PubMed Health⌕ Search

Biomedical subjects

R Winston

Publications and source records attributed to R Winston.

At least 19 recordsLinked to original sources
PubMed2003

Measurements of the Decay KL-->e+ e- mu+ mu-.

The KTeV experiment at Fermilab has isolated a total of 132 events from the rare decay K(L)-->e+ e- mu+ mu-, with an estimated background of 0.8 events. The branching ratio of this mode is determined to be [2.69+/-0.24(stat)+/-0.12(syst)]x10(-9), with a radiative cutoff of M(2)(ee mu mu)/M(2)(K)>0.95. The first measurement using this mode of the parameter alpha from the D'Ambrosio-Isidori-Portolès (DIP) model of the K(L)gamma*gamma* vertex yields a result of -1.59+/-0.37, consistent with values obtained from other decay modes. Because of the limited statistics, no sensitivity is found to the DIP parameter beta. We use this decay mode to set limits on CP and lepton violation.

Journal Article↗
PubMed2002

Search for the KL-->pi 0 pi 0 e+e- decay in the KTeV experiment.

The recent discovery of a large CP violating asymmetry in KL-->pi+pi-e+e- mode has prompted us to seach for the associated KL-->pi 0 pi 0 e+e- decay mode in the KTeV-E799 experiment at Fermilab. In 2.7 x 10(11) K(L) decays, one candidate event has been observed with an expected background of 0.3 event, resulting in an upper limit for the KL-->pi 0 pi 0 e+e- branching ratio of 6.6 x 10(-9) at the 90% C.L.

Journal Article↗
PubMed2002

Radiative decay width measurements of neutral kaon excitations using the primakoff effect.

We use K(L)'s in the 100-200 GeV energy range to produce 147 candidate events of the axial vector pair K1(1270)-K1(1400) in the nuclear Coulomb field of a Pb target and determine the radiative widths Gamma(K1(1400)-->K0+gamma)=280.8+/-23.2(stat)+/-40.4(syst) keV and Gamma(K1(1270)-->K0+gamma)=73.2+/-6.1(stat)+/-28.3(syst) keV. These first measurements appear to be lower than the quark-model predictions. We also place upper limits on the radiative widths for K(*)(1410) and K(*)(2)(1430) and find that the latter is vanishingly small in accord with SU(3) invariance in the naive quark model.

Journal Article↗
PubMed2002

Measurement of the K(L) charge asymmetry.

We present a measurement of the charge asymmetry delta(L) in the mode K(L)-->pi(+/-)e(-/+)nu based on 298 x 10(6) analyzed decays. We measure a value of delta(L) = [3322+/-58(stat)+/-47(syst)]x10(-6), in good agreement with previous measurements and 2.4 times more precise than the current best published result. The result is used to place more stringent limits on CPT and DeltaS = DeltaQ violation in the neutral kaon system.

Journal Article↗
PubMed2001

First measurement of form factors of the decay Xi(0) --> Sigma(+)e(-)nu macro(e).

We present the first measurement of the form factor ratios g(1)/f(1) (direct axial vector to vector), g(2)/f(1) (second class current), and f(2)/f(1) (weak magnetism) for the decay Xi(0)-->Sigma(+)e(-)nu macro(e) using the KTeV (E799) beam line and detector at Fermilab. From the Sigma(+) polarization measured with the decay Sigma(+)-->p pi(0) and the e(-)-nu; correlation, we measure g(1)/f(1) to be 1.32+/-(0.21)(0.17)(stat)+/-0.05(syst), assuming the SU(3)(f) (flavor) values for g(2)/f(1) and f(2)/f(1). Our results are all consistent with exact SU(3)(f) symmetry.

Journal Article↗
PubMed2001

Branching ratio measurement of the decay K(L) --> e(+)e(-)mu(+)mu(-).

We have collected a 43 event sample of the decay K(L)-->e(+)e(-)mu(+)mu(-) with negligible backgrounds and measured its branching ratio to be (2.62+/-0.40+/-0.17)x10(-9). We see no evidence for CP violation in this decay. In addition, we set the 90% confidence upper limit on the combined branching ratios for the lepton flavor violating decays K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+) at B(K(L)-->e(+/-)e(+/-)mu(-/+)mu(-/+))< or =1.23x10(-10), assuming a uniform phase space distribution.

Journal Article↗
PubMed2001

Measurement of the branching ratio and form factor of K(L)-->mu(+)mu(-)gamma.

We report on the analysis of the rare decay K(L)-->mu(+)mu(-)gamma the 1997 data from the KTeV experiment at Fermilab. A total of 9327 candidate events are observed with 2.4% background, representing a factor of 40 increase in statistics over the current world sample. We find that B(K(L)-->mu(+)mu(-)gamma) = (3.62 +/- 0.04(stat) +/- 0.08(syst)) x 10(-7). The form factor parameter alpha(K*) is measured to be alpha(K*) = -0.160(+0.026)(-0.028). In addition, we make the first measurement of the parameter alpha from the D'Ambrosio-Isidori-Portolés form factor, finding alpha = -1.54 +/- 0.10. In that model, this alpha measurement limits the Cabibbo-Kobayashi-Maskawa parameter rho>-0.2.

Journal Article↗
PubMed2001

Measurements of the rare decay K(L) --> e(+)e(-)e(+)e(-).

We observe 441 K(L)-->e(+)e(-)e(+)e(-) candidate events with a background of 4.2 events and measure B(K(L)-->e(+)e(-)e(+)e(-)) = [3.72+/-0.18(stat)+/-0.23(syst)]x10(-8) in the KTeV/E799II experiment at Fermilab. Using the distribution of the angle between the planes of the e(+)e(-) pairs, we measure the CP parameters beta(CP) = -0.23+/-0.09(stat)+/-0.02(syst) and gamma(CP) = -0.09+/-0.09(stat)+/-0.02(syst). We also present the first detailed study of the e(+)e(-) invariant mass spectrum in this decay mode.

Journal Article↗
PubMed2001

Measurement of the branching ratio and asymmetry of the decay Xi degrees -->Sigma degrees gamma.

We have studied the rare weak radiative hyperon decay Xi degrees -->Sigma degrees gamma in the KTeV experiment at Fermilab. We have identified 4045 signal events over a background of 804 events. The dominant Xi degrees -->Lambdapi degrees decay, which was used for normalization, is the only important background source. An analysis of the acceptance of both modes yields a branching ratio of B(Xi degrees -->Sigma degrees gamma)/B(Xi degrees -->Lambdapi degrees ) = (3.34+/-0.05+/-0.09)x10(-3). By analyzing the final state decay distributions, we have also determined that the Sigma degrees emission asymmetry parameter for this decay is alpha(XiSigma) = -0.63+/-0.09.

Journal Article↗
PubMed2001

Study of the K(0)(L) --> pi(+)pi(-)gamma Direct Emission Vertex.

We have performed studies of the K(0)(L)-->pi(+)pi(-)gamma direct emission ( DE) and inner Bremsstrahlung ( IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a(1)/a(2) = -0.737+/-0.034 GeV2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form factor to linear and quadratic functions as well. We concurrently measure gamma(K(0)(L)-->pi(+)pi(-)gamma,E(*)(gamma)>20 MeV)/gamma(K(0)(L)-->pi(+)pi(-)) = (20.8+/-0.3)x10(-3), and a K(0)(L)-->pi(+)pi(-)gamma DE/(DE+IB) branching ratio of 0.683+/-0.011.

Journal Article↗
PubMed2001

Search for the decay KL --> pi(0)e+e-.

We report on a search for the decay KL-->pi(0)e+e- carried out by the KTeV/E799 experiment at Fermilab. This decay is expected to have a significant CP violating contribution and the measurement of its branching ratio could support the Cabibbo-Kobayashi-Maskawa mechanism for CP violation or could point to new physics. Two events were observed in the 1997 data with an expected background of 1.06+/-0.41 events, and we set an upper limit B(KL-->pi(0)e+e-)<5.1 x 10(-10) at the 90% confidence level.

Journal Article↗
PubMed2001

Clinical experience with recombinant follicle-stimulating hormone (FSH) and urinary FSH: a retrospective case- controlled analysis.

OBJECTIVE: To compare the efficacy and efficiency of recombinant FSH (rFSH) and urinary FSH (uFSH). DESIGN: Retrospective case controlled analysis. SETTING: An assisted reproduction unit at a university center. PATIENT(S): 1388 patients undergoing long protocol in vitro fertilization/embryo transfer (IVF-ET) using buserelin acetate from day 2 of the cycle and either rFSH (follitropin beta) (n = 694) or uFSH (n = 694) with equal number of ampules started (rFSH: 50 IU, uFSH: 75 IU). INTERVENTION(S): Patients were included in the two groups of treatment after matching for similarity in age and type of treatment (IVF or intracytoplasmic sperm injection). MAIN OUTCOME MEASURE(S): Total dose of FSH, ovarian response, and IVF outcome. RESULT(S): Patients who received uFSH experienced a shorter period of stimulation, and a higher number of oocytes were collected. The total FSH used was lower in the rFSH group, and they required a lower FSH dose per oocyte retrieved. The implantation and pregnancy rates were similar between the uFSH and rFSH groups. In both groups implantation and pregnancy rates were higher when intracytoplasmic sperm injection was performed as compared with IVF. CONCLUSION(S): The implantation and pregnancy rates are similar when either rFSH or uFSH is used (when compared on an ampule-to-ampule basis, rFSH: 50 IU, and uFSH: 75 IU). However, a significantly lower total FSH dose was used in the rFSH group with a lower FSH dose per oocyte collected.

Adult↗
PubMed2001

Circulating natural IgM antibodies and their corresponding human cord blood cell-derived Mabs specifically combat the Tat protein of HIV.

OBJECTIVE: IgM antibodies reactive with each of two specifically defined sequences of HIV Tat protein have been identified in sera from both HIV(+) and normal (HIV(-)) humans. This study was designed to confirm that those antibodies are innate immune factors capable of restriction of specific mechanisms of HIV pathogenicity attributed to the Tat protein. MATERIALS AND METHODS: Antibody-secreting hybridomas were generated from human cord blood cells and processed for monoclonality. Those Mabs reactive with each of the sequences of Tat with which the circulating antibodies are reactive were isolated and their heavy and light chains identified and DNA sequenced. Pools of IgM isolated from blood of normal humans, chimpanzees, rhesus macaques, and mice and the isolated Tat reactive Mabs were tested for capacity to inhibit Tat-induced human T-cell apoptosis. RESULTS: Human and chimpanzee IgM pools, as well as the human cord blood cell-derived Mabs, showed a definite capacity to inhibit the Tat-induced apoptosis, while the IgM pools of rhesus macaques or of mice did not. CONCLUSIONS: These studies establish that the circulating IgM of normal humans include innate antibodies capable of restriction of HIV Tat-induced pathogenesis. That capacity is shared by chimpanzee IgM but not by IgM of other primates or of mice. The identification of those human circulating antibodies as innate is confirmed by the display of similar epitopic identity and apoptosis inhibition capacity by Mabs from human cord blood cell hybridomas. Thus, the arsenal of human cord blood cell hybridomas provides a resource by which, specifically, the potential therapeutic role of the identified HIV Tat-reactive Mabs and, broadly, the fundamental role of innate antibodies in infection control may be explored.

Adult↗
PubMed2001

Expression of Wilms' tumor suppressor gene (WT1) in human endometrium: regulation through decidual differentiation.

The Wilms' tumor suppressor gene (WT1) encodes a zinc-finger containing transcription factor that is selectively expressed in the developing urogenital tract and functions as a tissue-specific developmental regulator. In addition to its gene-regulatory function through DNA binding properties, WT-1 also regulates transcription by formation of protein-protein complexes. These properties place WT-1 as a major regulator of cell growth and differentiation. In view of these observations, we studied WT1 mRNA and protein in human endometrial extracts and in endometrial stromal cells (ESCs) differentiating into decidual cells in vitro, by RT-PCR and Western blotting, respectively. WT1 protein expression was also studied in situ in the proliferative and the secretory phase of the menstrual cycle in the early pregnant state. Analysis by PCR of total RNA prepared from human ESCs demonstrated the presence of WT1 mRNA and four WT1 mRNA splice variants. Western blot analysis of nuclear protein extracts from ESCs yielded one immunoreactive protein of the expected size (approximately 52-54 kDa) recognized by the WT1 antibody. Immunohistochemical staining showed that WT1 protein is localized only to nuclei of human endometrial stromal cells. It remains constant in the proliferative and the secretory phase of the menstrual cycle and is increased remarkably during decidualization in early pregnancy. ESCs decidualized in vitro were investigated for WT-1 expression, which confirmed that decidualizing stimuli (E2, medroxy-progesterone-acetate, and relaxin for 12 d or cAMP and progesterone for 1-4 d) induced WT-1 mRNA (P < 0.05) and increased protein levels (P < 0.05). These data indicate that in humans the WT1 gene is expressed in ESCs and its mRNA and protein levels remain constant in the proliferative and the secretory phase of the menstrual cycle and that WT1 mRNA and protein expression increases significantly in ESCs when these cells differentiate into decidual cells.

Cells, Cultured↗
PubMed2000

A prospective, randomized controlled trial comparing the efficacy of recombinant follicle-stimulating hormone in three different in vitro fertilization protocols.

OBJECTIVE: To compare the following IVF protocols: a short protocol and long protocols starting on day 2 or day 21. All protocols used recombinant FSH (rFSH) for ovarian stimulation. DESIGN: Prospective, randomized study. SETTING: An assisted reproduction unit at a university center. PATIENT(S): Patients undergoing IVF (n = 150) were treated according to one of the three treatment protocols allocated by a random method. INTERVENTION(S): All patients used buserelin acetate and rFSH. Patients began the long protocol on day 2 (group 1) or day 21 (group 2) of the cycle. Patients in group 3 began the short protocol on day 2 of the cycle. MAIN OUTCOME MEASURE(S): Ovarian response, implantation rates, and pregnancy rates (PRs). RESULT(S): Patients treated with the short protocol (group 3) were stimulated in a shorter time, required less rFSH, and achieved higher E(2) levels. The numbers of follicles, oocytes, and embryos were similar in all three groups. The implantation rates were similar in groups 1 and 2 (11.8% and 13.3%, respectively), and both were higher than in group 3 (4.1%). Clinical PRs per oocytes retrieved were 19.6%, 18.6%, and 8.3% in groups 1, 2, and 3, respectively. CONCLUSION(S): The implantation rate was significantly higher with the long protocols than with the short protocol, with a tendency for a higher PR as well.

Adult↗
PubMed2000

Comparison of pure tone and transient otoacoustic emissions screening in a grade school population.

HYPOTHESIS: Otoacoustic emissions provide an alternative to traditional pure tone hearing screening in a diverse grade school population. BACKGROUND: Mandated pure tone hearing screening programs for grade school children have several significant limitations. Otoacoustic emissions have been shown to be a reliable screening test in newborns, but there are no data on screening a diverse grade school population. METHODS: Five hundred eighty-three grade school children in four separate school populations were screened for hearing loss using the standard pure tone four-frequency protocol and transient evoked otoacoustic emissions. Students failing either test received a comprehensive audiogram by an audiologist that served as the "gold standard." Sensitivity and specificity of both tests were compared. RESULTS: The sensitivity and specificity of pure tone screening was 87% and 80%, respectively, compared with 65% and 91% for transient evoked otoacoustic emissions. CONCLUSION: Pure tone screening was a statistically significant better screening test for detecting hearing loss in this population of grade school children.

Arizona↗
PubMed2000

Dynamic assays of inhibin B and oestradiol following buserelin acetate administration as predictors of ovarian response in IVF.

The study was designed to examine whether dynamic measurements of inhibin B and oestradiol following single administration of buserelin acetate were correlated with the ovarian response to stimulation in IVF. A total of 37 patients undergoing IVF treatment was studied when the long protocol was started in the early follicular phase. Blood samples were taken twice: on day 2 of the menstrual cycle, before the first s.c. administration of buserelin acetate 0.5 mg and on day 3, 24 h later. Inhibin B and oestradiol concentrations were compared with the ovarian response to stimulation. The ovarian response was defined in two ways: 'number of oocytes/total recombinant (r) follicle stimulating hormone (FSH) dose'; and 'square-root (number of follicles/total rFSH dose)'. The following measurements were highly correlated with the ovarian response to stimulation: increase in oestradiol (day 3-day 2 oestradiol concentration) [correlation coefficient (r) = 0.68, P: < 0.0001] and sum of inhibin B (day 2 + day 3 inhibin B concentrations) (r = 0.6, P: < 0.0001). Age and basal concentrations of FSH and inhibin B were inferior to the above measurements in terms of correlation with the ovarian response. In conclusion, dynamic measurements of inhibin B and oestradiol following single administration of buserelin acetate were highly correlated with the ovarian response to stimulation for IVF treatment.

Adult↗