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Biomedical subjects

D Waters

Publications and source records attributed to D Waters.

At least 19 recordsLinked to original sources

In search of the origin of mass.

Particle physics explores the structure of matter by studying the behaviour of its most fundamental constituents. Despite the remarkable success of our theories, there remains much that is fundamental but unexplained. One of our most pressing questions concerns the origin of mass. Our favoured theoretical explanation for the existence of mass also predicts the existence of a particle that has never been seen-the Higgs boson. In this review, we survey our knowledge of the Higgs boson and explain why, if the theory is correct, we should expect to make our first observation of the elusive Higgs in the next few years, when a major new particle physics facility starts operating. This will be the most powerful particle accelerator in the world. Although searching for the Higgs boson will be challenging in this environment, we hope that our experimental results will allow us to finally understand the origin of mass and extend our knowledge of the Universe yet further.

Journal Article↗

Effects of atorvastatin on early recurrent ischemic events in acute coronary syndromes: the MIRACL study: a randomized controlled trial.

CONTEXT: Patients experience the highest rate of death and recurrent ischemic events during the early period after an acute coronary syndrome, but it is not known whether early initiation of treatment with a statin can reduce the occurrence of these early events. OBJECTIVE: To determine whether treatment with atorvastatin, 80 mg/d, initiated 24 to 96 hours after an acute coronary syndrome, reduces death and nonfatal ischemic events. DESIGN AND SETTING: A randomized, double-blind trial conducted from May 1997 to September 1999, with follow-up through 16 weeks at 122 clinical centers in Europe, North America, South Africa, and Australasia. PATIENTS: A total of 3086 adults aged 18 years or older with unstable angina or non-Q-wave acute myocardial infarction. INTERVENTIONS: Patients were stratified by center and randomly assigned to receive treatment with atorvastatin (80 mg/d) or matching placebo between 24 and 96 hours after hospital admission. MAIN OUTCOME MEASURES: Primary end point event defined as death, nonfatal acute myocardial infarction, cardiac arrest with resuscitation, or recurrent symptomatic myocardial ischemia with objective evidence and requiring emergency rehospitalization. RESULTS: A primary end point event occurred in 228 patients (14.8%) in the atorvastatin group and 269 patients (17.4%) in the placebo group (relative risk [RR], 0.84; 95% confidence interval [CI], 0.70-1.00; P =.048). There were no significant differences in risk of death, nonfatal myocardial infarction, or cardiac arrest between the atorvastatin group and the placebo group, although the atorvastatin group had a lower risk of symptomatic ischemia with objective evidence and requiring emergency rehospitalization (6.2% vs 8.4%; RR, 0.74; 95% CI, 0.57-0.95; P =.02). Likewise, there were no significant differences between the atorvastatin group and the placebo group in the incidence of secondary outcomes of coronary revascularization procedures, worsening heart failure, or worsening angina, although there were fewer strokes in the atorvastatin group than in the placebo group (12 vs 24 events; P =.045). In the atorvastatin group, mean low-density lipoprotein cholesterol level declined from 124 mg/dL (3.2 mmol/L) to 72 mg/dL (1.9 mmol/L). Abnormal liver transaminases (>3 times upper limit of normal) were more common in the atorvastatin group than in the placebo group (2.5% vs 0.6%; P<.001). CONCLUSION: For patients with acute coronary syndrome, lipid-lowering therapy with atorvastatin, 80 mg/d, reduces recurrent ischemic events in the first 16 weeks, mostly recurrent symptomatic ischemia requiring rehospitalization.

Aged↗

A quantification of human cells using an ERV-3 real time PCR assay.

A novel approach to quantifying human cells using a real time PCR assay was developed. The target sequence used in the assay is a 135 bp segment within the unique 1.7 kb Hind III / Pst I fragment of the ERV-3 envelope gene. ERV-3 is a full-length human endogenous retrovirus present in known copy number in all human cells. The detection range of ERV-3 by real time PCR is from 10(6) to 10(1). The precision described, sensitivity and specificity of the assay indicate that the ERV-3 sequence is an accurate cell quantitation marker. The quantitative ERV-3 assay enables simple, fast, and reproducible detection and quantitation of the cell number. The assay can be used to determine the sample DNA conditions and also it can be used to adjust the quantitative DNA measurements of other target gene assays relative to the number of cell equivalents.

Animals↗

Cephalometric comparison of maxillary second molar extraction and nonextraction treatments in patients with Class II malocclusions.

This retrospective cephalometric study compared the nature of the skeletodental correction of maxillary second-molar extraction and nonextraction treatments in correcting Class II malocclusions. The sample comprised 50 Class II, deep-bite, low-angle adolescents; half were treated with maxillary second-molar extraction and half were treated without extraction. Pretreatment and posttreatment lateral cephalograms were analyzed. Analysis relied primarily on the method of Lysle Johnston that evaluates sagittal changes in the teeth and supporting bones relative to the functional occlusal plane. All 18 cephalometric variables examined were statistically equivalent between the 2 groups at the start of treatment. In contrast, several skeletodental treatment changes differed significantly. The maxillary second-molar extraction group exhibited distal movement of the maxillary first molar (1.2 mm vs 0.0 mm), and there was greater flaring of the mandibular incisors in the nonextraction group (9.1 degrees vs 3.5 degrees ). The upper incisor root was torqued lingually in both groups, but there was more anterior crown movement in the nonextraction group (2.0 mm vs 0.0 mm). Also, the extraction group finished active treatment 7 months sooner on average. Sagittal molar correction in the maxillary second-molar group was a result of distalizing in the maxillary arch, whereas anchorage was expended in the mandibular arch to correct the malocclusion in the nonextraction group. In properly selected Class II malocclusions, maxillary second-molar extraction is a viable alternative treatment choice.

Adolescent↗

Search for new particles decaying to t&tmacr; in p&pmacr; collisions at radicals = 1.8 TeV

We use 106 pb (-1) of data collected with the Collider Detector at Fermilab to search for narrow-width, vector particles decaying to a top and an antitop quark. Model independent upper limits on the cross section for narrow, vector resonances decaying to t&tmacr; are presented. At the 95% confidence level, we exclude the existence of a leptophobic Z' boson in a model of top-color-assisted technicolor with mass M(Z')<480 GeV/c(2) for natural width gamma = 0.012M(Z'), and M(Z')<780 GeV/c(2) for gamma = 0.04M(Z').

Journal Article↗

Effects of estrogen replacement on the progression of coronary-artery atherosclerosis.

BACKGROUND: Heart disease is a major cause of illness and death in women. To understand better the role of estrogen in the treatment and prevention of heart disease, more information is needed about its effects on coronary atherosclerosis and the extent to which concomitant progestin therapy may modify these effects. METHODS: We randomly assigned a total of 309 women with angiographically verified coronary disease to receive 0.625 mg of conjugated estrogen per day, 0.625 mg of conjugated estrogen plus 2.5 mg of medroxyprogesterone acetate per day, or placebo. The women were followed for a mean (+/-SD) of 3.2+/-0.6 years. Base-line and follow-up coronary angiograms were analyzed by quantitative coronary angiography. RESULTS: Estrogen and estrogen plus medroxyprogesterone acetate produced significant reductions in low-density lipoprotein cholesterol levels (9.4 percent and 16.5 percent, respectively) and significant increases in high-density lipoprotein cholesterol levels (18.8 percent and 14.2 percent, respectively); however, neither treatment altered the progression of coronary atherosclerosis. After adjustment for measurements at base line, the mean (+/-SE) minimal coronary-artery diameters at follow-up were 1.87+/-0.02 mm, 1.84+/-0.02 mm, and 1.87+/-0.02 mm in women assigned to estrogen, estrogen plus medroxyprogesterone acetate, and placebo, respectively. The differences between the values for the two active-treatment groups and the value for the placebo group were not significant. Analyses of several secondary angiographic outcomes and subgroups of women produced similar results. The rates of clinical cardiovascular events were also similar among the treatment groups. CONCLUSIONS: Neither estrogen alone nor estrogen plus medroxyprogesterone acetate affected the progression of coronary atherosclerosis in women with established disease. These results suggest that such women should not use estrogen replacement with an expectation of cardiovascular benefit.

Adult↗

Limits on light gravitino production and new processes with large missing transverse energy in p&pmacr; collisions at sqrt

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% confidence level on the breaking scale sqrt[F]>/=217 GeV, which excludes gravitino masses smaller than 1.1x10(-5) eV/c(2).

Journal Article↗

Search for scalar top quark production in p&pmacr; collisions at sqrt

We have searched for direct production of scalar top quarks at the Collider Detector at Fermilab in 88 pb(-1) of p&pmacr; collisions at sqrt[s] = 1.8 TeV. We assume the scalar top quark decays into either a bottom quark and a chargino or a bottom quark, a lepton, and a scalar neutrino. The event signature for both decay scenarios is a lepton, missing transverse energy, and at least two b-quark jets. For a chargino mass of 90 GeV/c(2) and scalar neutrino masses of at least 40 GeV/c(2), we find no evidence for scalar top production and present upper limits on the production cross section in both decay scenarios.

Journal Article↗

Diffractive dijets with a leading antiproton in &pmacr;p collisions at sqrt

We report results from a study of events with a leading antiproton of beam momentum fraction 0.905 7 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA.

Journal Article↗

Real-time polymerase chain reaction assay for cell-associated HTLV type I DNA viral load.

We have developed a quantitative real-time PCR assay for HTLV-I DNA. This assay approach uses real-time monitoring of fluorescent signal generation as a consequence of Taq-mediated amplification of specific target sequences to allow real-time kinetic analysis of amplicon production. This kinetic approach yields excellent sensitivity and an extremely broad linear dynamic range, and ensures that quantitation is based on analysis during the exponential phase of amplification, regardless of the input template copy number. The HTLV-I DNA assay has a nominal threshold sensitivity of 10 copy Eq/reaction, although single-copy plasmid template can be detected at frequencies consistent with statistical prediction. The linear dynamic range is in excess of 5 logs. Interassay reproducibility averages 14% (coefficient of variation) for control templates over a range of 10(1) to 10(6) copy Eq/reaction and 25%, based on studies of extraction and analysis of replicate aliquots of PBMC specimens from HTLV-I-infected subjects. The primer/probe combination targets tax sequences conserved across described HTLV-I and HTLV-II isolates. Parallel quantitation in the same samples of an endogenous sequence present at a known copy number per cell allows normalization of results for potential variation in DNA recovery. Availability of this assay should facilitate studies of basic pathogenesis and clinical evaluation of HTLV-I and HTLV-II infection, as well as assessment of therapeutic approaches.

DNA Primers↗

Identification of coronary thrombus with a IIb/IIIa platelet inhibitor radiopharmaceutical, technetium-99m DMP-444: A canine model.

BACKGROUND: A diagnostic test that could distinguish between stable and unstable coronary atherosclerotic plaques would be useful. We tested the ability of a new glycoprotein IIb/IIIa platelet inhibitor DMP-444, labeled with technetium (Tc)-99 m, to identify platelet-rich thrombus by nuclear imaging in a canine model. METHODS AND RESULTS: Combinations of a flow-limiting stenosis and 0 to 15 minutes of endothelial electrical stimulation at a site in the left anterior descending coronary artery were used to induce varying amounts of thrombus formation. In 10 animals with markedly positive nuclear images after the injection of Tc-99m DMP-444, the presence of platelet-rich thrombus was confirmed postmortem by gross appearance, high nuclear counts, and abundant platelets on electron microscopy. The 10 animals with negative images had lower counts, smaller thrombus weights (P<0.05 for each), and fewer platelets by electron microscopy. CONCLUSIONS: Activated platelets participating in acute thrombus formation can be accurately detected by nuclear imaging using Tc-99 m DMP-444.

Animals↗

Identifying human herpesvirus 8 infection: performance characteristics of serologic assays.

Epidemiologic studies of infection with the oncogenic human herpesvirus 8 (HHV-8) depend on serologic methods to diagnose infection. However, optimal strategies for identifying HHV-8 infection remain undefined. We therefore evaluated four enzyme-linked immunoassays (EIAs) and one immunofluorescence assay (IFA) using sera from 87 individuals with the prototype HHV-8 disease, Kaposi's sarcoma (KS), and 210 participants in a hemophilia study (who were presumed not to be infected with HHV-8). Assays performed reasonably well in distinguishing between infected and uninfected persons, with receiver operator curve areas between 0.86 and 0.96. Nonetheless, IFA had only 86% sensitivity and 88% specificity, and no EIA simultaneously had sensitivity and specificity above 90% for any of the optical density (OD) cutpoints used to define seropositivity. Some assays were markedly less sensitive with diluted KS sera, suggesting that they poorly identify low-titer antibodies present in asymptomatic infection. We also developed a classification tree that categorized individuals as seropositive if they had OD > 2.00 on recombinant K8.1 protein EIA or if they had both K8.1 OD between 0.51 and 2.00 and positive IFA results; this strategy had between 80% and 90% sensitivity and 95% and 100% specificity. Overall, assays performed adequately for use in most epidemiologic investigations, but wider applications will require improved tests.

AIDS-Related Opportunistic Infections↗

Production of Upsilon(1S) mesons from chi(b) decays in p&pmacr; collisions at sqrt

We have reconstructed the radiative decays chi(b)(1P)-->Upsilon(1S)gamma and chi(b)(2P)-->Upsilon(1S)gamma in p&pmacr; collisions at sqrt[s] = 1.8 TeV, and measured the fraction of Upsilon(1S) mesons that originate from these decays. For Upsilon(1S) mesons with p(Upsilon)(T)>8.0 GeV/c, the fractions that come from chi(b)(1P) and chi(b)(2P) decays are [27.1+/-6.9(stat)+/-4. 4(syst)]% and [10.5+/-4.4(stat)+/-1.4(syst)]%, respectively. We have derived the fraction of directly produced Upsilon(1S) mesons to be [50.9+/-8.2(stat)+/-9.0(syst)]%.

Journal Article↗

Search for color singlet technicolor particles in p&pmacr; collisions at radicals = 1.8 TeV

We search for color singlet technirho and technipion production in p&pmacr; collisions at sqrt[s] = 1.8 TeV recorded with the Collider Detector at Fermilab. These exotic technimesons are present in a model of walking technicolor. The signatures studied are lepton plus two jets plus E(T) and multijet final states. No excess of events is seen in either final state. We set an upper limit on the technirho production cross section and exclude a region in the technipion mass versus technirho mass plane.

Journal Article↗

Search for a fourth-generation quark more massive than the Z0 boson in p&pmacr; collisions at radicals = 1.8 TeV

We present the results of a search for pair production of a fourth-generation charge -1 / 3 quark (b(')) in sqrt[s] = 1.8 TeV p&pmacr; collisions using 88 pb(-1) of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b(')-->bZ(0) and that the b(') mass is greater than m(Z)+m(b). We studied the decay mode b(')b(');-->Z(0)Z(0)b&bmacr; where one Z0 decays into e(+)e(-) or &mgr;(+)&mgr;(-) and the other decays hadronically, giving a signature of two leptons plus jets. An upper limit on the sigma(p&pmacr;-->b(')b(');)x[B(b(')-->bZ(0))](2) is established as a function of the b(') mass. We exclude at 95% confidence level a b(') quark with mass between 100 and 199 GeV/c(2) for B(b(')-->bZ(0)) = 100%.

Journal Article↗

A randomized controlled trial of smoking cessation counseling after myocardial infarction.

BACKGROUND: Smoking cessation after myocardial infarction (MI) has been associated with a 50% reduction in mortality but in-hospital smoking cessation interventions are rarely part of routine clinical practice. METHODS: One hundred cigarette smokers consecutively admitted during 1996 with MI were assigned to minimal care or to a hospital-based smoking cessation program. Intervention consisted of bedside cessation counseling followed by seven telephone calls over the 6 months following discharge. Primary outcomes were abstinence rates measured at 6 months and 1 year post-discharge. RESULTS: At follow-up, 43 and 34% of participants in minimal care and 67 and 55% of participants in intervention were abstinent at 6 and 12 months. respectively (P<0.05). Abstinence rates were calculated assuming that participants lost to attrition were smokers at follow-up. Intervention and self-efficacy were independent predictors of smoking status at follow-up. Low self-efficacy combined with no intervention resulted in a 93% relapse rate by 1 year (P<0.01). CONCLUSIONS: A hospital-based smoking cessation program consisting of inpatient counseling and telephone follow-up substantially increases smoking abstinence 1 year after discharge in patients post-MI. Patients with low self-efficacy are almost certain to relapse without intervention. Such smoking cessation programs should be part of the management of patients with MI.

Adult↗