Search PubMed⌕ Search

Biomedical subjects

P C Cooper

Publications and source records attributed to P C Cooper.

17 recordsLinked to original sources
PubMed1997

Co-inheritance of the 20210A allele of the prothrombin gene increases the risk of thrombosis in subjects with familial thrombophilia.

The presence of the 20210A allele of the prothrombin (PT) gene has recently been shown to be a risk factor for venous thromboembolism. This is probably mediated through increased plasma prothrombin levels. The aim of this study was to compare the prevalence of the prothrombin 20210A allele in control subjects and in subjects with recognised thrombophilia and to establish whether the additional inheritance of the PT 20210A allele is associated with an increased risk of venous thromboembolism. 101 subjects with a history of venous thromboembolism and diagnosed as having either factor V Leiden (R506Q) or heritable deficiencies of protein C, protein S or antithrombin were studied. The prevalence of the PT 20210A allele in this group was compared with the results obtained for 150 control subjects. In addition, the relationships were examined between genetic status and the number of documented thromboembolic episodes, and between plasma prothrombin levels and possession of the PT 20210A allele. 8 (7.9%) of the 101 patients were also heterozygous for the PT 20210A allele. This compares with 0.7% in the control subjects (p = 0.005). After exclusion of patients on warfarin, the mean plasma prothrombin of 113 subjects without 20210A was 1.09 U/ml, as compared with 1.32 U/ml in 8 with the allele (p = 0.0002). Among the 101 patients with either factor V Leiden, protein S deficiency, protein C deficiency or antithrombin deficiency, the age adjusted mean (SD) number of venous thromboembolic episodes at diagnosis was 3.7 (1.5) in those with the PT 20210A allele, as compared with 1.9 (1.1) in those without (p = 0.0001). We have demonstrated that the prevalence of the PT 20210A allele is significantly greater in subjects with venous thrombosis and characterised heritable thrombophilia than in normal control subjects and that the additional inheritance of PT 20210A is associated with an increased risk of venous thromboembolism. We have also confirmed that plasma prothrombin levels are significantly greater in subjects possessing the PT 20210A compared with those who do not.

Adolescent↗
PubMed1996

Molecular basis of protein S deficiency in three families also showing independent inheritance of factor V leiden.

The molecular basis of type I or III Protein S deficiency has been investigated in three kindred also showing independent inheritance of factor V (FV) Leiden. A T to C transition in codon 570 (Met-->Thr) was identified in the propositi and shown to segregate with protein S deficiency in all but one of the affected members of two kindred. This individual was heterozygous for a second transition (C to T) causing substitution of serine 624 by leucine. A second member of the same family, with markedly reduced free protein S levels when compared with affected relatives, was heterozygous for both mutations. Haplotype analysis of individuals with the mutated ATG570ACG allele in the two kindred suggested they may have been related by a common ancestor. A G to A transition resulting in substitution of cysteine 145 by tyrosine was detected in the third kindred. All mutations are believed to interfere with protein S binding to C4b-binding protein resulting in reduced free protein S levels. Of the five individuals studied who had experienced thrombotic events, three had combined protein S deficiency and FV Leiden reemphasising the importance of FV Leiden as an additional risk factor for thrombosis in protein S deficiency.

Alleles↗
PubMed1994

Further evidence that activated protein C resistance can be misdiagnosed as inherited functional protein S deficiency.

A recent report that activated protein C (APC) resistance interferes with functional protein S (PS) assays prompted us to re-investigate two pedigrees previously diagnosed as having functional PS deficiency. APC resistance was demonstrated in all individuals with apparent functional PS deficiency. The latter diagnosis was shown to be due to the assay being non-linear, functional protein S becoming normal at higher dilutions. This observation, taken in conjunction with results of in vitro recovery studies with purified PS, leads us to conclude that APC resistance was the primary disorder in both pedigrees. The misdiagnosis of APC resistance as functional PS deficiency can be prevented by performing the PS assay at several dilutions, including concentrations lower than those recommended by PS assay manufacturers. Subjects previously diagnosed as having functional PS deficiency should be re-investigated for APC resistance.

Antigens↗
PubMed1994

High prevalence of a mutation in the factor V gene within the U.K. population: relationship to activated protein C resistance and familial thrombosis.

Recent findings have indicated the importance of factor V (FV) in causing resistance to activated protein C (APC) in a high proportion of patients with venous thrombosis. This prompted us to investigate whether resistance could be due to defective inactivation of FVa by APC. Consequently, we amplified a 3.2 kb fragment of the FV gene sequence encoding the heavy chain APC cleavage site. DNA analysis showed a guanine to adenine transition at nucleotide 1691 in all affected members of two families with inherited APC resistance associated with thrombosis and confirmed suspected homozygosity in two individuals. The mutation, in heterozygous form, was also found in approximately 3.5% of our normal population (n = 144) and correlated with low APC resistance. The high prevalence of this mutation suggests that it may be a major contributory factor in early thrombosis.

Base Sequence↗
PubMed1987

Characterization of three group A klebicin plasmids: localization of their E colicin immunity genes.

We have investigated the immunity to E colicins conferred by three group A klebicin plasmids. pP5a, which encodes klebicin A1-P5, like pClo-DF13, confers immunity to colicin E6 on Escherichia coli K12, whilst pP5b and pP3, which encode klebicins A2-P5 and A3-P3 respectively, both confer immunity to colicin E3. We have determined the restriction endonuclease and functional maps of the three group A klebicin plasmids. By sub-cloning and transposon mutagenesis we have investigated the relationship between the klebicin immunity and the E colicin immunity conferred by these plasmids. The colicin E6 and the klebicin A1 immunity are encoded by a single gene present on pP5a. The colicin E3 and the klebicin A2 immunity are encoded by a single gene present on pP5b. The colicin E3 and the klebicin A3 immunity are encoded by separate genes present on pP3. Recombinant pML8412, which is derived from the ColE6-CT14 plasmid and encodes colicin E6 immunity, confers klebicin A1-P5 immunity upon Klebsiella pneumoniae UNF5023. Recombinant pKC23, which is derived from the ColE3-CA38 plasmid and confers colicin E3 immunity, confers immunity to klebicin A2-P5, but not to klebicin A3-P3.

Bacteriocins↗
PubMed1986

Incompatibility between E colicin plasmids.

We have tested the ability of pairs of colicin E plasmids to replicate stably in the same cell line. Although many of the pairs of E colicin plasmids were compatible, plasmids ColE3-CA38, ColE7-K317 and ColE8-J were mutually incompatible, as were ColE5-099, ColE6-CT14 and ColE9-J. Incompatibility between ColE6-CT14 and ColE5-099 or ColE9-J was asymmetrical, whereas incompatibility between the other plasmid pairs was symmetrical.

Bacteriocin Plasmids↗
PubMed1985

Biosynthetic labeling with 32P: radiation damage to mammalian cells.

Theoretical calculations showed that biosynthetic radiolabeling of cells using typical concentrations of 32P (1 mCi/ml) resulted in high radiation doses (200-500 rad/h) being absorbed by the cells. Subsequent investigations with a mouse myelomonocytic leukemia cell line (WEHI-3B(D+)) showed significant loss of replicative ability during brief (less than 1 h) exposures to 1 mCi/ml of 32P. Complete loss of cell replicative ability was found with isotopic doses less than 100 rad (i.e., 100 muCi/ml for 5 h). Experiments employing a less radiosensitive pre-B-cell line (18.81) revealed that significant loss of viability occurred during incubation with 32P under identical conditions to those employed for the WEHI-3B(D+) cell line. Control experiments utilizing decayed batches of 32P and physical separation of the isotope solution from the cells confirmed that the cytotoxicity was caused by radiation emission rather than the presence of toxic components in the isotopic solution. The radiation doses absorbed by cells biosynthetically labeled with 59Fe, 33P, 35S, and 14C were calculated. Although significant levels of radiation can be absorbed 32P was considerably more radiotoxic than the other isotopes. The results of calculations indicated that the judicious choice of container geometry could reduce the absorbed radiation dose from 32P solutions. In particular the biosynthetic radiolabeling of cells in capillary tubes (diameter less than 1 mm) can reduce the absorbed rate to less than one-tenth of the dose received by cells suspended in Petri dishes or centrifuge tubes.

Animals↗
PubMed1985

Three immunity types of klebicins which use the cloacin DF13 receptor of Klebsiella pneumoniae.

We have investigated a group of bacteriocinogenic strains used in the epidemiological investigation of Klebsiella infections. Transfer of plasmids from these strains to laboratory strains allowed the identification of three klebicins which use the cloacin DF13 receptor in Klebsiella, but are of three distinct immunity types. These klebicins use the ferric-aerobactin receptor determined by ColV-K30 in Escherichia coli, which is also used by cloacin DF13. We propose to call them group A klebicins, of immunity types A1, A2 and A3. On the basis of immunity, cloacin DF13 also belongs to the klebicin A1 group.

Bacterial Outer Membrane Proteins↗
PubMed1984

Electrophoretic analysis of the cytoplasmic and nuclear protein changes after induction of differentiation in WEHI-3B myelomonocytic leukemia cells.

In response to a differentiation factor (G-CSF) the myelomonocytic leukemia cell line (WEHI-3B(D+) differentiates to form mature macrophages and neutrophils. The effect of G-CSF on WEHI-3B(D+) differentiation was augmented by low concentrations (5 ng/ml) of actinomycin D. Quantitative binding of an antineutrophil serum was used to segregate the differentiated cells from the leukemic blast cells. Molecular markers of later myeloid differentiation were detected in myelocytes and macrophages purified from differentiating WEHI-3B(D+) cells. To study the initial molecular processes associated with the initiation of WEHI-3B(D+) cells to differentiation, the protein changes were analyzed using gel electrophoresis. Quantitative analysis of the fluorographs from the two-dimensional (2D) electrophorograms of the 35S-labeled proteins revealed major changes in the biosynthetic rates for 16 proteins within 5 hr: The biosynthesis of six proteins was increased and another ten proteins were synthesized at a reduced rate. Two of the proteins (17K and 36K daltons) were located in the nucleus. Pulse-chase experiments indicated that protein turnover for these proteins was rapid but the degradation of four proteins was suppressed. At least six of the proteins (16K to 120K daltons) were acidic and were associated with the cytoplasm. Electrophoretic analysis of the 35S-labeled proteins indicated that a 35K protein induced by G-CSF was found in high abundance only in purified cells of intermediate differentiation (eg, myelocytes). Other proteins (eg, a very high molecular weight protein, and a 16K dalton protein) were obviously late markers of differentiated neutrophils or macrophages.

Animals↗
PubMed1984

Two new E colicins, E8 and E9, produced by a strain of Escherichia coli.

We have isolated a strain of Escherichia coli from chicken caeca which produces two E colicins and colicin M. This strain has seven plasmids, five of which have been transferred to E. coli K12. Two E. coli K12 derivatives which produce the two E colicins separately have been tested against seven standard E colicin producing strains which define seven different immunity groups. Our results indicate that these new E colicins define two further immunity groups, E8 and E9.

Animals↗
PubMed1984

The platelet defect in acute myeloid leukaemia.

In a study of platelets from 13 patients with acute myeloid leukaemia abnormal aggregation and release reactions were found. A previously unrecognised quantitative defect of thromboxane B2 production may, at least in part, explain these findings. In contrast to a previous report, we were unable to show a convincing storage pool defect in these platelets. The platelet membrane glycoproteins were largely normal.

Adenosine Diphosphate↗
PubMed1982

Biochemical and functional characterization of mature progeny purified from a myelomonocytic leukemia cell line.

Comparative studies were performed on the cloned myelomonocytic leukemia cell line, WEHI-3B, and a subcloned line, WEHI-3BM6. WEHI-3BM6 cells were less responsive than WEHI-3B cells to differentiation factor (DF) present in the sera of mice injected with endotoxin (endotoxin serum, ES). WEHI-3BM6 cells produced only 8% monocytes after 6 days of incubation with ES compared with 68% monocytes produced by WEHI-3B cells. In the presence of ES the rate of differentiation of both cell lines was enhanced by the addition of actinomycin D (5 ng/ml) such that after 2 days of stimulation 62% of the cells were mature monocytes. Lysozyme content as well as the expression of alpha-napthyl acetate esterase were also increased by actinomycin D. As indicated by the shifts in modal fluoresence levels (209 vs 63), differentiating WEHI-3B cells showed an increase in the binding of an anti-neutrophil serum compared with untreated WEHI-3B cells. The binding of anti-neutrophil antibodies allowed the sorting of the mature monocytes from the blast cells in DF-treated WEHI-3B cells achieving a purity of 78%. Electrophoretic analysis of radiolabelled proteins from the cell extracts of WEHI-3B-derived monocytes showed close similarities to normal murine peritoneal macrophages and distinct differences from the protein profiles of purified murine peritoneal polymorphs. A protein of 75,000 mol, wt present in the polymorphs was absent from the WEHI-3B monocytes.

Animals↗