Biomedical subjects

J Chapman

Publications and source records attributed to J Chapman.

At least 55 records · Page 3Linked to original sources

PubMed2005

Measurement of the cross section for prompt diphoton production in pp collisions at square root of s=1.96 TeV.

We report a measurement of the rate of prompt diphoton production in pp collisions at square root of s=1.96 TeV using a data sample of 207 pb(-1) collected with the upgraded Collider Detector at Fermilab. The background from nonprompt sources is determined using a statistical method based on differences in the electromagnetic showers. The cross section is measured as a function of the diphoton mass, the transverse momentum of the diphoton system, and the azimuthal angle between the two photons and is found to be consistent with perturbative QCD predictions.

Journal Article↗

PubMed2005

Search for anomalous kinematics in tt dilepton events at CDF II.

We report on a search for anomalous kinematics of tt dilepton events in pp collisions at square root of s=1.96 TeV using 193 pb(-1) of data collected with the CDF II detector. We developed a new a priori technique designed to isolate the subset in a data sample revealing the largest deviation from standard model (SM) expectations and to quantify the significance of this departure. In the four-variable space considered, no particular subset shows a significant discrepancy, and we find that the probability of obtaining a data sample less consistent with the SM than what is observed is 1.0%-4.5%.

Journal Article↗

PubMed2005

Measurement of the W(+)W(-) production cross section in pp collisions at square root[s]=1.96 TeV using dilepton events.

We present a measurement of the W(+)W(-) production cross section using 184 pb(-1) of p(p) collisions at a center-of-mass energy of 1.96 TeV collected with the Collider Detector at Fermilab. Using the dilepton decay channel W(+)W(-)-->l(+)nul(-), where the charged leptons can be either electrons or muons, we find 17 candidate events compared to an expected background of 5.0(+2.2)(-0.8) events. The resulting W(+)W(-) production cross-section measurement of sigma(pp-->W(+)W(-))=14.6(+5.8)(-5.1)(stat)(+1.8)(-3.0)(syst) +/- 0.9(lum) pb agrees well with the standard model expectation.

Journal Article↗

PubMed2005

Measurement of charged-particle multiplicities in gluon and quark jets in pp collisions at square root of s = 1.8 TeV.

We report the first largely model independent measurement of charged particle multiplicities in quark and gluon jets, Nq and Ng, produced at the Fermilab Tevatron in pp collisions with a center-of-mass energy of 1.8 TeV and recorded by the Collider Detector at Fermilab. The measurements are made for jets with average energies of 41 and 53 GeV by counting charged particle tracks in cones with opening angles of theta(c) = 0.28, 0.36, and 0.47 rad around the jet axis. The corresponding jet hardness Q = Ejet theta c varies in the range from 12 to 25 GeV. At Q = 19.2 GeV, the ratio of multiplicities r = Ng/Nq is found to be 1.64+/-0.17, where statistical and systematic uncertainties are added in quadrature. The results are in agreement with resummed perturbative QCD calculations.

Journal Article↗

PubMed2005

Measurement of partial widths and search for direct CP violation in D0 meson decays to K-K+ and pi-pi+.

We present a measurement of relative partial widths and decay rate CP asymmetries in K-K+ and pi(-)pi(+) decays of D0 mesons produced in pp collisions at sqrt[s]=1.96 TeV. We use a sample of 2x10(5) D(*+)-->D0pi(+) (and charge conjugate) decays with the D0 decaying to K-pi(+), K-K+, and pi(-)pi(+), corresponding to 123 pb(-1) of data collected by the Collider Detector at Fermilab II experiment at the Fermilab Tevatron collider. No significant direct CP violation is observed. We measure Gamma(D0-->K-K+)/Gamma(D0-->K-pi(+))=0.0992+/-0.0011+/-0.0012, Gamma(D0-->pi(-)pi(+))/Gamma(D0-->K-pi(+))=0.035 94+/-0.000 54+/-0.000 40, A(CP)(K-K+)=(2.0+/-1.2+/-0.6)%, and A(CP)(pi(-)pi(+))=(1.0+/-1.3+/-0.6)%, where, in all cases, the first uncertainty is statistical and the second is systematic.

Journal Article↗

PubMed2005

Close association between valvar heart disease and central nervous system manifestations in the antiphospholipid syndrome.

BACKGROUND: Heart valves lesions and central nervous system involvement are among the most common manifestations of the antiphospholipid syndrome (APS). OBJECTIVE: To evaluate possible interrelations between these manifestations in a large group of APS patients. METHODS: 284 APS patients were evaluated retrospectively, 159 of whom had primary APS. Cardiac-CNS associations were determined for the entire study population, and for subgroups of patients with primary APS or APS associated with systemic lupus erythematosus (SLE). RESULTS: Significant associations where found between cardiac vegetations and epilepsy (p < 0.02), and between cardiac valve thickening or dysfunction and migraine (p = 0.002). Borderline association was found between valvar vegetations and migraine (p = 0.09). A significant association was also found between all valvar lesions and stroke or transient ischaemic attacks. Subanalyses showed that patients with primary APS had significant associations between cardiac valve pathology and all CNS manifestations, while patients with APS associated with SLE had no such associations. CONCLUSIONS: The study suggests potential differences in biological behaviour between primary APS and APS associated with SLE. The presence of cardiac valve pathology may be a risk factor for several types of CNS involvement in PAPS.

Adolescent↗

PubMed2005

Search for excited and exotic electrons in the egamma decay channel in pp collisions at sqrt[s] = 1.96 TeV.

We present a search for excited and exotic electrons (e(*)) decaying to an electron and a photon, both with high transverse momentum. We use 202 pb(-1) of data collected in pp collisions at sqrt[s] = 1.96 TeV with the Collider Detector at Fermilab II detector. No signal above standard model expectation is seen for associated ee(*) production. We discuss the e(*) sensitivity in the parameter space of the excited electron mass M(e(*)) and the compositeness energy scale Lambda. In the contact interaction model, we exclude 132 GeV/c(2)<M(e(*))<879 GeV/c(2) for Lambda = M(e(*)) at 95% confidence level (C.L.). In the gauge-mediated model, we exclude 126 GeV/c(2) < M(e(*)) < 430 GeV/c(2) at 95% C.L. for the phenomenological coupling f/Lambda approximately 10(-2) GeV-1.

Journal Article↗

PubMed2005

Measurement of the lifetime difference between Bs mass eigenstates.

We present measurements of the lifetimes and polarization amplitudes for B(0)(s)-->J/psiphi and B(0)(d)-->J/psiK(*0) decays. Lifetimes of the heavy and light mass eigenstates in the B(0)(s) system are separately measured for the first time by determining the relative contributions of amplitudes with definite CP as a function of the decay time. Using 203+/-15 B(0)(s) decays we obtain tau(L) = (1.05(+0.16)(-0.13) +/- 0.02) ps and tau(H) = (2.07(+0.58)(-0.46) +/- 0.03) ps. Expressed in terms of the difference DeltaGamma(s) and average Gamma(s), of the decay rates of the two eigenstates, the results are DeltaGamma(s)/Gamma(s) = (65(+25)(-33) +/- 1)% and DeltaGamma(s) = (0.47(+0.19)(-0.24) +/- 0.01) ps(-1).

Journal Article↗

PubMed2005

First measurements of inclusive W and Z cross sections from run II of the fermilab tevatron collider.

We report the first measurements of inclusive W and Z cross sections times leptonic branching ratios for pp collisions at square root[s]=1.96 TeV, based on their decays to electrons and muons. The data correspond to an integrated luminosity of 72 pb(-1) recorded with the CDF detector at the Fermilab Tevatron. We test e-mu universality in W decays, and we measure the ratio of leptonic W and Z rates from which the leptonic branching fraction B(W-->lnu) can be extracted as well as an indirect value for the total width of the W and the Cabibbo-Kobayashi-Maskawa matrix element, |V(cs)|.

Journal Article↗

PubMed2005

Measurement of Wgamma and Zgamma production in pp collisions at square root s=1.96 TeV.

The standard model predictions for Wgamma and Zgamma production are tested using an integrated luminosity of 200 pb(-1) of pp collision data collected at the Collider Detector at Fermilab. The cross sections are measured by selecting leptonic decays of the W and Z bosons, and photons with transverse energy ET>7 GeV that are well separated from leptons. The production cross sections and kinematic distributions for the Wgamma and Zgamma data are compared to SM predictions.

Journal Article↗

PubMed2005

Age-dependent differential expression of BACE splice variants in brain regions of tg2576 mice.

Plaques found in the brains of patients suffering from Alzheimer's disease (AD) mainly consist of beta-amyloid (Abeta), which is produced by sequential cleaving of amyloid precursor protein (APP) by two proteolytic enzymes, beta- and gamma-secretases. Any change in the fine balance between these enzymes and their substrate may contribute to the etio-pathogenesis of AD. Indeed, the protein level and enzymatic activity of beta-secretase (BACE), but not its mRNA level, were found elevated in brain areas of AD patients who suffer a high load of Abeta plaque formation. Similarly, increased BACE activity but no mRNA change was observed in a transgenic mouse model of AD, tg2576, in which over expression of the Swedish mutated human APP leads to Abeta plaque formation and learning deficits. Based on the recent demonstration of four BACE splice variants with different enzymatic activity, the discrepancy between BACE activity and mRNA expression may be explained by the altered BACE alternative splicing. To test this hypothesis, we studied the expression of all BACE splice variants in different brain areas of tg2576 mice at age of 4 months and 1 year old. We found developmental and regional differences between wild-type and tg2576 mice. Our results indicate that over expression of APP in tg2576 mice leads to the altered alternative splicing of BACE and the increase of its enzymatically more active splice variant (I-501).

Aging↗

PubMed2005

Effect of levothyroxine replacement therapy on coagulation and fibrinolysis in severe hypothyroidism.

OBJECTIVE: We previously demonstrated that patients suffering from moderate hypothyroidism were at increased risk of thrombosis contrasting with the bleeding tendency of those presenting severe hypothyroidism. The latter state is associated with hemostatic anomalies including von Willebrand type 1 disease and increased fibrinolytic capacity. With the exception of von Willebrand type 1 disease, reversibility of hemostatic changes is not established after levothyroxine replacement therapy. Therefore our objective was to analyze the reversibility of these anomalies. MATERIALS AND METHODS: We analyzed the impact of levothyroxine treatment on lipid parameters, fibrinogen, platelet count, D-dimers, alpha2 antiplasmin activity, plasminogen activity, tissue plasminogen activator antigen (t-PA Ag), plasminogen activator inhibitor type 1 antigen (PAI-1 Ag) and coagulation factors (factor VIII coagulant, von Willebrand factor antigen, von Willebrand factor and factor IX) in 23 patients with severe hypothyroidism (TSH level > 50 mU/ I). RESULTS: Mean fibrinogen levels increased by 14.2% while t-PA Ag and PAI-1 Ag increased by 42.6 and 69%, respectively, after correction of hypothyroidism. Interestingly, post-treatment PAI-1 Ag levels tended to be higher in patients with normal-high final TSH levels than in patients with normal-low final TSH levels. Our results suggest that normalization of fibrinolysis is obtained after a transient decrease of fibrinolytic activity. We also confirmed the correction of coagulation factor abnormalities upon levothyroxine replacement therapy. CONCLUSIONS: We demonstrated that the coagulation disorders and the hyperfibrinolytic status of severe hypothyroid patients were corrected upon levothyroxine therapy. However, the clinical consequences of the transient decrease of the fibrinolytic activity during the course of TSH normalization need further studies.

Adult↗

PubMed2005

Specialist public health capacity in England: working in the new primary care organizations.

OBJECTIVES: To determine the capacity and development needs, in relation to key areas of competency and skills, of the specialist public health workforce based in primary care organizations following the 2001 restructuring of the UK National Health Service. STUDY DESIGN: Questionnaire survey to all consultants and specialists in public health (including directors of public health) based in primary care trusts (PCTs) and strategic health authorities (SHAs) in England. RESULTS: Participants reported a high degree of competency. However, skill gaps were evident in some areas of public health practice, most notably "developing quality and risk management" and in relation to media communication, computing, management and leadership. In general, medically qualified individuals were weaker on community development than non-medically qualified specialists, and non-medically qualified specialists were less able to perform tasks that require epidemiological or clinical expertise than medically qualified specialists. Less than 50% of specialists felt that their links to external organizations, including public health networks, were strong. Twenty-nine percent of respondents felt professionally isolated and 22% reported inadequate team working within their PCT or SHA. Approximately 21% of respondents expressed concerns that they did not have access to enough expertise to fulfil their tasks and that their skills were not being adequately utilized. CONCLUSIONS: Some important skill gaps are evident among the specialist public health workforce although, in general, a high degree of competency was reported. This suggests that the capacity deficit is a problem of numbers of specialists rather than an overall lack of appropriate skills. Professional isolation must be addressed by encouraging greater partnership working across teams.

England↗

PubMed2005

Developing a speciality: regearing the specialist public health workforce.

OBJECTIVES: To identify issues surrounding the future training needs of the specialist public health workforce following the most recent restructuring of the National Health Service (NHS) in England. METHODS: All directors of public health (DsPH) based in strategic health authorities and nine senior staff working in public health at the regional level were invited to participate in a semi-structured telephone interview. RESULTS: Twenty-six people were interviewed. Many interviewees expressed concern that because consultants and specialists in public health will be working in much smaller teams than hitherto, they will have to generalize their skills to cover a much wider range of functions (including board-level duties). This may result in a loss of specialist expertise. Successful public health practice in the new structures will require new ways of interorganizational working that will add an administrative burden to specialists in public health. Also, the creation of a board-level post in each primary care trust (PCT) has resulted in more time spent on corporate responsibilities and less on public health for DsPH, who are often the only fully trained specialist in public health in their PCT. Furthermore, interviewees expressed their anxiety about the lack of diversity in the posts available to specialists in public health and particularly to those newly completing their specialist training. Generally, interviewees felt that traditional public health roles and responsibilities were being eclipsed by corporate and managerial ones. Professional development activities were being carried out, but in a rather ad-hoc fashion. Interviewees were hopeful that public health networks would lead professional development initiatives once they were more established. CONCLUSIONS: It is important that excellence in public health is maintained through a set of accreditable standards, whilst corporate skills, essential to successful public health practice in the new UK NHS, are developed among specialists in public health.

Accreditation↗

PubMed2005

The geographical distribution of specialists in public health in the United Kingdom: is capacity related to need?

OBJECTIVES: Recent organizational changes reflect the need to be more responsive to local populations and have included fostering a closer structural relationship between primary care and public health. In light of this, we explore the distribution of the specialist public health workforce and the relationship with population deprivation and need. STUDY DESIGN: Questionnaire survey to all directors of public health working in primary care trusts (PCTs) and strategic health authorities (SHAs) in England to determine the number of specialists in public health working in either PCTs or SHAs. All identified specialists were given the opportunity to self-define in a further questionnaire survey. Whole-time-equivalent staffing, per head of population, was analysed against socio-economic deprivation, measured by the DETR 2000 Index of Multiple Deprivation. The analysis was conducted at the SHA level. RESULTS: The survey was undertaken whilst public health in the UK was undergoing immense change. This presented specific challenges in identifying specialists in public health working within PCTs and SHAs. Seven hundred and eighty-three specialists working in PCTs and SHAs were identified. On average, in England, there are 1.69 specialists in public health per 100,000 population, with some variability at SHA level (range = 0.8-2.89). Findings indicate an overall positive association between capacity at SHA level and socio-economic need, although some discrepancies between need and provision are apparent. CONCLUSIONS: The general positive association between capacity and deprivation should offer some reassurance to policy makers, researchers and patients alike. However, further efforts are needed to redistribute specialists in some areas to address organizational capacity and equity issues.

England↗

PubMed2005

Antiphospholipid antibodies bind ATP: a putative mechanism for the pathogenesis of neuronal dysfunction.

Antiphospholipid antibodies (aPL) generated in experimental animals cross-react with ATP. We therefore examined the possibility that aPL IgG from human subjects bind to ATP by affinity column and an enzyme linked immunosorbent assay (ELISA). Sera with high levels of aPL IgG were collected from 12 patients with the antiphospholipid syndrome (APS). IgG fractions from 10 of 12 APS patients contained aPL that could be affinity-bound to an ATP column and completely eluted with NaCl 0.5 M. A significant (> 50%) inhibition of aPL IgG binding by ATP 5 mM was found in the majority. Similar inhibition was obtained with ADP but not with AMP or cAMP. All the affinity purified anti-ATP antibodies also bound beta2-glycoprotein-I (beta2-GPI, also known as apolipoprotein H) suggesting that, similar to most pathogenic aPL, their binding depends on this serum cofactor. We further investigated this possibility and found that the binding of beta2-GPI to the ATP column was similar to that of aPL IgG in that most was reversed by NaCl 0.5 M. Furthermore, addition of beta2-GPI to aPL IgG significantly increased the amount of aPL binding to an ATP column. We conclude that aPL IgG bind ATP, probably through beta32-GPI. This binding could interfere with the normal extracellular function of ATP and similar neurotransmitters.

Adenosine Triphosphate↗

PubMed2005

Anti-ribosomal P-protein and its role in psychiatric manifestations of systemic lupus erythematosus: myth or reality?

Systemic lupus erythematosus (SLE) is an autoimmune disease that may involve the central nervous system (CNS) resulting in neuropsychiatric manifestations. The associated psychiatric disorders include depression, psychosis, mood disorders, anxiety, cognitive dysfunction, and delirium/ encephalopathy. Several autoantibodies may play a role in the pathogenesis of psychiatric complications of SLE, particularly antibodies against ribosomal P-proteins (anti-P) and possibly antibodies against endothelial cells (AECA). The reported prevalence of anti-P is highly variable in SLE patients and is dependent on different ethnic backgrounds, sensitivity and specificity of the assays employed for autoantibody detection, and the time at which sera were analysed in relation to the clinical event. Controversial data exist on the association of anti-P with psychiatric manifestations of SLE. These autoantibodies have been suggested to be specific markers of the psychiatric manifestations of SLE, particularly of the psychosis and depression, and the antibody level varied with the clinical activity of the disease. Some studies have confirmed the hypothesis of an association of anti-P antibodies with psychiatric manifestations of neuropsychiatric SLE (NPSLE) while others have disputed this relationship. This review summarizes the recent studies about relationship between anti-P antibodies and psychiatric manifestation of SLE.

Autoantibodies↗

PubMed2005

Clinical muscular sarcocystosis in a dog.

Muscular sarcocystosis is a rare infection in dogs. Clinical myositis associated with an unidentified species of Sarcocystis was diagnosed in an adult dog from Canada. There was granulomatous myositis associated with numerous immature sarcocysts in a muscle biopsy obtained from the dog. The sarcocysts were up to 550 microm long and up to 45 microm wide. The sarcocyst wall was approximately 1 microm thick and contained short, stubby, villar protrusions that lacked microtubules. This is the first report on clinical muscular sarcocystosis in a dog.

Animals↗