Biomedical subjects

K Peters

Publications and source records attributed to K Peters.

At least 91 records · Page 5Linked to original sources

PubMed2003

Measurement of the branching fraction, and bounds on the CP-violating asymmetries, of neutral B decays to D*+/- D-/+.

We present measurements of the branching fraction and CP-violating asymmetries for neutral B decays to D(*+/-)D-/+. The measurement uses a data sample of approximately 88x10(6) Upsilon(4S)-->BBmacr; decays collected with the BABAR detector at the SLAC PEP-II asymmetric-energy e(+)-e(-) collider. By fully reconstructing the D(*+/-)D-/+ decay products, we measure the branching fraction to be (8.8+/-1.0+/-1.3)x10(-4) and the time-integrated CP-violating asymmetry between the rates to D(*-)D+ and D(*+)D- to be A=-0.03+/-0.11+/-0.05. We also measure the time-dependent CP-violating asymmetry parameters to be S(-+)=-0.24+/-0.69+/-0.12, C(-+)=-0.22+/-0.37+/-0.10 for B-->D(*-)D+ and S(+-)=-0.82+/-0.75+/-0.14, C(+-)=-0.47+/-0.40+/-0.12 for B-->D(*+)D-. In each case, the first error is statistical and the second error is systematic.

Journal Article↗

PubMed2003

Study of the rare decays B0-->D(()+)(s)pi(-) and B0-->D(()-)(s)K+.

We report evidence for the decays B0-->D(+)(s)pi(-) and B0-->D(-)(s)K+ and the results of a search for B0-->D(*+)(s)pi(-) and B0-->D(*-)(s)K+ in a sample of 84 x 10(6) upsilon(4S) decays into BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage ring. We measure the branching fractions B(B0-->D(+)(s)pi(-))=[3.2+/-0.9(stat)+/-1.0(syst)] x 10(-5) and B(B0-->D(-)(s)K+)=[3.2+/-1.0(stat)+/-1.0(syst)] x 10(-5). We also set 90% C.L. limits B(B0-->D(*+)(s)pi(-))<4.1 x 10(-5) and B(B0-->D(*-)(s)K+)<2.5 x 10(-5).

Journal Article↗

PubMed2003

Measurement of the Cabibbo-Kobayashi-Maskawa matrix element V(ub) with B-->rhoenu decays.

We present a measurement of the branching fraction for the rare decays B-->rhoenu and extract a value for the magnitude of V(ub), one of the smallest elements of the Cabibbo-Kobayashi-Maskawa quark-mixing matrix. The results are given for five different calculations of form factors used to para-metrize the hadronic current in semileptonic decays. Using a sample of 55 x 10(6) BB meson pairs recorded with the BABAR detector at the PEP-II e(+)e(-) storage ring, we obtain B(B0-->rho(-)e(+)nu)=(3.29+/-0.42+/-0.47+/-0.55) x 10(-4) and |V(ub)|=(3.64+/-0.22+/-0.25(+0.39)(-0.56)) x 10(-3), where the uncertainties are statistical, systematic, and theoretical, respectively.

Journal Article↗

PubMed2003

Measurement of the B0-->J/psipi+pi- branching fraction.

We present a measurement of the branching fraction for the decay of the neutral B meson into the final state J/psipi(+)pi(-). The data set contains approximately 56 x 10(6) BB pairs produced at the Upsilon(4S) resonance and recorded with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) storage ring. The result of this analysis is B(B0-->J/psipi(+)pi(-))=(4.6+/-0.7+/-0.6) x 10(-5), where the first error is statistical and the second is systematic. In addition, we measure B(B0-->J/psirho(0))=(1.6+/-0.6+/-0.4) x 10(-5).

Journal Article↗

PubMed2003

Experimental approaches to study vascularization in tissue engineering and biomaterial applications.

The success of tissue engineering and biomaterial applications is not only dependent on the growth and functioning of the organ- or tissue-specific cells on the biomaterial but is entirely dependent in most cases on a successful vascularization after implantation. The process of vascularization involves angiogenesis; the formation of new blood vessels which spread into the implant material and supply the existing cells with the nutrients to survive. We have established in vitro methods using human microvascular endothelial cells to evaluate novel biomaterials for endothelial cell attachment, cytotoxicity, growth, angiogenesis and the effects on gene regulation. These in vitro studies can be used to rapidly evaluate the potential success of a new biomaterial and for the development of matrix scaffolds which will promote a physiological vascularization response.

Journal Article↗

PubMed2003

A pilot clinical trial of oral pentosan polysulfate and oral hydroxyzine in patients with interstitial cystitis.

PURPOSE: This pilot study was designed to evaluate the feasibility of a multicenter, randomized, clinical trial in interstitial cystitis (IC). Secondary objectives were to evaluate the safety and efficacy of oral pentosan polysulfate sodium (PPS), hydroxyzine, and the combination to consider their use in a larger randomized clinical trial. MATERIALS AND METHODS: A 2 x 2 factorial study design was used to evaluate PPS and hydroxyzine. Participants met the National Institutes of Health-National Institute for Diabetes and Digestive and Kidney Diseases criteria for IC and reported at least moderate pain and frequency for a minimum of 6 months before study entry. The primary end point was a patient reported global response assessment. Secondary end points included validated symptom indexes and patient reports of pain, urgency and frequency. The target sample size was 136 participants recruited during 10 months. RESULTS: A total of 121 (89% of goal) participants were randomized over 18 months and 79% provided complete followup data. The response rate for hydroxyzine was 31% for those treated and 20% for those not treated (p = 0.26). A nonsignificant trend was seen in the PPS treatment groups (34%) as compared to no PPS (18%, p = 0.064). There were no treatment differences for any of the secondary end points. Adverse events were mostly minor and similar to those in previous reports. CONCLUSIONS: The low global response rates for PPS and hydroxyzine suggest that neither provided benefit for the majority of patients with IC. This trial demonstrated the feasibility of conducting a multicenter randomized clinical trial in IC using uniform procedures and outcomes. However, slow recruitment underscored the difficulties of evaluating commonly available IC drugs.

Adult↗

PubMed2002

Measurements of branching fractions and CP-violating asymmetries in B0-->pi+pi-, K+pi-, K+K- decays.

We present measurements of branching fractions and CP-violating asymmetries for two-body neutral B meson decays to charged pions and kaons based on a sample of about 88x10(6) Upsilon(4S)-->BB decays. From a time-independent fit we measure the charge-averaged branching fractions B(B0-->pi+pi-)=(4.7+/-0.6+/-0.2)x10(-6), B(B0-->K+pi-)=(17.9+/-0.9+/-0.7)x10(-6), and the direct CP-violating charge asymmetry A(Kpi)=-0.102+/-0.050+/-0.016 [-0.188,-0.016], where the ranges in square brackets indicate the 90% confidence intervals. From a time-dependent fit we measure the B0-->pi+pi- CP-violating parameters S(pipi)=0.02+/-0.34+/-0.05 [-0.54,+0.58] and C(pipi)=-0.30+/-0.25+/-0.04 [-0.72,+0.12].

Journal Article↗

PubMed2002

Measurement of the CP asymmetry amplitude sin2beta with B0 mesons.

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 x 10(6) Upsilon(4S)-->B(-)B decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B(0) or B(-0) from its decay products. The amplitude of the CP asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta=0.741+/-0.067(stat)+/-0.034(syst) and |lambda|=0.948+/-0.051(stat)+/-0.030(syst). The magnitude of lambda is consistent with unity, in agreement with the standard model expectation of no direct CP violation in these modes.

Journal Article↗

PubMed2002

Measurement of the branching fraction and CP content for the decay B0-->D(+)D(-).

We report a measurement of the branching fraction of the decay B0-->D(*+)D(*-) and of the CP-odd component of its final state using the BABAR detector. With data corresponding to an integrated luminosity of 20.4 fb (-1) collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B0-->D(*+)D(*-) with an estimated background of 6.2+/-0.5 events. From these events, we determine the branching fraction to be B(B0-->D(*+)D(*-))=[8.3+/-1.6(stat)+/-1.2(syst)]x10(-4). The measured CP-odd fraction of the final state is 0.22+/-0.18(stat)+/-0.03(syst).

Journal Article↗

PubMed2002

Measurement of the B(0) lifetime with partially reconstructed B(0)-->D(-)l(+)nu(l) decays.

The B(0) lifetime was measured with a sample of 23 million BB pairs collected by the BABAR detector at the PEP-II e(+)e(-) storage ring during 1999 and 2000. Events from the semileptonic decay B(0)-->D(*-)l(+)nu(l) have been selected with a partial reconstruction method in which only the charged lepton and the slow pi from the D*--->D(0)pi(-) decay are reconstructed. The result is tau(B(0)) = 1.529+/-0.012(stat)+/-0.029(syst) ps.

Journal Article↗

PubMed2002

Search for the rare decays B-->Kl(+)l(-) and B-->K(*)l(+)l(-).

We present results from a search for the flavor-changing neutral current decays B-->Kl(+)l(-) and B-->K(*)l(+)l(-), where l(+)l(-) is either an e(+)e(-) or mu(+)mu(-) pair. The data sample comprises 22.7 x 10(6) Upsilon(4S)-->B(-)B decays collected with the BABAR detector at the PEP-II B Factory. We obtain the 90% C.L. upper limits B(B-->Kl(+)l(-))<0.51 x 10(-6) and B(B-->K(*)l(+)l(-))<3.1 x 10(-6), close to standard model predictions for these branching fractions. We have also obtained limits on the lepton-family-violating decays B-->Ke+/-mu(-/+) and B-->K(*)e(+/-)mu(-/+).

Journal Article↗

PubMed2002

Measurement of B0-B-0 flavor oscillations in hadronic B0 decays.

Flavor oscillations of neutral B mesons have been studied in e+e- annihilation data collected with the BABAR detector at center-of-mass energies near the upsilon(4S) resonance. The data sample used for this purpose consists of events in which one B0 meson is reconstructed in a hadronic decay mode, while the flavor of the recoiling B0 is determined with a tagging algorithm that exploits the correlation between the flavor of the heavy quark and the charges of its decay products. From the time development of the observed mixed and unmixed final states, we determine the B0-B-0 oscillation frequency deltamd to be 0.516+/-0.016(stat)+/-0.010(syst) ps-1.

Journal Article↗

PubMed2002

Measurement of the B0-B-0 oscillation frequency with inclusive dilepton events.

The B0-B-0 oscillation frequency has been measured with a sample of 23 x 10(6) BB- pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives deltamd = 0.493+/-0.012(stat)+/-0.009(syst) ps-1.

Journal Article↗

PubMed2002

Search for T and CP violation in B0-B-0 mixing with inclusive dilepton events.

We report the results of a search for T and CP violation in B0-B-0 mixing using an inclusive dilepton sample collected by the BABAR experiment at the PEP-II B Factory. The asymmetry between l+l+ and l-l- events allows us to compare the probabilities for B-0-->B0 and B0-->B-0 oscillations and thus probe T and CP invariance. Using a sample of 23 x 10(6) BB- pairs, we measure a same-sign dilepton asymmetry of A(T/CP) = [0.5+/-1.2(stat)+/-1.4(syst)]%. For the modulus of the ratio of complex mixing parameters p and q, we obtain q/p = 0.998+/-0.006(stat)+/-0.007(syst).

Journal Article↗

PubMed2002

Measurement of B --> K*gamma branching fractions and charge asymmetries.

The branching fractions of the exclusive decays B0-->K(*0)gamma and B+-->K(*+)gamma are measured from a sample of (22.74+/-0.36)x10(6) BB decays collected with the BABAR detector at the PEP-II asymmetric e(+)e(-) collider. We find B (B0-->K(*0)gamma) = [4.23+/-0.40(stat)+/-0.22(syst)]x10(-5), B(B+-->K(*+)gamma) = [3.83+/-0.62(stat)+/-0.22(syst)]x10(-5) and constrain the CP-violating charge asymmetry to be -0.170 K(*)gamma)<0.082 at 90% C.L.

Journal Article↗

PubMed2002

Apoptosis causes lumen formation during angiogenesis in vitro.

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Apoptosis↗

PubMed2002

[Pathomechanisms of impaired wound healing by metallic corrosion products].

BACKGROUND: Metallic materials of variable chemical composition have been used in dental practice for a long time. Complications with respect to tissue healing after insertion of implants are well documented. In this paper we present relevant aspects of the related fields of inflammation and repair processes and focus on the pathomechanisms of this impaired healing response. MODULATION OF WOUND HEALING: This latter process is modulated by specific metal ions released by corrosion activity as well as by wear particles, which influence the function of the participating cell types (e.g. endothelial cells). IN VITRO MODELS: In this context, in vitro models are presented that permit study of isolated aspects of the complex sequence of events at the biomaterial-tissue interface. Furthermore, newly developed, computer-assisted methods allowing an objective quantification of biomaterial/corrosion product-induced effects on complex processes, such as angiogenesis in vitro, are demonstrated. Because of the central importance of titanium implants in maxillofacial surgery, new experimental approaches to study possible negative effects are presented. Finally, the relevance of such studies for clinical implantology is evaluated.

Animals↗

PubMed2002

Tissue response and biomaterial integration: the efficacy of in vitro methods.

Implantation involves tissue trauma, which evokes an inflammatory response, coupled to a wound healing reaction, involving angiogenesis, fibroblast activation and matrix remodelling. Until now the type and extent of such reactions to give optimal integration of various biomaterials are practically unknown. Three principal fields of research can yield useful data to understand these phenomena better: studies on explanted biomaterials, animal models and relevant in vitro techniques. This paper will present examples of the latter field and the application of endothelial cell (EC) culture systems to study the effects of important tissue (e.g. pro-inflammatory cytokines, chemokines) and material (e.g. metal ions, particulate debris) factors on the regulation of the inflammatory and angiogenic response. A central feature is the use of microvascular endothelial cells (MEC), which can be used in both 2-and 3-dimensional (3-D) assays. We have also used genetic manipulation to develop a permanent MEC line from the human lung (HPMEC-ST1), which is being tested for its suitability to study cell-biomaterial interactions. In addition, suitable in vitro techniques are being developed in order to investigate drug delivery systems (DDS). Of particular interest is the targeting of the central nervous system, our approach being to establish a human model of the blood-brain barrier (BBB). A mainstay of our scientific philosophy is that such in vitro methods can make an important contribution to understanding biological reactions at the tissue-biomaterial interface and thus further a causal approach to tissue engineering (TE) and drug delivery applications.

Animals↗