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Derrick J Bowen

Publications and source records attributed to Derrick J Bowen.

10 recordsLinked to original sources
PubMed2005

The prevalence of the cysteine1584 variant of von Willebrand factor is increased in type 1 von Willebrand disease: co-segregation with increased susceptibility to ADAMTS13 proteolysis but not clinical phenotype.

The molecular pathogenesis of type 1 von Willebrand disease (VWD) is uncertain in most patients. We examined 30 type 1 VWD families in the UK Haemophilia Centre Doctors' Organization study. Heterozygosity for Y/C1584 was present in eight of 30 (27%) families and 19 of 76 (25%) individuals with type 1 VWD recruited into the study. Eighteen (95%) of these 19 individuals were blood group O. C1584 did not co-segregate with VWD in four families, and co-segregated in one family; the results were equivocal in three families. In all families increased susceptibility of von Willebrand factor (VWF) to a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS) 13 proteolysis co-segregated with C1584 in affected and unaffected individuals. These data show that C1584, associated with blood group O, is prevalent among patients with type 1 VWD but not necessarily causative of disease and should not be used in isolation to diagnose VWD. Increased susceptibility of C1584 VWF to ADAMTS13 proteolysis may be physiologically significant and increase an individual's risk of bleeding and presenting with VWD.

ABO Blood-Group System↗
PubMed2004

A single, multiplex analysis for all relevant activating NRAS gene mutations using heteroduplex generators.

We describe a multiplex polymerase chain reaction (PCR)-based test that detected all relevant NRAS activating mutations using a single PCR followed directly by electrophoresis. The test uses a Universal Heteroduplex Generator (UHG) to detect exon-2 (codon 61) NRAS mutations in multiplex with an UHG for exon-1 (codons 12 and 13). The method differentiated all 19 relevant mutations in these exons and showed a mutation independent sensitivity of approximately 6%. The sensitive, specific detection of all NRAS activating mutations using this single rapid test represents a minimum workload and could be applied readily for large-scale screening and for routine analysis.

Base Sequence↗
PubMed2003

Haptoglobin type neither influences iron accumulation in normal subjects nor predicts clinical presentation in HFE C282Y haemochromatosis: phenotype and genotype analysis.

In the UK, 90% of patients with hereditary haemochromatosis (HH) are homozygous for HFE C282Y, as are one in 150 people in the general population. However, only a minority of these will develop clinical haemochromatosis. Iron loss modifies iron accumulation but so may other genetic factors. Haptoglobin (Hp) exists as three major types (Hp 1-1, Hp 2-1 or Hp 2-2) and binds free plasma haemoglobin. In men, Hp 2-2 has been shown to be associated with increased macrophage iron accumulation and serum ferritin concentration. Furthermore, the frequency of Hp 2-2 was shown to be increased in patients with HH. We determined Hp types by phenotyping and genotyping 265 blood donor control subjects and 173 subjects who were homozygous for HFE C282Y. The latter group included 66 blood donors lacking clinical features suggestive of haemochromatosis and without a known family history, and 68 patients presenting clinically with haemochromatosis. Hp 2-2 frequencies did not differ in control subjects and C282Y homozygotes. Hp 2-2 was not a risk factor for disease development in HH. To investigate the relationship between iron accumulation and haptoglobin type, we determined transferrin saturation and serum ferritin concentration in 192 male, first-time blood donors aged 20-40 years who lacked both HFE C282Y and H63D. Transferrin saturation and serum ferritin concentrations did not vary with Hp type.

Adult↗
PubMed2002

The CpG island in intron 22 of the factor VIII gene is predominantly methylated on the X chromosome of human males.

The inactivation of one of the two X chromosomes in females is a random process associated with methylation principally in CpG islands. The methylation status of a CpG island in intron 22 of the human factor VIII (FVIII) gene was investigated using a novel practical approach. Genomic DNA from men and women was digested with various methylation-sensitive (MS) restriction enzymes, the recognition sequences of which occurred at least once in the FVIII CpG island. Long distance-polymerase chain reaction (LD-PCR) was then used to amplify the island. Successful amplification indicated that the island was methylated and the absence of a PCR product indicated that at least one restriction site was unmethylated. To analyze the relative methylation status of the extragenic and intragenic copies of the island, we used Southern blot with MS restriction enzymes. The MS LD-PCR patterns obtained from male and female DNA samples indicated that at least some copies of the intragenic CG island were fully methylated at all sites investigated. Additionally, the island showed consistent differences among individuals. Southern blot studies using female DNA showed partial resistance to MS digestion for the intragenic and extragenic CpG island homologs. Our observations indicate that this CpG island is predominantly methylated on the X chromosome of males and suggest that its methylation pattern does not correlate with X inactivation of females. This prevents the use of this island coupled with DNA polymorphisms for investigation of X-chromosome inactivation.

Blotting, Southern↗
PubMed2002

Identification and characterization of a novel gene encoding a SEREX antigen in chronic myeloid leukaemia.

The novel gene encoding Clone 4, previously isolated through the Serological screening of recombinant expression cDNA library (SEREX) in chronic myeloid leukaemia (CML), was characterized. It is localized to chromosome 7 at q22, occupies approximately 4.5 kb of DNA and comprises 4 exons. Three single nucleotide polymorphisms and a 13 base deletion/insertion polymorphism have been identified. The mRNA transcript was approximately 2.4 kb and contained a long 5'-untranslated region of almost 1 kb before the candidate open reading frame. Northern blot analysis and multiple tissue expression array indicated a restricted normal tissue distribution. Our findings provide a platform for future investigations into the role of the gene product in CML.

Antigens, Neoplasm↗
PubMed2002

Factor VIIa induced release of von Willebrand factor from human umbilical vein endothelial cells by a tyrosine kinase dependent pathway.

The interaction of FVIIa with surface-bound tissue factor (TF) induces various cellular changes including cytosolic Ca2+ signals. The release of von Willebrand factor (VWF) from endothelial cell stores may be triggered by an elevation in cytosolic free Ca2+, therefore we investigated the effect of rFVIIa on the release of VWF from human umbilical vein endothelial cells (HUVEC). We show here that rFVIIa induces the release of VWF from HUVEC with or without prestimulation with lipopolysaccharide (LPS). The effect of rFVIIa was dose dependent. However, the release of VWF by HUVEC in response to rFVIIa was significantly greater with LPS prestimulation (3.18 times control) than without LPS prestimulation (1.45 times control) (p < 0.001). Cytosolic Ca2+ signals were detectable only after LPS prestimulation of HUVEC and these were small compared to those elicited by thrombin. No effect on rFVIIa induced release of VWF was seen in the presence of hirudin, site inactivated rFVIIa or the protein kinase C (PKC) inhibitor staurosporine. However, a tyrosine kinase inhibitor genistein, inhibited the rFVIIa induced release of VWF. These data show that release of VWF can occur without involvement of the cytosolic Ca2+/ PKC pathway. FVIIa induced VWF release from endothelial cells may have in vivo significance at sites of TF expression.

Calcium Signaling↗
PubMed2002

Heterogeneous detection of A-antigen on von Willebrand factor derived from platelets, endothelial cells and plasma.

The exact function of the carbohydrate component of von Willebrand factor (VWF) is unknown. ABO blood group antigens are present as integral structures on the oligosaccharide side chains and it has long been recognised that ABO blood group is a determinant of VWF levels. The mechanism for this is not known. Using a monoclonal antibody against the A-antigen, we investigated the presence of this antigen on VWF from plasma, platelets, human umbilical vein endothelial cells (HUVEC) and saphenous vein endothelial cells. Initial studies on plasma VWF revealed that 23.5% of samples appeared to be negative for the A-antigen. This was shown to correlate with the A2 subtype of the A-antigen (p < 0.01). Analysis of intracellular VWF from saphenous vein endothelial cells revealed low levels of A-antigen to be present in comparison to the corresponding plasma VWF. In contrast, VWF from platelets and HUVEC gave no detectable A-antigen. However, within 1 h of administration of DDAVP to type 1 VWD patients, there was a > 2-fold increase in the A-antigen/VWF: Ag ratio for VWF in the plasma. In vitro experiments with serum N-acetlygalactosaminyltransferase failed to demonstrate any addition of A-antigen to platelet or HUVEC VWF. These data are consistent with heterogeneity in the content of A-antigen on VWF from different physiological compartments. Also, they are consistent with either a change in the A-antigen content of VWF after release from the intracellular compartment or a difference in the intracellular addition of A-antigen to VWF by endo thelium from different vascular beds.

ABO Blood-Group System↗