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I Collins

Publications and source records attributed to I Collins.

34 records · Page 2Linked to original sources
PubMed1994

Normal human tissues, in addition to some tumors, express multiple different CD44 isoforms.

At least 20 different isoforms of the human CD44 lymphocyte-homing receptor/hyaluronan receptor have been described to date that arise from the differential splicing of up to 10 alternative exons (termed v1-v10) encoding the membrane-proximal extracellular domain. Although numerous analyses at the mRNA level have indicated tissue-specific expression of CD44 variants, few analyses have been performed at the protein level because of limited availability of suitable monoclonal antibodies. Recently, however, exon-specific monoclonal antibodies have been generated using bacterial fusion proteins, and these have been reported to detect high levels of vCD44 containing the v6 exon on human tumors. Together with earlier evidence linking this particular exon with tumor metastasis in the rat, these latter experiments have led to the interpretation that v6 splice variants play a causative role in tumor dissemination. In this paper we describe the use of a new and comprehensive panel of CD44 exon-specific monoclonal antibodies generated against a recombinant CD44(v3-10)-immunoglobulin chimera to study vCD44 expression in a large number of normal and neoplastic tissues. We show that the expression of vCD44 varies greatly among different human tumors and that some express either very low levels of vCD44 or no CD44 at all. Furthermore, we demonstrate that expression is not limited to isoforms containing the v6 exon but includes variants carrying v3, v4/5, and v8/9. Additionally, normal epithelial tissues are shown to express considerable levels of these same vCD44 isoforms. Such results argue against a ubiquitous role for vCD44 isoforms in promoting tumor growth and metastasis.

Antibodies, Monoclonal↗
PubMed1994

Meiosis-specific formation of joint DNA molecules containing sequences from homologous chromosomes.

All recombination models postulate one or more recombination intermediates that are joint molecules containing two homologous parental molecules. A spike of branched DNA molecules not seen in DNA from mitotic cells was found in the two-dimensional gel analysis of meiotic DNA from S. cerevisiae. The mass of molecules in the spike, the timing of its appearance and disappearance, and its absence from a recombination-defective spo11 mutant are consistent with the hypothesis that it contains recombination intermediates. The spike changes in mass as predicted for joint molecules containing DNA from homologous chromosomes rather than sister chromatids in a strain heterozygous for an RFLP. Finally, joint molecules containing DNA from homologous chromosomes were not found, suggesting that the block to recombination between homologous sequences occurs prior to the formation of joint molecules.

Blotting, Southern↗
PubMed1994

A physical comparison of chromosome III in six strains of Saccharomyces cerevisiae.

We have tested the clones used in the European Yeast Chromosome III Sequencing Programme for possible artefacts that might have been introduced during cloning or passage through Escherichia coli. Southern analysis was performed to compare the BamHI, EcoRI, HindIII and PstI restriction pattern for each clone with that of the corresponding locus on chromosome III in the parental yeast strain. In addition, further enzymes were used to compare the restriction maps of most clones with the map predicted by the nucleotide sequence (Oliver et al., 1992). Only four of 506 6-bp restriction sites predicted by the sequence were not observed experimentally. No significant cloning artefacts appear to disrupt the published sequence of chromosome III. The restriction patterns of six yeast strains have also been compared. In addition to two previously identified sites of Ty integration on chromosome III (Warmington et al., 1986; Stucka et al., 1989; Newlon et al., 1991), a new polymorphic site involving Ty retrotransposition (the Far Right-Arm transposition Hot-Spot, FRAHS) has been identified close to CRY1. On the basis of simple restriction polymorphisms, the strains S288C, AB972 and W303-1b are closely related, while XJ24-24a and J178 are more distant relatives of S288C. A polyploid distillery yeast is heterozygous for many polymorphisms, particularly on the right arm of the chromosome.

Artifacts↗
PubMed1994

Characterization and pathological significance of monoclonal DNA-binding antibodies from mice with experimental malaria infection.

Malaria infection is accompanied by the production of a number of autoantibodies, including some that react with DNA. Epidemiological evidence implicates these in the nephritides that arise in human quartan malaria and in experimental malaria infections in mice. Through parallels with the involvement of DNA-reactive antibodies in the autoimmune syndrome systemic lupus erythematosus, a role for DNA-reactive antibodies in forming phlogistic immune deposits in the kidneys is implied. To more fully understand the relationship between antibodies of this specificity made in malaria and systemic lupus erythematosus, we prepared monoclonal DNA-reactive antibodies from BALB/c mice infected with Plasmodium berghei (clone RC) and compared their properties with those of other antibodies previously isolated from lupous MRL/Mp lpr/lpr and (NZB x NZW)F1 mice. Antibodies from malarial mice were all immunoglobulin M class and bound to single-stranded but not double-stranded DNA in an enzyme-linked immunosorbent assay. They also reacted with synthetic polyribonucleotides in the enzyme-linked immunosorbent assay and with parasitized erythrocytes and parasite pigment in kidney sections. None of the antibodies from lupous mice had identical specificities. The potential involvement of the DNA-reactive antibodies in malarial nephritis was demonstrated, by use of immunocytochemical methods, on the basis of their binding to existing immune deposits in kidney sections from malarial mice, a similar property having been previously demonstrated for antibodies from lupous mice. Furthermore, antibodies from malarial mice expressed public idiotypes, notably Id.V-88, which is a member of the Id.16/6 family, commonly found on DNA-reactive antibodies in lupus and other infectious and connective tissue diseases. This study indicates that DNA-reactive antibodies in malaria have immunochemical properties similar but not identical to those of such antibodies in systemic lupus erythematosus and that they have the potential to participate in the formation of immune deposits in nephritic malarial kidneys.

Animals↗
PubMed1994

Chromosomal DNA replication initiates at the same origins in meiosis and mitosis.

Autonomously replicating sequence (ARS) elements are identified by their ability to promote high-frequency transformation and extrachromosomal replication of plasmids in the yeast Saccharomyces cerevisiae. Six of the 14 ARS elements present in a 200-kb region of Saccharomyces cerevisiae chromosome III are mitotic chromosomal replication origins. The unexpected observation that eight ARS elements do not function at detectable levels as chromosomal replication origins during mitotic growth suggested that these ARS elements may function as chromosomal origins during premeiotic S phase. Two-dimensional agarose gel electrophoresis was used to map premeiotic replication origins in a 100-kb segment of chromosome III between HML and CEN3. The pattern of origin usage in premeiotic S phase was identical to that in mitotic S phase, with the possible exception of ARS308, which is an inefficient mitotic origin associated with CEN3. CEN3 was found to replicate during premeiotic S phase, demonstrating that the failure of sister chromatids to disjoin during the meiosis I division is not due to unreplicated centromeres. No origins were found in the DNA fragments without ARS function. Thus, in both mitosis and meiosis, chromosomal replication origins are coincident with ARS elements but not all ARS elements have chromosomal origin function. The efficiency of origin use and the patterns of replication termination are similar in meiosis and in mitosis. DNA replication termination occurs over a broad distance between active origins.

Chromosomes, Fungal↗
PubMed1991

Analysis of a circular derivative of Saccharomyces cerevisiae chromosome III: a physical map and identification and location of ARS elements.

DNA was isolated from a circular derivative of chromosome III to prepare a library of recombinant plasmids enriched in chromosome III sequences. An ordered set of recombinant plasmids and bacteriophages carrying the contiguous 210-kilobase region of chromosome III between the HML and MAT loci was identified, and a complete restriction map was prepared with BamHI and EcoRI. Using the high frequency transformation assay and extensive subcloning, 13 ARS elements were mapped in the cloned region. Comparison of the physical maps of chromosome III from three strains revealed that the chromosomes differ in the number and positions of Ty elements and also show restriction site polymorphisms. A comparison of the physical map with the genetic map shows that meiotic recombination rates vary at least tenfold along the length of the chromosome.

Chromosomes, Fungal↗
PubMed1991

Absence of autoimmunity to type II collagen in generalised nodal osteoarthritis.

A cardinal feature of generalised nodal osteoarthritis is the loss of articular cartilage. To determine if autoimmunity to these cartilage collagens occurred, serum antibodies to native and denatured type II collagen were measured by enzyme linked immunosorbent assay (ELISA) in 96 patients (90 women, six men, aged 47-91 years) with generalised nodal osteoarthritis. Generalised nodal osteoarthritis was diagnosed by typical clinical and radiological features. Serum samples from 42 blood donors were assayed as controls. No significant difference was found between the patients with generalised nodal osteoarthritis and the controls. Furthermore, the 20 patients who were HLA-A1, B8 positive had similar antibody levels to the group as a whole. One woman patient with generalised nodal osteoarthritis (HLA-A1, B8 negative) had markedly increased antibody levels to native and denatured type II collagen in a pattern similar to that seen in patients with rheumatoid arthritis. This patient did not develop super added rheumatoid arthritis during a three year follow up period. Autoimmunity to type II collagen is therefore rare in generalised nodal osteoarthritis. A lack of collagen antibodies in a condition characterised by hyaline cartilage loss suggests that the presence of such antibodies in rheumatoid arthritis is more than a secondary event to joint damage.

Aged↗
PubMed1990

Diversity of antibodies to type II collagen in patients with rheumatoid arthritis: detection by binding to alpha-chains and to cyanogen bromide peptides.

Antibodies to denatured type II collagen were detected in the sera of a group of patients with rheumatoid arthritis by ELISA and by immunoblotting. The antibodies were further examined by immunoblotting against cyanogen-bromide derived peptides of type II collagen. The majority of sera reacted against only one or two peptides and antibodies to the CB-10 and CB-11 peptides were those most commonly found. However, some sera reacted with up to eight peptides, indicating that patients had antibodies to differing combinations of epitopes on type II collagen. Examination of sequential serum samples from an individual patient showed that there were changes in the class of antibody produced to type II collagen and that antibodies to different peptides were preferentially produced at different times in the course of the disease. Thus there was a selective response to different peptides of type II collagen not only between patients but also at different times in the course of disease in the same patient.

Antibodies↗
PubMed1989

A longitudinal study of anticollagen antibodies in patients with rheumatoid arthritis.

Antibodies to native and denatured collagens (types I, II, IX, and XI) were measured in sequential serum samples collected over 1.5-8.7 years (median 4.3) from 15 patients with rheumatoid arthritis. Eleven patients were seropositive and 4 were seronegative. Disease duration ranged from 3 years to 25 years before the first sample was tested. The patients showed a selective and varying response to collagens, even after disease had been present for a long time. Changes in the levels of antibody to one collagen type were not necessarily linked to changes in the levels of antibody to other collagens. Only some patients showed a strong correlation between C-reactive protein levels (a measure of disease activity) and antibodies to individual collagens. These findings suggest that rheumatoid arthritis patients produce antibodies to a wide variety of epitopes on these collagen molecules, as a result of different antigenic epitopes being exposed by cartilage degradation at different times throughout the disease.

Adult↗
PubMed1988

Antibodies to type II and XI collagens: evidence for the formation of antigen specific as well as cross reacting antibodies in patients with rheumatoid arthritis.

Antigen specific and cross reacting antibodies to native and denatured types II and XI collagen were detected in the sera of rats immunised with either of these antigens. The antibodies from rats immunised with type XI collagen initially showed the strongest binding to the alpha 2(XI) chain of type XI collagen but later binding to the alpha 3(XI) chain was seen. Sera from patients with rheumatoid arthritis had antibodies that bound to both type II and XI collagens. Immunoblotting studies showed that most patients had antibodies which bound to the alpha 1(II) chain of type II collagen and to the alpha 3(XI) chain of type XI collagen. Some patients also had antibodies which bound to the alpha 1(XI) and to the alpha 2(XI) chains of type XI collagen. Thus antibodies to unique as well as to common epitopes on each of the two types of collagen molecule occur in some patients with rheumatoid arthritis.

Animals↗
PubMed1988

IgG subclass distribution of antinative type II collagen and antidenatured type II collagen antibodies in patients with rheumatoid arthritis.

In 81 patients with rheumatoid arthritis (RA) with antibodies to native type II collagen, the frequencies of each IgG subclass to native type II collagen were IgG1 (70%), IgG2 (12%), IgG3 (84%) and IgG4 (6%) and to denatured type II collagen were IgG1 (86%), IgG2 (23%), IgG3 (86%) and IgG4 (6%). Thus serum antibodies to type II collagen in patients with RA were predominantly of the complement fixing subclasses IgG1 and IgG3.

Arthritis, Rheumatoid↗
PubMed1987

Incidence of antibodies to native and denatured cartilage collagens (types II, IX, and XI) and to type I collagen in rheumatoid arthritis.

The frequencies of antibodies to the cartilage type IX and XI collagens and to type I collagen were determined in 188 patients with rheumatoid arthritis, of whom 76 were positive for antibodies to native type II collagen. A higher proportion of patients with antibodies to native type II collagen had antibodies to these other collagens, but about one third of patients without antibodies to native type II collagen had antibodies to one or more denatured collagens. The patterns of antibodies present in individual sera suggested that there was a selective response to the collagens in an individual patient. The incidence of patients having antibodies to these native and denatured collagens in a random group of patients with rheumatoid arthritis was calculated.

Antibodies↗
PubMed1987

Gm allotypes and HLA in rheumatoid arthritis patients with circulating antibodies to native type II collagen.

HLA antigens and immunoglobulin heavy chain allotypes (Gm) were determined in 166 unrelated patients with rheumatoid arthritis (RA), 44 of whom had circulating antibodies to native type II collagen. Collagen antibody positive patients showed an association with HLA-DR3 and DR7 (68% compared with 39% of collagen antibody negative RA, p less than 0.005), and with the Gm phenotype, Gm(zafngb). This contrasted with the collagen antibody negative RA patients where there was an association with HLA-DR4 and, in DR4 positive disease only, with the Gm allotype, G1m(x). The Gm(zafngb) phenotype was found in 26% of DR3 or DR7 positive patients overall and only 9% of RA patients negative for these DR antigens (p less than 0.005), suggesting an interaction between HLA-DR3/7 and Gm(zafngb). The differing Gm associations for collagen antibody positive and negative RA provide further evidence for genetic heterogeneity in susceptibility to RA.

Antibodies↗
PubMed1986

Distribution and possible abnormality in antigenic composition of sodium channels in peripheral axons of dystrophic mice.

In some dystrophic mice (Bar-Harbour 129 dy/dy), axons of the sciatic nerve are a-myelinated but are capable of carrying action potentials. In this study, we showed by immunofluorescence that such excitability is supported by the presence of voltage-gated sodium channels along the a-myelinated axon. In addition, the number of sodium channels measured by radioimmunoassay in sciatic nerves of these dystrophic mice is significantly higher. Furthermore, the composition of sodium channel epitopes is abnormal. This suggested a link between the disease and the biogenesis of the sodium channels.

Animals↗
PubMed1982

Arylethanolamines derived from salicylamide with alpha- and beta-adrenoceptor blocking activities. Preparation of labetalol, its enantiomers, and related salicylamides.

A series of phenethanolamines (3) based on salicylamide has been prepared and shown to possess beta-adrenergic blocking properties. When the basic nitrogen atom was substituted by some aralkyl groups, the compounds also blocked alpha-adrenoceptors. The 1-methyl-3-phenylpropyl derivative labetalol (34) is antihypertensive in animals and man, and syntheses of its four stereoisomers are described. The enantiomer 90 with the R configuration at both asymmetric centers possessed most of the beta-blocking activity but little alpha-blocking activity. That with the S configuration at the alcoholic carbon and the R configuration on the amino substituent, 89, is predominantly an alpha-adrenoceptor blocking agent.

Adrenergic alpha-Antagonists↗