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J Payne

Publications and source records attributed to J Payne.

At least 37 records · Page 2Linked to original sources
PubMed1999

Visualization and functional assessment of proximal and middle left anterior descending coronary stenoses in humans with magnetic resonance imaging.

BACKGROUND: Coronary artery bypass grafting improves survival in patients with >70% luminal diameter narrowing of the 3 major epicardial coronary arteries, particularly if there is involvement of the proximal portion of the left anterior descending (LAD) coronary artery. Measurement of coronary flow reserve can be used to identify functionally important luminal narrowing of the LAD artery. Although magnetic resonance imaging (MRI) has been used to visualize coronary arteries and to measure flow reserve noninvasively, the utility of MRI for detecting significant LAD stenoses is unknown. METHODS AND RESULTS: Thirty subjects (23 men, 7 women, age 36 to 77 years) underwent MRI visualization of the left main and LAD coronary arteries as well as measurement of flow in the proximal, middle, or distal LAD both at rest and after intravenous adenosine (140 microgram/kg per minute). Immediately thereafter, contrast coronary angiography and when feasible, intracoronary Doppler assessments of coronary flow reserve, were performed. There was a statistically significant correlation between MRI assessments of coronary flow reserve and (a) assessments of coronary arterial stenosis severity by quantitative coronary angiography and (b) invasive measurements of coronary flow reserve (P<0.0001 for both). In comparison to computer-assisted quantitative coronary angiography, the sensitivity and specificity of MRI for identifying a stenosis >70% in the distal left main or proximal/middle LAD arteries was 100% and 83%, respectively. CONCLUSIONS: Noninvasive MRI measures of coronary flow reserve correlated well with similar measures obtained with the use of intracoronary Doppler flow wires and predicted significant coronary stenoses (>70%) with a high degree of sensitivity and specificity. MRI-based measurement of coronary flow reserve may prove useful for identification of patients likely to obtain a survival benefit from coronary artery bypass grafting.

Adult↗
PubMed1999

Spatial and temporal trends and effects of contaminants in the Canadian Arctic marine ecosystem: a review.

Recent studies have added substantially to our knowledge of spatial and temporal trends of persistent organic pollutants and heavy metals in the Canadian Arctic marine ecosystem. This paper reviews the current state of knowledge of contaminants in marine biota in the Canadian Arctic and where possible, discusses biological effects. The geographic coverage of information on contaminants such as persistent organochlorines (OCs) (PCBs, DDT- and chlordane-related compounds, hexachlorocyclohexanes, toxaphene) and heavy metals (mercury, selenium, cadmium, lead) in tissues of marine mammal and sea birds is relatively complete. All major beluga, ringed seal and polar bear stocks along with several major sea bird colonies have been sampled and analysed for OC and heavy metal contaminants. Studies on contaminants in walrus are limited to Foxe Basin and northern Québec stocks, while migratory harp seals have only been studied recently at one location. Contaminant measurements in bearded seal, harbour seal, bowhead whale and killer whale tissues from the Canadian Arctic are very limited or non-existent. Many of the temporal trend data for contaminants in Canadian Arctic biota are confounded by changes in analytical methodology, as well as by variability due to age/size, or to dietary and population shifts. Despite this, studies of OCs in ringed seal blubber at Holman Island and in sea birds at Prince Leopold Island in Lancaster Sound show declining concentrations of PCBs and DDT-related compounds from the 1970s to 1980s then a levelling off during the 1980s and early 1990s. For other OCs, such as chlordane, HCH and toxaphene, limited data for the 1980s to early 1990s suggests few significant declines in concentrations in marine mammals or sea birds. Temporal trend studies of heavy metals in ringed seals and beluga found higher mean concentrations of mercury in more recent (1993/1994) samples than in earlier collections (1981-1984 in eastern Arctic, 1972-1973 in western Arctic) for both species. Rates of accumulation of mercury are also higher in present day animals than 10-20 years ago. Cadmium concentrations in the same animals (eastern Arctic only) showed no change over a 10-year period. No temporal trend data are available for metals in sea birds or polar bears. There have been major advances in knowledge of specific biomarkers in Canadian Arctic biota over the past few years. The species with the most significant risk of exposure to PCBs and OC pesticides may be the polar bear which, based on comparison with EROD activity in other marine mammals (beluga, ringed seal), appears to have elevated CYP1A-mediated activity. The MFO enzyme data for polar bear, beluga and seals suggest that even the relatively low levels of contaminants present in Arctic animals may not be without biological effects, especially during years of poor feeding.

Animals↗
PubMed1999

4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL)--An enzyme of phenylpropanoid chain cleavage from Pseudomonas.

The enzyme 4-hydroxycinnamoyl-CoA hydratase/lyase (HCHL), which catalyzes a hydration and two-carbon cleavage step in the degradation of 4-hydroxycinnamic acids, has been purified and characterized from Pseudomonas fluorescens strain AN103. The enzyme is a homodimer and is active with three closely related substrates, 4-coumaroyl-CoA, caffeoyl-CoA, and feruloyl-CoA (Km values: 5.2, 1.6, and 2.4 microM, respectively), but not with cinnamoyl-CoA or with sinapinoyl-CoA. The abundance of the enzyme reflects a low catalytic center activity (2.3 molecules s-1 at 30 degrees C; 4-coumaroyl-CoA as substrate).

Acyl Coenzyme A↗
PubMed1999

A role for the hepatobiliary system in IgE-mediated intestinal inflammation in the rat.

BACKGROUND: For many years the central focus of research into gastrointestinal hypersensitivity reactions has been the mast cell population of the intestinal lamina propria. Since bile is known to deliver immunological mediators to the gastrointestinal tract, the possibility arises that extra-intestinal populations of mast cells may also contribute to IgE-mediated intestinal damage. OBJECTIVES: To characterize hepatic mast cells in the rat and to investigate the role of the hepatobiliary system in a model of IgE-mediated reactivity to dietary antigen. METHODS: Wistar rats were passively sensitized with monoclonal antidinitrophenyl (DNP) IgE antibodies, and were later challenged orogastrically with DNP-HSA. Additional animals were sensitized, then bile duct-cannulated prior to antigen challenge. At various time points, liver and intestinal samples were collected for histological examination, and bile was collected and assayed for histamine and TNFalpha. RESULTS: Hepatic mast cells display a mucosal mast cell-like phenotype, and are closely associated with the vessels of the portal triads. Orogastric antigen challenge led to a rapid and significant decline (P<0.0001) in detectable mast cells as a result of anaphylactic degranulation. The median number of granulated mast cells associated with each portal triad in liver sections declined from six per portal triad to one per portal triad post-antigen challenge. After 15 min, biliary histamine concentrations rose above background levels (P<0.01). TNFalpha was also detectable in the majority (4/6) of bile samples within 15 min of challenge. Histological examination of the gastrointestinal mucosa revealed disruption to the villous epithelium ranging from oedematous changes to gross destruction. Such damage was not seen in animals in which bile had been externally drained. CONCLUSION: The data indicate that biliary products are major contributors to the gastrointestinal damage arising from IgE-mediated hypersensitivity reactions in the rat, and such hypersensitivity reactions may involve a population of mast cells which reside in the liver.

Animals↗
PubMed1999

Using multiple response true-false multiple choice questions.

The Royal Australasian College of Surgeons (RACS) Board of Examiners, having agreed to replace Type K with Type X multiple choice questions (MCQ), undertook a study to determine the most appropriate method of scoring the latter. Retrospective scoring of candidates' responses in a previous examination, using six reported scoring techniques for Type X items, showed that the Middlesex technique yielded a mean score closest to the mean score of the Type K items which were being replaced. However, as candidates' responses are affected by instructions, and the latter could not be controlled, a prospective study was carried out on three examinations, in each of which the nature of Part C varied among the three papers, while Parts A and B were similar. Paper 1 contained Type K items in Part C, Paper 2 contained Type X items with instructions appropriate for the Middlesex technique, and Paper 3 contained Type X items scored +1 if correct, -1 if incorrect and 0 if omitted. Items sampling the same content areas were randomly distributed among the three papers. The results indicated that the two Type X systems yielded significantly lower mean scores than Type K, probably due to combinations characteristic of the latter, enabling candidates with partial knowledge to obtain a maximum score. The difference in mean scores between the two Type X systems was not significant. A significantly higher mean percentage score in reused Type X (Middlesex system) items over that of the same items when they were previously used as Type K items was attributed to the combined effects of credit for partial knowledge, practice on reused items and differences in mean candidate ability across years. Pearson product-moment correlation coefficients between pairs of Part C mean percentage scores at each examination were positive and significant. The Board decided to replace Type K with Type X items, and the +1, 0, -1 system of scoring was adopted as it was considered more efficient than the Middlesex system, which did not give credit for identifying false statements as false.

Australia↗
PubMed1999

Generation of PSA-ACT-specific monoclonal antibodies and their application in a sandwich immunoassay.

The prostate-specific antigen (PSA) immunoassay is an important tool for the detection and monitoring of prostate cancer. PSA exists in serum mainly as complexes with serine protease inhibitors including alpha1 antichymotrypsin (ACT) and alpha2 macroglobulin (MG). PSA-MG complex is not detected by the existing PSA immunoassays since MG (720 kDa) sequesters PSA and masks the antibody binding sites. Existing immunoassays for quantitation of total serum PSA measure PSA-ACT (CPSA) and free PSA (FPSA), which comprise the major and minor components of total PSA, respectively. Monoclonal antibodies (MAb) specific for CPSA alone were generated using a unique immunogen prepared by blocking the major antigenic determinants on FPSA and ACT. The blocked immunogen greatly enhanced the frequency of hybridomas reactive against the CPSA complex. CPSA prototype immunoassays were established using anti-CPSA (PX1G359) or anti-ACT (AC1A212) MAb as tracer MAb and anti-PSA (PSA399) MAb as capture MAb. The complex-selective MAbs demonstrated minimal cross-reactivity with Cathepsin-G (CG) ACT (CG-ACT), ACT or FPSA. CG-ACT complex interfered with the accuracy of initial prototype assays specific for CPSA measurement and caused over-recovery (1 to 3 ng/mL, with 40 to 180 ng/mL range of CG-ACT in serum) of apparent CPSA values. Addition of 0.4% NP-40 and 0.1% 0.088 micron microparticles in clinical specimens eliminated this interference. Specimens from 39 prostate cancer (PCa) patients and 44 benign prostatic hyperplasia (BPH) patients were analyzed with the PX1G359 CPSA assay. In this study, the area under the curve (AUC) values for ROC analysis of total PSA (CPSA+FPSA), FPSA to total PSA ratio (f/t), and FPSA to CPSA ratio (f/c) were 0.357, 0.634, and 0.624, respectively. In a second study using AC1A212 CPSA assay, where specimens from 16 PCa patients and 48 BPH patients were tested, the AUC values for total PSA, f/t and f/c ratios were 0.62, 0.785, and 0.732, respectively. Using the CPSA assay with minimal interference our studies are consistent with previous CPSA data showing that the f/t PSA ratio remains superior to the f/c PSA ratio in differentiating PCa and BPH diseases. Complex PSA by itself or as ratio with free or total PSA does not provide any advantage over the established method of FPSA to total PSA ratio.

Animals↗
PubMed1999

Shiga toxin-producing Escherichia coli can impair T84 cell structure and function without inducing attaching/effacing lesions.

Enteropathogenic Escherichia coli (EPEC) intimately adhere to epithelial cells producing cytoskeletal rearrangement with typical attaching and effacing lesions and altered epithelial barrier and transport function. Since EPEC and Shiga toxin-producing E. coli (STEC) share similar genes in the "locus for enterocyte effacement" (LEE) thought to cause these changes, it has been assumed that STEC shares similar pathogenic mechanisms with EPEC. The aims of this study were to compare the effects of EPEC and STEC on bacterial-epithelial interactions and to examine changes in epithelial function. T84 monolayers were infected with STEC O157:H7 (wild strain EDL 933 or non-toxin-producing strain 85/170), EPEC (strain E2348/69), or HB101 (nonpathogenic) and studied at various times after infection. EPEC bound more avidly than EDL 933, but both strains exhibited greater binding than HB101. Attaching and effacing lesions and severe disruption to the actin cytoskeleton were observed in EPEC by 3 h postinfection but not in EDL 933 or HB101 at any time point. EPEC and EDL 933 increased monolayer permeability to [(3)H]mannitol 5- to 10-fold. In contrast to EPEC, EDL 933 completely abolished secretagogue-stimulated anion secretion as assessed under voltage clamp conditions in Ussing chambers. Several other STEC strains induced changes similar to those of EDL 933. In conclusion, STEC impairs epithelial barrier function and ion transport without causing major disruption to the actin cytoskeleton. Pathogenic factors other than products of LEE may be operant in STEC.

Bacterial Adhesion↗
PubMed1998

ErbB-4 ribozymes abolish neuregulin-induced mitogenesis.

The epidermal growth factor-like receptor tyrosine kinase (ErbB) family is frequently overexpressed in a variety of human carcinomas, including breast cancer. To assist in characterizing the role of ErbB-4 in breast cancer, we generated three specific hammerhead ribozymes targeted to the ErbB-4 mRNA. These ribozymes, Rz6, Rz21, and Rz29, efficiently catalyzed the specific cleavage of ErbB-4 message in a cell-free system. We demonstrated that the neuregulin-induced mitogenic effect was abolished in ribozyme Rz29- and Rz6-transfected 32D/ErbB-4 cells. Inhibition of mitogenesis was characterized by ribozyme-mediated down-regulation of ErbB-4 expression. In addition, we provide the first evidence that different threshold levels of ErbB-4 expression and activation correlate with different responses to neuregulin stimulation. High levels of ErbB-4 expression, phosphorylation, and homodimerization are necessary for neuregulin-stimulated, interleukin 3-independent cell proliferation in the 32D/E4 cells. In the case of Rz29-transfected 32D/E4 cells, low levels of ErbB-4 expression allowed neuregulin-induced phosphorylation but were insufficient to couple the activated receptor to cellular signaling. Furthermore, expression of the functional ErbB-4 ribozyme in T47D human breast carcinoma cells led to a down-regulation of endogenous ErbB-4 expression and a reduction of anchorage-independent colony formation. These studies support the use of ErbB-4 ribozymes to define the role of ErbB-4 receptors in human cancers.

Animals↗
PubMed1998

Metabolism of ferulic acid to vanillin. A bacterial gene of the enoyl-SCoA hydratase/isomerase superfamily encodes an enzyme for the hydration and cleavage of a hydroxycinnamic acid SCoA thioester.

A gene encoding a novel enoyl-SCoA hydratase/lyase enzyme for the hydration and nonoxidative cleavage of feruloyl-SCoA to vanillin and acetyl-SCoA was isolated and characterized from a strain of Pseudomonas fluorescens. Feruloyl-SCoA is the CoASH thioester of ferulic acid (4-hydroxy-3-methoxy-trans-cinnamic acid), an abundant constituent of plant cell walls and a degradation product of lignin. The gene was isolated by a combination of mutant complementation and biochemical approaches, and its function was demonstrated by heterologous expression in Escherichia coli under the control of a T7 RNA polymerase promoter. The gene product is a member of the enoyl-SCoA hydratase/isomerase superfamily.

Acetyl Coenzyme A↗
PubMed1998

To drive or not to drive: the influence of social factors on the decisions of elderly drivers.

Being able to drive is considered to be an important, if not vital, component of mobility in many jurisdictions. From a large population-based health survey, carried out in Ontario, Canada in 1990 it is estimated that 37.5% of the population aged 80 or older drives a motor vehicle at least once a year. Data from the survey have been used to make comparisons of drivers and non-drivers: people who drive are more likely to be male, to be married and to report no more than one chronic disease. People who do not drive are more likely to live in larger households and to report two or more chronic diseases. Although many of these factors are clearly related to one another, they exert independent associations with whether people drive after other factors have been controlled. Drivers and non-drivers have similar frequency of contact with family and friends after other variables have been controlled for.

Aged↗
PubMed1998

Renal function in primary liver transplant recipients receiving neoral (cyclosporine) versus prograf (tacrolimus).

Immunosuppressive efficacy of Neoral and Prograf following primary hepatic transplantation was comparable. Incidence of rejection episodes, infectious complications, hypertension, and postoperative diabetes mellitus was comparable. Although clinical use of both immunosuppressants was associated with early compromise in renal function, no progressive renal dysfunction was observed.

Analysis of Variance↗
PubMed1998

Impact of Sandimmune, Neoral, and Prograf on rejection incidence and renal function in primary liver transplant recipients.

Following primary liver transplantation, immunosuppressive efficacy of Neoral and Prograf was similar and superior to that of Sandimmune. Rejection incidence was statistically increased with Sandimmune therapy. Incidence of hypertension, posttransplant diabetes mellitus, and infectious complications was not statistically different. Although early compromise in renal function was associated with Sandimmune, Neoral, and Prograf immunosuppression, no progressive renal dysfunction was identified.

Adult↗
PubMed1998

Generation of murine monoclonal antibodies in serum-free medium.

Traditional hybridoma fusion technology requires complete medium with serum supplements to support the growth of hybridoma cells. Serum is also required for subcloning of hybridoma cells to support low density cell growth. IL-6 has been shown to enhance the growth of hybridomas and stimulate antibody production by B cells. We found that the serum requirement in media used for generation of hybridomas can be totally eliminated by substituting with 300 units/ml of IL-6. Stable hybridoma cell lines were generated to peptide and protein antigens using serum-free adapted P3.653 myelomas as the fusion partner and medium containing IL-6. Our results indicate that, in general, the fusion efficiencies of serum-free IL-6 supplemented fusions are lower than the fusions employing serum containing media (40%-60% vs. 80%-100%). However, in spite of the lower fusion efficiency, the number of antigen-specific clones generated using IL-6 was equal to or greater than fusions using serum supplements. The use of IL-6 instead of serum in the generation of monoclonal antibodies (MAbs) has several advantages. We are able to eliminate the costly need for serum in media by using IL-6 that is prepared in house. In addition, we eliminate the need for time-consuming serum-free adaptation of hybridoma cell lines prior to transfer to hollow fiber bioreactors.

Animals↗
PubMed1998

Enhancing clinical pathway placement.

Soaring health care costs have fueled the immense growth in managed care. To contain these costs, health care organizations have turned to clinical pathways. However, clinical pathways cannot do an effective job if health care personnel are not aware of their existence. The article presents a simple, effective, and efficient method to increase placement of clinical pathways in inpatient medical records.

Cost Control↗
PubMed1998

Measuring the impact of conjugate vaccines on invasive Haemophilus influenzae type b infection in Western Australia.

Haemophilus influenzae type b (Hib) causes serious infections in 26-59 per 100,000 non-Aboriginal Australian children under five years of age. Aboriginal children suffer much higher rates of infection (> or = 150 per 100,000), and at an earlier age, and have a greater risk of death and disability due to Hib infection. In 1992 and 1993, four conjugate Hib vaccines were introduced in Australia, and a nationally funded program of infant vaccination was begun in July 1993. This study aimed at evaluating the effectiveness of Hib vaccination in Aboriginal and non-Aboriginal children in Western Australia using a population-based active surveillance system for non-Aboriginal children and a case control study for Aboriginal children. The incidence of invasive Hib disease in non-Aboriginal children fell from 30.9 per 100,000 before vaccination was available to 6.3 per 100,000 in the second year after its introduction. The vaccine efficacy was estimated to be 80 per cent for Aboriginal children (odds ratio 0.20, 95 per cent CI 0.01-2.76) and, after adjustment for confounders, 75 per cent (odds ratio 0.25, CI 0.02-3.66). Based on the adjusted value (75 per cent), and using a Bayesian approach, we estimate that the posterior probability was 0.55 that the true vaccine efficacy is greater than 70 per cent, and 0.69 that the efficacy is greater than 50 per cent. We conclude that Hib vaccination is effective in preventing invasive Hib disease in Aboriginal and non-Aboriginal children in Australia.

Bacteremia↗
PubMed1998

Tetracyclines inhibit connective tissue breakdown by multiple non-antimicrobial mechanisms.

A seminal experiment involving a germ-free rat model of connective tissue breakdown (followed soon thereafter by a series of in vitro studies) identified an unexpected non-antimicrobial property of tetracyclines (TCs). This ability of TCs to inhibit matrix metalloproteinases (MMPs) such as collagenase was found to reflect multiple direct and indirect mechanisms of action, and to be therapeutically useful in a variety of dental (e.g., adult periodontitis) and medical (e.g., arthritis, osteoporosis, cancer) diseases. The site on the TC molecule responsible for its MMP-inhibitory activity was identified which led to the development of a series of chemically modified non-antimicrobial analogs, called CMTs, which also have therapeutic potential but do not appear to induce antibiotic side-effects. Longitudinal double-blind studies on humans with adult periodontitis have demonstrated that a sub-antimicrobial dose of doxycycline (previously reported to suppress collagenase activity in the periodontal pocket) is safe and effective and has recently been approved by the FDA as an adjunct to scaling and root planing.

Animals↗
PubMed1998

Recombinant heregulin-Pseudomonas exotoxin fusion proteins: interactions with the heregulin receptors and antitumor activity in vivo.

Growth factor receptors provide unique opportunities for development of targeted anticancer therapy. Members of the type I receptor tyrosine kinase family, including epidermal growth factor (EGF) receptor (EGFR) and ErbB-2/neu, are often overexpressed in various human cancer cells, including breast. Recently, it has been shown that both ErbB-3 and ErbB-4 are receptors for heregulin (HRG)/Neu differentiation factor. Eight chimeric toxins composed of the extracellular and EGF-like domains of four different HRG isoforms and truncated Pseudomonas exotoxin (PE38KDEL) were constructed. The fusion proteins exhibited activity similar to the native HRG in inducing ErbB receptors phosphorylation. The EGF-like domain of HRG13 and HRGbeta2 fused to PE38KDEL showed the highest cytotoxic activity, with a IC50 of < or = 0.001 ng/ml. The alpha isoforms that were fused to PE38KDEL were 100-fold less active than the beta isoforms. The HRG-Pseudomonas exotoxin (PE) toxins show extremely high activity against cells expressing ErbB-4 receptor, alone or together with other members of the ErbB receptor family. Cells that do not express ErbB-4 but express ErbB-3 receptor, together with the ErbB-2 or EGFR, exhibited moderate sensitivity to HRG-PE toxins. HRG-PE toxins have little or no activity against cells expressing EGFR, ErbB-2, or ErbB-3 alone. More than an 80% tumor regression was achieved by intratumor injection of 1 microg of fusion proteins per day for 5 days. Continuous i.p. administration of EGF-like domain of HRGbeta1-PE38KDEL for 7 days via a miniosmotic pump at a dose of 40 microg/kg/day inhibited the growth of ErbB-4 receptor positive but not ErbB-4 receptor negative cell lines in athymic nude mice. We conclude that there is therapeutic potential of HRG-PE toxins in the therapy of cancers overexpressing the ErbB-4 or ErbB-2 plus ErbB-3 receptors.

Animals↗