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Biomedical subjects

V Williamson

Publications and source records attributed to V Williamson.

At least 19 recordsLinked to original sources
PubMed2005

Interspecies exchange mutagenesis of the first epidermal growth factor-like domain of human factor VII.

The first epidermal growth factor-like (EGF1) domain of human factor VII (FVII) is essential for binding to tissue factor (TF). We hypothesized that the previously observed increased coagulant activity of rabbit plasma (i.e. FVII) with human TF might be explained by the five non-conserved amino acids in the rabbit vs. the human FVII EGF1 domain. Accordingly, we 'rabbitized' the human FVII EGF1 domain either by exchanging the entire EGF1 domain creating human FVII(rabEGF1) or by the single amino acid substitutions S53N, K62E, P74A, A75D and T83K. After transient expression in HEK293 cells, the recombinant FVII (rFVII) mutant proteins were analyzed for biological activity and binding affinity to human TF by competitive enzyme-linked immunosorbent assay (ELISA). Biological activity of the unpurified rFVII mutant proteins was either depressed or statistically unchanged vs. rFVII(WT). However, three of six rFVII mutant proteins had increased affinity for human TF in the rank order rFVII(rabEGF1) (3.3-fold) > rFVII(K62E) (2.9-fold) > rFVII(A75D) (1.7-fold). The mutant protein rFVII(K62E) was then permanently expressed and purified. Fully activated, purified rFVIIa(K62E) had a twofold greater clotting activity and 2.8-fold greater direct FVIIa amidolytic activity when compared with rFVIIa(WT). Quantitation of the affinity of TF binding by surface plasmon resonance indicated that the KD of purified rFVII(K62E) for human soluble TF (sTF) was 1.5 nM compared with 7.5 nM for rFVII(WT), i.e. fivefold greater affinity. We conclude that substitution of selected amino acid residues of the FVII EGF1 domain facilitated the creation of human rFVII chimeric proteins with both enhanced biological activity and increased affinity for TF.

Amino Acid Substitution↗
PubMed2002

Plain abdominal radiographs in acute medical emergencies: an abused investigation?

Plain abdominal radiographs are commonly requested for acute medical emergencies on patients with non-specific abdominal symptoms and signs. In this study 131 plain abdominal radiographs performed on the day of admission were prospectively analysed. In only 16 cases (12%) the reasons for requests conformed to the recommended guidelines by the Royal College of Radiologists. The reason for the request was stated in the case notes in only three cases. In 62 cases (47%), there was no comment made on the film by the requesting clinician. There was a discrepancy in the interpretation of the radiograph between the clinician and the radiologist in 31 cases (24%). The clinical management was influenced by plain abdominal radiographs in only nine cases (7%). The majority of plain abdominal radiographs requested on acute medical emergencies is inappropriate. There is a need to ensure guidelines are followed to prevent unnecessary exposure of patients to radiation as well as preventing expenditure on irrelevant investigations.

Abdominal Injuries↗
PubMed1999

Plasmid-mediated expression of the UmuDC mutagenesis proteins in an Escherichia coli strain engineered for human cytochrome P450 1A2-catalyzed activation of aromatic amines.

The mutagenic actions of many chemicals depend on the activities of bacterial "mutagenesis proteins", which allow replicative bypass of DNA lesions. Genes encoding these proteins occur on bacterial chromosomes and plasmids, often in the form of an operon (such as umuDC or mucAB) encoding two proteins. Many bacterial strains used in mutagenicity testing carry mutagenesis protein genes borne on plasmids, such as pKM101. Our objective was to introduce mutagenesis protein function into Escherichia coli strain DJ4309. This strain expresses recombinant human cytochrome P450 1A2 and NADPH-P450 reductase and carries out the metabolic conversion of aromatic and heterocyclic amines into DNA-reactive mutagens. We discovered that many mutagenesis-protein plasmids severely inhibit the response of strain DJ4309 to 2-amino-3,4-dimethylimid-azo[4,5-f]quinoline (MeIQ), a typical heterocyclic amine mutagen. Among many plasmids examined, one, pGY8294, a pSC101 derivative carrying the umuDC operon, did not inhibit MeIQ mutagenesis. Strain DJ4309 pGY8294 expresses active mutagenesis proteins, as shown by its response to mutagens such as 1-nitropyrene and 4-nitroquinoline 1-oxide (4-NQO), and is as sensitive as the parent strain DJ4309 to P450-dependent mutagens, such as MeIQ and 1-aminopyrene.

Amines↗
PubMed1997

Phylogenetic analysis of nematodes of the genus Pratylenchus using nuclear 26S rDNA.

We used nucleotide sequences of the large subunit ribosomal genes (26S rDNA) to examine evolutionary relationships among species of the genus Pratylenchus (Order: Tylenchida, Family: Pratylenchidae), commonly known as root-lesion nematodes. Ten species of Pratylenchus were studied including, P. penetrans, P. crenatus, P. minyus, P. vulnus, P. thornei, P. musicola, P. coffeae, P. hexincisus, P. scribneri, and P. brachyurus. The species Hirschmanniella belli, Meloidogyne javanica, Heterorhabditis bacteriophora, Nacobbus aberrans, Radopholus similis, and Xiphinema index were used as outgroups. Based on parsimony analyses of approximately 307 aligned nucleotides of the D3 expansion region of the 26S rDNA, it is clear that species of Pratylenchus are a paraphyletic assemblage. The outgroup taxon H. belli shares a common ancestor with the clade that includes P. vulnus and P. crenatus while N. aberrans and R. similis share a common ancestor with 5 other species included in this study.

Animals↗
PubMed1995

Examining patient perceptions of quality care in general practice: comparison of quantitative and qualitative methods.

BACKGROUND: The consultation satisfaction questionnaire and surgery satisfaction questionnaire, and the critical incident technique have been identified as examples of, respectively, quantitative and qualitative (interview) techniques with considerable theoretical merit regarding the measurement of patients' views in a general practice context. AIM: This study set out to assess these techniques in terms of ease of administration and analysis, respondent acceptability, and the extent to which the information provided was useful to the practitioner/practice manager, as well as validity. METHOD: Patients from three practices completed the interview and questionnaires. Data were provided for each practice giving their own results as well as data from the other two practices and the results of previous research. RESULTS: Both methods were, in the main, received positively by general practitioners, managers and patients. Patient responses to the questionnaires in general followed predictable patterns, variations from which suggested practice-specific problems. CONCLUSION: There are caveats regarding the use and interpretation of both methods, of which potential users should be aware. This is particularly the case with the consultation satisfaction questionnaire, scores on which, it is suggested, may be on a downward trend over time. It is possible that results from the consultation satisfaction questionnaire/surgery satisfaction questionnaire could be merely demoralizing for practice staff in some instances. Other research supports this notion of demoralization which, although unproven, would reduce the instrument's potential for comparison between studies, and which is, therefore, a finding which requires further attention. Increasing patient expectations are implicated in this.

Adult↗
PubMed1989

Patients' satisfaction with general practitioner services: a survey by a community health council.

Brighton community health council responded to the invitation of five local general practitioners to undertake a patient satisfaction survey of their practices. A total of 177 mothers of children under five years old were interviewed in their own homes. Satisfaction with the services provided by the general practitioners and members of the primary health care team to the respondents and to their young children was high overall, but critical comment reflected a dissatisfaction with professionals' unwillingness to take mothers' concerns at face value and to recognize the validity of mothers' own experiential knowledge. Some women were not satisfied with the extent to which they could ask questions or explain their problem. They resented attempts by receptionists to bar access to doctors and the apparent reluctance of doctors and health visitors to make home visits. It is suggested that various strategies such as telephone consultations, written guidelines on childhood ailments and parent support groups within the context of a more interactive partnership between patients and professionals could lead to a more effective service.

Adolescent↗
PubMed1981

Efficient and selective initiation by yeast RNA polymerase B in a dinucleotide-primed reaction.

Yeast RNA polymerase B catalyzes an efficient abortive initiation on double-stranded DNA templates using the appropriate combination of primer and substrate. The specificity of initiation was investigated using a recombinant plasmid (pJD14 DNA) containing the structural gene for yeast alcohol dehydrogenase I (ADHI). The combination of the dinucleotide UpA and UTP was 10 fold more efficient with pJD14 DNA than with the vector pBR322 DNA to direct the synthesis of the trinucleotide UpApU. Under these conditions, stable enzyme-DNA complexes were formed and could be retained on nitrocellulose filters. Using the UpA-primed system and a short pulse of RNA synthesis, transcription complexes were located on the yeast part of pJD14 DNA as evidenced by agarose gel electrophoresis. Southern hybridization of the pulsed RNA was restricted to a region, within the yeast DNA fragment, upstream to the initial region of the ADHI gene.

Alcohol Oxidoreductases↗
PubMed1967

3-Methyleneoxindole reductase of peas.

A 100-fold purification of a reduced triphosphopyridine nucleotide/3-methyleneoxindole reductase of peas has been achieved using conventional protein fractionation procedures. Reduced diphosphopyridine nucleotide is 25-fold less effective than reduced triphosphopyridine nucleotide as the reductant. The preparation is free of other reductase activities including those linking the oxidation of reduced pyridine nucleotide coenzymes to the reduction of cytochrome c; vitamins K(1), K(2), and K(3); O(2); nitrate; oxidized glutathione; and thiazolyl blue tetrazolium. The affinity of the enzyme for 3-methyleneoxindole (K(s) = 0.5 mm 3-methyleneoxindole) is relatively high. It is, therefore, reasonable to assume that 3-methyleneoxindole is the normal substrate.The enzyme is inhibited by indole-3-acetic acid, indole-3-aldehyde, and by l-naph-thaleneacetic acid. While these are not especially powerful inhibitors (K(1) = 1.9-4.0 mm) the competitive relationship with 3-methyleneoxindole indicates that significant inhibition might occur at low intracellular concentrations of the substrate.

Coenzymes↗