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Biomedical subjects

M W Taylor

Publications and source records attributed to M W Taylor.

At least 37 records · Page 2Linked to original sources
PubMed1998

Audit of populations in general practice: the creation of a national resource for the study of morbidity in Scottish general practice.

STUDY OBJECTIVE: To create a national data resource for studying morbidity in Scottish general practice, complementary to existing information systems and available for management and research purposes at national and local levels. DESIGN: The Department of General Practice, University of Aberdeen has worked since 1988 to collect and analyse computerised information at practice, regional, and national levels by distribution of a floppy disk-based software program, which extracts a predetermined dataset from each general practice computer system. SETTING: Almost 100% of patients in Scotland are registered with a general practitioner. Scotland has a national computer system, General Practice Administration System for Scotland (GPASS), used by over 75% of all Scottish practices. Escalating costs of health care and demographic changes in the national population emphasise the monetary value of the gatekeeper role of general medical practice. General practitioners' increasing involvement in the provision and purchasing of care has raised the importance of the management of populations as well as the care of individual patients. PATIENTS: Collection of major morbidity and prescribing data from up to 2.4 million patients, approximately half the population of Scotland, takes place biannually. A subset of practices (population 282,700 patients; 52 practices) are continuously collecting doctor/patient contact information (symptoms or diagnoses). MAIN RESULTS: The data collected provide information at the level of the individual patient. Morbidity, prescribing, screening, and administrative data can be linked by patient, date or postcode. The sample population studied is representative by age, sex, deprivation, and sparsity (using the postcode) of the national population. Large sub-populations of patients satisfying a selected criteria can be extracted for further study of needs assessment or of epidemiological research. CONCLUSIONS: The gatekeeping role of Scottish general practice and the predominance of GPASS favours standardisation of methods of data capture and the construction of large regional, national, and Continuous Morbidity databases. Analysis by geographical, demographic, and temporal distributions allows the changing patterns of illness and provision of health care to be studied in substantial detail to the benefit of patients, doctors, and the national health service.

Adolescent↗
PubMed1997

Purification and characterization of adenine phosphoribosyltransferase from Saccharomyces cerevisiae.

Adenine phosphoribosyltransferase (APRT) from Saccharomyces cerevisiae was purified approximately 1500-fold. The enzyme catalyzes the Mg-dependent condensation of adenine and 5-phosphoribosylpyrophosphate (PRPP) to yield AMP. The purification procedure included anion exchange chromatography, chromatofocusing and gel filtration. Elution of the enzyme from the chromatofocusing column indicated a pI value of 4.7. The molecular mass for the native enzyme was 50 kDa; however, upon electrophoresis under denaturing conditions two bands of apparent molecular mass of 29 and 20 kDa were observed. We have previously reported the presence of two separate coding sequences for APRT, APT1 and APT2 in S. cerevisiae. The appearance of two bands under denaturing conditions suggests that, unlike other APRTs, this enzyme could form heterodimers. This may be the basis for substrate specificity differences between this enzyme and other APRTs. Substrate kinetics and product inhibition patterns are consistent with a ping-pong mechanism. The Km for adenine and PRPP were 6 microM and 15 microM, respectively and the Vmax was 15 micromol/min. These kinetic constants are comparable to the constants of APRT from other organisms.

Adenine↗
PubMed1996

Importance of the two interferon-stimulated response element (ISRE) sequences in the regulation of the human indoleamine 2,3-dioxygenase gene.

Indoleamine 2,3-dioxygenase (INDO) is the rate-limiting enzyme in the catabolism of the essential amino acid L-tryptophan. It is induced strongly in many cell lines following interferon-gamma treatment. We report the cloning and characterization of the full-length human INDO promoter. This promoter is 1,245 base pairs long and includes two interferon-stimulated response elements (ISRE) separated by an approximately 1-kilobase sequence. The presence of these two ISREs is critical for maximum INDO promoter activity (50-fold induction). When the ISREs are present in two separate fragments cloned upstream of the chloramphenicol acetyltransferase (CAT) reporter vector, the INDO promoter activity drops significantly (7-fold induction). 5' end deletions of the wild type promoter sequence indicate that removal of the ISRE (ISRE1) at position -1126 reduces the induction level to approximately 25-fold. This activity does not change appreciably when the promoter is deleted down to position -241. Furthermore, site-directed mutagenesis of ISRE1 also decreases the promoter activity in a similar way. When ISRE1 is kept intact, deletion of the second ISRE (ISRE2) at position -111 leads to only 11-fold induction of the promoter. A similar result is obtained when substitution mutations are introduced in ISRE2. Deletion of a 748-base pair sequence between the two ISREs only shows a slight decrease in the INDO promoter activity. These data indicate that the two ISRE sequences are required for the full transcriptional induction of the interferon-gamma-inducible human INDO gene. INDO activity is not induced in the hepatic cell line HepG2. An analysis of INDO-CAT activity in this cell line indicated that the lack of INDO activity was at the transcriptional level and could reflect either the presence of a repressor or lack of a transcription factor. This lack of induction could be correlated with a truncated or unstable IRF-1. However, the levels of IRF-2, JAK2, and STAT 91 were similar in both ME180 and HepG2 cells.

Base Sequence↗
PubMed1996

Treatment of a human breast cancer xenograft with an adenovirus vector containing an interferon gene results in rapid regression due to viral oncolysis and gene therapy.

Treatment of a human breast cancer cell line (MDA-MB-435) in nude mice with a recombinant adenovirus containing the human interferon (IFN) consensus gene, IFN-con1 (ad5/IFN), resulted in tumor regression in 100% of the animals. Tumor regression occurred when virus was injected either within 24 hr of tumor cell implantation or with established tumors. However, regression of the tumor was also observed in controls in which either the wild-type virus or a recombinant virus containing the luciferase gene was used, although tumor growth was not completely suppressed. Tumor regression was accompanied by a decrease in p53 expression. Two other tumors, the human myelogenous leukemic cell line K562 and the hamster melanoma tumor RPMI 1846, also responded to treatment but only with ad5/IFN. In the case of K562 tumors, there was complete regression of the tumor, and tumors derived from RPMI 1846 showed partial regression. We propose that the complete regression of the breast cancer with the recombinant virus ad5/IFN was the result of two events: viral oncolysis in which tumor cells are being selectively lysed by the replication-competent virus and the enhanced effect of expression of the IFN-con1 gene. K562 and RPMI 1846 tumors regressed only as a result of IFN gene therapy. This was confirmed by in vitro analysis. Our results indicate that a combination of viral oncolysis with a virus of low pathogenicity, itself resistant to the effects of IFN and IFN gene therapy, might be a fruitful approach to the treatment of a variety of different tumors, in particular breast cancers.

Adenoviruses, Human↗
PubMed1996

Cell surface binding characteristics correlate with consensus type I interferon enhanced activity.

The binding characteristics of a genetically engineered consensus interferon with unusually high biologic activity were compared to the characteristics of recombinant interferon-alpha 2. Both interferon-alpha 2 and the consensus interferon produced typical biphasic Scatchard plots, indicating multiple independent binding sites. The consensus interferon, which exhibited a biologic potency more than 10-fold greater than all other type I interferons, also exhibited binding site affinities greater than those for IFN-alpha 2b. In addition, a larger number of high, and low-affinity cell surface sites were recognized by the consensus interferon, resulting in equivalent numbers of sites at reduced molar concentrations compared to IFN-a2b. Thus, at any given biologic activity, similar numbers of sites were bound by the consensus interferon and IFN-alpha 2, despite differences in their molar concentrations. No differences in internalization kinetics were identified between the two interferons, indicating that the differences in cell surface binding may be sufficient to produce the differences in biologic activity.

Cell Line↗
PubMed1996

The biologic activity and molecular characterization of a novel synthetic interferon-alpha species, consensus interferon.

Consensus interferon (Infergen) is a wholly synthetic type I interferon (IFN), developed by scanning several interferon-alpha nonallelic subtypes and assigning the most frequently observed amino acid in each position, resulting in a consensus sequence. The antiviral, antiproliferative, NK cell activation activity, cytokine induction, and interferon-stimulated gene-induction activity of consensus interferon has been compared with naturally occurring type I interferons. In all of these comparisons, consensus interferon had a higher activity when compared, on a mass basis, with IFN-alpha 2a and IFN-alpha 2b, although the activity was the same for all of these parameters on an antiviral unit basis. That a synthetic type I interferon could have higher activities than naturally occurring molecules is surprising and may be a result of the higher affinity for the array of type I interferon receptors demonstrated for consensus interferon when compared with IFN-alpha. In contrast, consensus interferon was shown to be an inferior inducer of IL-1 beta when compared with IFN-alpha. These results may reflect differential binding to multiple accessory proteins interacting with a type I interferon receptor. These unique biologic properties may lead to a favorable clinical benefit for consensus interferon when compared with the naturally occurring recombinant molecules. Ongoing clinical trials will ascertain whether consensus interferon can be used in a wide array of disease situations, such as chronic viral infections and certain malignancies.

Amino Acid Sequence↗
PubMed1996

Treatment of ME180 cells with interferon-gamma causes apoptosis as a result of tryptophan starvation.

Indoleamine 2'3 dioxygenase (INDO), the rate-limiting enzyme in the catabolism of the essential amino acid L-tryptophan, is induced in many cell lines following interferon gamma (IFN-gamma) treatment. The induction of this enzyme has been associated with the antiparasitic and cytotoxic activities of human IFN-gamma. DNA analysis coupled to morphologic studies indicated that ME180 cells underwent apoptosis within 48 h of treatment with IFN-gamma. We hypothesized that apoptosis results from L-tryptophan starvation following INDO induction. This was confirmed by the prevention of apoptosis on adding back tryptophan to IFN-gamma-treated cells and the induction of apoptosis by removing tryptophan from the medium in the absence of IFN-gamma.

Apoptosis↗
PubMed1996

General practice blood pressure recording in Scotland: variations in the classification of hypertension.

A questionnaire concerning blood pressure assessment, as part of health promotion activity, was circulated to all 770 Gpass practices in Scotland producing a 64.6% response rate. The results reveal a wide range in both the systolic and diastolic levels chosen to classify blood pressure as normal, borderline raised or raised. Practices are using a variety of values to indicate hypertension when considering systolic and, to a lesser extent, diastolic pressure. The variations found suggest that both over and under treatment are a significant risk to patients. The introduction of the 1993 health promotion regulations means that practices are required to actively target their practice population for blood pressure assessment and appropriate intervention. We suggest that this process will be enhanced if doctors are encouraged to adopt the established guidelines for the classification of blood pressure or general practice computer software is adopted to offer blood pressure protocol support.

Adolescent↗
PubMed1996

Completeness and accuracy of morbidity and repeat prescribing records held on general practice computers in Scotland.

BACKGROUND: A high proportion of Scottish general practices use a standard computer software package (GPASS, general practice administration system for Scotland), and thus, Scotland is uniquely placed to amalgamate primary care data on a national scale. Practices, however, vary widely in the nature and extent of data entered on computer and a major limitation on the use of the collected data is the absence of information on the completeness and accuracy of the computer database. AIM: This study set out to assess the quality of morbidity and repeat prescribing records held on computer by general practices in Scotland. METHOD: Forty-one practices, with above average levels of morbidity data recorded on computer, were selected on a geographic basis in relation to the national population distribution. Within each practice, 250 patients aged 45-64 years were selected at random. Data relating to 19 diagnoses, six surgical procedures and 40 repeat prescription drugs were extracted from the computer records of these patients and compared with information held on patients' paper records and supplied by patients in response to a postal questionnaire. The completeness and accuracy of computer entries were assessed in terms of sensitivity and positive predictive value, respectively. RESULTS: For the 5567 patients for whom all three sources of data (validated computer records, paper records and questionnaire responses) were available, sensitivity (completeness) of morbidity recording had median values of 0.67 for diagnoses, 0.93 for surgical procedures and 0.75 over all conditions examined. Practices varied both in the completeness of recording of each condition and in their overall performance. The predictive value (accuracy) of morbidity data was uniformly high for all conditions examined (median 1.00). For repeat prescription drugs, recording on GPASS was both complete and accurate. CONCLUSION: The recording of morbidity data on GPASS for 45-64-year-old patients in a selected group of 41 highly-computerized practices is about 75% complete and highly accurate. For national morbidity studies, it seems likely that amalgamated data from the best GPASS practices will be as complete and accurate as the morbidity statistics currently derived from hospital-based activities in Scotland.

Drug Prescriptions↗
PubMed1995

Cloning and characterization of the adenine phosphoribosyltransferase-encoding gene (APT1) from Saccharomyces cerevisiae.

We have cloned, sequenced and characterized the APT1 (adenine phosphoribosyltransferase) gene from Saccharomyces cerevisiae. The APT1 sequence includes an open reading frame encoding 221 amino acids and is contained within a 1322-bp insert that complements APRT-deficient mutants to wild-type levels of enzyme activity. Analysis by primer extension revealed multiple transcription start points (tsp) and a major tsp 21-bp upstream from the ATG start codon. A transcript initiated at the major tsp would yield a 700-nt mRNA which is in agreement with the size observed by Northern analysis. Sequence comparison indicates that the yeast enzyme shares strong similarities with other known APRT of bacterial, invertebrate, plant and mammalian origins.

Adenine Phosphoribosyltransferase↗
PubMed1995

Identification of the cis-elements required for transcriptional control of the Chinese hamster ovary APRT gene.

Transcriptional regulation of the Chinese hamster ovary (CHO) adenine phosphoribosyltransferase-encoding gene (APRT) was studied. The 5' region of the CHO APRT is G + C-rich, but lacking TATA or CCAAT boxes. RNase protection assays indicate that it contains multiple transcription start points (tsp). A tsp 64 bp upstream from the translation start codon is denoted as +1. Linker-scanning (LS) mutation analysis indicates that the -33 to +19 region is important in regulating APRT transcription. Mutations in the -23 to -14 region abolish transcription initiated from the -23 downstream region. An unidentified protein complex binds to this region. Three Sp1-binding sites are found in the APRT promoter; however, mutations of the Sp1-binding sites do not reduce APRT transcription. Mutations at two putative GCF-binding sites increase levels of transcription.

Adenine Phosphoribosyltransferase↗
PubMed1995

Modulation of APRT transcription by altering spacing between cis-regulatory elements.

Three regulatory regions on the promoter of CHO adenine phosphoribosyltransferase gene (APRT) were identified. Spacing constraints between these regions were analyzed. With normal spacing, region II (-33 to +19), which separates regions I (-101 to -53) and III (+56 to +85), is critical for APRT transcription. However, when regions I and III are artificially placed in proximity to each other (region II deleted), they are able to drive transcription as efficiently as the wild-type APRT promoter. Neither region I nor III alone is sufficient for efficient transcription. As the spacing between the two regions increases, the transcription decreases. Region I may activate transcription in two ways: through a stringent sequence-specific manner (as in the transcription mediated by regions I and III) and through a manner with relaxed requirement for sequence specificity (as in the transcription from the wild-type APRT promoter).

Adenine Phosphoribosyltransferase↗
PubMed1995

Comparison of the in vitro host range of recombinant met-interferon-con1, interferon-alpha 2b, and interferon-beta [corrected].

The antiviral activity of human r-metIFN-con1 was compared with that of IFN-alpha 2b and IFN-beta on a number of human, other primate, rodent, feline, and canine cell lines. Although the specific activities of r-metIFN-con1 and IFN-alpha 2b differed 10-fold, the host range was very similar. The host range of IFN-beta differed from that of r-metIFN-con1 and IFN-alpha 2b in that Vero cells were 100-fold better protected by IFN-beta and MDBK protected at a 100-fold less efficiency. In general, there were only minor differences between the host ranges of the three interferons, human and primate cells being better protected than those of other species. However, the tissue of origin of the cell appears to be more important than the species of origin in defining host range [corrected].

Animals↗
PubMed1995

Type 1 interferon as an antiinflammatory agent: inhibition of lipopolysaccharide-induced interleukin-1 beta and induction of interleukin-1 receptor antagonist.

The effect of two type 1 interferons (r-metIFN-con1 and IFN-alpha 2b) on the induction of specific cytokines and IL-1Ra in whole blood was examined. IFN-gamma was induced at low levels following treatment of diluted whole blood in some but not all subjects. IL-1Ra was induced by both r-metIFN-con1 and IFN-alpha 2b, but with 10- to 100-fold higher induction per ng IFN with r-metIFN-con1 than with IFN-alpha 2b. There was no detectable induction of TNF-alpha, IL-4, or IL-6 by either IFN. The effect of both IFN preparations was measured on LPS-induced inflammatory cytokines. Both IFN preparations inhibited the production of IL-1 beta when added to the diluted blood samples before LPS addition. However, neither IFN had any effect on IL-1 beta synthesis when added at the same time or after LPS induction. When added to total blood cells in the absence of LPS at low concentration (up to 100 pg/ml), IFN slightly stimulated IL-1 beta production, but at 1000 pg/ml or greater there was significant inhibition of IL-1 beta production. These results suggest that type I IFNs play a role in regulating the inflammatory response.

Anti-Inflammatory Agents↗
PubMed1995

Health promotion and the use of Gpass in Scotland.

OBJECTIVE: To identify how computerised practices using Gpass software (General Practice Administration System for Scotland), currently implement the new health promotion regulations. DESIGN: Postal questionnaire to all Gpass practices in Scotland. Data were gathered on types and methods of recording health promotion data, Read code selection, health education given and intended methods of data analysis. Questionnaire results were compared with data from an Electronic Questionnaire analysing actual data recorded on practice computers. RESULTS: Overall response rate: 64.6%, 94.8% of the responding practices have been approved for health promotion band three. Most practices (94.5%) use their computer for data collection, 63.6% of practices use a manual data capture form and 28.8% use computer data capture methods. Methods of collecting patient data and selection of Read codes for computer data entry are variable. Most practices use one method of data collection; a significant minority use multiple methods or more than one Read code to record the same item. The recording of health promotion on computer has increased greatly since the introduction of the new regulations: the current levels of recording are alcohol history (26.3%), blood pressure reading (57.6%), smoking (35.4%), exercise (7.1%), weight (21.4%) and height (16.4%). Most practices (94.3%) intend using Gpass for data analysis. CONCLUSION: Methods of collecting and recording health promotion data differ greatly between practices, with variable standardisation of health promotion codes and differing use of appropriate elements of the Gpass software.

Adult↗
PubMed1995

Tumor suppressor activity of the human consensus type I interferon gene.

Type I interferons have potent antiproliferative activity both in vitro and in vivo, and their tumor suppressor activity has been suggested. A series of eukaryotic vectors containing a synthetic human consensus type I interferon gene (IFN-con1) under the control of different promoters (cytomegalovirus early promoter, murine metallothionein promoter and the Rous sarcoma virus LTR) were constructed and stably transfected into type I IFN-deficient myelogenous leukemic K562 cells. Constitutive expression of IFNcon1 reverted the malignant phenotype, as indicated by loss of tumorgenicity in nude mice. When stably transformed cells were mixed with parental tumor cells, there was retardation of tumor growth. Constitutive expression of IFNcon1 reverted the malignant phenotype in vitro, as indicated by growth inhibition in culture, and reduction in colony formation on soft agar. Furthermore, IFNcon1 gene expression resulted in elevated erythroid differentiation, growth arrest in S phase and induced apoptosis. Thus the presence of an active IFNcon1 gene overcomes the oncogenic potential of K562 by coordinated modulation of cell proliferation, differentiation and programmed cell death, and it acts as a tumor suppressor in vivo.

Animals↗