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Biomedical subjects

D Bauer

Publications and source records attributed to D Bauer.

At least 55 records · Page 3Linked to original sources
PubMed2005

[Do antisense oligonucleotides improve viral immunopathology?].

BACKGROUND: Tumor necrosis factor (TNF)-alpha as a proinflammatory cytokine is of great importance during the development of herpes simplex virus-1 keratitis (HSK). In this study the local administration of antisense oligonucleotides (ASON) targeting TNF-alpha was examined for its usefulness in ameliorating this disease. METHODS: Uptake and efficacy of the oligonucleotides were studied in vitro by fluorescence microscopy and flow cytometry. Substance- and sequence-specific influences on the development of HSK were scrutinized in an animal model. RESULTS: Quick and stable uptake of FITC-labeled ASON by isolated spleen and lymph node cells was proved. The production of TNF-alpha by these cells after stimulation with HSV antigen or concanavalin A (ConA) was clearly downregulated after addition of ASON. In vivo, incidence and development of HSK were ameliorated after subepithelial corneal injection of ASON targeting TNF-alpha. When buffer and control oligonucleotides were given, no significant influence on the disease was found. CONCLUSION: The ASON effectively reduced TNF-alpha secretion in vitro and suppressed the development of experimental HSK in vivo.

Animals↗
PubMed2005

Improvement of herpetic stromal keratitis with fumaric acid derivate is associated with systemic induction of T helper 2 cytokines.

Fumaric acid derivates have been shown to stimulate T helper-2-cytokines (interleukin (IL)-4, -5) without affecting the T-helper-1-cytokine (IL-2, interferon (IFN)-gamma)-response. Herein, the influence of systemic treatment with the fumaric acid derivate dimethylfumarate (DMF) on the secretion of T helper-cytokines and the development of HSV-1 stromal keratitis (HSK) was studied in mice. The corneas from BALB/c mice were infected with 10(5) PFU of HSV-1 (KOS strain). While one group of mice was treated intraperitoneally with PBS, another group of mice received DMF at 15 mg/kg of body weight. Expression of IL-2, -4, -10 and IFN-gamma was analysed in HSV-1 activated lymphocytes by ELISA. The severity of epithelial and stromal herpetic keratitis was investigated clinically. Corneas were studied for the inflammatory cell infiltration, and the CD3-, CD4- and CD8-positive cells were analysed by immunohistochemistry. The IL-2, -4, 10 and IFN-gamma content was measured in the corneas. Virus replication in the eyes was analysed by a plaque-assay. The DTH-response, the HSV-specific T cell proliferation and the serum neutralizing antibody-titres were investigated. DMF increased IL-4 and IL-10, but not IL-2 and IFN-gamma, secretion in activated lymphocytes from the spleen. Incidence and severity of stromal HSV-1 keratitis was reduced in the DMF group (P < 0.01). In the corneas from DMF-treated mice, the numbers of CD3+ and CD4+ cells were decreased and IL-4 was increased. Severity of epithelial disease and the virus-clearance from the eyes did not differ between the PBS and DMF group of mice. DTH, HSV-specific T cell proliferation and the neutralizing antibody-titres were not impaired. DMF increased the T helper-2-cytokine secretion in activated lymphocytes. After corneal HSV-1 infection, corneas from DMF treated mice had increased IL-4 content. This is associated with an improvement of herpetic stromal keratitis and reduced corneal T cell infiltration. DMF did not impair the systemic antiviral response.

Animals↗
PubMed2004

Observation and properties of the X(3872) decaying to J/psipi(+)pi(-) in pp collisions at sqrt[s]=1.96 TeV.

We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in pp collisions at sqrt[s]=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.

Journal Article↗
PubMed2004

Search for doubly charged higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in pp collisions at sqrt[s]=1.96 TeV.

A search for pair production of doubly charged Higgs bosons in the process pp -->H(++)H(--) -->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of sqrt[s]=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H(+/-+/-)(L))>118.4 GeV/c(2) and M(H(+/-+/-)(R))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs.

Journal Article↗
PubMed2004

Influence of dimethylfumarate on experimental HSV-1 necrotizing keratitis.

BACKGROUND: This study was performed to investigate the influence of fumaric acid esters on the course of herpes stromal keratitis (HSK). METHODS: The corneas of BALB/c mice were inoculated with 105 plaque-forming units of herpes simplex virus 1 (HSV-1, KOS strain). Groups of mice were treated intraperitoneally with phosphate buffered saline (PBS) (control mice), or with dimethylfumarate (DMF) at 15 mg/kg of body weight dissolved in PBS daily for 28 days pre-infection and for 14 days post-infection. The course of HSV-1 keratitis was studied clinically. Corneal sections were examined for inflammatory cell infiltration. The numbers of CD3, GR-1, CD11b and F4/80-expressing cells infiltrating the corneas were analyzed by immunohistochemistry. RESULTS: On day 14 after HSV infection, 72% of the mice in the control group had severe HSK. The development of HSK was reduced by DMF treatment in the DMF group (22%) (P=0.004). The total number of inflammatory cells and infiltration of polymorphonuclear-neutrophils (PMNs) were reduced in the corneas of DMF-treated mice. Compared to the PBS-treated mice, numbers of CD3, CD11b, GR-1 and F4/80-positive cells were reduced in the DMF group of mice. CONCLUSIONS: The course of experimental herpes stromal keratitis can be improved with systemic fumaric acid ester treatment. The improvement of keratitis correlates with a reduced corneal infiltration of T cells and mononuclear cells.

Animals↗
PubMed2004

A precision measurement of the mass of the top quark.

The standard model of particle physics contains parameters--such as particle masses--whose origins are still unknown and which cannot be predicted, but whose values are constrained through their interactions. In particular, the masses of the top quark (M(t)) and W boson (M(W)) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of M(t) can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10(-24) s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of +/- 5.3 GeV/c2) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for M(t) becomes 178.0 +/- 4.3 GeV/c2. As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c2, which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c2.

Journal Article↗
PubMed2004

Search for narrow tt resonances in pp collisions at square root of (s)=1.8 TeV.

A search for narrow resonances that decay into tt pairs has been performed using 130 pb(-1) of data in the lepton + jets channel collected by the Dphi detector in pp collisions at square root of (s)=1.8 TeV. There is no significant deviation observed from the standard-model predictions at a top-quark mass of 175 GeV/c2. We therefore present upper limits at the 95% confidence level on the product of the production cross section and branching fraction to tt for narrow resonances as a function of the resonance mass MX. These limits are used to exclude the existence of a leptophobic top-color particle with mass MX<560 GeV/c2, using a theoretical cross section for a width GammaX=0.012MX.

Journal Article↗
PubMed2004

[Amniotic membrane transplantation improves experimental herpetic keratitis. Modulation of matrix metalloproteinase-9].

PURPOSE: Transplantation of human amniotic membrane (AMT) accelerates the healing of experimental ulcerative herpetic keratitis. Here the expression and activity of matrix metalloproteinase (MMP)-9 was studied. METHODS: BALB/c mice were corneally infected with HSV-1. Whereas the infected corneas of mice in group 1 were covered with AM, tarsorrhaphies were performed in others (group 2). After 2 days, the appearance of corneal ulcers and stromal inflammation was judged clinically, and the corneal PMN infiltration was studied histologically. The expression of MMP-9 in the corneas was localized by immunohistochemistry and analyzed by Western-blot technique. The MMP-9 activity in the corneas was determined by zymography. RESULTS: On day 14, the ulcerating corneas had a dense PMN infiltration, the ulcers and the majority of PMNs were highly positive for MMP-9, and the active forms of MMP-9 were detected. Gelatinolytic activity was found in these corneas by zymography. Compared with the mice of group 2, ulceration, stromal inflammation and neovascularization markedly improved clinically and histologically within 2 days in mice of group 1. This was associated with a reduced expression of MMP-9 in corneal tissue and in PMNs. The gelatinolytic activity of MMP-9 was reduced after AMT. CONCLUSIONS: These observations suggest that improvement of herpetic corneal ulcers and reduced corneal neovascularization after AMT may result from a reduced expression and activity of MMP-9.

Adjuvants, Immunologic↗
PubMed2003

Search for large extra dimensions in the monojet+E(T) channel with the DØ detector.

We present a search for large extra dimensions (ED) in pp collisions at a center-of-mass energy of 1.8 TeV using data collected by the DØ detector at the Fermilab Tevatron in 1994-1996. Data corresponding to 78.8+/-3.9 pb(-1) are examined for events with large missing transverse energy, one high-p(T) jet, and no isolated muons. There is no excess observed beyond expectation from the standard model, and we place lower limits on the fundamental Planck scale of 1.0 and 0.6 TeV for 2 and 7 ED, respectively.

Journal Article↗
PubMed2003

[Amniotic membrane transplantation improves herpetic keratitis by local and not by systemic effects].

PURPOSE: The immune mediated HSV-1 stromal keratitis (HSK) rapidly improves after amniotic membrane transplantation (AMT). This study investigated whether AMT modulates the T cell response and whether the anti-inflammatory action of AMT is due to local or systemic effects. METHODS: Corneas of BALB/c mice were infected with 10(5) (PFU) of HSV-1. Animals with ulcerating keratitis on day 14 post-infection were divided into 4 groups: group 1 ( n=12): right eye AMT;group 2 ( n=12): right eye tarsorrhaphy; group 3 ( n=8): right eye tarsorrhaphy, left eye AMT;group 4 ( n=8): both eyes tarsorrhaphy. The mice were examined for clinical signs of HSV keratitis after 2 days. Corneal sections were studied histologically and the inflammatory cell infiltration was studied by immunohistochemical staining. DTH response and the HSV-specific 3H-thymidin-uptake were compared between the groups. RESULTS: Compared to group 2, ulceration and stromal inflammation was profoundly improved in group 1 ( p<0.01). The corneas in the AMT mice had fewer inflammatory cells, CD3+,CD4+ and CD8+ cells than the control mice ( p<0.01). There were no significant differences between groups 1 and 2 with respect to the delayed type hypersensitivity reaction (DTH response) and the HSV-specific 3H-thymidin uptake. AMT or tarsorrhaphy on the left eyes in groups 3 and 4 had no influence on the course of keratitis or the T cell response. CONCLUSIONS: Ulcerating herpetic keratitis markedly improves after AMT. Our observations indicate that this is caused predominantly by local and not by systemic AMT-related effects.

Animals↗
PubMed2003

Intracranial metastasis of testicular seminoma in an HIV-positive. Case report and review.

We present what appears to be the first case of an intracranial metastasis from testicular seminoma in an HIV-positive patient. The computed tomography and magnetic resonance imaging appearance of the lesion mimicked meningioma or lymphoma. A significant increase in the risk of testicular seminoma has been reported in AIDS patients. Whenever there is lymph-node involvement upon diagnosis of testicular seminoma, intracranial metastases may appear. After surgical removal of an intracranial metastasis from testicular seminoma, radiotherapy should be considered. Chemotherapy is to be included in the treatment of intracranial metastases from testicular seminoma with systemic involvement.

Brain Neoplasms↗
PubMed2002

Search for the production of single sleptons through R-parity violation in pp; collisions at square root (s) =1.8 TeV.

We report the first search for supersymmetric particles via s-channel production and decay of smuons or muon sneutrinos at hadronic colliders. The data for the two-muon and two-jets final states were collected by the D0 experiment and correspond to an integrated luminosity of 94+/-5 pb(-1). Assuming that R parity is violated via the single coupling lambda'211, the number of candidate events is in agreement with expectation from the standard model. Exclusion contours are given in the (m(0),m(1/2)) and (m(x),m(v)) planes for lambda(')(211)=0.09, 0.08, and 0.07.

Journal Article↗
PubMed2002

Search for R-parity violating supersymmetry in two-muon and four-jet topologies.

We present results of a search for R-parity-violating decay of the neutralino chi;01, taken as the lightest supersymmetric particle, to a muon and two jets. The decay proceeds through a lepton-number violating coupling lambda(')(2jk) (j=1,2; k=1,2,3), with R-parity conservation in all other production and decay processes. In the absence of candidate events from 77.5+/-3.9 pb(-1) of data collected by the D0 experiment at the Fermilab Tevatron in pp collisions at sqrt[s]=1.8 TeV, and with an expected background of 0.18+/-0.03+/-0.02 events, we set limits on squark and gluino masses within the framework of the minimal low-energy supergravity-supersymmetry model.

Journal Article↗
PubMed2002

Search for leptoquark pairs decaying into nunu+jets in pp collisions at square root[s] = 1.8 TeV.

We present the results of a search for leptoquark (LQ) pairs in (85.2+/-3.7) pb(-1) of pp* collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for leptoquark production and set a limit on sigma(pp*-->LQLQ-->nunu+jets) as a function of the mass of the leptoquark (m(LQ)). Assuming the decay LQ-->nuq, we exclude scalar leptoquarks for m(LQ) < 98 GeV/c(2), and vector leptoquarks for m(LQ) < 200 GeV/c(2) and coupling which produces the minimum cross section, at a 95% confidence level.

Journal Article↗
PubMed2002

Search for the scalar top quark in pp collisions at square root[s] = 1.8 TeV.

We have performed a search for scalar top quark (stop) pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of pp events corresponding to 108.3 pb(-1) of data collected with the D0 detector at Fermilab. The search is done in the framework of the minimal supersymmetric standard model assuming that the sneutrino is the lightest supersymmetric particle. For the dominant decays of the lightest stop, t-->b chi+1 and t-->blnu, no evidence for signal is found. We derive cross-section limits as a function of stop ( t ), chargino ( chi+1), and sneutrino ( nu) masses.

Journal Article↗
PubMed2002

Direct search for charged higgs bosons in decays of top quarks.

We present a search for charged Higgs bosons in decays of pair-produced top quarks in pp collisions at sqrt[s] = 1.8 TeV recorded by the D0 detector at the Fermilab Tevatron collider. With no evidence for signal, we exclude most regions of the ( M(H+/-),tan(beta)) parameter space where the decay t--> H(+)b has a branching fraction >0.36 and B(H+/--->tau(nu)(tau)) is large.

Journal Article↗
PubMed2002

Rapid, ultra-sensitive detection of gas phase elemental mercury under atmospheric conditions using sequential two-photon laser induced fluorescence.

We have examined the sensitivity of sequential two photon laser induced fluorescence (LIF) detection of elemental mercury, Hg(0) in the gas phase. The most sensitive approach involves an initial laser excitation of the 6(3)P1-6(1)S0 transition at 253.7 nm, followed by excitation with a second laser to the 7(1)S0 level. Blue shifted fluorescence is observed on the 6(1)P1-6(1)S0 transition at 184.9 nm. The excitation scheme, involving sequential excitation of two atomic transitions, followed by detection of the emission from a third is extremely specific and precludes detection of anything other than atomic mercury. Using our 10 Hz laser system we have achieved a detection sensitivity of 0.1 ng m(-3) at a sampling rate of 0.1 Hz, i.e. averaging 100 laser shots at a pressure of one atmosphere in air. At low concentrations we sampled simultaneously with an automated mercury analyzer (Tekran 2537A), to ensure accuracy. We have examined the linearity of the technique, generating flows containing mercury concentrations between 1 and 10,000 ng m(-3) using a permeation tube and dynamic dilution, but relying on the concentrations given by the Tekran at low levels and the concentration calculated from dilution at high levels. We find that the detection is linear over the five orders of magnitude that we were able to vary the concentration. Our measured detection limits in He and Ar are much lower as these gases are inefficient fluorescence quenchers.

Air Pollutants↗