Biomedical subjects
Publications and source records attributed to D Bauer.
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.
The inclusive cross section for production of isolated photons has been measured in pp macro collisions at square root of s = 630 GeV with the D0 detector at the Fermilab Tevatron Collider. The photons span a transverse energy (E(T)) range from 7-49 GeV and have pseudorapidity absolute value of eta < 2.5. This measurement is combined with the previous D0 result at square root of s = 1800 GeV to form a ratio of the cross sections. Comparison of next-to-leading-order QCD with the measured cross section at 630 GeV and the ratio of cross sections show satisfactory agreement in most of the E(T) range.
We describe QUAERO, a method that (i) enables the automatic optimization of searches for physics beyond the standard model, and (ii) provides a mechanism for making high energy collider data generally available. We apply QUAERO to searches for standard model WW, ZZ, and t t macro production, to searches for these objects produced through a new heavy resonance, and to the first direct search for W'-->WZ. Through this interface, we make three data sets collected by the D0 experiment at square root of [s] = 1.8 TeV publicly available.
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We present results of searches for technirho (rho(T)), techniomega (omega(T)), and Z' particles, using the decay channels rho(T),omega(T),Z'-->e(+)e(-). The search is based on 124.8 pb(-1) of data collected by the D0 detector at the Fermilab Tevatron during 1992-1996. In the absence of a signal, we set 95% C.L. upper limits on the cross sections for the processes pp-->rho(T),omega(T),Z'-->e(+)e(-) as a function of the mass of the decaying particle. For certain model parameters, we exclude the existence of degenerate rho(T) and omega(T) states with masses below about 200 GeV. We exclude a Z' with mass below 670 GeV, assuming that it has the same couplings to fermions as the Z boson.
Numerous xenobiotics are capable of inducing their own metabolism and by enzyme induction can also lead to enhanced biotransformation of other xenobiotics. In this project, we examined the influence of pyrethroids (permethrin, cypermethrin, and fenvalerate) on the expression and activity of the phenobarbital (PB)-inducible cytochrome P450 2B1 isoform (CYP2B1) in primary rat hepatocyte cultures. Incubation of hepatocyte cultures with pyrethroids resulted in a marked CYP2B1 induction. Among the tested pyrethroids, permethrin elicited the most pronounced induction of CYP2B1 mRNA, which exceeded maximal induction achieved by PB at concentrations approximately 10-fold higher. Furthermore, permethrin induced CYP3A1 mRNA expression, while the expression of the CYP1A1 isoform, which in vivo is not responsive to PB treatment, was not significantly affected by pyrethroids. Permethrin-dependent enhancement of CYP2B1 and CYP3A1 mRNA expression was repressed by the hepatotrophic cytokine epidermal growth factor, which is known to also inhibit PB-dependent induction of CYP2B1. Several metabolites of permethrin formed by hepatocytes (3-(2',2'-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid, 3-phenoxybenzyl alcohol, and 3-phenoxybenzoic acid) were ineffective in inducing CYP2B1 mRNA. Furthermore, permethrin stimulated the expression of the luciferase reporter gene under control of the CYP2B1 promoter (comprising the PB-responsive enhancer module) in transiently transfected primary hepatocyte cultures. Thus, permethrin-stimulated gene expression occurred on the transcriptional level. Taken together, these results indicate that the pyrethroid permethrin is a PB-like inducer. Due to its superior potency in induction, permethrin appears as a useful substance for mechanistic studies to elucidate the mechanism of enzyme induction by phenobarbital.
STUDY DESIGN: This is a report of an exceptional case of isolated cervical juvenile xanthogranuloma in a child. OBJECTIVES: This case report draws attention to the fact that isolated xanthogranuloma of the central nervous system should be considered among possible diagnosis of subdural extramedullary spinal masses in children and young adults. SUMMARY AND BACKGROUND DATA: Isolated juvenile xanthogranuloma of the central nervous system is extremely rare. When located in the spinal canal it behaves like any extramedullary mass-occupying lesion. MRI depicts the tumor's association with adjacent structures. In cases in which a subtotal surgical removal was possible, radiotherapy has been indicated. METHODS: A three-year-old girl presented severe pain in the right shoulder and spastic tetraparesis. The MRI showed an intradural extramedullary mass homogeneously enhancing after DTPA-gadolinium infusion. Complete surgical removal of the tumor was performed through open-door laminoplasty. RESULTS: The child was pain free immediately after the surgical removal of the tumor. A gradual complete recovery of the neurologic deficits followed. Open-door laminoplasty provided sufficient operative space, and it minimized the impact on the growing spinal column. CONCLUSIONS: Isolated juvenile xanthogranuloma does not show any predilections of localization inside the central nervous system. Both intracranial and spinal juvenile xanthogranulomas appear isointense in MRI and enhance homogeneously with gadolinium. Whenever possible, total surgical removal alone seems to be curative. Otherwise, a subtotal removal of the tumor might be followed by radiotherapy. Immunohistochemical tests ensure the diagnosis.
We apply a quasi-model-independent strategy ("Sleuth") to search for new high p(T) physics in approximately 100 pb(-1) of pp collisions at square root of (s) = 1.8 TeV collected by the D0 experiment during 1992-1996 at the Fermilab Tevatron. We systematically analyze many exclusive final states and demonstrate sensitivity to a variety of models predicting new phenomena at the electroweak scale. No evidence of new high p(T) physics is observed.
We report a new measurement of the pseudorapidity (eta) and transverse-energy ( E(T)) dependence of the inclusive jet production cross section in pp(macro) collisions at square root of s = 1.8 TeV using 95 pb(-1) of data collected with the D0 detector at the Fermilab Tevatron. The differential cross section d(2)sigma/(dE(T)d eta) is presented up to eta = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.
HSV-1 induced stromal keratitis (HSK) is an immune-mediated disease. The role of macrophages in this process is still unclear. In this study we investigated the influence of specific macrophage depletion from the spleen and the submandibular lymph nodes by dichloromethylene diphosphonate liposomes (Cl(2)MDP-LIP) on the course of HSV-1 keratitis. BALB/c mice were infected corneally with 10(5)PFU of HSV-1 (KOS). Groups of mice received Cl(2)MDP-LIP 7 and 2 days prior to infection. Cl(2)MDP-LIP were given by various routes: intravenously (i.v.) for macrophage depletion in the spleen; subcutaneously for macrophage depletion in the submandibular regional lymph node (s.c.); or both i.v. and s.c. The development of HSV-1 keratitis was evaluated clinically and histologically. A standard plaque assay from the infected eyes was used to measure virus clearance. Seventy-nine percent of the HSV-1-infected control mice (n = 14) developed severe stromal keratitis by day 14 p.i. The development of stromal keratitis was inhibited by Cl(2)MDP-LIP given s.c. (64%;n = 14;P < 0.05), i.v. and s.c. (50%;n = 14;P < 0.05), but not by i.v. treatment alone (77%;n = 13). After s.c., i.v. and s.c. Cl(2)MDP-LIP injection, histologically the corneal stroma had a decrease in inflammatory cell infiltration by day 14 p.i. compared to the control group, and the DTH response was reduced. The healing of epithelial HSV-1 keratitis and the virus clearance were not affected significantly. These results indicate an important function of macrophages in the course of HSV-1 keratitis. Virus replication in the eye does not appear to be affected by monocytes/macrophages of lymph nodes and spleen. In contrast, the immunopathological process of stromal HSV-keratitis that results in corneal destruction is profoundly accelerated by macrophages in the lymph nodes.
Xenobiotic-metabolizing cytochrome P-450 (P-450) enzymes not only play a pivotal role in elimination of foreign compounds but also contribute to generation of toxic intermediates, including reactive oxygen species, that may elicit cellular damage if produced excessively. Expression of several xenobiotic-metabolizing P-450 enzymes is induced by phenobarbital (PB). Pronounced induction is observed for the rat CYP2B1 isoform. A primary rat hepatocyte culture system was used to investigate whether reactive oxygen species might modulate PB-dependent CYP2B1 induction. In cells cultivated for 3 days with 1.5 mM PB, substantial CYP2B1 mRNA induction was observed (100%). Addition of H(2)O(2) or of the catalase inhibitor 3-amino-1,2,4-triazole (AT) to the medium repressed induction to approximately 30% (at 1 mM H(2)O(2) and 2 mM AT, respectively). Accordingly, treatment of hepatocytes with PB and the glutathione precursor N-acetylcysteine (NAC) led to enhanced PB-dependent induction (to over 1000% at 10 mM NAC). In primary hepatocyte cultures transfected with a CYP2B1 promoter-luciferase construct containing approximately 2.7 kilobase pairs of the native CYP2B1 promoter sequence, PB-dependent reporter gene activation was repressed by AT and stimulated by N-acetylcysteine. Furthermore, a 263-base pair CYP2B1 promoter fragment encompassing the phenobarbital-responsive enhancer module conferred suppression of PB-dependent luciferase expression by AT and activation by NAC in a heterologous SV40-promoter construct. In summary, these data demonstrate a regulatory mechanism that is dependent on the cellular redox status, which modulates CYP2B1 mRNA induction by PB on the transcriptional level, thus representing a feedback mechanism preventing further P-450-dependent production of reactive oxygen intermediates under oxidative stress.
PURPOSE: Stromal herpes simplex virus keratitis (HSK) is an immune-mediated disease. Previous studies have indicated that T cells, neutrophils, and macrophages contribute to the tissue damage in HSK. It has been shown that human amniotic membrane promotes epithelial wound healing and has diverse anti-inflammatory effects. In this study, the effect of amniotic membrane transplantation (AMT) on corneal wound healing and on inflammation in mice with necrotizing HSK was examined. METHODS: BALB/c mice were corneally infected with 10(5) plaque-forming units (PFU) of HSV-1 (KOS strain). In 16 mice that exhibited severe ulcerating HSK, the cornea was covered with a preserved human amniotic membrane as a patch. Corneas in 16 infected mice remained uncovered and served as a control. On days 2 and 7 after surgery, the amniotic membrane was removed (eight mice in each group), the HSV-1-infected cornea was evaluated clinically, and the eye was enucleated. Tissue sections were analyzed histologically for epithelialization and cellular infiltration and immunohistochemically with anti-CD3 mAb to T cells, anti-CD11b mAb to both macrophages and neutrophils, or anti-F4/80 mAb to macrophages. RESULTS: Profound regression of corneal inflammation and rapid closure of epithelial defects were observed clinically within 2 days in the amniotic membrane-covered eyes, whereas HSV-1 keratitis and ulceration progressed in all mice in the control group (P < 0.001). Histologically, corneal edema and inflammatory infiltration, and immunohistochemically the number of CD3(+), CD11b(+), and F4/80(+) cells in the cornea were markedly decreased at 2 and 7 days after amniotic membrane application, compared with the uncovered control corneas (P < 0.001). CONCLUSIONS: AMT promotes rapid epithelialization and reduces stromal inflammation and ulceration in HSV-1 keratitis. AMT in mice with HSV necrotizing stromal keratitis appears to be a useful model for investigating the effect and the action mechanism of human amniotic membrane.
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The production of recombinant woodchuck cytokines is an essential prerequisite to study the immune response to hepadnavirus infection in the woodchuck model. Woodchuck tumour necrosis factor-alpha (TNF-alpha) was expressed in mammalian cells and in Escherichia coli. A test system for the biological activity of woodchuck TNF-alpha was established on basis of its cytotoxic effect to the murine fibrosarcoma cell line L929. Recombinant TNF-alpha was purified and used for the production of neutralizing antisera.
BACKGROUND: Herpes simplex virus (HSV-1) stromal keratitis is an immune-mediated disease. Recently, it has been shown that infection of cells with HSV-1 induces apoptosis. In this study we investigated the presence of apoptotic cell death in keratectomy specimens from patients with HSV-1 stromal keratitis. PATIENTS AND METHODS: Keratectomy specimens from six patients with HSV-1 non-necrotizing stromal keratitis were chosen and compared to healthy corneas. Paraffin sections were analyzed histologically and cryosections were studied by the immunoperoxidase technique for the presence of HSV-1, Fas and FasLigand (FasL) antigens. Apoptosis was assessed by TUNEL assay (TdT-mediated dUTP nick-end labeling). RESULTS: In healthy corneas, Fas was detected in the epithelium, keratocytes and endothelium; FasL was present in the epithelium and endothelium; TUNEL-positive cells were only found in the superficial epithelial cells. In contrast, inflammatory cells and scars were found in all HSV-diseased corneas; HSV-1 antigen was detected in only one specimen. Cells within inflammatory infiltrations and epithelium were apoptotic. Fas was detected in all corneal cell layers and inflammatory cells. FasL was restricted to areas of inflammation. CONCLUSIONS: The data suggest that apoptosis plays a role in the pathogenesis of HSV keratitis. The Fas-FasL system appears to be involved in the induction of apoptosis. Apoptosis could be involved in the depletion of inflammatory cells in the cornea and may limit the extension of viral replication to the eye.
PURPOSE: Herpes simplex virus type 1 infection of the cornea induces an immune-mediated disease termed "herpes stromal keratitis" (HSK) that is a major cause of blindness. In this study we investigated the influence of macrophage depletion by Cl(2) MDP encapsulated in liposomes (Cl(2) MDP-LIP) on the course of HSV-1 keratitis. METHODS: The corneas of BALB/c mice were infected with 10(5) PFU of HSV-1 (KOS strain). Mice groups received sub-conjunctival PBS or Cl( 2) MDP-LIP injections 7 and 2 days prior to infection. The eyes were studied clinically, histologically and immunohistochemically with F4/80 antibody at various time points after treatment. Clearance of the virus from the HSV-infected eyes was measured with a standard plaque assay. RESULTS: After subconjunctival Cl(2) MDP-LIP treatment, the HSV-1-induced epithelial keratitis was more severe (P < 0.05). The virus titers were significantly higher after macrophage depletion (day 7, P < 0.005). Stromal keratitis developed in 78.6% of HSV-1 infected PBS treated control mice ( n = 14) by day 14 after infection. By subconjunctival Cl(2) MDP-LIP treatment (n = 14) the incidence of stromal keratitis was reduced to 42.9%, and the keratitis was less severe (P < 0.05). CONCLUSIONS: The data demonstrate an influence of macrophages on the course of HSV-1 keratitis in mice. Macrophage depletion influence the viral replication in the cornea and the immune-mediated process of HSK.
BACKGROUND: Using the lymphocytic choriomeningitis virus (LCMV) model in mice, a number of studies show that memory cytotoxic T-lymphocyte (CTL) responses are maintained in the presence of continuous antigenic stimulation. Yet, other groups found that memory CTL specific for LCMV could last for a lifetime in mice without viral antigens. Thus, the extent to which an antigen is required for the maintenance of virus-specific CTL remains controversial. In humans, very few studies have been conducted to investigate the relationship between the quantity of antigen and the magnitude of CTL responses. MATERIALS AND METHODS: We quantified CTL precursors (CTLp) using a limiting-dilution analysis (LDA) and CTL effectors (CTLe) using a new Major Histocompatibility Complex (MHC) class I tetramer technology in six long-term nonprogressors (LTNPs) with human immunodeficiency virus type-1 (HIV-1) infection, as well as in eight patients whose viral loads were well suppressed by antiretroviral therapy. The viremia levels in these patients were measured using an reverse transcription polymerase chain reaction (RT-PCR) assay. The proviral DNA load in peripheral blood mononuclear cell (PBMC) was also measured by PCR in four LTNPs. RESULTS: The LTNPs had high levels of HIV-1-specific memory CTLp and CTLe, while maintaining a low plasma viral load. Despite also having low viral loads, patients whose plasma viremia was well-suppressed by effective therapy had low levels of CTLe. CONCLUSIONS: Our findings suggest that a complex, rather than a monotonic, relationship exists between CTL levels and HIV-1 viremia, including what appears to be an antigenic threshold for the maintenance of CTL at a measurable level. Under conditions of "antigen excess,", CTLe levels correlate inversely with viral load. On the other hand, under conditions that are "antigen limited," the correlation appears to be direct.
Recent advances in telecommunications technology are leading to new developments in postacute and rehabilitative care. For about $400 per patient and a telephone hookup, physicians and therapists can provide ongoing, direct care to patients at remote clinics or in their homes. The lack of large-scale randomized controlled trials demonstrating clinical and cost effectiveness in rehabilitation and telemedicine has precluded many payers from reimbursing for services. Guidelines for best use do not currently exist, yet the benefits for payers, providers, and patients could be substantial. Telerehabilitation could become an important modality to MCOs seeking to extend the continuum of postacute care to nonclinical settings.