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Biomedical subjects

G Fellows

Publications and source records attributed to G Fellows.

9 recordsLinked to original sources
PubMed1997

Telomerase activity in bladder carcinoma and its implication for noninvasive diagnosis by detection of exfoliated cancer cells in urine.

BACKGROUND: Telomerase is an enzyme that can reconstitute the ends (telomeres) of chromosomes after cell division and thus circumvent the cumulative damage that occurs in normal adult somatic cells during successive mitotic cycles. Recently, it has been proposed that this enzyme should, therefore, be detectable in immortal malignant cells but not in their normal counterparts, which stop dividing and senesce. Accordingly, telomerase activity has been reported in many types of malignant tumors, including those of the gastrointestinal tract, breast, and lung but little information was available regarding its status in bladder carcinoma or in exfoliated cancer cells. METHODS: In the current study, telomerase activity was examined by a polymerase chain reaction-based assay designated TRAP (telomeric repeat amplification protocol) in tissue samples from 56 bladder carcinomas, 17 nonneoplastic bladder lesions, and 2 dysplastic lesions of the urinary tract. The feasibility of identifying cancer patients by the detection of telomerase activity in exfoliated cancer cells in the urine was also investigated. Such activity was assayed in centrifuged urine cell pellets from 26 bladder carcinoma patients and from 83 patients with no evidence of malignant disease. RESULTS: Evidence of telomerase was detected in solid tissue specimens from 48 of the 56 bladder carcinomas (86%) regardless of tumor stage or differentiation, whereas it was not found in any normal bladder tissue specimen. However, it was present in the dysplastic bladder lesions as well as in nearly all Stage I well differentiated carcinomas, suggesting that its activation occurs for the early stages of carcinogenesis and could perhaps be a useful marker for the detection of early primary or recurrent bladder tumors. Telomerase activity was detected with various signal intensities in urine specimens from 16 of the 26 patients with bladder carcinoma (62% sensitivity), whereas only 3 of 83 nonmalignant urine samples showed any activity (96.4% specificity); this was very weak. CONCLUSIONS: These results suggest that telomerase could be a good diagnostic marker for the early noninvasive identification of patients with bladder carcinoma by facilitating the detection of exfoliated immortal cancer cells in their urine.

Aged↗
PubMed1989

Specific antibodies reveal ordered and cell-cycle-related use of histone-H4 acetylation sites in mammalian cells.

Antibodies specific for the acetylated forms of histone H4 (H4) were produced in rabbits with a synthetic peptide corresponding to the 18 N-terminal residues of tetra-acetylated H4 (i.e. with acetyllysine at positions 5, 8, 12 and 16). Specificity was determined by inhibition assays using four additional peptides, each acetylated at only a single site. Using an antiserum (R6) specific for the acetylation site at Lys-5 we have estimated the proportion of Lys-5 sites acetylated in the mono-, di- and tri-acetylated forms of H4 from randomly growing human HL-60 cells. The values obtained (7%, 29% and 61% respectively) differ from those expected if acetylation were random (i.e. 25%, 50% and 75%) or if site usage followed a set order for all H4 molecules (i.e. a jump from 0% to 100%). Antibodies from a second animal (R5) bound preferentially to peptides acetylated at Lys-12 and also bound to mono-acetylated H4 relatively weakly in several cell types. In contrast, mono-acetylated H4 from metaphase HeLa cells labelled more strongly with both antisera, indicating significant acetylation at Lys-5 and Lys-12. We conclude that (1) the sites at Lys-5 and Lys-12 are under-used in mono-acetylated H4 from a variety of mammalian cell types and Lys-8 and/or Lys-16 are therefore the first to be acetylated, (2) more than one order of site usage is possible and (3) there is a metaphase-specific shift in site usage. These results suggest that H4 acetylation plays a role in the modulation of chromatin structure in mammalian cells.

Acetylation↗
PubMed1988

Individual variation in the isotype profile of anti-histone autoantibodies in systemic lupus erythematosus.

Using a solid-phase radioimmunoassay we have measured levels of anti-histone autoantibodies of the IgG, IgA and IgM heavy chain classes in 40 patients with systemic lupus erythematosus. Twenty-two patients (55%) had significantly elevated levels of at least one anti-histone isotype. Our results reveal four characteristics of the anti-histone response. (1) There is wide variation between patients in the isotype profile of anti-histone antibodies and these isotype profiles are a consistent individual characteristic. (2) There is no significant correlation between the level of IgG, IgA and IgM anti-histone in individual patients and a marked tendency for a single isotype (either IgG, IgA or IgM) to predominate in any one patient. (3) IgG anti-histone antibodies are predominantly of the IgG1 subclass. (4) Among 12 patients tested, IgG and IgA antibodies showed a preference for histones 1 and 2B whereas IgM antibodies showed no consistent preference for individual histones.

Adult↗
PubMed1986

Characterization of monoclonal antibodies to histone 2B. Localization of epitopes and analysis of binding to chromatin.

Two mouse monoclonal IgM antibodies have been isolated which bind to histone 2B (H2B), as shown by protein blotting and immunostaining and by solid-phase radioimmunoassay (RIA). One of these (HBC-7) was specific for H2B by both techniques whereas the other (2F8) cross-reacted with histone H1 by RIA. Both antibodies failed to recognize H2B limit peptides from trypsin-digested chromatin and did not bind to Drosophila H2B, which differs extensively from vertebrate H2B only in the N-terminal region. These findings indicate that both antibodies recognize epitopes within the trypsin-sensitive, N-terminal region comprising residues 1-20. Binding of antibody HBC-7 was inhibited by in vitro ADP-ribosylation of H2B at glutamic acid residue 2. This strongly suggests that the epitope recognized by HBC-7 is located at the N-terminus of H2B, probably between residues 1 and 8. We have used solid-phase radioimmunoassay to investigate factors which influence the accessibility of this epitope in chromatin. Removal of H1 ('stripping') from high-molecular-mass chromatin had no effect on HBC-7 binding, nor was any difference observed between binding to stripped chromatin and to 146-base-pair (bp) core particles derived from it by nuclease digestion. These results suggest that accessibility of the N-terminal region of H2B is not influenced by H1 itself or by the size or conformation of linker DNA. In contrast, binding of antibody HBC-7 to 146-bp core particles derived from unstripped chromatin was reduced by up to 70%. Binding was restored by exposure of these core particles to the conditions used for stripping. Analysis of the protein content of core particle preparations from stripped and unstripped chromatin suggests that these findings may be attributable to redistribution of non-histone proteins during nuclease digestion. Pre-treatment of high-molecular-mass chromatin or 146-bp core particles with the intercalating dye ethidium bromide resulted in a severalfold increase in binding of HBC-7. The major changes in nucleosome morphology induced by ethidium are therefore accompanied by an increase in accessibility of the N-terminal region of H2B, possibly as a direct result of changes in the spatial relationship between H2B and core DNA.

Adenosine Diphosphate Ribose↗
PubMed1981

Bladder cancer after spinal cord injury.

We reviewed 25 patients who developed carcinoma of the bladder following spinal cord injury among a series of 6744 paraplegic and tetraplegic patients. An analysis of the incidence, presentation, possible predisposing factors and prognosis was carried out. The majority presented at a younger age and there was a significantly higher incidence of squamous carcinoma than in the non-paraplegic population. The anterior bladder wall was involved in about 25 per cent of the cases. The prognosis is poor.

Adult↗
PubMedDate not supplied

Results from a new renal transplantation unit.

158 kidneys, 9 from living related donors and 149 from cadavers, have been transplanted in the first 42 months of the establishment of a transplant unit at Oxford. Patients' ages ranged from 11 to 56 (mean 35) years. Azathioprine and prednisolone alone were used for immunosuppression, and a minimum-transfusion policy was in operation throughout. After cadaveric transplantation actuarial patient-survival is 70% and 68%, respectively, at the same intervals. 85% of patients who had a functioning graft are fully rehabilitated. Matching for HLA-DR, pregraft blood-transfusions, and the finding that a transplant could be performed in the presence of a positive B-cell crossmatch have proved to be the most significant of the many factors examined both prospectively and retrospectively. The function of the unit is based on dialysis and transplantation for all patients in end-stage renal failure, with transplantation being considered the first line of treatment for patients under the age of 56. The results of transplantation reported here, which have been achieved with conventional immunosuppressive therapy and minimum-transfusion policy, might be considered a standard against which modifications of the practice of renal transplantation can be compared.

Adolescent↗