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Biomedical subjects

M Weigert

Publications and source records attributed to M Weigert.

At least 19 recordsLinked to original sources
PubMed1992

Selective pathogenicity of murine rheumatoid factors of the cryoprecipitable IgG3 subclass.

To analyze the involvement of rheumatoid factors (RF) in the generation of cryoglobulins and the development of related tissue injuries, we have established a panel of anti-IgG2a RF mAbs derived from MRL/MpJ-lpr/lpr (MRL-lpr), C3H/HeJ-lpr/lpr, and 129/Sv mice. After injection of hybridoma cells to normal mice, all four IgG3 RF mAbs induced cryoglobulinemia, and various degrees of glomerulonephritis and skin leukocytoclastic vasculitis. In contrast, none of the RF mAbs of the other isotypes generated cryoglobulins or tissue lesions. Since the same observation was obtained with another panel of five clonally related anti-IgG2a RF mAbs of MRL-lpr origin with almost identical heavy and light chain variable (V) regions but five different isotypes, it seems unlikely that the absence of pathogenicity of non-IgG3 RF mAbs was due to differences in fine specificity or V framework regions. In addition, the analysis of serum RF in MRL-lpr mice has demonstrated that a majority of 4 month old MRL-lpr mice produced substantial amounts of IgG3 RF with cryoglobulin activity. Because the cryoglobulin activity is associated with the murine IgG3 heavy chain constant region, RF of this subclass may play a significant role in the development of autoimmune-related tissue injuries, especially in MRL-lpr mice.

Animals↗
PubMed1991

Expression of anti-DNA immunoglobulin transgenes in non-autoimmune mice.

Self-reactive B cells can be regulated by either deletion or inactivation. These manifestations of self-tolerance have been dramatically shown in transgenic mice in which the number of self-reactive cells has been artificially expanded. We have now extended these models to ask if B-cell tolerance as described for non-disease-associated antigens also operates for the targets of autoimmunity. The target we have chosen is DNA. Anti-DNA antibodies are diagnostic of certain autoimmune syndromes in humans and are a characteristic of the murine model of systemic autoimmunity, the MRl/lpr mouse. Antibodies to both single-stranded and double-stranded DNA have been implicated in disease. By generating anti-DNA transgenic mice, we have addressed the question of whether DNA-specific B cells are regulated in normal (non-autoimmune) mice. We indeed found that most transgenic B cells bind DNA, yet we failed to detect secreted anti-DNA. We suggest that as a consequence of their self-reactivity these B cells are developmentally arrested.

Animals↗
PubMed1991

Ig H and L chain contributions to autoimmune specificities.

An Ig H chain expression vector has been constructed by using the V region of 3H9, an antibody that binds ssDNA, dsDNA, and cardiolipin. The H chain construct was transfected into six hybridoma cell lines expressing Ig L chains. All resulting H and L chain combinations had at least some affinity for ssDNA, whereas five also bound dsDNA to a similar degree as 3H9. The loss of dsDNA binding was correlated with a single amino acid difference between two V kappa 8 L chains. A further characteristic of 3H9, its immunofluorescent staining pattern, was shared by four of the recombinant antibodies, whereas its specificity for cardiolipin was shared with five. The transfections reported here show that a V kappa 3 L chain confers specificity for an RNA-associated epitope and that a V kappa 21E L chain prevents cardiolipin binding. These experiments suggest that the 3H9 H chain contributes essential determinants required for binding to DNA as well as cardiolipin but that L chains can modulate or prevent this binding. L chains may also expand the specificity of a recombinant antibody.

Amino Acid Sequence↗
PubMed1990

Heavy-chain class switch does not terminate somatic mutation.

We studied the H-chain class switch rearrangement in four groups of clonally related B cell hybridomas, to test the hypothesis that class switch terminates somatic mutation in a B cell. Using switch region-specific probes in Southern blot analysis individual mu-gamma switch rearrangement events can be distinguished. We show that clonally related IgG-producing hybridomas that differ by mutations often share a common switch rearrangement. This indicates that class switch in these cells did not terminate somatic mutation.

Animals↗
PubMed1990

Anti-DNA antibodies from autoimmune mice arise by clonal expansion and somatic mutation.

The proximate cause of autoantibodies characteristic of systemic autoimmune diseases has been controversial. One hypothesis is that autoantibodies are the result of polyclonal nonspecific B cell activation. Alternatively, autoantibodies could be the result of antigen-driven B cell activation, as observed in secondary immune responses. We have approached this question by studying monoclonal anti-DNA autoantibodies derived from unmanipulated spleen cells of the autoimmune MRL/lpr mouse strain. This analysis shows that anti-DNAs, like rheumatoid factors (19), are the result of specific antigen-driven stimulation. In addition, correlation of sequences with fine specificity shows that: (a) somatic mutations can cause specificity for dsDNA and that such mutations are selected for; (b) arginine residues play an important role in determining specificity; and (c) anti-idiotypes that recognize the majority of anti-DNA are probably not specific for any one family of V regions.

Amino Acid Sequence↗
PubMed1979

A search for hapten-binding mouse plasmacytoma proteins.

Six hundred and twelve mouse plasmacytomas were screened for hapten binding by using eleven different bacteriophage-hapten conjugates (phage T4 conjugated with haptens NP, NIP, DIP, DNP,BOC-ABA-Tyr, ABA-NP, ABA-MIP, ABS-HOP, PAB-HOP, penicillin G, cloxacillin). Fifteen ascites fluids (2.4%) inactivated at least one of the phage conjugates at a high dilution indicating binding. The specificity of these reactions was studied by titrating one ascites fluid with phage conjugates carring unrelated haptens, and by inhibiting the phage inactivation with free haptens. Of the 15 myeloma proteins, 10 had high titers (at least 30 times higher than the ascites fluid background) with the NIP-cap phage or the NP-cap phage or both. Four had high titers with the DNP-cap phage and one with the ABA-MIP phage. Thirteen of the 15 myeloma proteins were IgA, one was IgM and one IgG2b.

Animals↗
PubMed1979

Total replacement of the femur and its adjacent joints.

We report three cases of alloplastic replacement of the femur and its adjacent joints. The indications and operative technique are described. The femoral shaft of polyethylene can be manufactured within a short time and may be individually adapted to standard replacements of the hip and knee. The operation may be performed even on older patients, it preserves the limb and allows early mobilisation with full weight bearing.

Aged↗
PubMed1979

Myeloma proteins from NZB and BALB/c mice: structural and functional differences.

Structural and functional analyses of myeloma immunoglobulins from inbred BALB/c mice and humans have provided important insights into the structure of the antibody molecule and the expression and evolution of antibody genes. One important question concerning these analyses is whether the myeloma process selects, in a nonrandom manner, the lymphocytes to be transformed. The availability of myeloma tumors in a second inbred strain of mouse, NZB, permits us to approach this question. In this respect. the NH2-terminal amino acid sequences of 27 kappa light chains as well as data relating to the antigen-binding properties and immunoglobulin class distribution of NZB myeloma proteins are presented and compared with similar data from the BALB/c mouse. These studies suggest that the myeloma proteins from the BALB/c and NZB mice constitute two populations of immunoglobulins with distinct functional and structural properties. The implication of this observation are discussed.

Amino Acid Sequence↗
PubMed1979

Comparisons of myeloma proteins from NZB and BALB/c mice: structural and functional differences of heavy chains.

The N-terminal sequences from heavy variable regions of 47 myeloma proteins of the NZB mouse have been analyzed. Sixteen of these VH regions have unblocked alpha amino groups and have been analyzed over their N-terminal 20 residues by automatic sequence analysis. These sequence data along with the antigen-binding profiles and immunoglobulin class distribution are compared with comparable data from BALB/c myeloma proteins. These comparisons suggest that the NZB and BALB/c populations of myeloma proteins are distinct from one another. The genetic implications of this conclusion are discussed.

Amino Acid Sequence↗
PubMed1979

[Fractures of the forearm in children; operative treatment (author's transl)].

The knowledge of the special characteristics of fractures in childhood determine the method of treatment. Within 2 1/2 years 162 fractures of the forearm were treated, 23 of them by open reposition. The specialities of the different anatomical regions and the best way of treatment are discussed. Conservative and operative methods complement each other to obtain the best result while the risk for the little patient is reduced.

Adolescent↗
PubMed1979

[Different indications for endoprotheses of the hip joint (ceramics (Al2O3) or internal shells?) (author's transl)].

The internal shell endoprothesis for the hip joint after Wagner has considerably limited the indications for the implantation of ceramic endoprotheses to patients under 60 years, because less bone substance has to be sacrificed. Furthermore there are indications for ceramic endoprotheses in cases of substance defects of the femoral head and neck, to some extent also in cases of dysplasia and protrusio acetabuli, and by loosening traditional total hip endoprotheses.

Adult↗
PubMed1979

[Inter- and subtrochanterie fractures treated by Ender's method (author's transl)].

308 patients with intertrochanteric and subtrochanteric femoral fractures were treated by Ender's method of intramedullary fixation from June 1975 to September 1978. The average age was 78,4 years, the mortality rate was 16,3 per cent. There was no infection of the bone and no non-union. In 78 per cent of re-examined patients the hip function was good and very good. The treatment of old patients with this operation is the method of choice.

Adult↗
PubMed1979

[Rare injuries of the Achilles tendon (author's transl)].

The problems of Achilles tendon rupture become more important, because the number of sport injuries is increasing. The typical rupture (transverse rupture) is well known. However in literature the medial rupture between muscle and tendon of the musc. gastrocnemius and the longitudinal rupture of the Achilles tendon are rarely mentionaled. This article describes the special symptoms of these injuries and their therapy.

Achilles Tendon↗
PubMed1978

Chromosomal locations of mouse immunoglobulin genes.

The chromosomal locations of the structural genes coding for the constant portions of mouse heavy (H) and light chain immunoglobulins were studied by molecular hybridization techniques. Complementary DNA probes containing the constant-region sequences of kappa and lambdaI light chain and alpha, gamma2b, and mu heavy chain mRNAs were annealed to a large excess of DNA from a series of eight mouse-human hybrid cell lines that are deficient for various mouse chromosomes. The lines were scored as positive when a high proportion of a probe annealed and negative when an insignificant proportion annealed. Some lines were clearly negative for H and lambda and clearly positive for kappa. Others were positive or intermediate for lambda, positive for kappa and negative for H. Still others, including a line that was selected for the absence of the mouse X chromosome, were positive for all immunoglobulin species. These results demonstrate that the Clambda, Ckappa, and CH genes are located on different autosomes in the mouse. In contrast, the three heavy-chain families exhibited consistently uniform hybridization results, suggesting that the genes for Calpha, Cgamma, and Cmu are located on the same chromosome. A comparison of karyotypic data with hybridization data has limited the possible locations of the Ig genes to only a few chromosomes.

Animals↗