Biomedical subjects

K Peters

Publications and source records attributed to K Peters.

At least 55 records · Page 3Linked to original sources

PubMed2005

[Undifferentiated pancreatic carcinomas. Leap into chaos].

Undifferentiated pancreatic carcinomas are rare anaplastic variants of ductal adenocarcinoma of the pancreas. They have to be distinguished immunohistochemically from metastases of malignant melanoma or an infiltrating sarcoma. An uncommon variant is undifferentiated pancreatic carcinoma with osteoclast-like giant cells. This variant can be associated with mucinous cystic neoplasms and is characterized by abundant non-neoplastic osteoclast-like giant cells.

Adenocarcinoma↗

PubMed2005

[Cystic pancreas tumors and their classification: features old and new].

Cystic tumors and tumor-like lesions of the pancreas are rare, but have attracted a great deal of attention because they are easily recognized with new imaging methods and, in contrast to ductal adenocarcinoma, they can usually be cured surgically. The increasing resection rate in recent years has also increased our knowledge of cystic pancreatic tumors by conspicuously enlarging their morphological spectrum. Known entities have been better characterized (i.e. solid pseudopapillary neoplasm, intraductal papillary mucinous neoplasm) and new ones described (serous oligocystic adenoma, mucinous non-neoplastic cyst, acinar cell cystadenoma and cystic hamartoma). This review discusses the most important cystic tumors and tumor-like lesions, presents a new classification, and summarizes the immunohistochemical differential diagnosis.

Humans↗

PubMed2005

Growth of human cells on polyethersulfone (PES) hollow fiber membranes.

A novel material of porous hollow fibers made of polyethersulfone (PES) was examined for its ability to support the growth of human cells. This material was made in the absence of solvents and had pore diameters smaller than 100 microm. Human cell lines of different tissue and cell types (endothelial, epithelial, fibroblast, glial, keratinocyte, osteoblast) were investigated for adherence, growth, spread and survival on PES by confocal laser microscopy after staining of the cells with Calcein-AM. Endothelial cell attachment and growth required pre-coating PES with either fibronectin or gelatin. The other cell types exhibited little difference in growth, spread or survival on coated or uncoated PES. All the cells readily adhered and spread on the outer, inner and cut surfaces of PES. With time confluent monolayers of cells covered the available surface area of PES and in some cases cells grew as multilayers. Many of the cells were able to survive on the PES for up to 7 weeks and in some cases growth was so extensive that the underlying PES was no longer visible. Scanning electron microscope observations of cells on the materials correlated with the confocal morphometric data. Thus, PES is a substrate for the growth of many different types of human cells and may be a useful scaffolding material for tissue engineering.

Biocompatible Materials↗

PubMed2005

[Corrosion behaviour, metal release and biocompatibility of implant materials coated by TiO2-sol gel chemistry].

Alloys based on titanium or cobalt have been used as implant materials for decades with good success. Because of their natural oxide layer these alloys reveal good corrosion behaviour. In contact with physiological solution metal release takes place, which can cause inflammation. Coatings can improve the corrosion behaviour. In this study Ti6Al4V and Co28Cr6Mo alloys, which are frequently used as implant materials, were tested. Polished discs of these alloys and polished discs, which were coated with TiO2-layers by sol-gel chemistry, were compared regarding their corrosion behaviour and metal ion releasing. The releasing of Al, V, Ti, Co, Cr and Mo was quantified by ICP-MS analysis. The TiO2-coating reduced the release of all ions except of the Al-ion. Both alloys showed a deviating kinetic of ion releasing. In addition, cell response (cell vitality, cell proliferation, endothelial marker CD31 and actin allocation) of osteoblasts and endothelial cells were investigated.

Cells, Cultured↗

PubMed2004

Osteopontin expression in ductal adenocarcinomas and undifferentiated carcinomas of the pancreas.

Osteopontin (OPN) is a non-collagenous extracellular matrix protein with pleiotropic functions, including mediation of cell adhesion and migration. Recently, high OPN serum levels were found in pancreatic ductal adenocarcinomas (PDACs) in which OPN mRNA was identified in macrophages. We investigated OPN expression at the protein level in 15 PDACs and 10 undifferentiated pancreatic carcinomas (UCs), 4 of them with osteoclast-like giant cells (OCGCs), to find out whether the degree of OPN expression is related to tumor infiltration by macrophages and the adhesive capacity of tumor cells. With regard to its potential adhesive function, we compared OPN expression in PDACs and UCs with that of E-cadherin and beta-catenin, two well-known adhesive molecules. OPN positivity was observed in two-thirds of PDACs (10/15) and in 7 UCs (7/10), including all 4 UCs with OCGCs. Apart from tumor cells, OPN was expressed in macrophages and OCGCs. When we assessed the relationship between the number of OPN-positive macrophages and tumor cells, we did not find any statistically significant correlation. There was also no correlation, either positive or negative, between OPN expression and E-cadherin and beta-catenin expression. The results demonstrated that, in PDACs and UCs, OPN is expressed in both tumor-associated macrophages and tumor cells. The biological significance of this dual expression pattern is not yet known. It is, however, unlikely that OPN has an adhesive function, since its expression pattern differs distinctly from that of E-cadherin or beta-catenin.

Adult↗

PubMed2004

Study of high momentum eta' production in B --> eta'Xs.

We measure the branching fraction for the charmless semi-inclusive process B --> eta'Xs, where the eta' meson has a momentum in the range 2.0 to 2.7 GeV/c in the upsilon4S center-of-mass frame and Xs represents a system comprising a kaon and zero to four pions. We find B(B --> eta'Xs) = [3.9 +/- 0.8(stat) +/- 0.5(syst) +/- 0.8(model)] x 10(-4). We also obtain the Xs mass spectrum and find that it fits models predicting high masses.

Journal Article↗

PubMed2004

Measurement of branching fractions and charge asymmetries in B+/--->rho+/-pi0 and B+/--->rho0pi+/- decays, and search for B0-->rho0pi0.

We present measurements of branching fractions and charge asymmetries in B-meson decays to rho(+)pi(0), rho(0)pi(+), and rho(0)pi(0). The data sample comprises 89x10(6) Upsilon(4S)-->BBmacr; decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find the charge-averaged branching fractions B(B+-->rho(+)pi(0))=[10.9+/-1.9(stat)+/-1.9(syst)]x10(-6) and B(B+-->rho(0)pi(+))=(9.5+/-1.1+/-0.9)x10(-6), and we set a 90% confidence-level upper limit B(B0-->rho(0)pi(0))<2.9x10(-6). We measure the charge asymmetries ACP(pi(0))(rho(+))=0.24+/-0.16+/-0.06 and ACP(pi(+))(rho(0))=-0.19+/-0.11+/-0.02.

Journal Article↗

PubMed2004

Measurement of time-dependent CP asymmetries in B0-->D(*)+/-pi-/+ decays and constraints on sin(2beta+gamma).

We present a measurement of CP-violating asymmetries in fully reconstructed B0-->D(*)+/-pi-/+ decays in approximately 88 x 10(6) upsilon(4S)-->BBmacr; decays collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. From a time-dependent maximum-likelihood fit we obtain the following for the CP-violating parameters: a=-0.022+/-0.038 (stat)+/-0.020 (syst), a*=-0.068+/-0.038 (stat)+/-0.020 (syst), c(lep)=+0.025+/-0.068 (stat)+/-0.033 (syst), and c*(lep)=+0.031+/-0.070 (stat)+/-0.033 (syst). Using other measurements and theoretical assumptions we interpret the results in terms of the angles of the Cabibbo-Kobayashi-Maskawa unitarity triangle, and find |sin((2beta+gamma)|>0.69 at 68% confidence level. We exclude the hypothesis of no CP violation [sin(2beta+gamma)=0] at 83% confidence level.

Journal Article↗

PubMed2004

Measurement of time-dependent CP asymmetries and constraints on sin(2beta+gamma) with partial reconstruction of B0-->D*-/+pi+/- decays.

We present a measurement of time-dependent CP-violating asymmetries in decays of neutral B mesons to the final states D(*-/+)pi(+/-), using approximately 82x10(6) BBmacr; events recorded by the BABAR experiment at the PEP-II e(+)e(-) storage ring. Events containing these decays are selected with a partial reconstruction technique, in which only the high-momentum pi(+/-) from the B decay and the low-momentum pi(-/+) from the D(*-/+) decay are used. We measure the amplitude of the asymmetry to be -0.063+/-0.024(stat)+/-0.014(syst) and compute bounds on |sin((2beta+gamma)|.

Journal Article↗

PubMed2004

Cystic neoplasms of the pancreas and tumor-like lesions with cystic features: a review of 418 cases and a classification proposal.

Although cystic neoplasms and lesions of the pancreas are rare, they have attracted a great deal of attention because of their potential curability. Since, in recent years, several new entities have been identified, the relative frequency of the tumors and their classification need to be reevaluated. In a series of 1454 tumorous lesions of the pancreas collected between 1971 and 2003 in our surgical pathology files and consultation files, all cystic pancreatic neoplasms and tumor-like lesions were identified and typed both histologically and immunohistochemically. There were 418 cases (29%) showing cysts with a diameter ranging between 0.5 cm and 27 cm. Most common were solid pseudopapillary neoplasms (21%) and intraductal papillary-mucinous neoplasms (18%). When only the cystic neoplasms and lesions that had been resected in a single institution were considered, intraductal papillary mucinous neoplasms were the most frequent cystic neoplasms, while solid pseudopapillary neoplasms took fifth place behind ductal adenocarcinomas with cystic features, serous cystic neoplasms and mucinous cystic neoplasms. The most frequent cystic tumor-like lesions were pancreatitis-associated pseudocysts. New and rare entities that have recently been identified are mucinous nonneoplastic cysts, acinar cell cystadenomas and cystic hamartomas. Bearing in mind that figures from referral centers such as ours may be biased regarding the relative frequency of lesions, we concluded from our data that intraductal papillary-mucinous neoplasms are the most frequently occurring pancreatic cystic neoplasms, rather than solid pseudopapillary neoplasms. It was possible to classify all cystic lesions encountered in our files or described in the literature in a new system that distinguishes between neoplastic and nonneoplastic lesions, with further subdivisions into epithelial (adenomas, borderline neoplasms and carcinomas) and nonepithelial tumors. This classification is easy to handle and enables a distinction on the basis of clinical behavior and prognosis.

Adolescent↗

PubMed2004

Search for the rare leptonic decay B+-->mu(+)nu(mu).

We have performed a search for the rare leptonic decay B+-->mu(+)nu(mu) with data collected at the Upsilon(4S) resonance by the BABAR experiment at the PEP-II storage ring. In a sample of 88.4 x 10(6) BB pairs, we find no significant evidence for a signal and set an upper limit on the branching fraction B(B+-->my(+)nu(my))< 6.6 x 10(-6) at the 90% confidence level.

Journal Article↗

PubMed2004

Measurements of branching fractions and CP-violating asymmetries in B meson decays to charmless two-body states containing a K(0).

We present measurements of branching fractions and CP-violating asymmetries in decays of B mesons to two-body final states containing a K0. The results are based on a data sample of approximately 88 x 10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure B(B+-->K(0)pi(+))=(22.3+/-1.7+/-1.1)x10(-6), B(B0-->K(0)pi(0)=(11.4+/-1.7+/-0.8)x10(-6), B(B+-->K(0)K+)<2.5 x 10(-6), and B(B0-->K(0)K(0)<1.8 x 10(-6), where the first uncertainty is statistical and the second is systematic, and the upper limits are at the 90% confidence level. In addition, the following CP-violating asymmetries have been measured: A(CP)(B+-->K(0)pi(+))=-0.05+/-0.08+/-0.01 and A(CP)(B0-->K(0)pi(0)=0.03+/-0.36+/-0.11.

Journal Article↗

PubMed2004

Measurement of the branching fractions and CP asymmetry of B--->D(0)((CP))K- decays with the BABAR detector.

We present a study of B--->D(0)(CP)K- decays, where D(0)(CP) is reconstructed in CP-even channels, based on a sample of 88.8 x 10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at the PEP-II e(+)e(-) storage ring. We measure the ratio of Cabibbo-suppressed to Cabibbo-favored branching fractions B(B--->D(0)(CP)K-)/B(B--->D(0)(CP)pi(-))=[8.8+/-1.6(stat)+/-0.5(syst)]x10(-2) and the CP asymmetry A(CP)=0.07+/-0.17(stat)+/-0.06(syst). We also measure B(B--->D0K-)/B(B--->D0pi(-))=[8.31+/-0.35(stat)+/-0.20(syst)]x10(-2) using a sample of 61.0 x 10(6) BB pairs.

Journal Article↗

PubMed2004

Limits on the decay-rate difference of neutral B mesons and on CP, T, and CPT violation in B(0-0)B oscillations.

Using events in which one of two neutral B mesons from the decay of an Upsilon(4S) meson is fully reconstructed, we determine parameters governing decay (DeltaGamma(d)/Gamma(d)), CP, and T violation (|q/p|), and CP and CPT violation (Re z,Im z). The results, obtained from an analysis of 88 x 10(6) Upsilon(4S) decays recorded by BABAR, are sgn(Re lambda(CP))DeltaGamma(d)/Gamma(d)=-0.008+/-0.037(stat)+/-0.018(syst)[-0.084,0.068],|q/p|=1.029+/-0.013(stat)+/-0.011(syst)[1.001,1.057],(Re lambda(CP)/|lambda(CP)|) Re z=0.014+/-0.035(stat)+/-0.034(syst)[-0.072,0.101],Im z=0.038+/-0.029(stat)+/-0.025(syst)[-0.028,0.104]. The values inside the square brackets indicate the 90% confidence-level intervals. These results are consistent with standard model expectations.

Journal Article↗

PubMed2004

Measurement of the branching fraction and polarization for the decay B--->D0K-.

We present a study of the decay B--->D(*0)K(*-) based on a sample of 86 x 10(6) Upsilon(4S)-->BBmacr; decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We measure the branching fraction B(B--->D(*0)K(*-))=(8.3+/-1.1(stat)+/-1.0(syst)) x 10(-4), and the fraction of longitudinal polarization in this decay to be Gamma(L)/Gamma=0.86+/-0.06(stat)+/-0.03(syst).

Journal Article↗

PubMed2004

Measurements of the mass and width of the eta(c) meson and of an eta(c)(2S) candidate.

The mass m(eta(c)) and total width Gamma(eta(c))(tot) of the eta(c) meson have been measured in two-photon interactions at the SLAC e(+)e(-) asymmetric B Factory with the BABAR detector. With a sample of approximately 2500 reconstructed eta(c)-->K(0)(S)K+/-pi(-/+) decays in 88 fb(-1) of data, the results are m(eta(c))=2982.5+/-1.1(stat)+/-0.9(syst) MeV/c(2) and Gamma(eta(c))(tot)=34.3+/-2.3(stat)+/-0.9(syst) MeV/c(2). Using the same decay mode, a second resonance with 112+/-24 events is observed with a mass of 3630.8+/-3.4(stat)+/-1.0(syst) MeV/c(2) and width of 17.0+/-8.3(stat)+/-2.5(syst) MeV/c(2). This observation is consistent with expectations for the eta(c)(2S) state.

Journal Article↗

PubMed2004

Search for the radiative decays B-->rhogamma and B0-->omegagamma.

A search of the exclusive radiative decays B-->rho(770)gamma and B0-->omega(782)gamma is performed on a sample of about 84x10(6) BBmacr; events collected by the BABAR detector at the SLAC PEP-II asymmetric-energy e+e- storage ring. No significant signal is seen in any of the channels. We set upper limits on the branching fractions B of B(B0-->rho(0)gamma)<1.2 x 10(-6), B(B+-->rho+gamma)<2.1 x 10(-6), and B(B0-->omegagamma)<1.0 x 10(-6) at 90% confidence level (C.L.). Using the assumption that Gamma(B-->rhogamma)=Gamma(B+-->rho(+)gamma)=2 x Gamma(B0-->rho(0)gamma), we find the combined limit B(B-->rhogamma)<1.9 x 10(-6), corresponding to B(B-->rhogamma)/B(B-->K*gamma)<0.047 at 90% C.L.

Journal Article↗

PubMed2004

Measurement of the inclusive charmless semileptonic branching ratio of B mesons and determination of |V ub|.

We report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 x 10(6) (-)BB events recorded with the BABAR detector at the Upsilon(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. The number of signal events is extracted from the mass distribution of the hadronic system accompanying the lepton and is used to determine the ratio of branching fractions B((-)B-->X(u)lnu;)/B((-)B-->Xlnu;)=[2.06+/-0.25(stat)+/-0.23(syst)+/-0.36(theo)]x10(-2). Using the measured branching fraction for inclusive semileptonic B decays, we find B((-)B-->X(u)lnu;)=[2.24+/-0.27(stat)+/-0.26(syst)+/-0.39(theo)]x10(-3) and derive the Cabibbo-Kobayashi-Maskawa matrix element |V(ub)|=[4.62+/-0.28(stat)+/-0.27(syst)+/-0.48(theo)]x10(-3).

Journal Article↗