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R C Williams

Publications and source records attributed to R C Williams.

At least 91 records · Page 5Linked to original sources
PubMed1996

Restriction fragment length polymorphisms of constant region genes of immunoglobulin lambda chains in Venezuelan patients with systemic lupus erythematosus.

Previous studies suggest a potential association between human immunoglobulin (Ig) genes and susceptibility to systemic lupus erythematosus (SLE). Ig allotypic determinants seem to confer an increased risk for the disease in various ethnic patient populations. In this study we have examined the pattern of restriction fragment length polymorphisms (RFLP) of constant region lambda (C lambda) light chain genes in a group of 78 Venezuelan patients with SLE and 70 healthy controls. The frequency of the 8-kb allele and the 8/8 genotype was significantly lower in normal Venezuelan controls as compared to healthy British Caucasians (P = 0.0002 and 0.0007 respectively). In turn, Venezuelan controls showed a higher frequency of the 18-kb allele and the 18/18 genotype (P = 0.0002 and 0.0052 respectively). However, there were no statistically significant differences in either parameter between Venezuelan SLE patients and healthy controls. Our study argues against a role for lambda light chain constant region genes in predisposition to SLE.

Autoimmune Diseases↗
PubMed1996

Immunity in the connective tissue diseases. The humoral side of the coin.

Clinicians who care for patients with various connective tissue diseases frequently employ measurements of autoantibodies such as rheumatoid factors (RFs), anti-Sm antibodies, or anti-neutrophil cytoplasmic antibodies (cANCA) as a method to follow patients. Although the primary specificity of RFs appears to be directed against the Fc portion (C gamma 3 and C gamma 2 domains) of IgG, epitope mapping studies have now also demonstrated that many RFs also react with linear regions on beta 2-microglobulin and Class I HLA molecules. Cross reacting regions of IgG, beta 2m, and HLA Class I frequently show immunodominant tyrosines, trytophanes, valines, leucines, glutamic acids, aspartic acids, and threonines. Immunodominant linear epitopes on Sm antigen may be limited to regions expressing the PPPGMRPP or PPPGIRGP motifs. A number of linear regions of Proteinase 3 reacting with IgG antibodies in the sera of patients with Wegener's granulomatosis have now been identified. However, affinity purified rabbit antibodies to two of these major PR3 antigenic sties (ATVQLPQ and RVGAHDP) linked to Sepharose to form affinity columns, absorbed equal amounts of a mixture of many serum proteins from both Wegener's patients and normal controls. Continued study of this interface between autoantibody production, disease, and normal immune modulation is necessary.

Amino Acid Sequence↗
PubMed1995

Determination of microtubule polarity in vitro by the use of video-enhanced differential-interference contrast light microscopy and Chlamydomonas flagellar axonemal pieces.

Microtubules nucleated by sea urchin sperm-tail axonemes have polar ends that differ both functionally and structurally but cannot be distinguished from one another when viewed by light microscopy. Ambiguity and circularity surround any classification of microtubule polarity by conventional methods. Chlamydomonas flagellar axonemal pieces have distinct morphological differences at their plus- and minus-ends, and microtubules nucleated from these pieces can be distinguished as plus- or minus-ended based on the morphological differences present in the Chlamydomonas flagellar axonemal pieces. Plus- and minus-ended microtubules were polymerized in this fashion and analyzed for differences in growth rates, shortening rates, and frequencies of transitions. The results were in good agreement with similar data generated by the more time-consuming and difficult use of kinesin-coated beads (R. J. Kowalski, and R. C. Williams, Jr. (1993) Cell Motil. Cytoskeleton 26, 282-290) to determine microtubule polarity. This is a relatively simple and effective method for determining the polarity of microtubules in vitro by video-enhanced differential-interference contrast light microscopy.

Animals↗
PubMed1995

Microtubule-associated proteins and the flexibility of microtubules.

Experiments were conducted to learn whether the binding of microtubule-associated proteins (MAPs) to microtubules alters the flexibility of the microtubules. Flexibility was measured in vitro by two established techniques. The first employed measurement of the bending of the microtubule in a flow of buffer; the second involved repeated measurement of random thermal fluctuations in the microtubule's shape. Similar values were obtained from microtubules prepared from purified tubulin and those prepared from microtubule protein containing saturating concentrations of MAPs isolated from bovine brain. When measured by the flow technique at 37 degrees C and pH 6.9, the persistence length of pure tubulin microtubules was found to be 8.4 +/- 2.2 mm and that of MAP-containing microtubules was 9.4 +/- 2.7 mm, not significantly different from each other. When measured by the thermal fluctuation technique under identical conditions, values of 6.2 +/- 0.8 and 6.5 +/- 0.8 mm were obtained, again not significantly different from each other. The results show that the binding of MAPs to native microtubules in vitro has little or no effect on their flexibility. MAP-induced effects on the cytoskeleton observed in vivo are likely to be due to other causes, such as formation of microtubule bundles.

Animals↗
PubMed1995

Self-association of Escherichia coli DNA-dependent RNA polymerase core enzyme.

The extent of self-association of Escherichia coli DNA-dependent RNA polymerase core enzyme has been investigated by velocity sedimentation as a function of both NaCl and protein concentrations. The core enzyme, existing as essentially monomeric species having a sedimentation coefficient of 13.1 S at NaCl concentrations greater than 0.2 M, undergoes reversible self-association at lower salt concentrations. Estimates for the stoichiometry of association and equilibrium constants of reaction were determined from the effect of protein concentration on the weight-average sedimentation coefficient measured at different NaCl concentrations. Data analysis by a nonlinear curve-fitting procedure indicated that protein self-association is best described by a sequential model characterized by weaker association constants for each additional step of oligomerization, and any model that involves cooperative formation of oligomeric species can be excluded. These findings are at variance with the conclusion of a previous study [Shaner, S. L., Platt, D. M., Wensley, C. G., Yu, H., Burgess, R. R., & Record, M. T. (1982) Biochemistry 26, 5539-5551] which suggested that core RNA polymerase exists in equilibrium between monomeric and tetrameric forms of the enzyme and excluded the existence of intermediate species. Simulation of sedimentation velocity boundary and gradient profiles are used to assess the validity of both models of association of core protein. It was clear that had the core enzyme undergone a cooperative monomer<-->tetramer mode of association, then bimodality would have been observed in the derivative tracings of the sedimentation boundary under these experimental conditions. Nevertheless, no such observation was reported by Shaner et al. and this study. The sequential model favored by the results of this study is consistent with the proposed model resulted from a small-angle X-ray study [Heumann, H, Meisenberger O., & Pilz, I. (1982) FEBS Lett. 138, 273-276]. Further analysis of the data by the Wyman linked-function relationship [Wyman, J. (1964) Adv. Protein Chem. 19, 223-286] implies that core enzyme monomer loses approximately three counterions per contact upon association to higher oligomeric species.

DNA-Directed RNA Polymerases↗
PubMed1995

Autoreactivity in HIV-1 infection: the role of molecular mimicry.

Autoimmunity during HIV-1 infection may contribute to the immunopathogenesis of AIDS. Titers of autoantibodies to HLA molecules and other surface markers of CD4+ T cells appear to increase with the progression of disease and may correlate with lymphopenia. Other autoantibodies are directed at a number of regulatory molecules of the immune system. Genesis of autoreactivity may be related to structural homologies of HIV-1 env-products to such functional molecules involved in the control of self-tolerance. The most impressive similarities include the HLA-DR4 and DR2, the variable regions of TCR alpha-, beta-, and gamma-chain, the Fas protein, and several functional domains of IgG and IgA. Thus, HIV-1 infection may induce dysregulation leading to autoimmune response, through a number of molecular mimicry mechanisms. Pathogenicity of antibodies to T cells could also include the activation of membrane-to-nucleus signal transducers resulting in increased apoptosis. The evolution of autoimmune mechanisms during HIV-1 infection cannot exclude, however, progression to immunoproliferative malignancy, since aspects of oligoclonal immune response to HIV-1 components may occur in several autoimmune diseases which in some instances evolve to lymphoma.

Amino Acid Sequence↗
PubMed1995

IgG anti-F(ab')2 antibodies from SLE patients react with immunodominant residues in kappa CDRs, but show reduced C kappa region reactivity.

We studied reactivity of affinity-purified human IgG anti-F(ab')2 antibodies for antigenic determinants on kappa light chains. Variable (VL) and constant (CL) regions of a human kappa I light chain (EU) were studied for enzyme-linked immunosorbent assay reactivity with monoclonal anti-k antibodies and human IgG antiF(ab')2 using overlapping heptamers of primary sequence synthesized as peptides on polypropylene pins. Polyclonal IgG anti-F(ab')2 antibodies isolated by affinity chromatography from the serum of patients with systemic lupus erythematosus (SLE) were found to react primarily with CDR1- and CDR3-related peptides. The most reactive residues included IL29, TRY32, LEU33, ALA34, GLU90, TYR91, and ASN 92. No striking difference in overall V-region anti-F(ab')2 reactivity profiles was noted when 10 IgG anti-F(ab')2 preparations from normal subjects and SLE patients were compared. In contrast, however, when tested against overlapping C kappa heptamer sequences, the reactivity in SLE-associated anti-F(ab')2 antibodies was markedly decreased. We report that this difference may reflect a defect in anti-idiotypic control mechanisms in SLE.

Amino Acid Sequence↗
PubMed1995

Molecular localization of human IgG anti-F(ab')2 reactivity with variable- and constant-region lambda light-chain epitopes.

Human IgG antibodies reacting with antigenic determinants on F(ab')2 fragments represent generic antiidiotypic antibodies present in the serum of normal individuals. Additionally, the titers of these antibodies in the sera of patients with systemic lupus erythematosus (SLE) are inversely related to disease activity. Because these autoantibodies recognize predominantly light chain-related epitopes, especially lambda type, we synthesized constant (C)lambda- and variable (V)lambda-related overlapping 7-mer peptides on polypropylene pins to determine anti-F(ab')2-reactive epitopes on human lambda light chains. ELISA reactivity of affinity-purified anti-F(ab')2 antibodies obtained from normal individuals and from patients with SLE, as well as murine anti-human light-chain monoclonal antibodies specific for C lambda and V lambda subgroup-related determinants, was tested using the overlapping 7-mers of human lambda light-chain sequence. The patterns of reactivity against C lambda-related peptides were similar in both normal and SLE-derived anti-F(ab')2 antibodies. However, reactivity profiles against V lambda-related peptides were distinctively different between the normal and the SLE-associated anti-F(ab')2 autoantibodies. A decrease in reactivity among the SLE IgG anti-F(ab')2 antibodies was noted for particular amino acid V lambda complementarity-determining region (CDR) residues, including glycine at positions 27 and 54, alanine at 16 and 37, and tyrosine at 28 and 91. This different pattern of reactivity from normal may indicate that in SLE there is a failure of antiidiotypic control mechanisms, as reflected by a defect in production of antibody to immunodominant V lambda CDR residues.

Alanine↗
PubMed1995

Rheumatoid-factor-reactive sites on CH3 established by overlapping 7-mer peptide epitope analysis.

Polyclonal IgM rheumatoid factors (RF) from ten patients with rheumatoid arthritis and six monoclonal IgM RF were isolated from monomeric IgG affinity columns and studied for their reactivity with the entire CH3 domain of IgG synthesized as overlapping 7-mers using a pin-ELISA assay. All ten polyclonal IgM RF showed similar profiles of reactivity which included peptides with solvent accessible residues PREPQVY (residues 343-349), PQVYTLP (residues 346-352), TLPPRSE (350-356), DGSFFLY (401-407), WQQGNVF (417-423), CSVMHEG (425-430), EGLHNHY (430-436) and KSLSLSP (439-446) of the CH3 domain. Substitution of a neutral glycine or alanine for each residue within these RF-reactive epitopes indicated that tyrosine at position 349, prolines at 343, 346 and 352, glutamine 347, valine 348, threonine 350, leucine 351, arginine 354, aspartic acid 401, tyrosine 407, serine 426, histidine 429, leucine 432, tyrosine 436 and lysine 439 represented important single amino acids within CH3 for RF reactivity. Regions of CH3 primary sequence with and without the single allotype-specific amino acid substitutions of glycine for alanine 431 (Gmx) or aspartic acid for glutamic acid (356) and leucine for methionine (358) (Gma) often showed considerable differences in reactivity with individual polyclonal and monoclonal RF. However, these differences in RF reactivity did not correlate with the individual anti-Gm RF specificity. Assays using monoclonal IgM RF produced from RA synovial B cells or peripheral blood B cells frequently showed a much more restricted spectrum of reactive CH3 epitopes. 7-mer peptides representing RF-reactive sites on CH3 preincubated with polyclonal IgM RF showed strong inhibition (55-66%) of RF binding to whole IgG on the ELISA plate. These studies indicate that it is possible to define portions of the IgG CH3 domain participating in the reaction with IgM RF using reactive epitope-mapping with sequential linear peptides derived from the primary IgG CH3 sequence.

Amino Acid Sequence↗
PubMed1995

Meta-analysis reveals association between most common class II haplotype in full-heritage Native Americans and rheumatoid arthritis.

The association of RA with the alleles at the HLA system was tested among Pima and Tohono O'odham Indians (Pimans) of the Gila River Indian Community of Arizona. Serologic class I (HLA-A, -B, and -C) alleles were typed in 51 individuals with RA and in 302 without RA. Serologic class II (HLA-DR, DQ; DR52 DR53) alleles were typed in a subset of 47 with RA and 147 without RA. Molecular subtypes of DR3X6, DRB1*1402, and *1406 were determined in 29 individuals, 16 with RA and 13 without RA. Among the cases with RA, 46 of 47 had the serologic antigen HLA-DR3X6, as did 140 of 147 of those without the disease. However, this association was not statistically significant because of the high prevalence of the antigen in the controls. Data from Pimans were analyzed with similar results from the Tlingit and Yakima Indians. A meta-analysis employing the Mantel-Haenszel procedure, stratified by tribe, revealed a statistically significant association between the most common haplotype, DRB1*1402 DQA1*0501 DQB1*0301 DRB3*0101, and RA (summary odds ratio = 2.63, 95% confidence interval = 1.08, 6.46). There was also a statistically significant difference in the genotype distributions of one class I locus, HLA-C, between those with and without RA (chi 2 = 12.4, 5 df; p = 0.03). It is concluded that the association with the most common class II haplotype in full-heritage Native Americans might help explain their high prevalence of RA.

Adolescent↗
PubMed1995

Crevicular fluid osteocalcin and pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) as markers of rapid bone turnover in periodontitis. A pilot study in beagle dogs.

The objective of this study was to correlate the levels of 2 putative markers of bone metabolism, namely osteocalcin and pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP), to the progression of experimental alveolar bone loss in the beagle dog. 36 control sites and 36 experimental sites in 2 beagle dogs were assessed longitudinally at 2-week intervals for gingival crevicular fluid (GCF) osteocalcin and ICTP levels during a 6-month observation period. Analysis of osteocalcin and ICTP in GCF was performed by RIA. During the study, bone-seeking radiopharmaceutical uptake (BSRU) of 99mTc-MDP was assessed monthly; standardized radiographs were taken at 2-week intervals. The results showed osteocalcin and ICTP levels in GCF increased significantly (p < 0.05) by 2 weeks following initiation of disease. This increase preceded significant increases in BSRU by 2 weeks and radiographic evidence of bone loss by 4 weeks. BSRU was significantly elevated (p < 0.05) at experimental sites as compared to controls at 4 and 8 weeks post-disease initiation. Osteocalcin in GCF peaked 8 and 10 weeks after ligature placement in experimental sites at levels nearly 10-fold greater than contralateral paired control sites. ICTP levels in GCF remained elevated throughout the entire disease progression phase. Following the removal of ligatures, both GCF osteocalcin and ICTP levels dropped precipitously approaching control values. Osteocalcin revealed overall a positive predictive value (PPV) and negative predictive value (NPV) for future bone loss during disease progression of 0.87 and 0.34, respectively, while ICTP showed both high PPV and NPV of 0.87 and 0.91 respectively. Results from this study in the dog model indicate that osteocalcin and especially ICTP relate to indices of active periodontal bony destruction and suggest that these molecules may serve as predictive markers for future alveolar bone loss.

Alveolar Bone Loss↗
PubMed1995

Genetic influence in rheumatoid arthritis.

Development of rheumatoid arthritis is influenced by genetic and environmental factors. Over the years intense interest has been focused on analysis of genetic factors contributing to pathogenesis and it appears that the major histocompatibility complex class II genes make a major contribution. Utilizing epidemiological data as well as molecular techniques, an epitope located on a number of HLA-DR molecules (class II) seems to be associated with an increased susceptibility to development of the condition. Furthermore, the disease may be more severe among individuals homozygous for the disease-associated DR types. The specific immunological mechanisms accounting for these findings are not known but are likely related to the ability of class II molecules to bind autoantigens and stimulate the appropriate T cells which can lead to joint damage. A search for additional genetic factors contributing to disease development should be high on the list of objectives and would help to further elucidate the pathogenesis of this complex disorder.

Arthritis, Rheumatoid↗
PubMed1995

Active systemic lupus erythematosus is associated with depletion of the natural generic anti-idiotype (anti-F(ab')2) system.

OBJECTIVE: To study the relationship of serum IgG anti-F(ab')2 and clinical disease activity in 108 patients with systemic lupus erythematosus (SLE) and to determine whether low serum anti-F(ab')2 with active renal disease is accompanied by deposition of anti-F(ab')2 in renal immune complex lesions. METHODS: We studied 108 patients with definite SLE over a 5 yr period and assayed serum anti-F(ab')2 levels in relation to degree of clinical disease activity. Renal biopsy eluates of 26 patients with SLE were examined by enzyme linked immunosorbent assay (ELISA) for relative amounts of IgG, anti-DNA, and IgG anti-F(ab')2. RESULTS: Active SLE was strongly associated with low serum anti-F(ab')2. SLE renal biopsy eluates frequently contained high levels of IgG and IgG anti-DNA and lower, but definite, IgG anti-F(ab')2 activity. When specific activity of IgG anti-DNA and IgG anti-F(ab')2 was compared between kidney biopsy eluates and concomitant serum, marked relative renal concentration was found for both anti-DNA (19-fold) and anti-F(ab')2 (74-fold). Some biopsy eluates contained IgG antibodies bearing apparent double specificity for both DNA and F(ab')2. CONCLUSION: Active SLE is often associated with low serum anti-F(ab')2. Relative enrichment over specific activity in serum of both IgG anti-F(ab')2 and anti-DNA in SLE kidney biopsy eluates may indicate participation of both reactants in the glomerular disease process. Low serum anti-F(ab')2 in active SLE may reflect down modulation of failure of idiotypic control mechanisms associated with disease progression.

Adolescent↗
PubMed1995

An E-M algorithm and testing strategy for multiple-locus haplotypes.

This paper gives an expectation maximization (EM) algorithm to obtain allele frequencies, haplotype frequencies, and gametic disequilibrium coefficients for multiple-locus systems. It permits high polymorphism and null alleles at all loci. This approach effectively deals with the primary estimation problems associated with such systems; that is, there is not a one-to-one correspondence between phenotypic and genotypic categories, and sample sizes tend to be much smaller than the number of phenotypic categories. The EM method provides maximum-likelihood estimates and therefore allows hypothesis tests using likelihood ratio statistics that have chi 2 distributions with large sample sizes. We also suggest a data resampling approach to estimate test statistic sampling distributions. The resampling approach is more computer intensive, but it is applicable to all sample sizes. A strategy to test hypotheses about aggregate groups of gametic disequilibrium coefficients is recommended. This strategy minimizes the number of necessary hypothesis tests while at the same time describing the structure of disequilibrium. These methods are applied to three unlinked dinucleotide repeat loci in Navajo Indians and to three linked HLA loci in Gila River (Pima) Indians. The likelihood functions of both data sets are shown to be maximized by the EM estimates, and the testing strategy provides a useful description of the structure of gametic disequilibrium. Following these applications, a number of simulation experiments are performed to test how well the likelihood-ratio statistic distributions are approximated by chi 2 distributions. In most circumstances the chi 2 grossly underestimated the probability of type I errors. However, at times they also overestimated the type 1 error probability. Accordingly, we recommended hypothesis tests that use the resampling method.

Algorithms↗
PubMed1994

Fv structure of monoclonal antibody II-481 against herpes simplex virus Fc gamma-binding glycoprotein gE contains immunodominant complementarity determining region epitopes that react with human immunoglobulin M rheumatoid factors.

Human immunoglobulin M (IgM) rheumatoid factors (RFs) show primary direct enzyme-linked immunosorbent assay (ELISA) reactivity with Fab rather than Fc fragments of monoclonal antibody (mAb) II-481 directed against the Fc gamma-binding site of herpes simplex virus glycoprotein gE. This preferential anti-Fab specificity suggests that RFs react with antigen-binding portions of mAb II-481 as anti-idiotypic antibodies directed at the combining site regions of mAb reacting with the Fc gamma-binding region of gE. Analysis of this idiotype-anti-idiotype reaction employed polymerase chain reaction amplification and sequencing of the variable heavy and light (VH and VL) regions of mAb II-481. When VH and VL regions of mAb II-481 were synthesized as overlapping 7-mer peptides on polypropylene pins, a panel of 10 polyclonal and 6 monoclonal human IgM RFs reacted primarily with epitopes within the three solvent-exposed mAb II-481 complementarity determining regions (CDRs). Preincubation of single CDR heptamer peptides with IgM RFs in free solution, resulted in 63-100% inhibition of RF binding to mAb II-481 on the ELISA plate, confirming the antigenic importance of linear CDR regions for RF reactivity. Combinations of two or three CDR peptides frequently produced 94-100% inhibition of RF binding to whole mAb II-481. Control peptides, singly or in combination, showed no inhibition. Computer modeling suggested that the RF-reactive mAb II-481 Fv region and a previously demonstrated RF-reactive CH3 epitope displayed considerable three-dimensional similarities in conformation. These studies may provide insight into limited shape homologies possibly involved in an RF anti-idiotypic reaction.

Amino Acid Sequence↗
PubMed1994

Epitopes on proteinase-3 recognized by antibodies from patients with Wegener's granulomatosis.

The 228 amino acid primary sequence of proteinase-3 (PR3) was studied for antigenic epitopes, which react with IgG Ab in sera of patients with Wegener's granulomatosis, by synthesizing overlapping 7 mers of PR3 linear sequence on pins. Main regions of linear sequence reactivity included GHEAQPH (at residues 4-10), QPHSRPY (8-14), TQEPTQQ (65-71), ATVQLPQ (108-114), QLPQQDQ (111-117), PVPHGTQ (118-124), RVGAHDP (132-138), FCRPHNI (154-160), PRRKAGI (165-171), FGDSGGP (173-179), and IDSFVIW (189-195). All of these regions were surface accessible and seemed to be on the outside of the molecule. By substituting a glycine or an alanine for each residue within each reactive epitope, we identified the arginine at 12, valine at 119, proline at 120, histidine at 121, arginine at 132, alanine at 135, histidine at 136, and glycine at 178 as major immunodominant single residues that contribute to antigenic determinants. Visualization of these reactive regions on a three-dimensional computer-generated carbon PR3 trace diagram showed that one aspect of the molecule on the inferolateral surface comprised most of the antigenic regions. Two peptides, ATVQLPQ and RVGAHDP, when preincubated with Wegener's granulomatosis sera, produced almost complete inhibition of Wegener's granulomatosis IgG Abs either binding to PR3 on the ELISA plate or by reacting with polymorphonuclear leukocyte azurophilic granules in immunofluorescence assays for cANCA. FGDSGGP (at residues 173-179), one epitope that was recognized by Wegener's patient sera Abs, included part of the active catalytic triad for PR3. Rabbit Abs against the PR3 peptides ATVQLPQ or RVGAHDP showed a cANCA cytoplasmic granular pattern of immunofluorescence staining when they were incubated with polymorphonuclear leukocytes. These findings indicate that it is possible to identify various antigenic sites on PR3 by using overlapping 7 mers of portions of the solvent, accessible linear sequence.

Amino Acid Sequence↗