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Biomedical subjects

M Campbell

Publications and source records attributed to M Campbell.

At least 109 records · Page 6Linked to original sources

Study of B0 --> J/psiK(*)0pi(+)pi(-) decays with the collider detector at Fermilab.

We report a study of the decays B0 --> J/psiK(*)0pi(+)pi(-), which involve the creation of a uu or dd quark pair in addition to a b -->c(cs) decay. The data sample consists of 110 pb(-1) of pp collisions at square root[s] = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching fractions to be B(B0 --> J/psiK(*0)pi(+)pi(-)) = (6.6 +/- 1.9 +/- 1.1)x10(-4) and B(B0 --> J/psiK0pi(+)pi(-)) = (10.3 +/- 3.3 +/- 1.5)x10(-4). Evidence is seen for contributions from psi(2S)K(*)0, J/psiK0rho(0), J/psiK(*+)pi(-), and J/psiK1(1270).

Journal Article↗

Measurement of the strong coupling constant from inclusive jet production at the Tevatron pp collider.

We report a measurement of the strong coupling constant, alpha(s)(MZ), extracted from inclusive jet production in pp collisions at square root[s] = 1800 GeV. The QCD prediction for the evolution of alpha(s) with jet transverse energy ET is tested over the range 40<ET<450 GeV using ET for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. The value of alpha(s) at the mass of the Z0 boson averaged over the range 40<ET<250 GeV is found to be alpha(s)(MZ) = 0.1178+/-0.0001(stat)+0.0081(-0.0095)(expt. syst). The associated theoretical uncertainties are mainly due to the choice of renormalization scale ((+6%)(-4%)) and input parton distribution functions (5%).

Journal Article↗

Search for gluinos and scalar quarks in pp collisions at square root[s] = 1.8 TeV using the missing energy plus multijets signature.

We have performed a search for gluinos (g) and scalar quarks (q) in a data sample of 84 pb(-1) of pp collisions at square root[s] = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and three or more jets, a characteristic signature in R-parity-conserving supersymmetric models. The analysis has been performed "blind," in that the inspection of the signal region is made only after the predictions from standard model backgrounds have been calculated. Comparing the data with predictions of constrained supersymmetric models, we exclude gluino masses below 195 GeV/c2 (95% C.L.), independent of the squark mass. For the case m(q) approximately m(g), gluino masses below 300 GeV/c2 are excluded.

Journal Article↗

Frequency of administration of recombinant human erythropoietin for anaemia of end-stage renal disease in dialysis patients.

BACKGROUND: Although the benefits of recombinant human erythropoietin (rHu EPO) administration in dialysis patients have been demonstrated the optimal frequency regimen has not as yet been established. Treatment with rHu EPO is expensive, there is therefore a need for optimising the efficiency of its administration. OBJECTIVES: The objectives of this review were to assess the effects of different frequency regimens of rHu EPO administration in dialysis patients in terms of i) effectiveness (correction of anaemia, quality of life and freedom from adverse events) ii) efficiency (optimal resource use) of different rHu EPO dose regimen policies. SEARCH STRATEGY: We searched MEDLINE (1980 to May Week 3 2001), EMBASE (1984 to Week 24 2001), BIOSIS (1985 to January 1997), CINAHL (1982 to October 1997), The Cochrane Library (Issue 1, 1997), CHEMABS (1984 to November 1996), SIGLE (1980 to June 1996), CRIB (10th edition, 1995), UK NRR (14th consolidation, September 1996), RSC ( 1980 to February 1997), HealthSTAR (1995 to October 1997), IBSS (1984 to July 1997), NEED (July 1997) and reference lists of relevant articles. We contacted biomedical companies and investigators in the field and we hand searched Kidney International (including all supplements but excluding all conference proceedings except for 1994) July 1983 to May 1997 inclusive. The Internet was also searched on: August 1997. We had also identified some studies from a previous broad search for all randomised controlled trials (RCTs) relevant to the management of end-stage renal disease. Date of the most recent search: June 2001. SELECTION CRITERIA: All randomised or quasi randomised controlled trials comparing different frequencies of rHu EPO administration in dialysis patients. Subgroup analyses were performed comparing haemodialysis and CAPD patients and also subcutaneous and intravenous administration. DATA COLLECTION AND ANALYSIS: Only published data were used. Data were abstracted by a single investigator on to a standard form. The data abstracted were relevant to the predetermined outcome measures: measures of correction of anaemia, rHu EPO dose, quality of life measures, adverse events, number of withdrawals from study, mortality. Where appropriate, a summary relative risk (RR) was calculated for dichotomous data and a weighted mean difference (WMD) or standardised mean difference (SMD) for continuous data. MAIN RESULTS: Eight studies met our inclusion criteria. When once a week administration was compared with twice weekly there was no significant difference in the ability to maintain the target haemoglobin (RR 1.00, 95% CI 0.42 to 2.40). Mean haemoglobin after twelve weeks of therapy was not different between the two groups (WMD -0.21g/dl, 95% CI -0.98 to 0.56). No difference was found in mean haemoglobin or haematocrit at the end of any studies which compared once with thrice weekly administration of rHu EPO (SMD -0.31, 95% CI -0.67 to 0.06). A single study which compared once with more that thrice weekly administration showed no significant difference in mean haemoglobin at the end of the maintenance phase (mean difference -0.2g/dl, 95% CI -0.65 to 0.25). The dosage of erythropoietin required by those on haemodialysis receiving rHu EPO once weekly was just significantly more (WMD 12.0 U/kg, 95% CI 0.24 to 23.76) than those receiving it twice weekly but the confidence interval is wide. No such difference was found for CAPD patients nor when the results were combined (WMD 5.15 U/kg, 95% CI -3.74 to 14.05). The result was not significant when comparing once weekly with thrice weekly administration (WMD 10.00 U/kg, 95% CI -80.87 to 100.87). There was no difference in the frequency of adverse events between any of the groups studies. REVIEWER'S CONCLUSIONS: There is no significant difference between once weekly versus thrice weekly subcutaneous administration of rHu EPO. Once weekly administration of rHu EPO would require an additional 12U/kg/week for patients on haemodialysis, however this is based on one very small study. The cost of this additional hRu EPO nee, however this is based on one very small study. The cost of this additional hRu EPO needs to assessed, in particular with regard to patient preference and compliance.

Anemia↗

Dose finding study of mosapride in functional dyspepsia: a placebo-controlled, randomized study.

BACKGROUND: Prokinetic agents have shown variable efficacy in the treatment of functional dyspepsia. Mosapride is a new prokinetic 5-hydroxytryptamine-4 agonistic agent. AIM: To evaluate the efficacy of three dosage regimens of mosapride compared with placebo in the treatment of functional dyspepsia. METHODS: Patients were randomly allocated to treatment with placebo or mosapride (5 mg b.d., 10 mg b.d. or 7.5 mg t.d.s.) in a double-blind, prospective, multicentre, multinational study. The change in symptom severity score from an untreated baseline week to the sixth week of treatment was used to compare treatment efficacy. RESULTS: There were 141, 140, 143 and 142 patients valid for evaluation in the intention-to-treat population in the placebo, mosapride 5 mg b.d., mosapride 10 mg b.d. and mosapride 7.5 mg t.d.s. groups, respectively. The mean changes in the overall dyspeptic symptom score were - 0.90, - 0.94, - 0.88 and - 0.89, respectively, and the proportions of patients feeling better at the end of the treatment period were 60%, 59%, 59% and 61%, respectively. No statistically significant difference was seen. CONCLUSIONS: Treatment of functional dyspepsia with mosapride was not superior to placebo. The result raises the question of whether treatment with prokinetic agents is appropriate for functional dyspepsia.

Adult↗

Video-based spatio-temporal maps for analysis of gastric motility in vitro: effects of vagal stimulation in guinea-pigs.

Our aim was to evaluate topographically specific gastric motility changes induced by graded vagal activation. A recently developed method of constructing spatio-temporal maps of motility from video movies was adapted to the in vitro perfused guinea-pig stomach with an intact vagal nerve supply. In the unstimulated preparation, spontaneous activity was low or absent. Bilateral vagal stimulation with frequencies as low as 0.2 Hz triggered weak anally, and in some cases orally, propagating antral contractions at rates of about 5-6 min-1. Upon stimulation with higher frequencies, antral contractions increased significantly in length (starting more proximally) and amplitude, and produced large pressure peaks of up to 25 hPa, with maximal effects at 2-4 Hz. In contrast, the speed of propagation and the interval between peristaltic waves did not change with vagal stimulation at any frequency. Vagal stimulation also produced a significant and frequency-dependent enlargement of the fundus with a maximal effect at 4 Hz. It is concluded that a very low tonic vagal activity is apparently necessary and sufficient to express basic antral motility, while more sustained vagal activity is necessary for high-amplitude gastric contractions and significant sustained fundic relaxation. The constant interval between propagating contractions supports the concept that vagal input impinges on intrinsic enteric neural circuits that have a modulatory role in the myogenic mechanism underlying slow-wave peristalsis, rather than directly on gastric musculature.

Animals↗

The storage and re-infusion of autologous blood and BM as back-up following failed primary hematopoietic stem-cell transplantation: a survey of European practice.

BACKGROUND: Traditionally, autologous BM or PBSC have been stored as a secondary source ('back-up') of hematopoietic stem cells (HSC) prior to allogeneic and autologous HSC transplantation. METHOD: We conducted an audit of a single transplant center practice for providing back-up HSC and compared this practice with other European centers. Laboratory records relating to the collection and re-infusion of consecutive HSC harvests were reviewed for 515 transplants (300 autologous and 215 allogeneic HSC transplants). RESULTS: In our experience, 2.3% (five of 215) of allogeneic HSC transplants required secondary HSC rescue for failure to engraft or graft failure (MUD, n = 2; un-manipulated sibling BMT, n = 1; T-cell depleted sibling BMT, n = 2). For autologous transplants, 4.7% (14 of 300) required rescue due to failure to engraft or late graft failure (ABMT for AML, n = 8; CD34+ cell selection/ex vivo expanded, n = 4; ABMT/PBSCT, n = 2). Among the European centers, 69.7% replied to a postal questionnaire, demonstrating that 81.4% and 45.6% of centers stored a secondary HSC source for manipulated and unmanipulated MUD BMT, respectively; 50% and 11.6% of centers stored a secondary source of HSC for manipulated and unmanipulated matched sibling BMT, respectively; 36.4% and 12.7% of centers stored HSC for manipulated and unmanipulated matched sibling PBSCT, respectively. In the autologous setting, 15.2% and 62.1% of centers stored back-up for unmanipulated and manipulated BMT, respectively and 19.5% and 68.5% stored back-up for unmanipulated and manipulated PBSCT, respectively, when myeloablative conditioning regimens were used. DISCUSSION: These data suggest that a small minority of patients require a secondary source of HSC rescue, most commonly in transplants with higher risk of graft failure. This is reflected in the practice across Europe of storing 'back-up' HSC. Guidelines should accommodate the need for storage of a secondary source of HSC only in those transplants associated with a higher risk of graft failure, especially in relation to graft engineering.

Blood Banks↗

Radioecological survey at selected sites hit by depleted uranium ammunitions during the 1999 Kosovo conflict.

A field study, organised, coordinated and conducted under the responsibility of the United Nations Environment Programme (UNEP), took place in Kosovo in November 2000 to evaluate the level of depleted uranium (DU) released into the environment by the use of DU ammunition during the 1999 conflict. Representatives of six different scientific organisations took part in the mission and a total of approximately 350 samples were collected. During this field mission, the Italian National Environmental Protection Agency (ANPA) collected water, soil, lichen and tree bark samples from different sites. The samples were analysed by alpha-spectroscopy and in some cases by inductively coupled plasma-source mass spectrometry (ICP-MS). The 234U/238U and 235U/238U activity concentration ratios were used to distinguish natural from anthropogenic uranium. This paper reports the results obtained on these samples. All water samples had very low concentrations of uranium (much below the average concentration of drinking water in Europe). The surface soil samples showed a very large variability in uranium activity concentration, namely from approximately 20 Bq kg(-1) (environmental natural uranium) to approximately 2.3 x 10(5) Bq kg(-1) (approximately 18000 mg kg(-1) of depleted uranium), with concentrations above environmental levels always due to DU. The uranium isotope measurements refer to soil samples collected at places where DU ammunition had been fired; this variability indicates that the impact of DU ammunitions is very site-specific, reflecting both the physical conditions at the time of the impact of the DU ammunition and any physical and chemical alteration which occurred since then. The results on tree barks and lichens indicated the presence of DU in all cases, showing their usefulness as sensitive qualitative bio-indicators for the presence of DU dusts or aerosols formed at the time the DU ammunition had hit a hard target. This result is particularly interesting considering that at some sites, which had been hit by DU ammunition, no DU ground contamination could be detected.

Aerosols↗

Changes in cortical and striatal neurons predict behavioral and electrophysiological abnormalities in a transgenic murine model of Huntington's disease.

Neurons in Huntington's disease exhibit selective morphological and subcellular alterations in the striatum and cortex. The link between these neuronal changes and behavioral abnormalities is unclear. We investigated relationships between essential neuronal changes that predict motor impairment and possible involvement of the corticostriatal pathway in developing behavioral phenotypes. We therefore generated heterozygote mice expressing the N-terminal one-third of huntingtin with normal (CT18) or expanded (HD46, HD100) glutamine repeats. The HD mice exhibited motor deficits between 3 and 10 months. The age of onset depended on an expanded polyglutamine length; phenotype severity correlated with increasing age. Neuronal changes in the striatum (nuclear inclusions) preceded the onset of phenotype, whereas cortical changes, especially the accumulation of huntingtin in the nucleus and cytoplasm and the appearance of dysmorphic dendrites, predicted the onset and severity of behavioral deficits. Striatal neurons in the HD mice displayed altered responses to cortical stimulation and to activation by the excitotoxic agent NMDA. Application of NMDA increased intracellular Ca(2+) levels in HD100 neurons compared with wild-type neurons. Results suggest that motor deficits in Huntington's disease arise from cumulative morphological and physiological changes in neurons that impair corticostriatal circuitry.

Age of Onset↗

Search for gluinos and squarks using like-sign dileptons in pp macro collisions at square root of s = 1.8 TeV.

We present results of the first search for like-sign dilepton ( e(+/-)e(+/-), e(+/-)mu(+/-), mu(+/-)mu(+/-)) events associated with multijets and large missing energy using 106 pb(-1) of data in pp macro collisions at square root of s = 1.8 TeV collected during 1992-1995 by the CDF experiment. Finding no events that pass our selection, we examine pair production of gluinos (tilde g) and squarks (tilde q) in a constrained framework of the minimal supersymmetric standard model. At tan beta = 2 and mu = -800 GeV/c(2), we set 95% confidence level limits of M(tilde g)>221 GeV/c(2) for M(tilde g) approximately M(tilde q), and M(tilde q)>168 GeV/c(2) for M(tilde q)>>M(tilde g), both with small variation as a function of mu.

Journal Article↗

Observation of diffractive J/psi production at the Fermilab Tevatron.

We report the first observation of diffractive J/psi(--> mu+mu-) production in pp collisions at root square[s] = 1.8 TeV. Diffractive events are identified by their rapidity gap signature. In a sample of events with two muons of transverse momentum p(mu)T>2 GeV/c within the pseudorapidity region /eta/ < 1.0, the ratio of diffractive to total J/psi production rates is found to be R(J/psi) = [1.45 +/- 0.25]%. The ratio R(J/psi)(x) is presented as a function of x-Bjorken. By combining it with our previously measured corresponding ratio R(jj)(x) for diffractive dijet production, we extract a value of 0.59 +/- 0.15 for the gluon fraction of the diffractive structure function of the proton.

Journal Article↗

Charged-particle multiplicity pp collisions at square root of (s) = 1.8 TeV.

We report on a measurement of the mean charged-particle multiplicity of jets in dijet events with dijet masses in the range 80-630 GeV/c(2), produced at the Tevatron in pp collisions with square root (s) = 1.8 TeV and recorded by the Collider Detector at Fermilab. The data are fit to perturbative-QCD calculations carried out in the framework of the modified leading log approximation and the hypothesis of local parton-hadron duality. The fit yields values for two parameters in that framework: the ratio of parton multiplicities in gluon and quark jets, r identical withN(g-jet)(partons)/N(q-jet)(partons) = 1.7+/-0.3, and the ratio of the number of charged hadrons to the number of partons in a jet, K(charged)(LPHD) identical with N(charged)(hadrons)/N(partons) = 0.57+/-0.11.

Journal Article↗

Search for quark-lepton compositeness and a heavy W' Boson using the enu channel in p p macro collisions at square root of [s] = 1.8 TeV.

We present searches for quark-lepton compositeness and a heavy W' boson at high electron-neutrino transverse mass. We use approximately 110 pb(-1) of data collected in p p macro collisions at square root of [s] = 1.8 TeV by the CDF Collaboration during 1992-1995. The data are consistent with standard model expectations. Limits are set on the quark-lepton compositeness scale Lambda, the ratio of partial cross sections sigma(W'-->enu)/sigma(W-->enu), and the mass of a W' boson with standard model couplings. We exclude Lambda<2.81 TeV and a W' boson with mass below 754 GeV/c(2) at the 95% confidence level. Combining with our previously published limit obtained using the muon channel, we exclude a W' boson with mass below 786 GeV/c(2) at the 95% confidence level.

Journal Article↗

Double diffraction dissociation at the Fermilab Tevatron collider.

We present results from a measurement of double diffraction dissociation in pp collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width Deltaeta(0)>3 (overlapping eta = 0) is found to be 4.43+/-0.02(stat)+/-1.18(syst) mb [ 3.42+/-0.01(stat)+/-1.09(syst) mb] at square root of (s) = 1800[630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.

Journal Article↗

Measurement of d sigma/dM and forward-backward charge asymmetry for high-mass Drell-Yan e(+)e(-) pairs from pp macro collisions at square root of s = 1.8 TeV.

We report on a measurement of the mass dependence of the forward-backward charge asymmetry, A(FB), and production cross section d sigma/dM for e(+)e(-) pairs with mass M(ee)>40 GeV/c(2). The data sample consists of 108 pb(-1) of pp macro collisions at square root of s = 1.8 TeV taken by the Collider Detector at Fermilab during 1992-1995. The measured asymmetry and d sigma/dM are compared with the predictions of the standard model and a model with an extra Z' gauge boson.

Journal Article↗

Measurement of the top quark p(T) distribution.

We have measured the p(T) distribution of top quarks that are pair produced in pp collisions at sqrt[s] = 1.8 TeV using a sample of tt decays in which we observe a single high- p(T) charged lepton, a neutrino, and four or more jets. We use a likelihood technique that corrects for the experimental bias introduced due to event reconstruction and detector resolution effects. The observed distribution is consistent with the standard model prediction. We use these data to place limits on the production of high- p(T) top quarks suggested in some models of anomalous top quark pair production.

Journal Article↗

Synthesis of C-3 nitrogen-containing derivatives of N-acetyl-alpha,beta-D-mannosamine as substrates for N-acetylneuraminic acid aldolase.

The synthesis of 3-azido-3-deoxy, 3-amino-3-deoxy and 3-N-tert-butyloxycarbonyl-3-deoxy derivatives of 2-acetamido-2-deoxy-alpha,beta-D-mannose (N-acetyl-alpha,beta-D-mannosamine, ManNAc), is presented. The 3-azido-3-deoxy- and 3-N-tert-butyloxycarbonyl compounds were further characterised as their peracetates. A preliminary study has found that these C-3 nitrogen-substituted derivatives of ManNAc not to be substrates for Neu5Ac aldolase.

Hexosamines↗

Search for neutral supersymmetric Higgs bosons in pp collisions at sqrt[s] = 1.8TeV.

We present the results of a search for neutral Higgs bosons produced in association with b quarks in pp-->bb(phi)-->bbb final states with 91+/-7 pb(-1) of pp collisions at sqrt[s] = 1.8 TeV recorded by the Collider Detector at Fermilab. We find no evidence of such a signal and the data are interpreted in the context of the neutral Higgs sector of the minimal supersymmetric extension of the standard model. With basic parameter choices for the supersymmetric scale and the stop-quark mixing, we derive 95% C.L. lower mass limits for neutral Higgs bosons for tan(beta) values in excess of 35.

Journal Article↗