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S Shall

Publications and source records attributed to S Shall.

At least 55 records · Page 3Linked to original sources
PubMed1987

DNA repair in human promyelocytic cell line, HL-60.

The human promyelocytic cell line, HL-60, shows large changes in endogenous poly(ADP-ribose) and in nuclear ADP-ribosyl transferase activity (ADPRT) during its induced myelocytic differentiation. DNA strand-breaks are an essential activator for this enzyme; and transient DNA strand breaks occur during the myelocytic differentiation of HL-60 cells. We have tested the hypothesis that these post-mitotic, terminally differentiating cells are less efficient in DNA repair, and specifically in DNA strand rejoining, than their proliferating precursor cells. We have found that this hypothesis is not tenable. We observe that there is no detectable reduction in the efficiency of DNA excision repair after exposure to either dimethyl sulphate or gamma-irradiation in HL-60 cells induced to differentiate by dimethyl sulphoxide. Moreover, the efficient excision repair of either dimethyl sulphate or gamma-irradiation induced lesions, both in the differentiated and undifferentiated HL-60 cells, is blocked by the inhibition of ADPRT activity.

Cell Differentiation↗
PubMed1987

Nicotinamide deficiency and benzamide-induced sister chromatid exchanges.

Benzamides induce sister chromatid exchanges (SCE) in L1210 cells. This induction is strongly potentiated when the cells are grown in nicotinamide-free medium. There is no dependence on the concentration of bromodeoxyuridine (BrdUrd) except at toxic doses, high enough to inhibit BrdUrd incorporation into the DNA. Nicotinamide starvation by itself does not increase the frequency of SCE markedly. These observations are consistent with the notion that BrdUrd and benzamides induce SCE by different mechanisms. The mode of action of benzamides in inducing SCE is still unclear.

Animals↗
PubMed1987

Profile of autoantibodies in the serum of patients with tuberculosis, klebsiella and other gram-negative infections.

Autoantibody profiles were examined in the sera of untreated patients with tuberculosis, and those with klebsiella septicaemia, and klebsiella and E. coli urinary tract infections. Rheumatoid factors of the IgM, IgA and IgG isotypes, antinuclear antibodies and antibodies to poly(ADP-ribose) were all frequently detected (generally 15-40%). In contrast, antibodies to the extractable nuclear antigens and to the organ specific antigens were unusual (generally less than 10%). In comparison, in a group of lupus patients IgM rheumatoid factor, anti-nuclear antibodies, antibodies to poly(ADP-ribose) and antibodies to the extractable nuclear antigens were more frequently found, but IgA and IgG rheumatoid factors and antibodies to the organ-specific antigens were present in much the same frequency.

Antibodies, Antinuclear↗
PubMed1986

Transformation of Schizosaccharomyces pombe by non-homologous, unstable integration of plasmids in the genome.

In the fission yeast, Schizosaccharomyces pombe, transformation with recombinant plasmids always results in a high proportion of mitotically unstable transformants. This suggested that specialised (ARS) sequences might not be required for autonomous replication of plasmids in S. pombe, contrary to the situation in Saccharomyces cerevisiae. We have shown that specialised ARS sequences, analogous to those in S. cerevisiae, do exist in S. pombe, supporting the view that ARS elements are a general feature of eukaryotes. In addition, there is a further mechanism of plasmid maintenance which involves homologous and non-homologous integration into, and excision from the genome.

DNA Replication↗
PubMed1986

A mammalian cell variant in which 3-aminobenzamide does not potentiate the cytotoxicity of dimethyl sulphate.

Variants of mouse leukaemia L1210 cells have been isolated in which cytotoxicity to dimethyl sulphate is not fully potentiated by ADP-ribosyl transferase inhibitor 3-aminobenzamide, as occurs in normal L1210 cells. These variants were selected after mutagenesis by growing the cells in dimethyl sulphate and 3-aminobenzamide. The characterisation of one of these variants is described. Variant 3 cells repair low doses of DNA damage in the presence of ADP-ribosyl transferase inhibitors. The Vmax of the ADP-ribosyl transferase enzyme in these cells is only increased 35% compared to normal wild-type L1210 cells. The basal DNA ligase I activity is increased 66% above wild-type whereas DNA ligase II activity appears to be unchanged. The most striking observation, however, is that the DNA ligase II activity is not increased after dimethyl sulphate treatment as occurs in wild-type L1210 cells. It seems that by increasing DNA ligase I levels these cells can survive DNA damage in the presence of 3-aminobenzamide. This variant (mutant) provides genetic evidence for our previously published hypothesis that (ADP-ribose)n biosynthesis is required for efficient DNA repair after DNA damage by monofunctional alkylating agents, because ADP-ribosyl transferase activity regulates DNA ligase activity. This variant is the first mammalian cell reported in which DNA ligase activity is altered, as far as we are aware. In yeast, a DNA ligase mutant has a cell division cycle (cdc) phenotype. Presumably, DNA ligase is essential for DNA synthesis, repair and recombination. The present variant provides further evidence that in mammalian cells, DNA ligase II activity is related to ADP-ribosyl transferase activity.

Animals↗
PubMed1986

A study of anti-poly (ADP-ribose) antibodies and an anti-DNA antibody idiotype and other immunological abnormalities in lupus family members.

The genetic background of systemic lupus erythematosus (SLE) has been reexamined in a study of the serum of 31 lupus patients and 80 asymptomatic first degree relatives by measuring a common, cross reacting anti-DNA antibody idiotype designated 134, antibodies to poly(ADP-ribose), serum C3, circulating immune complexes, and antinuclear antibodies (ANA). Over 30% of the relatives had raised 134 and anti-poly(ADP-ribose) levels, and 9% had ANA titres greater than 1/20. In contrast, only one relative had a low serum C3 level. These results confirm that immunogenetic abnormalities associated with the production of autoantibodies and particular idiotypes must exist amongst lupus relatives as well as the patients. The production of autoantibodies, however, is not necessarily matched to the clinical expression of SLE.

Adolescent↗
PubMed1985

Effect of 3-aminobenzamide on antigenic variation of Trypanosoma brucei.

African trypanosomes, like Trypanosoma brucei, depend on antigenic variation to evade the immune response of the vertebrate host. An antigenic switch corresponds to the activation of a variable surface glycoprotein (VSG) gene from a large silent repertoire. Most switches require the duplicative transposition of a VSG gene, which involves strand breaks in DNA and subsequent repair. The nuclear enzyme adenosine-diphosphoribosyl transferase (ADPRT), which is dependent on the presence of DNA strand breaks for its activity, might be involved in this process because it has a regulatory role in DNA repair in all eukaryotic cells studied so far. In previous work, the presence of ADPRT activity was demonstrated in T. brucei. Moreover, it was also shown in isolated trypanosomes the ADPRT activity, which is stimulated by the induction of DNA strand breaks, could be blocked by the competitive inhibitor 3-aminobenzamide. Here we report experiments using rats which were infected with small numbers of T. brucei expressing VSG gene 118. After two days, the rats were coupled to a continuous intraperitoneal infusion system administrating 3-aminobenzamide in 0.9% NaCl (81.4 mM) at a rate of 0.65 ml/hr/rat for a period of up to five days. Control rats received only a 0.9% NaCl infusion. At days 1, 3 and 5, 250 microliters blood was obtained from a tail artery. Plasma 3-aminobenzamide was determined using a new high performance liquid chromatography method, developed for these experiments. In most rats the plasma concentrations were maintained between 0.8 and 1.2 mM. The rate of antigenic switching was determined by quantitating the fraction of trypanosomes that had lost their VSG 118 coat, using antibody against VSG 118 and a limiting dilution in mice. The average switching rate found was 2.0 X 10(-6) in controls and 1.3 X 10(-7) in drug-treated rats (15-fold reduction). This suggests that ADPRT is required for completing most antigenic switching events. We discuss the possibility that drug-resistant switching only involves non-duplicative VSG gene activation.

Animals↗
PubMed1985

The dynamic nature of DNA-strand breaks present in differentiating muscle cells and quiescent lymphocytes.

Cellular differentiation in a number of eukaryotic systems is associated with changes in the number of DNA-strand breaks and involves the activity of adenosine diphosphoribosyl transferase (ADPRT). DNA-strand breaks are essential for activation of nuclear ADPRT, the activity of which is required for efficient religation of DNA-strand breaks. In this study we demonstrate the dynamic nature of DNA-strand breaks formed in the genome of differentiating avian skeletal muscle cells and quiescent human lymphocytes. Inhibition of ADPRT activity blocks DNA-strand ligation in both cell types and leads to the accumulation of a higher number of strand breaks.

Animals↗
PubMed1985

Evaluation of heterologous ARS activity in S. cerevisiae using cloned DNA from S. pombe.

Cloned segments of Schizosaccharomyces pombe genomic DNA were screened for ARS activity in the native host, S. pombe, using high frequency transformation, phenotypic instability and extrachromosomal maintenance of unrearranged plasmid sequences as criteria for ARS function. This analysis revealed 12 ARS elements in a total of 230 kb of chromosomal DNA, indicating an average frequency of one ARS every 19 kb of genomic DNA. We then used these clones to assess the reliability of the S. cerevisiae assay for detecting ARS elements in heterologous DNA. The results show that not only does the S. cerevisiae assay fail to detect a large proportion of true ARS elements but it also wrongly identifies a significant proportion of clones which did not display ARS activity in the native host. We would therefore recommend restraint when extrapolating from observed ARS function of heterologous DNA in S. cerevisiae to a presumed analogous role in the original host.

Base Sequence↗
PubMed1985

Effect of DNA intercalators on poly(ADP-ribose) glycohydrolase activity.

Proflavine, ethacridine (2-ethoxy-6,9-acridine diamine), ellipticine, daunomycin and Tilorone R10,556 DA (2,7-bis(piperidinobutyryl)-9H-fluoren-9-one) inhibit poly(ADP-ribose) glycohydrolase activity. The Ki values for proflavine and Tilorone R10,556 DA are 36 microM and 7.3 microM, respectively. The inhibition by intercalators is relieved by DNA but not by DNA-histone complexes. On the contrary, DNA-histone complexes increase the inhibition of some intercalators. Ethidium bromide is not inhibitory by itself. However, in the presence of DNA-histone complexes it strongly inhibits the enzyme activity. m-AMSA (4'-(9-acridinylamino)methanesulphon-m-anisidide) and chloroquine have no effect on the enzyme activity, even in the presence of DNA-histone complexes.

Aminoacridines↗
PubMed1985

ADP-ribosyl transferase activity in Trypanosoma brucei.

Nuclear adenosine diphosphoribosyl transferase (ADPRT) catalyses the covalent modification of chromatin proteins by (ADP-ribose)n. This activity, which is entirely dependent on DNA containing strand breaks, is required for efficient DNA excision repair possibly because it regulates DNA ligation. ADPRT activity is also required for cytodifferentiation in a number of different cell types. We report here the presence of ADPRT activity in the blood-stream form of Trypanosoma brucei and its activation by DNA strand breaks formed by exposure to, either exogenously supplied deoxyribonuclease I, or treatment with the methylating agent, dimethylsulphate. 3-Aminobenzamide, but not its chemical analogue 3-aminobenzoic acid, is a competitive inhibitor of ADPRT activity in T. brucei. Intact trypanosomes are readily permeable to this competitive inhibitor of ADPRT activity.

Animals↗
PubMed1984

Kinetics of in vitro ageing of mouse embryo fibroblasts.

The kinetics of ageing of normal mouse embryo fibroblast cells in culture have been determined. The growth pattern during every passage was established. It was observed that the growth pattern was not exponential, but that the growth rate declined progressively both within and with every passage. We also estimated the cell cycle parameters using the Fraction of Labelled Mitoses method at every passage. We found that the cell cycle duration was constant throughout the lifespan of this cell strain; the median value of the cell cycle duration was found to be 15.5 +/- 0.5 h (S.D., n = 8). From these two sets of observations we infer that the fraction of dividing cells declines smoothly from the beginning of the culture. Our data exclude quite positively any description of ageing of the fibroblast population in terms of a catastrophe or any abrupt change in the population. Our data are also inconsistent with a linear decline in growth fraction. On the contrary, we observed that there was a gradual and smooth decline in the growth rate of the strain, due to a smoothly declining growth fraction. This smooth change in the growth behaviour of this cell strain is accurately described by the mortalization theory of Shall & Stein in which the single parameter gamma (gamma), describes the change in reproductive potential over the entire lifespan. The parameter gamma describes the rate at which the doubling time of the culture increases. It is the number of generations at which half of the newborn cells are themselves reproductively sterile. Our present data provided an estimate of gamma for this cell strain, which was consistent during the entire lifespan of the strain; the best estimate of gamma for this cell strain was 20.3 +/- 0.6 generations (S.D., n = 19).

Animals↗
PubMed1984

The reproductive potential of normal mouse embryo fibroblasts during culture in vitro.

A direct estimate of the reproductive potential of mouse embryo fibroblasts through their entire lifespan has been made using the mini-clone technique, which permits the direct observation of the growth fraction in a bulk population by inspection of the growth behaviour of individual cells. We have measured the colony size on each island that contained one or two cells at the beginning and the fraction of islands which, starting from one or two cells failed to divide even once. We observed that even in a young culture there are individual cells that can only reproduce two or three times. With each succeeding passage the distribution of colony sizes shifts to a greater proportion of small colonies. The median colony size decreases with each passage. Furthermore, the fraction of non-dividers directly observed increases smoothly with time; the fraction of non-dividers is quite small at the first passage but increases steadily to reach 0.6 at the last passage, after about 30 generations. These smooth changes in the growth behaviour of this cell strain are accurately described by the mortalization theory of Shall and Stein, in which the single parameter gamma, describes the change in reproductive potential over the entire lifespan. The parameter gamma describes the rate at which the doubling time of the culture increases; it is the number of generations at which half of the newborn cells are themselves reproductively sterile. Our present data provide an estimate of gamma for this cell strain equal to 21.2 generations, which compares well with a previous estimate of 20.3 generations.

Animals↗
PubMed1984

Measurement of antibody to poly (adenosine diphosphate-ribose): its diagnostic value in systemic lupus erythematosus.

Poly (ADP-ribose) and dsDNA binding activity have been measured in sera from 61 patients with systemic lupus erythematosus (SLE) and 188 control sera from 20 normal individuals, 144 patients with clinically similar diseases and 24 patients with drug-induced anti-nuclear antibodies (ANA). Elevated poly (ADP-ribose) binding was not observed with normal sera. Five of 144 samples from diseases entering the differential diagnosis of SLE gave raised poly (ADP-ribose) binding compared with 12 in the 125I-dsDNA binding. Only two of these false positive samples gave elevated binding in the 14C-dsDNA assay. The apparent high specificity of the poly(ADP-ribose) assay was not observed with samples containing drug-induced ANA where 62% had elevated binding values. The frequency with which the poly(ADP-ribose) assay was positive with SLE sera (sensitivity) was lower than either of the dsDNA assays. This low sensitivity and the high rate of false positives in patients with drug-induced ANA limit the value of the poly(ADP-ribose) assay as a diagnostic test for SLE. However the restriction of poly(ADP-ribose) antibody to SLE and patients with drug-induced ANA together with the known role of poly(ADP-ribose) in DNA excision repair suggest that the antibody may be of fundamental significance.

Adult↗
PubMed1983

Isolation and purification of poly(ADP-ribose) glycohydrolase from pig thymus.

Poly(ADP-ribose) glycohydrolase has been purified about 12 300-fold from pig thymus with a recovery of 8.5%. The specific activity of the purified enzyme is 13.8 mumol min -1 mg protein -1. The molecular weight was estimated to be 59 000 by gel filtration through Sephadex G-100 in a non-denaturing solvent. Analysis of the final preparation by sodium dodecyl sulphate gel electrophoresis reveals two protein bands of molecular weight, 61 500 and 67 500. The Km value for poly(ADP-ribose) is estimated to be 1.8 microM monomer units. The enzyme preparation is free from phosphodiesterase, NADase and ADP-ribosyltransferase activities. The purified enzyme is inhibited by cyclic AMP, ADP-ribose, naphthylamine, histones H1, H2A, H2B, H3, polylysine, polyarginine, polyornithine and protamine. The inhibition by histone is relieved by an equal mass of DNA. Single-stranded DNA, poly(A), poly(I) and polyvinyl sulphate were inhibitory, but double-stranded DNA was not inhibitory.

Animals↗
PubMed1983

NAD turnover during early development of Xenopus laevis.

The NAD pools of Xenopus laevis oocytes and early embryos can be radioactively labelled by microinjection of [adenine-3H]NAD. This technique is used to study the metabolism of NAD in oocytes and during early development. The rate at which NAD is degraded in vivo has been monitored by determining the rate of transfer of adenine residues from the NAD pool into other nucleotides and polynucleotides. In oocytes, NAD turnover is extremely slow, with a half-life of about 400 h. NAD turnover increases dramatically after fertilisation, and the half-life of the compound decreases to 37 h in 5-h-old embryos and to 10 h in 40-h-old embryos. 2 mM 3-aminobenzamide, a specific inhibitor of poly(ADP-ribose) polymerase, reduces the NAD turnover rate by about 20%, whereas 5 mM isonicotinic acid hydrazide, a specific inhibitor of NAD glycohydrolase, produces no significant inhibition. This indicates that a significant fraction of the considerable NAD turnover observed involves poly(ADP-ribose) polymerase. Our results indicate that poly(ADP-ribose) polymerase is active during early development and suggest that this activity may be involved in one or more aspects of the nuclear metabolism of the embryo.

Animals↗