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Biomedical subjects

G Taylor

Publications and source records attributed to G Taylor.

At least 109 records · Page 6Linked to original sources
PubMed1999

Priming with a secreted form of the fusion protein of respiratory syncytial virus (RSV) promotes interleukin-4 (IL-4) and IL-5 production but not pulmonary eosinophilia following RSV challenge.

The attachment (G) protein of respiratory syncytial virus (RSV) is synthesized as two mature forms: a membrane-anchored form and a smaller secreted form. BALB/c mice scarified with vaccinia virus (VV) expressing the secreted form develop a greater pulmonary eosinophilic influx following RSV challenge than do mice scarified with VV expressing the membrane-anchored form. To determine if a soluble form of an RSV protein was sufficient to induce eosinophilia following RSV challenge, a cDNA that encoded a secreted form of the fusion (F) protein of RSV was constructed and expressed in VV (VV-Ftm(-)). Splenocytes and lung lymphocytes from mice primed with VV-Ftm(-) produced significantly more of the Th2 cytokines interleukin-4 (IL-4) and IL-5 than did mice vaccinated with VV expressing either the native (membrane-anchored) form of the F protein or the G protein. Although mice scarified with VV-Ftm(-) developed a slight increase in the number of pulmonary eosinophils following RSV infection, the increase was not as great as that seen in VV-G-primed mice. Despite the increased IL-4 and IL-5 production and in contrast to mice primed with VV-G, mice primed with VV-Ftm(-) developed RSV-specific cytotoxic T lymphocytes (CTL) and maintained high levels of gamma interferon production. These data demonstrate that recombinant VV strains expressing soluble forms of RSV proteins induce immune responses that are more Th2-like. However, this change alone does not appear sufficient to induce vaccine-augmented disease in the face of active CD8(+) CTL populations.

Animals↗
PubMed1999

High-density lipoproteins differentially modulate cytokine-induced expression of E-selectin and cyclooxygenase-2.

Atherogenesis is a multifactorial chronic inflammatory disease in which low plasma levels of HDLs are a strong predictor of the condition. Although the mechanism of protection by HDLs is not precisely known, HDLs have been shown to influence many of the events involved in the development of atherosclerosis. Previously we have shown that HDLs inhibited the cytokine-induced expression of adhesion molecules (E-selectin, VCAM-1, and ICAM-1) by endothelial cells (ECs). As the complete transcriptional regulation of all 3 genes requires the NF-kappaB family of transcription factors, we examined the effect of HDLs on activation of NF-kappaB. We also investigated the effect of HDLs on 2 other cytokine-induced genes, granulocyte-macrophage colony-stimulating factor (GM-CSF) and cyclooxygenase (Cox-2; prostaglandin H2 synthase, EC 0.1.14.99.1). E-selectin expression in response to tumor necrosis factor-alpha (TNFalpha) was, as expected, inhibited in ECs that had been preincubated with HDLs. However, the level of secretion of GM-CSF in the same cultures was no different from control. In a similar manner, although HDLs had no effect on steady-state mRNA levels of GM-CSF, the levels of E-selectin were significantly inhibited by HDLs. In transient cotransfection experiments we found that HDLs inhibited the cytokine-induced expression of a reporter gene driven by the E-selectin proximal promoter (-383 to 80) but had no effect on the expression of a reporter gene driven under the control of the proximal promoter of GM-CSF (-627 to 28). As would be predicted from this differential response, HDLs did not influence the nuclear translocation or DNA binding of NF-kappaB, or alter the kinetics of degradation and resynthesis of the inhibitory protein IkappaBalpha. We found that HDLs synergized with cytokine to enhance the expression of Cox-2 and induce the synthesis of its main EC product, prostacyclin (PGI2), a potent inhibitor of platelet and leukocyte functions. In conclusion, HDL induces an antiinflammatory phenotype in cytokine-induced ECs, synergizing with cytokine to induce elevation of Cox-2 in addition to inhibiting adhesion molecule expression. Our studies show that these differential effects are mediated in a manner that is likely to be independent of NF-kappaB per se.

Adult↗
PubMed1999

Recombinant human thyroid peroxidase expressed in insect cells is soluble at high concentrations and forms diffracting crystals.

Human thyroid peroxidase (TPO), the key enzyme in thyroid hormone synthesis, can be produced in active form in the High Five insect cell line and when purified from the cell culture medium is soluble at concentrations of up to 18 mg/ml. This contrasts to a recent report in which human TPO produced in insect cells was found to be insoluble at high concentrations. Our concentrated TPO grows trigonal trapezohedral crystals of up to 0.5 mm in length in a vapour diffusion apparatus using polyethelene glycol as a precipitant. The crystals diffract X-rays to a 6 A resolution and the diffraction data from the crystals have been analysed giving unit cell dimensions. A potential molecular replacement solution has been identified using myeloperoxidase (MPO) as a phasing model.

Animals↗
PubMed1999

Ethics resources of US organ procurement organizations and transplant centers.

The medical disciplines of organ and tissue donation and transplantation present many life-enriching benefits but are often fraught with ethical ramifications. This article examines the current and potential ethics resources of US organ procurement organizations (OPOs) and transplant centers (TCs). The organizations were surveyed regarding established ethical guidelines and the frequency with which ethical issues in need of resolution were encountered. All OPOs and 76% of TCs reported confronting ethical issues in the workplace. A majority of those surveyed in TCs and OPOs felt adequately prepared to face the ethical challenges of their jobs. More than half the surveyed personnel had some type of ethics training, but only 25% of the TC staffs and 16% of the OPO staffs' training was during the survey year. The potential for ethics-related interactions for TC and OPO staff must be recognized and adequate preparatory measures provided.

Attitude of Health Personnel↗
PubMed1999

Pharmacists' concerns and perceived benefits from the deregulation of hormonal emergency contraception (HEC).

OBJECTIVE: To ascertain pharmacists' views, assess willingness for involvement and delineate individual perceived competence in the supply of deregulated hormonal emergency contraception (HEC). DESIGN: Cross-sectional postal questionnaire utilising closed, open and Likert-scale questions. SUBJECTS: Three thousand nine hundred and ninety-nine registered pharmacists abstracted from the mailing list of the Royal Pharmaceutical Society of Great Britain. RESULTS: In total 1543 (38.6%) questionnaires were returned and analysed. Overall 1165 (75.5%) of pharmacists stated their willingness to be involved in the deregulated supply of HEC. However, pharmacists identified the need for specific training before effective deregulation should take place. Overall, 616 (39.9%) of respondents felt individually competent to supply deregulated HEC with a positive association between perceived competence and willingness to supply deregulated HEC (p < 0.05). Pharmacists perceive the major benefits of deregulation to be a reduced unwanted pregnancy rate and a subsequent reduced abortion rate. They perceive that deregulation would allow quicker and less restricted access to HEC by clients, facilitating an increased overall supply of HEC. Pharmacists express a number of concerns, tempering their collective desire to see HEC deregulation. The majority of these concerns related to safeguarding clients and the possible adverse public health effects associated with the possible reduced use of barrier methods of contraception. CONCLUSIONS: Most pharmacists would be willing to supply HEC if it were deregulated to 'pharmacy only' from 'prescription only' medicine status. Although concerns were raised, these were mainly related to safety issues, with few pharmacists identifying moral and ethical barriers to deregulation. For effective deregulation to occur issues of professional competence need to be addressed.

Abortion, Induced↗
PubMed1999

Sugar, drinks, deprivation and dental caries in 14-year-old children in the north west of England in 1995.

OBJECTIVES: To examine associations between dental caries and reported drink consumption. DESIGN: A cross-sectional caries prevalence study including reported drink consumption. SETTING: Secondary schools across the former North Western Region of England. SUBJECTS: A random sample of 6,014, 14-year-old children. RESULTS: The mean DMFT of the sample was 2.74. The reported mean weekly consumption of cans of carbonated drinks was 5.66, with a range of zero to 42. There was a significant gender difference in drink consumption and a significant correlation between the reported weekly consumption of cans of carbonated drinks and DMFT. Logistic regression analysis showed tea drinkers had a significantly lower DMFT than coffee drinkers and that this effect was independent of the addition of sugar and the number of cans of drink consumed. Reported use of sugar-free carbonated drinks was not associated with better dental health. CONCLUSIONS: Reported consumption of sugared drinks and carbonated drinks was associated with significantly higher levels of dental caries. Drinking tea was associated with lower levels of caries. Sugar-free drinks were not associated with better dental health.

Adolescent↗
PubMed1999

A model framework comparing resources required for activities in the Community Dental Service validated using the Delphi technique.

OBJECTIVE: To validate a model framework comparing resources required for activities in the Community Dental Service. The framework consisted of five levels of care of increasing complexity for six groups of patients. The patient groups were: children with behavioural problems, mentally disabled patients, anxious adults, paedodontic patients, medically compromised and physically disabled patients. DESIGN: Delphi study using two sequential questionnaires. Participants were asked to rate the difficulty of 29 different treatments on a scale from 1 to 100. PARTICIPANTS: Six clinical directors and eleven senior dental officers working in the Community Dental Service in the North West of England. RESULTS: Seventeen of the 29 treatments were rated at the level of care predicted by the model. Nine were rated lower and three higher. Within the patient groups the order of increasing complexity, predicted by the model, was verified with only one exception. CONCLUSIONS: The research confirmed that it is possible to measure CDS activity in a rational way. Consensus was reached on a suitable framework which was simpler than the original model in having only four levels of care. The use of the modified model is now being tested in the Community Dental Service.

Adult↗
PubMed1998

Genetic studies in Borrelia burgdorferi.

Borrelia burgdorferi, the agent of Lyme disease, has recently joined a growing number of micro-organisms for which the entire genomic sequence is known. Despite this wealth of information, little is known about the contribution of specific spirochetal components to the pathogenesis of Lyme disease or their function in the normal life cycle of the organism. This discrepancy is due in part to the lack of a well-developed genetic system in B. burgdorferi, which in turn can be attributed to its relatively recent isolation and the dissimilarity of Borrelia from other genetically tractable bacteria. We are interested in several plasmid-encoded gene products in B. burgdorferi that may play a role in sensing and adaptation to the different environments the spirochete encounters as it completes an infectious cycle between the tick vector and the mammalian host. We are developing genetic tools with which to test the roles of specific B. burgdorferi gene products in the transmission cycle in an animal model of Lyme disease. We have demonstrated targeted gene inactivation by allelic exchange, using the gyrBr gene encoding coumermycin-resistant topoisomerase as a selectable marker. Spirochetes are transformed by electroporation and coumermycin-resistant colonies are screened by PCR for allelic exchange at the targeted locus. We have successfully inactivated several genes of interest in the type strain B31. We are investigating the utility of additional antibiotic resistance genes as selectable markers in B. burgdorferi. Targeted gene inactivation is a powerful tool with which to investigate the role of particular proteins in the basic biology and virulence of a pathogenic microorganism. We have made significant advances in our ability to genetically manipulate B. burgdorferi in order to address these issues. However, the available methods are incomplete and far from routine. We are currently improving existing methods as well as developing additional genetic tools with which to augment genetic studies in B. burgdorferi.

Borrelia burgdorferi Group↗
PubMed1998

Subcellular site of expression and route of vaccination influence pulmonary eosinophilia following respiratory syncytial virus challenge in BALB/c mice sensitized to the attachment G protein.

The attachment glycoprotein (G) of respiratory syncytial virus (RSV) is synthesized as two mature forms: a membrane-anchored form and a smaller secreted form. Mutant cDNAs were constructed that encoded one or the other form of the protein and were expressed in recombinant vaccinia viruses (rVV). Mice were immunized with rVV by dermal scarification or i.p. injection to determine the contribution of the membrane-anchored and secreted forms of the G protein on the augmentation of pulmonary pathology seen following RSV challenge. Mice scarified with rVV expressing the membrane-anchored G protein had a markedly reduced pulmonary eosinophilic response following RSV challenge compared with mice scarified with rVV expressing either wild-type or secreted G protein. The induction of pulmonary eosinophilia in rVV-primed mice was also dependent upon the route of vaccination. An eosinophilic response was not observed in any groups of mice immunized i.p. with rVV expressing any of the different forms of the G protein. The difference in pulmonary pathology observed between dermal scarification or i.p. vaccinated mice was not reflected in a difference in cytokine production by splenocytes from vaccinated and challenged mice restimulated with RSV in vitro. Both groups produced significant levels of IL-4 and IL-5. These data suggest that the local APCs and lymphoid environment, together with the form of the G protein, influence pulmonary pathology following RSV challenge.

Administration, Cutaneous↗
PubMed1998

Underperforming doctors: a postal survey of the Northern Deanery.

OBJECTIVES: To discover the perceived size of pool of doctors considered to be underperforming in general practice in the Northern Deanery and to discover whether these perceptions are based on formal assessments. DESIGN: Postal questionnaire. SETTING: Area covered by the Northern Deanery. SUBJECTS: Seven health authority directors of primary care, seven secretaries of local medical committees, and 14 chief officers of community health councils. RESULTS: The response rate was 100% for directors of primary care and secretaries of local medical committees and, after one reminder, 92% for chief officers of community health councils. Numbers of doctors perceived to be underperforming ranged from none to over 15 in different health authority areas. Main areas for concern were communication skills, clinical skills, and management skills. Patients' representatives were concerned about lack of power of patients and health authorities and doctors' lack of accountability. Health authorities were concerned about lack of power, identification of underperforming doctors, and doctors' professional loyalty. Local medical committees were concerned about the problem of identifying underperformance. A number of methods were used for identification, and there was no common method applied. CONCLUSIONS: The number of doctors thought to be underperforming was small. Work still needs to be done on developing tools that can be used in everyday practice to enable doctors to confirm for themselves, their colleagues, and their patients that they are providing an adequate level of care.

Clinical Competence↗
PubMed1998

The short Sendai virus leader region controls induction of programmed cell death.

The replication of nonsegmented minus-strand RNA genomes, like that of Sendai paramyxovirus (SeV), are controlled by the short leader regions present at each end of the linear genomes and antigenomes; the left and right promoters (PL and PR), respectively. Wild-type SeV is highly cytopathic in cell culture, because it induces programmed cell death (PCD). We have found that a recombinant SeV (rSeVGP42), in which the first 42 nt of le+ sequences at PL were replaced with the equivalent sequences of PR, and which produces infectious virus in amounts comparable to wild type, does not kill cells. Further, the increasing replacement of the terminal le+ sequences at PL with le- sequences led to a decreasing fraction of infected cells being apoptotic. This property (PCD-), moreover, is dominant in cells co-infected with SeVwt and rSeVGP42, and the mutant virus therefore appears to have gained a function which prevents PCD induced by SeVwt. Even though this virus has not been selected for naturally, it excludes SeVwt during co-infections of cultured cells or embryonated chicken eggs. The noncytopathic nature of cells infected or co-infected with rSeVGP42 leads automatically to stable, persistent infections. The mutation in rSeVGP42 is not in the protein coding regions of the viral genome, but in the 55-nt-long leader region which controls antigenome synthesis from genome templates. The SeV leader regions, which are expressed as short RNAs, thus appear to control the induction of PCD.

Animals↗
PubMed1998

Sendai viruses with altered P, V, and W protein expression.

Wild-type Sendai virus expresses three proteins containing the N-terminal half of the P protein open reading frame due to mRNA editing; a full-length P protein (ca. 70% of the total), a V protein with the N-terminal half fused to a Cys-rich Zn(2+)-binding domain (ca. 25% of the total), and a W protein representing the N-terminal half alone (ca. 5% of the total). To examine the role of these proteins in the virus life cycle, we have prepared recombinant viruses in which the normal V mRNA expresses a W protein (V-stop; 70% P, 30% W), one which cannot edit its P gene mRNA (delta 6A; 100% P), and one which overedits its mRNA like parainfluenza virus type 3 (swap/8;20-40% P, 30% V, 30% W). All these viruses were readily recovered and grew to similar titers in eggs, and except for the P gene products, cell lines individually infected with these viruses accumulated similar amounts of viral macromolecules. The relative competitive advantage of each virus was determined by multiple cycle coinfections of eggs and found to be rSeV-Vstop = rSeV-wt >> rSeV-delta 6A > rSeV-swap/8. On the other hand, rSeV-swap/8 underwent multiple cycles of replication in C57BI/6 mouse lungs and was highly virulent for these animals, whereas rSeV-delta 6A was avirulent in mice and this infection was quickly cleared. Remarkably, rSeV-Vstop appeared to be more virulent for inbred C57BI/6 mice than rSeV-wt, but was partially attenuated in infections of outbred ICR mice. Thus, the expression of either the V or the W proteins is sufficient for multiple cycles of infection and pathogenesis in C57BI/6 mice, whereas W can only partially substitute for V for pathogenesis in ICR mice.

Animals↗
PubMed1998

Preparation and characterization of the recombinant selenomethionine analogue of insulin-like growth factor-I.

Insulin-like growth factor-I (IGF-I), a single-chain polypeptide consisting of 70 amino acids and 3 disulfide bridges, is a member of a class of growth factors that are involved in many proliferative and metabolic processes. To assist in solving the crystallographic three-dimensional structure, we have expressed a recombinant fusion protein precursor of IGF-I in a methionine auxotrophic strain of Escherichia coli grown in the presence of selenomethionine. An homogeneous preparation of selenomethionyl-IGF-I was then obtained by chemical cleavage of the fusion protein. The selenomethionine analogue of IGF-I was characterized by electrospray mass spectrometry, peptide mapping, analytical chromatography, and electrophoresis as well as by biological assays. The final preparation of IGF-I was found to incorporate about 90% of selenium and fully retained the functional activity.

Chromatography, High Pressure Liquid↗
PubMed1998

Evolutionary rate and genetic heterogeneity of human T-cell lymphotropic virus type II (HTLV-II) using isolates from European injecting drug users.

Seven new Italian and two new British HTLV-II isolates were obtained from injecting drug users and the entire long terminal repeat (LTR) region was sequenced. Restriction analysis showed that all the Italian isolates are of the IIb subtype, whereas the British isolates are of the IIa subtype. To understand whether the further differentiation of each two principal HTLV-II subtypes in several subgroups could be statistically supported by phylogenetic analysis, the neighbor-joining, parsimony, and maximum likelihood methods were used. The separation between IIa and IIb is very well supported by all three methods. At least two phylogenetic subgroups exist within the HTLV-IIa and at least three within the HTLV-IIb subtype. In the present analysis, no statistical support was obtained for additional phylogroups. Two particular subgroups seem interesting because they include all European and North American injecting drug user strains within the IIa and IIb subtypes, respectively. These data confirm that European HTLV-II infection among drug users is probably derived from North America. They also suggest that though a certain differentiation by restriction analysis in different subgroups is possible, carefully interpreted phylogenetic analyses remain necessary. Using the likelihood ratio test, a molecular clock for the drug user strains was calibrated. A fixation rate between 1.08 x 10(-4) and 2.7 x 10(-5) nucleotide substitutions per site per year was calculated for the IIa and IIb injecting drug user strains. This is the lowest fixation rate so far reported for RNA viruses, including for HIV, which typically range between 10(-2) and 10(-4).

Biological Evolution↗
PubMed1998

Experience with papillary and solid epithelial neoplasms of the pancreas in children.

BACKGROUND: Papillary cystic tumour of the pancreas in children is a rare tumour. METHODS: Ten patients admitted to The Hospital for Sick Children, Toronto, have been reviewed, and presentation and management are documented. RESULTS: One patient who had disseminated disease at presentation died. CONCLUSION: Excision of the tumour irrespective of size is recommended.

Adolescent↗
PubMed1998

Phenotypic and functional characterization of mobilized peripheral blood CD34+ cells coexpressing different levels of c-Kit.

In this report we evaluated the exact expression pattern of c-Kit on mobilized peripheral blood (PB) CD34+ cells. Using a monoclonal antibody against CD117 antigen (95C3), flow cytometric analysis revealed that approximately 25% of the mobilized PB CD34+ cells coexpress c-Kit. This cell fraction showed a considerable heterogeneity with respect to c-Kit expression, consisting of a small fraction with high levels of c-Kit (4.2%) (CD34+/CD117high fraction) and a larger proportion of cells expressing low levels of this antigen (21.0%) (CD34+/CD117low fraction). Clonogenic assays showed that CD34+/CD117high cell fraction consisted almost exclusively of erythroid progenitors, in contrast to CD34+/CD117low cell subset which gave rise mostly to granulocyte-monocyte colonies. The majority of CFU-GEMM and the most primitive week 6 cobblestone area forming cells (CAFCs) segregated in the CD34+/CD117low cell subset, suggesting the highest content of multipotential progenitors within this cell fraction. None of the sorted cell subsets was able to produce reactive oxygen intermediates (ROI). However, ex vivo expansion of the sorted subsets with interleukin 3, stem cell factor and FLT3 ligand for 2 weeks resulted in a significant production of O2- and H2O2/HOCl by CD34+/CD117low cell fraction, compared to the same sorted but not expanded counterparts. According to the major content of multipotential hematopoietic progenitors and highest capacity to generate sufficient amounts of ROI after ex vivo expansion, we suggest that CD34+/CD117low cell subset would be one of the most potential candidates for transplantation in patients with acute lymphoblastic leukemia, which lack c-Kit antigen expression.

Antigens, CD34↗