helical, adopting a coiled-coil formation, and may account for the cell surface hydrophobicity associated with expression of antigen I/II. In contrast the C-terminal region (residues 800-1549) is proline-rich, favouring an extended conformation. Comparison with the sequence determined from Strep. mutans strain MT8148 showed that antigen I/II is highly conserved with the exception of a short central region (residues 750-805). N-terminal sequencing of purified antigens I and II components indicated that antigen I extends from the amino-terminus of the intact Mr 185,000 surface antigen while antigen II extends from residue 996.

Amino Acid Sequence↗
PubMed1990

Identification of T- and B-cell epitopes in synthetic peptides derived from a Streptococcus mutans protein and characterization of their antigenicity and immunogenicity.

Natural immunity to synthetic peptides (SP) derived from the sequences of a 3800 Mr Streptococcus mutans antigen was found in human subjects. Significant serum IgG antibodies were detected both to the native streptococcal antigen and to the SP17, containing essentially residues 1-15. A series of short peptides with deletions at the amino- and carboxy-termini were then tested to identify the B-cell epitopes. Residues 8-13 and 1-6 bound significant serum IgG antibodies but only the former consistently inhibited human antibodies, suggesting that residues 8-13 constitute a major B-cell epitope. The human CD4 subset of T-cells was then examined and this showed a significant uptake of [3H]-thymidine when stimulated with both the native streptococcal antigen and the SP17. The series of short peptides was then used to stimulate CD4 cells, in order to determine the T-cell epitope. The synthetic peptide with residues 6-15 was the shortest peptide that stimulated significant [3H]-thymidine uptake and this peptide was designated as a T-cell epitope. The immunogenicity and antigenicity of SP17 was also investigated in macaques. Immunization of monkeys with the free SP17 failed to elicit serum antibodies or T-cell responses. However, immunization with SP17 linked to tetanus toxoid as a carrier elicited serum antibodies and proliferative responses of lymphocytes, not only to the synthetic peptide but also to the native streptococcal antigen. As in the human studies a B-cell epitope was found in residues 8-13, whereas an overlapping T-cell epitope was located in residues 7-15.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1990

Prevention of colonization of Streptococcus mutans by topical application of monoclonal antibodies in human subjects.

Topical application of Streptococcus mutans-specific MAbs was examined as a means of preventing colonization in the mouth. The MAbs recognize the cell surface antigen (SA I/II) of Strep. mutans and also bind to the intact bacterial cell. In experiments with implantation of an exogenous Strep. mutans strain, specific MAb significantly reduced the levels of implantation when compared with that in controls given a non-specific MAb. In a second investigation, the effect of MAb on recolonization by indigenous Strep. mutans was studied in subjects after treatment with a topical antibacterial mouthwash (chlorhexidine), which had decreased Strep. mutans to undetectable levels. In control subjects, the indigenous Strep. mutans started to recolonize within days, but those receiving MAb remained free of Strep. mutans for up to 2 yr. By using different Strep. mutans-specific MAbs, it was found that the serotype and epitope specificities of the IgG MAb were essential, but that the IgG sub-class may not be important. No clinical side-effects were detected in any of the subjects receiving MAb and there was no evidence of serum, salivary or gingival fluid antibody responses against the antibody. Local passive immunization with MAbs is a safe method for preventing colonization of Strep. mutans in the mouth.

Administration, Topical↗
PubMed1990

Report of a workshop on genetic linkage studies in schizophrenia.

A workshop on genetic linkage studies in schizophrenia was held at Columbia University's Arden House Conference Center in October 1989. This report summarizes the contents of invited talks by Drs. Arno Motulsky and T. Conrad Gilliam and the discussions at the five workshop sessions. Topics of the workshop sessions were (1) diagnostic boundaries and hierarchies in schizophrenia, (2) genetic models and linkage parameters, (3) selection and ascertainment of pedigrees, (4) future extensions of molecular genetics strategies, and (5) possibilities for future collaboration.

Genetic Linkage↗
PubMed1990

Identification and characterization of IgA and Vicia villosa-binding T cell subsets in rheumatoid arthritis.

Autoimmunity may be due to augmentation of immune responses by human CD8 cells which bind the lectin Vicia villosa (VV). We have investigated T cells in rheumatoid arthritis (RA) by double immunofluorescence flow cytometry, in order to assess VV-binding CD8 and CD4 cells from the peripheral blood and synovial fluid. A significant increase in CD8+VV adherent (P less than 0.0001) and CD4+VV adherent cells (P less than 0.001) was found in synovial fluid, as compared with peripheral blood from patients with RA. A significant increase in VV-binding CD8+ or CD4+ cells was, however, not found in the blood of patients with RA, as compared with controls. We suggest that the lack of VV-binding T cells separated from blood, in contrast to those from synovial fluid, may be due to an inhibiting agent expressing N-acetyl D-galactosamine. Indeed, IgA1 is rich in N-acetyl D-galactosamine, it inhibits VV binding to T cells and is significantly bound to CD8 cells (P less than 0.001). The IgA1 was then characterized and in about half the patients J chains and secretory component was found, suggesting that the IgA1 is of the polymeric and secretory variety. IgA bound to the T cells engaged the Fc alpha receptors and a significant decrease in the Fc alpha receptors was found in CD8 cells (P less than 0.0001) and CD4 cells (P less than 0.01). Desorption studies were then carried out on CD8 and CD4 cells which showed that a loss of cell-bound IgA1 was associated with an increase in VV binding. Conversely, adsorption of IgA to T cells was associated with a loss in VV binding. The results suggest that the failure of VV binding to CD8+ and CD4+ cells from peripheral blood of patients with RA can be ascribed to cell-bound IgA1. Cytophilic IgA1 may inhibit the function of CD8+VV binding cells, thereby preventing augmentation of the systemic immune response, consistent with the lack of extra-articular disease in these patients with RA.

Adult↗
PubMed1990

The expression of gamma delta T cell receptor and the prevalence of primed, activated and IgA-bound T cells in Behçet's syndrome.

Mucosal ulceration of the oral, and to a lesser extent genital tissues is an essential feature of Behçet's syndrome and is associated with changes in the IgA class of immune responses. Indeed, a significant increase in the proportion of cytophilic IgA1 was found in circulating CD8 and CD4 cells (P less than 0.01), with a corresponding decrease in IgA-Fc receptors on these T cells. Furthermore, 30-40% of the cytophilic IgA1 on T cells may have been of the polymeric secretory type and the rest of the monomeric variety. IgA isotype of B cells was also significantly increased (P less than 0.001), without an overall change in circulating B cells. However, a surprising finding was the significant up-regulation of gamma delta T cell receptor in the CD8 (P less than 0.01) in the absence of a change in the proportion of alpha beta T cell receptor. The results suggest that some common microbial antigen might initiate at the mucosal surface an immune defence reaction characterized by T cells with gamma delta receptors and IgA-specific B cells. However, IgA1 bound to circulating T cells may down-regulate the central T cell function.

Adult↗
PubMed1990

An investigation into the mechanism of protection by local passive immunization with monoclonal antibodies against Streptococcus mutans.

Local oral passive immunization with Streptococcus mutans-specific monoclonal antibody (MAb) (Guy's 13) prevented recolonization by indigenous S. mutans in human volunteers who had first been treated with a conventional antibacterial agent (chlorhexidine). The F(ab')2 fragment of the MAb was as protective as the intact immunoglobulin G, but the Fab fragment of the molecule failed to prevent recolonization of S. mutans. In subjects receiving the MAb Fab fragment, S. mutans levels in dental plaque and saliva reappeared at a similar rate to that found in sham-immunized subjects who received either saline or a nonprotective MAb. In vitro, MAb had no bacteriostatic or bacteriocidal effect on S. mutans. However, S. mutans grown in the presence of either intact immunoglobulin G MAb or the F(ab')2 fragment formed very long chains, which resulted in clumping of the cells. S. mutans grown with either saline or the MAb Fab fragment formed significantly shorter chains, more characteristic of streptococcal growth in liquid media. The results suggest that the two binding sites of the MAb molecule may be an essential feature for preventing streptococcal colonization but that the ability to bind to phagocytes and activate complement which resides in the Fc fragment is not essential. Protection against colonization by S. mutans lasting up to 2 years was observed in immunized subjects, although MAb was applied over a period of only 3 weeks. Furthermore, functional MAb was detected up to 3 days following application of MAb to the teeth. The long-term protection could not be accounted for by a persistence of MAb on the tooth surface, and we have suggested that it may be due to a shift in the balance of the oral flora which discouraged recolonization by S. mutans. However, examination of the proportions of Streptococcus sanguis and veillonella species in the recolonization experiments failed to reveal a significant change in the proportions of either organism, which returned to approximately the preexperimental levels in both the immunized and control groups. These findings confirm the in vivo functional specificity of the MAb to S. mutans but are not consistent with the suggestion that S. sanguis or veillonella take over the niche vacated by S. mutans, unless the shift in the proportion of these organisms cannot be detected by the method used.

Adult↗