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P Wilson

Publications and source records attributed to P Wilson.

At least 55 records · Page 3Linked to original sources
PubMed2001

Novel 6-substituted uracil analogs as inhibitors of the angiogenic actions of thymidine phosphorylase.

Thymidine phosphorylase (TP) catalyzes the reversible phosphorolysis of thymidine and other pyrimidine 2'-deoxyribonucleosides. In addition, TP has been shown to possess angiogenic activity in a number of in vitro and in vivo assays, and its angiogenic activity has been linked to its catalytic activity. A series of 5- and 6-substituted uracil derivatives were synthesized and evaluated for their abilities to inhibit TP activity. Among the most active compounds was a 6-amino-substituted uracil analog, 6-(2-aminoethyl)amino-5-chlorouracil (AEAC), which was a competitive inhibitor with a K(i) of 165 nM. The inhibitory activity of AEAC was selective for TP, as it did not inhibit purine nucleoside phosphorylase or uridine phosphorylase at concentrations up to 1 mM. Human recombinant TP induced human umbilical vein endothelial cell (HUVEC) migration in a modified Boyden chamber assay in vitro, and this action could be abrogated by the TP inhibitors. The actions of the inhibitors were specific for TP, as they had no effect on the chemotactic actions of vascular endothelial growth factor (VEGF). HUVEC migration was also induced when TP-transfected human colon and breast carcinoma cells were co-cultured in the Boyden chamber assay in place of the purified angiogenic factors, and a TP inhibitor blocked the tumor cell-mediated migration almost completely. These studies suggest that inhibitors of TP may be useful in pathological conditions that are dependent upon TP-driven angiogenesis.

Angiogenesis Inhibitors↗
PubMed2001

Relatively normal human lymphopoiesis but rapid turnover of newly formed B cells in transplanted nonobese diabetic/SCID mice.

Human B lineage lymphocyte precursors in chimeric nonobese diabetic/SCID mice transplanted with umbilical cord blood cells were directly compared with those present in normal bone marrow. All precursor subsets were represented and in nearly normal proportions. Cell cycle activity and population dynamics were investigated by staining for the Ki-67 nuclear Ag as well as by incorporation experiments using 5-bromo-2'-deoxyuridine. Again, this revealed that human B lymphopoiesis in chimeras parallels that in normal marrow with respect to replication and progression through the lineage. Moreover, sequencing of Ig gene rearrangement products showed that a diverse repertoire of V(H) genes was utilized by the newly formed lymphocytes but there was no evidence for somatic hypermutation. The newly formed B cells frequently acquired the CD5 Ag and had a short life span in the periphery. Thus, all molecular requirements for normal B lymphocyte formation are present in nonobese diabetic/SCID mice, but additional factors are needed for recruitment of B cells into a fully mature, long-lived pool. The model can now be exploited to learn about species restricted and conserved environmental cues for human B lymphocyte production.

Animals↗
PubMed2001

The role of recombination activating gene (RAG) reinduction in thymocyte development in vivo.

Assembly of T cell receptor (TCR)alpha/beta genes by variable/diversity/joining (V[D]J) rearrangement is an ordered process beginning with recombination activating gene (RAG) expression and TCRbeta recombination in CD4(-)CD8(-)CD25(+) thymocytes. In these cells, TCRbeta expression leads to clonal expansion, RAG downregulation, and TCRbeta allelic exclusion. At the subsequent CD4(+)CD8(+) stage, RAG expression is reinduced and V(D)J recombination is initiated at the TCRalpha locus. This second wave of RAG expression is terminated upon expression of a positively selected alpha/beta TCR. To examine the physiologic role of the second wave of RAG expression, we analyzed mice that cannot reinduce RAG expression in CD4(+)CD8(+) T cells because the transgenic locus that directs RAG1 and RAG2 expression in these mice is missing a distal regulatory element essential for reinduction. In the absence of RAG reinduction we find normal numbers of CD4(+)CD8(+) cells but a 50-70% reduction in the number of mature CD4(+)CD8(-) and CD4(-)CD8(+) thymocytes. TCRalpha rearrangement is restricted to the 5' end of the Jalpha cluster and there is little apparent secondary TCRalpha recombination. Comparison of the TCRalpha genes expressed in wild-type or mutant mice shows that 65% of all alpha/beta T cells carry receptors that are normally assembled by secondary TCRalpha rearrangement. We conclude that RAG reinduction in CD4(+)CD8(+) thymocytes is not required for initial TCRalpha recombination but is essential for secondary TCRalpha recombination and that the majority of TCRalpha chains expressed in mature T cells are products of secondary recombination.

Animals↗
PubMed2001

Validation of the Framingham coronary heart disease prediction scores: results of a multiple ethnic groups investigation.

CONTEXT: The Framingham Heart Study produced sex-specific coronary heart disease (CHD) prediction functions for assessing risk of developing incident CHD in a white middle-class population. Concern exists regarding whether these functions can be generalized to other populations. OBJECTIVE: To test the validity and transportability of the Framingham CHD prediction functions per a National Heart, Lung, and Blood Institute workshop organized for this purpose. DESIGN, SETTING, AND SUBJECTS: Sex-specific CHD functions were derived from Framingham data for prediction of coronary death and myocardial infarction. These functions were applied to 6 prospectively studied, ethnically diverse cohorts (n = 23 424), including whites, blacks, Native Americans, Japanese American men, and Hispanic men: the Atherosclerosis Risk in Communities Study (1987-1988), Physicians' Health Study (1982), Honolulu Heart Program (1980-1982), Puerto Rico Heart Health Program (1965-1968), Strong Heart Study (1989-1991), and Cardiovascular Health Study (1989-1990). MAIN OUTCOME MEASURES: The performance, or ability to accurately predict CHD risk, of the Framingham functions compared with the performance of risk functions developed specifically from the individual cohorts' data. Comparisons included evaluation of the equality of relative risks for standard CHD risk factors, discrimination, and calibration. RESULTS: For white men and women and for black men and women the Framingham functions performed reasonably well for prediction of CHD events within 5 years of follow-up. Among Japanese American and Hispanic men and Native American women, the Framingham functions systematically overestimated the risk of 5-year CHD events. After recalibration, taking into account different prevalences of risk factors and underlying rates of developing CHD, the Framingham functions worked well in these populations. CONCLUSIONS: The sex-specific Framingham CHD prediction functions perform well among whites and blacks in different settings and can be applied to other ethnic groups after recalibration for differing prevalences of risk factors and underlying rates of CHD events.

Black or African American↗
PubMed2001

Assessment of impact of information booklets on use of healthcare services: randomised controlled trial.

OBJECTIVES: To investigate the effect of patient information booklets on overall use of health services, on particular types of use, and on possible interactions between use, deprivation category of the area in which respondents live, and age. To investigate the possibility of a differential effect on health service use between two information booklets. DESIGN: Randomised controlled trial of two patient information booklets (covering the management and treatment of minor illness). SETTING: 20 general practices in Lothian, Scotland. PARTICIPANTS: Random sample of patients from the community health index (n=4878) and of those contacting out of hours services (n=4530) in the previous 12 months in each of the study general practices. INTERVENTION: Booklets were posted to participants in intervention groups (3288 were sent What Should I Do?; 3127 were sent Health Care Manual). Patients randomised to control group (2993) did not receive a booklet. MAIN OUTCOME MEASURES: Use of health services audited from patients' general practice notes in 12 months after receipt of booklet. RESULTS: Receipt of either booklet had no significant effect on health service use compared with a control group. However, nine out of ten matched practices allocated to receive Health Care Manual had reduced consultation rates compared with matched practices allocated to What Should I Do? CONCLUSION: Widespread distribution of information booklets about the management of minor illness is unlikely to reduce demand for health services.

Family Practice↗
PubMed2001

Gentamicin causes endocytosis of Na/Pi cotransporter protein (NaPi-2).

BACKGROUND: Renal toxicity is a major side-effect of aminoglycoside antibiotics and is characterized by an early impairment in proximal tubular function. In a previous study, we have shown that gentamicin administration to the rat causes an early impairment in sodium gradient-dependent phosphate (Na/Pi) cotransport activity. The purpose of our current study was to determine the molecular mechanisms of the impairment in Na/Pi cotransport activity, specifically the role of the proximal tubular type II Na/Pi cotransporter. METHODS: Rats were treated for one, two, and three days with two daily injections of 30 mg/kg body weight gentamicin or the vehicle. RESULTS: Gentamicin caused a progressive decrease in superficial cortical apical brush-border membrane (SC-BBM) Na/Pi cotransporter activity (856 +/- 93 in control vs. 545 +/- 87 pmol/mg BBM protein in 3-day gentamicin, P < 0.01). Western blot analysis showed a parallel and progressive decrease in SC-BBM Na/Pi cotransporter protein abundance, a 50% decrease after one day of treatment, a 63% decrease after two days of treatment, and an 83% decrease after three days treatment with gentamicin. In contrast, gentamicin treatment had no effect on Na/Pi cotransport activity or Na/Pi cotransporter protein abundance in BBM isolated from the juxtamedullary cortex (JMC-BBM). Immunofluorescence microscopy showed a major decrease in the expression of Na/Pi cotransporter protein in the apical membrane of the proximal convoluted tubule, with progressive intracellular accumulation of Na/Pi protein. Colocalization studies showed that in gentamicin-treated rats, Na/Pi protein was colocalized in the early endosomes and especially in the lysosomes. Northern blot analysis of cortical RNA interestingly showed no reduction in Na/Pi cotransporter mRNA abundance even after three days of gentamicin treatment. CONCLUSION: We conclude that gentamicin inhibits Na/Pi cotransport activity by causing a decrease in the expression of the type II Na/Pi cotransport protein at the level of the proximal tubular apical BBM and that inhibition of Na/Pi cotransport activity is most likely mediated by post-transcriptional mechanisms.

Animals↗
PubMed2001

Glycosphingolipids modulate renal phosphate transport in potassium deficiency.

BACKGROUND: Potassium (K) deficiency (KD) and/or hypokalemia have been associated with disturbances of phosphate metabolism. The purpose of the present study was to determine the cellular mechanisms that mediate the impairment of renal proximal tubular Na/Pi cotransport in a model of K deficiency in the rat. METHODS: K deficiency in the rat was achieved by feeding rats a K-deficient diet for seven days, which resulted in a marked decrease in serum and tissue K content. RESULTS: K deficiency resulted in a marked increase in urinary Pi excretion and a decrease in the V(max) of brush-border membrane (BBM) Na/Pi cotransport activity (1943 +/- 95 in control vs. 1184 +/- 99 pmol/5 sec/mg BBM protein in K deficiency, P < 0.02). Surprisingly, the decrease in Na/Pi cotransport activity was associated with increases in the abundance of type I (NaPi-1), and type II (NaPi-2) and type III (Glvr-1) Na/Pi protein. The decrease in Na/Pi transport was associated with significant alterations in BBM lipid composition, including increases in sphingomyelin, glucosylceramide, and ganglioside GM3 content and a decrease in BBM lipid fluidity. Inhibition of glucosylceramide synthesis resulted in increases in BBM Na/Pi cotransport activity in control and K-deficient rats. The resultant Na/Pi cotransport activity in K-deficient rats was the same as in control rats (1148 +/- 52 in control + PDMP vs. 1152 +/- 61 pmol/5 sec/mg BBM protein in K deficiency + PDMP). These changes in transport activity occurred independent of further changes in BBM NaPi-2 protein or renal cortical NaPi-2 mRNA abundance. CONCLUSION: K deficiency in the rat causes inhibition of renal Na/Pi cotransport activity by post-translational mechanisms that are mediated in part through alterations in glucosylceramide content and membrane lipid dynamics.

Animals↗
PubMed2001

Food allergy--towards predictive testing for novel foods.

The risks associated with IgE-mediated food allergy highlight the need for methods to screen for potential food allergens. Clinical and immunological tests are available for the diagnosis of food allergy to known food allergens, but this does not extend to the evaluation, or prediction of allergenicity in novel foods. This category, includes foods produced using novel processes genetically modified (GM) foods, and foods that might be used as alternatives to traditional foods. Through the collation and analysis of the protein sequences of known allergens and their epitopes, it is possible to identify related groups which correlate with observed clinical cross-reactivities. 3-D modelling extends the use of sequence data and can be used to display eptiopes on the surface of a molecule. Experimental models support sequence analysis and 3-D modelling. Observed cross-reactivities can be examined by Western blots prepared from native 2-D gels of a whole food preparation (e.g. hazelnut, peanut), and common proteins identified. IgEs to novel proteins can be raised in Brown Norway rat (a high IgE responder strain) and the proteins tested in simulated digest to determine epitope stability. Using the CSL serum bank, epitope binding can be examined through the ability of an allergen to cross-link the high affinity IgE receptor and thereby release mediators using in vitro cell-based models. This range of methods, in combination with data mining, provides a variety of screening options for testing the potential of a novel food to be allergenic, which does not involve prior exposure to the consumer.

Allergens↗
PubMed2001

Double blind, randomised, placebo controlled study of a platelet activating factor antagonist, lexipafant, in the treatment and prevention of organ failure in predicted severe acute pancreatitis.

BACKGROUND: Platelet activating factor (PAF) is believed to amplify the activity of key mediators of the systemic inflammatory response syndrome (SIRS) in acute pancreatitis, resulting in multiorgan dysfunction syndrome. We tested the hypothesis that a potent PAF antagonist, lexipafant, could dampen SIRS and reduce organ failure in severe acute pancreatitis. METHODS: We conducted a randomised, double blind, placebo controlled, multicentre trial of lexipafant (100 mg/24 hours intravenously for seven days commenced within 72 hours of the onset of symptoms) involving 290 patients with an APACHE II score >6. Power calculations assumed that complications would be reduced from 40% to 24%. Secondary end points studied included severity of organ failure, markers of the inflammatory response, and mortality rate. FINDINGS: Overall, 80/138 (58%) patients in the placebo group and 85/148 (57%) in the lexipafant group developed one or more organ failures. The primary hypothesis was invalidated by the unexpected finding that 44% of patients had organ failure on entry into the study; only 39 (14%) developed new organ failure. Organ failure scores were reduced in the lexipafant group only on day 3: median change -1 (range -4 to +8) versus 0 (-4 to +10) in the placebo group (p=0.04). Systemic sepsis affected fewer patients in the lexipafant group (13/138 v 4/148; p=0.023). Local complications occurred in 41/138 (30%) patients in the placebo group and in 30/148 (20%) in the lexipafant group (20%; p=0.065); pseudocysts developed in 19 (14%) and eight (5%) patients, respectively (p=0.025). Deaths attributable to acute pancreatitis were not significantly different. Interleukin 8, a marker of neutrophil activation, and E-selectin, a marker of endothelial damage, decreased more rapidly in the lexipafant group (both p<0.05); however, absolute values were not different between the two groups. INTERPRETATION: The high incidence of organ failure within 72 hours of the onset of symptoms undermined the primary hypothesis, and power calculations for future studies in severe acute pancreatitis will need to allow for this. Lexipafant had no effect on new organ failure during treatment. This adequately powered study has shown that antagonism of PAF activity on its own is not sufficient to ameliorate SIRS in severe acute pancreatitis

Acute Disease↗
PubMed2001

Access to the evidence base from general practice: a survey of general practice staff in Northern and Yorkshire Region.

AIM: To identify and describe current methods of making health related research evidence accessible to general practice staff in the Northern and Yorkshire Region. METHOD: A postal survey questionnaire of general practice staff in the Northern and Yorkshire Region. RESULTS: At least one completed questionnaire was obtained from 70% of the general practices surveyed, and the individual response rate to the survey was 45%. Just under 60% of all respondents reported having no access to the NHS internet and just under 50% also reported having no access to the internet. All respondents in this survey reported greater access to paper based information than to electronic databases. However, this research provides evidence of differential access to information resources between different professions in general practice with GPs clearly having easier access than other professions to both paper based resources and electronic databases. 70% of all respondents said that they would need to be trained to use either a computer, the internet, or to search databases if the opportunity for easy access to any of these information services was available. CONCLUSIONS: At the time of this survey, general practices seemed to be struggling to set up the infrastructure and develop the skills that are necessary to make best use of available research evidence. In addition, there is a need for further investigation into the reasons why different professions working in the same practice setting have differential access to information resources available in primary care.

Computer User Training↗
PubMed2001

Thy1 glomerulonephritis induced in young lewis rats accelerates age-related glomerulosclerosis.

Age-related and disease-induced glomerulosclerosis (GS) in rats have both been well defined in a number of strains and experimental models, but the inter-relationship between the two is not clear. The present study was undertaken to compare the pattern of glomerular injury in these two types of GS. One- and two-shot Thy1 glomerulonephritis (GN) was induced at 2 months of age and followed for 12 months. At 12 months histological injury in proteinuric rats was characterized by segmental hyaline lesions. Two-shot Thy1 GN resulted in accelerated, but morphologically identical injury at 8 months. Histological lesions predictive of subsequent accelerated GS were evaluated at 1, 2, 4 and 6 months. In this regard, glomerular hypercellularity, rather than hypertrophy or matrix increase, was the most consistent histological index of later accelerated disease. The profibrotic cytokines transforming growth factor (TGF)-beta(1) and -beta(3) were localized distinctly to segmental hyaline lesions, but not to areas of matrix increase within the glomerular tuft. This study reveals that GS after Thy1 GN represents acceleration of an age-related disease, presents evidence for use of prolonged glomerular hypercellularity as the best histological index of future disease progression, and correlates the key lesion of GS in these animals, the segmental hyaline lesion, with the presence of TGF-beta peptides.

Aging↗
PubMed2001

Physiological and molecular characterization of urea transport by the gills of the Lake Magadi tilapia (Alcolapia grahami).

The Lake Magadi tilapia (Alcolapia grahami) is an unusual fish, excreting all its nitrogenous waste as urea because of its highly alkaline and buffered aquatic habitat. Here, using both physiological and molecular studies, we describe the mechanism of branchial urea excretion in this species. In vivo, repeated short-interval sampling revealed that urea excretion is continuous. The computed urea permeability of A. grahami gill is 4.74x10(-)(5)+/-0.38x10(-)(5 )cm s(-)(1) (mean +/- s.e.m., N=11), some 10 times higher than passive permeability through a lipid bilayer and some five times higher than that of even the most urea-permeable teleosts studied to date (e.g. the gulf toadfish). Transport of urea was bidirectional, as demonstrated by experiments in which external [urea] was elevated. Furthermore, urea transport was inhibited by classic inhibitors of mammalian and piscine urea transporters in the order thiourea>N-methylurea>acetamide. A 1700 base pair cDNA for a putative Magadi tilapia urea transporter (mtUT) was cloned, sequenced and found to display high homology with urea transporters from mammals, amphibians and other fishes. When cRNA transcribed from mtUT cDNA was injected into Xenopus laevis oocytes, phloretin-inhibitable urea uptake was enhanced 3.4-fold relative to water-injected controls. Northern analysis of gill, red blood cells, liver, muscle and brain using a portion of mtUT as a probe revealed that gill is the only tissue in which mtUT RNA is expressed. Magadi tilapia gill pavement cells exhibited a trafficking of dense-cored vesicles between the well-developed Golgi cisternae and the apical membrane. The absence of this trafficking and the poor development of the Golgi system in a non-ureotelic relative (Oreochromis niloticus) suggest that vesicle trafficking could be related to urea excretion in Alcolapia grahami. Taken together, the above findings suggest that the gills of this alkaline-lake-adapted species excrete urea constitutively via the specific facilitated urea transporter mtUT.

Amino Acid Sequence↗
PubMed2001

Deprivation, psychological distress, and consultation length in general practice.

BACKGROUND: Recent research has shown the benefits of longer consultations in general practice. Approximately 40% of patients presenting to general practitioners (GPs) are psychologically distressed. Studies have shown that psychological morbidity increases with increasing socioeconomic deprivation. The combined effects of psychological morbidity and socioeconomic deprivation on consultation length are unknown. In addition, though it is known that doctors correctly identify half their distressed patients as such, the effect of consultation length on identification is unknown. AIM: To examine factors associated with presentation and recognition of psychological distress in GPs' surgeries and the interaction of these factors with consultation length. DESIGN OF STUDY: A cross-sectional study. SETTING: Nine general practices in the West of Scotland, involving 1075 consultations of 21 full-time GPs. METHOD: The main outcome measures were patient psychological distress (measured by General Health Questionnaire-12), doctors' identification of psychological distress, consultation length, and Carstairs deprivation category scores. RESULTS: The mean consultation length was 8.71 minutes (SD = 4.40) and the prevalence of positive GHQ scores was 44.7%. Increasing GHQ (greater psychological distress) and lower deprivation category scores (greater affluence) were associated with longer consultations. Positive GHQ scoring increased with greater socioeconomic deprivation and also peaked in the 30 to 39 years age group. Recognition of psychological distress was greater in longer consultations (50% increase in consultation length associated with 32% increase in recognition). CONCLUSION: Increasing socioeconomic deprivation is associated with higher prevalence of psychological distress and shorter consultations. This provides further evidence to support Tudor Hart's 'inverse care law' and has implications for the resourcing of primary care in deprived areas.

Adolescent↗
PubMed2001

Assessing dissatisfaction with an out of hours service: reasons and remedies.

OBJECTIVE: To identify characteristics associated with dissatisfaction following contact with an out of hours co-operative in Glasgow, and to identify reasons for this dissatisfaction. To make recommendations for good practice in the light of these findings. DESIGN: Survey of attenders during one week of operation of an out of hours co-operative. Analysis of factors associated with dissatisfaction. SETTING: The Glasgow Emergency Medical Service, October 1996. SUBJECTS: Questionnaires were received from 1115 patients or their carers, representing a 69.3% response rate. RESULTS: Dissatisfaction was associated with unmet expectations, particularly among those expecting home visits. Parents of young children, more affluent patients, and those experiencing problems with daytime services also tended to be dissatisfied. Seventy four (7%) respondents indicated that they were very dissatisfied with aspects of the service. A high proportion of this dissatisfaction was related to telephone contact. Transport to out of hours centres caused problems for some patients, particularly for those with young children. Perceptions of dismissive attitudes by medical staff, and of incorrect diagnoses and treatment were causes of strong dissatisfaction. Patients with adverse medical outcomes were also likely to be very dissatisfied. CONCLUSION: Clear reasons for dissatisfaction were found among our sample. In most cases, remedial management action could be taken to reduce the likelihood of major dissatisfaction with the service.

Adolescent↗
PubMed2000

Extracellular ATP-dependent suppression of proliferation and induction of differentiation of human HL-60 leukemia cells by distinct mechanisms.

Extracellular ATP suppressed the growth of HL-60 leukemia cells and induced their differentiation as revealed by N-formyl-methionyl-leucyl-phenylalanine-induced beta-glucuronidase release. ATP degraded to ADP, AMP, and adenosine, and the effect of ATP on cell growth was mimicked by these metabolites added to the cultures. The stable analog alpha,beta-methylene ATP, however, had only a weak inhibitory effect on cell growth. Adenine nucleotide-induced growth suppression was reversed by uridine, suggesting the involvement of intracellular pyrimidine starvation secondary to adenosine accumulation. Consistent with this, ATP induced intracellular starvation of pyrimidine nucleotides, and this effect was also prevented by pretreatment of cells with uridine. The order of effectiveness of ATP-induced differentiation of HL-60 cells, unlike that for growth suppression, was ATP > ADP > AMP, and adenosine had no effect. Furthermore, uridine had no effect and the stable analog, alpha,beta-methylene ATP also induced HL-60 cell differentiation, suggesting that differentiation was due to ATP per se. We tested the hypothesis that ATP-induced differentiation arises from activation of adenylyl cyclase by the novel P2Y(11) receptor using the cell-permeable inhibitor of protein kinase A, Rp-CPT-cAMPS (8-(4-chlorophenylthio)adenosine-3',5'-cyclic monophosphorothioate, Rp isomer). Rp-CPT-cAMPS (1-100 microM) prevented ATP-induced differentiation of HL-60 cells as assessed by fMLP-induced beta-glucuronidase release. However, Rp-CPT-cAMPS did not prevent ATP-induced growth suppression. Taken together, the data indicate that extracellular ATP suppresses HL-60 growth and induces their differentiation by distinct mechanisms. Growth suppression arises from adenosine generation and consequent pyrimidine starvation. Differentiation arises, at least in part, from a distinct mechanism involving the activation of cell surface P2 receptors coupled to cAMP generation and activation of protein kinase A.

Adenosine↗