MINOS is a long baseline neutrino oscillation experiment that uses two detectors separated by 734
km. The readout systems used for the two detectors are different and have to be independently ...calibrated. To verify and make a direct comparison of the calibrated response of the two readout systems, test beam data were acquired using a smaller calibration detector. This detector was simultaneously instrumented with both readout systems and exposed to the CERN PS T7 test beam. Differences in the calibrated response of the two systems are shown to arise from differences in response non-linearity, photomultiplier tube crosstalk, and threshold effects at the few percent level. These differences are reproduced by the Monte Carlo (MC) simulation to better than 1% and a scheme that corrects for these differences by calibrating the MC to match the data in each detector separately is presented. The overall difference in calorimetric response between the two readout systems is shown to be consistent with zero to a precision of 1.3% in data and 0.3% in MC with no significant energy dependence.
The MINOS calibration detector Adamson, P.; Crone, G.; Jenner, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2006, 2006-1-00, Letnik:
556, Številka:
1
Journal Article
Recenzirano
This paper describes the MINOS calibration detector (CalDet) and the procedure used to calibrate it. The CalDet, a scaled-down but functionally equivalent model of the MINOS Far and Near detectors, ...was exposed to test beams in the CERN PS East Area during 2001–2003 to establish the response of the MINOS calorimeters to hadrons, electrons and muons in the range 0.2–10
GeV/
c
. The CalDet measurements are used to fix the energy scale and constrain Monte Carlo simulations of MINOS.
MINOS: Design & detectors Symes, P.A.
Progress in particle and nuclear physics,
07/2006, Letnik:
57, Številka:
1
Journal Article
Recenzirano
MINOS is a 735 km long-baseline neutrino oscillation experiment from Fermilab (IL, USA) to the Soudan mine (MN, USA). The experiment measures
ν
μ
at various energies from Fermilab’s NuMI beam. The ...near and far detectors are almost identical steel–scintillator sandwich tracking calorimeters. MINOS has been running in atmospheric mode since 2003 and in beam mode since February 2005. MINOS is designed to make precision measurements of the neutrino oscillation parameters in the atmospheric sector while also being able to improve the current limit on reactor sector oscillations. Several stages of calibration have to be performed to achieve this.
The magnetized steel and scintillator calorimeters of the MINOS experiment Allison, W.W.M.; Andreopoulos, C.; Ayres, D.S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2008, Letnik:
596, Številka:
2
Journal Article
Recenzirano
Odprti dostop
The Main Injector Neutrino Oscillation Search (MINOS) experiment uses an accelerator-produced neutrino beam to perform precision measurements of the neutrino oscillation parameters in the ...“atmospheric neutrino” sector associated with muon neutrino disappearance. This long-baseline experiment measures neutrino interactions in Fermilab's NuMI neutrino beam with a near detector at Fermilab and again 735
km downstream with a far detector in the Soudan Underground Laboratory in northern Minnesota. The two detectors are magnetized steel-scintillator tracking calorimeters. They are designed to be as similar as possible in order to ensure that differences in detector response have minimal impact on the comparisons of event rates, energy spectra and topologies that are essential to MINOS measurements of oscillation parameters. The design, construction, calibration and performance of the far and near detectors are described in this paper.
On the linearity of the MINOS light-injection calibration system Adamson, P; Barrett, L; Belias, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2004, Letnik:
521, Številka:
2
Journal Article
Recenzirano
The MINOS light-injection calibration system has been fully documented in a previous article (Nucl. Instr. and Meth. A 492 (2002) 353). Upon commissioning in the MINOS detectors, the system was found ...to give a non-linear response to variations in the intensity of injected light. The source of this non-linearity has been traced to a small change in the spectrum of the injected light as a function of the current applied to the original blue LEDs, in combination with a rapidly varying spectral response function of the wavelength-shifting fibre used in the detector. Both aspects of the problem have been addressed successfully by use of LEDs with different spectral characteristics, and the system now has a linear response.
Bordetella pertussis and the other Bordetella species produce a novel adenylate cyclase toxin which enters target cells to catalyze the production of supraphysiologic levels of intracellular cyclic ...adenosine monophosphate (cAMP). In these studies, dialyzed extracts from B. pertussis containing the adenylate cyclase toxin, a partially purified preparation of adenylate cyclase toxin, and extracts from transposon Tn5 mutants of B. pertussis lacking the adenylate cyclase toxin, were used to assess the effects of adenylate cyclase toxin on human peripheral blood monocyte activities. Luminol-enhanced chemiluminescence of monocytes stimulated with opsonized zymosan was inhibited greater than 96% by exposure to adenylate cyclase toxin-containing extract, but not by extracts from adenylate cyclase toxin-deficient mutants. The chemiluminescence responses to particulate (opsonized zymosan, Leishmania donovani, and Staphylococcus aureus) and soluble (phorbol myristate acetate) stimuli were inhibited equivalently. The superoxide anion generation elicited by opsonized zymosan was inhibited 92% whereas that produced by phorbol myristate acetate was inhibited only 32% by B. pertussis extract. Inhibition of oxidative activity was associated with a greater than 500-fold increase in monocyte cAMP levels, but treated monocytes remained viable as assessed by their ability to exclude trypan blue and continued to ingest particulate stimuli. The major role of the adenylate cyclase toxin in the inhibition of monocyte oxidative responses was demonstrated by: 1) little or no inhibition by extracts from B. pertussis mutants lacking adenylate cyclase toxin; 2) high level inhibition with extract from B. parapertussis, a related species lacking pertussis toxin; and 3) a reciprocal relationship between monocyte cAMP levels and inhibition of opsonized zymosan-induced chemiluminescence using both crude extract and partially purified adenylate cyclase toxin. Pertussis toxin, which has been shown to inhibit phagocyte responses to some stimuli by a cAMP-independent mechanism, had only a small (less than 20%) inhibitory effect when added at concentrations up to 100-fold in excess of those present in B. pertussis extract. These data provide strong support for the hypothesis that B. pertussis adenylate cyclase toxin can increase cAMP levels in monocytes without compromising target cell viability or impairing ingestion of particles and that the resultant accumulated cAMP is responsible for the inhibition of oxidative responses to a variety of stimuli.
Two morphologic variants of acute promyelocytic leukemia (AML M3) are recognized--the hypergranular form, in which Auer rods are usually numerous; and the microgranular form. The case of AML M3 ...reported here lacked numerous Auer rods but was hypergranular and demonstrated prominent giant Chediak-Higashi-like granules in the leukemic cells. Although routine karyotypic studies were inconclusive, at t(15;17) translocation was documented using Southern blot genotypic analysis and probes for the retinoic acid receptor-alpha and pml genes. This is the first case of this unusual morphologic anomaly in which the granules are described in routine histologic sections and the first with evidence of a t(15;17) chromosomal translocation. It also illustrates the importance of Southern blot analysis in suspected cases of AML M3 with "negative" karyotypic studies.
Leishmania donovani, interaction of promastigote and amastigote stages with monocyte-derived macrophages, L. donovani does not survive in macrophages by interfering with phagocytic oxidative burst, ...does not produce continuing oxidative response, and only transiently alters oxidative response of macrophages to subsequent particulate stimulation
Therapeutic proteins are often potent and have rapid onsets of action. Unfortunately protein-based medicines can be immunogenic and have short half-lives. The circulation half-life of many proteins ...has been improved by the covalent conjugation of poly(ethylene)glycol (PEG) to the protein. For example, PEGylated interferon-2 (PEGASYS® and PEG-INTRON®) has become a first line treatment for hepatitis C. The aim of this thesis was to examine the possibility of using a homobifunctional PEG reagent to make protein dimers. Our group has developed PEGylation reagents that undergo conjugation by bis-alkylation to selectively conjugate either (i) two cysteine thiols from a native disulfide or (ii) two histidine residues in a polyhistidine tag. It was hypothesised that IFN dimers (IFN-PEG-IFN) could be prepared with higher retained activity than monoPEGylated IFN. It was also hypothesised that a heterodimer of IFN and an antibody fragment (Fab) could be made while retaining the activity of both proteins within the heterodimer. His8IFN-PEG-His8IFN and IFN-PEG-IFN homodimers were prepared by site-selective conjugation to the N-terminal 8-polyhistidine tag and to one of the disulfides of IFN respectively. These homodimer conjugates were characterised in terms of purity and in vitro activity. The in vitro cell based assays were optimised to accurately elucidate the specific activities of the IFN conjugates. The His8IFN-PEG20-His8IFN homodimer was found to retain greater activity than IFN-PEG20-IFN. The increased activity was thought to be due to conjugation to the polyhistidine tag, which is distal from the IFN binding surface. It was also found that IFN-PEG10-IFN homodimer retained greater activity than PEG10-IFN, which could be due to the presence of the second IFN molecule in the IFN-PEG10-IFN homodimer. Two different Fabs were used to prepare the IFN-PEG-Fab heterodimers. Conjugation was conducted at one disulfide of IFN and the accessible interchain disulfide of the Fab. One Fab was derived from a polyclonal antibody to albumin (Fabalb) and the rationale for this heterodimer was that a longer lasting form of IFN could be made (IFN-PEG20-Fabalb). The other Fab was derived from bevacizumab (Fabbeva) to give an IFN-PEG20-Fabbeva heterodimer that could, in principle, display antiangiogenic properties. Both heterodimers were evaluated using antiviral and antiproliferative assays to determine the activity of IFN in the conjugate. The IFN-PEG20-Fabalb conjugate displayed a 10-fold reduction in activity compared to IFN-PEG20-Fabbeva. It was thought that Fabalb underwent competitive binding with components of the media. Interestingly, the IFN-PEG20-Fabbeva heterodimer displayed greater activity than PEG20-IFN and IFN-PEG20-IFN in both the antiviral and antiproliferative assays. The binding properties of Fabbeva were determined by SPR. It was observed that the dissociation rate of IFN-PEG20-Fabbeva was similar to Fabbeva and PEG20-Fabbeva. IFN-PEG20-Fabalb was found to have a similar dissociation rate to Fabalb. However, PEG20-Fabalb was found to have a slower dissociation to both IFN-PEG20-Fabalb and Fabalb, this result requires further investigation but was thought to be due to the sample impurity. The association rates of heterodimers were found to similar to the PEG-Fab conjugates but slower than their native Fabs. This data suggests that the novel IFN-PEG20-Fabbeva and IFN-PEG20-Fabalb heterodimer conjugates have retained their binding affinities to their antigens. Overall, it was shown that a homobifunctional bis-alkylating conjugation reagent (e.g. PEG di(bis)sulfone 4) could be used successfully to prepare dimeric protein conjugates. This work highlighted the importance to ensure the homobifunctional conjugation reagent was pure, especially for the preparation of protein heterodimeric conjugates. To develop this work further, it would be important to investigate three broad areas: i) improving the purity of the starting homobifunctional reagents, ii) evaluate the in vivo efficacy of the resulting protein homo-/hetero-dimers and iii) determine the overall potential for efficient scaling of the process to make the desired protein homo-/hetero-dimers.
Therapeutic proteins are often potent and have rapid onsets of action. Unfortunately protein-based medicines can be immunogenic and have short half-lives. The circulation half-life of many proteins ...has been improved by the covalent conjugation of poly(ethylene)glycol (PEG) to the protein. For example, PEGylated interferon-2 (PEGASYS® and PEG-INTRON®) has become a first line treatment for hepatitis C. The aim of this thesis was to examine the possibility of using a homobifunctional PEG reagent to make protein dimers. Our group has developed PEGylation reagents that undergo conjugation by bis-alkylation to selectively conjugate either (i) two cysteine thiols from a native disulfide or (ii) two histidine residues in a polyhistidine tag. It was hypothesised that IFN dimers (IFN-PEG-IFN) could be prepared with higher retained activity than monoPEGylated IFN. It was also hypothesised that a heterodimer of IFN and an antibody fragment (Fab) could be made while retaining the activity of both proteins within the heterodimer. His8IFN-PEG-His8IFN and IFN-PEG-IFN homodimers were prepared by site-selective conjugation to the N-terminal 8-polyhistidine tag and to one of the disulfides of IFN respectively. These homodimer conjugates were characterised in terms of purity and in vitro activity. The in vitro cell based assays were optimised to accurately elucidate the specific activities of the IFN conjugates. The His8IFN-PEG20-His8IFN homodimer was found to retain greater activity than IFN-PEG20-IFN. The increased activity was thought to be due to conjugation to the polyhistidine tag, which is distal from the IFN binding surface. It was also found that IFN-PEG10-IFN homodimer retained greater activity than PEG10-IFN, which could be due to the presence of the second IFN molecule in the IFN-PEG10-IFN homodimer. Two different Fabs were used to prepare the IFN-PEG-Fab heterodimers. Conjugation was conducted at one disulfide of IFN and the accessible interchain disulfide of the Fab. One Fab was derived from a polyclonal antibody to albumin (Fabalb) and the rationale for this heterodimer was that a longer lasting form of IFN could be made (IFN-PEG20-Fabalb). The other Fab was derived from bevacizumab (Fabbeva) to give an IFN-PEG20-Fabbeva heterodimer that could, in principle, display antiangiogenic properties. Both heterodimers were evaluated using antiviral and antiproliferative assays to determine the activity of IFN in the conjugate. The IFN-PEG20-Fabalb conjugate displayed a 10-fold reduction in activity compared to IFN-PEG20-Fabbeva. It was thought that Fabalb underwent competitive binding with components of the media. Interestingly, the IFN-PEG20-Fabbeva heterodimer displayed greater activity than PEG20-IFN and IFN-PEG20-IFN in both the antiviral and antiproliferative assays. The binding properties of Fabbeva were determined by SPR. It was observed that the dissociation rate of IFN-PEG20-Fabbeva was similar to Fabbeva and PEG20-Fabbeva. IFN-PEG20-Fabalb was found to have a similar dissociation rate to Fabalb. However, PEG20-Fabalb was found to have a slower dissociation to both IFN-PEG20-Fabalb and Fabalb, this result requires further investigation but was thought to be due to the sample impurity. The association rates of heterodimers were found to similar to the PEG-Fab conjugates but slower than their native Fabs. This data suggests that the novel IFN-PEG20-Fabbeva and IFN-PEG20-Fabalb heterodimer conjugates have retained their binding affinities to their antigens. Overall, it was shown that a homobifunctional bis-alkylating conjugation reagent (e.g. PEG di(bis)sulfone 4) could be used successfully to prepare dimeric protein conjugates. This work highlighted the importance to ensure the homobifunctional conjugation reagent was pure, especially for the preparation of protein heterodimeric conjugates. To develop this work further, it would be important to investigate three broad areas: i) improving the purity of the starting homobifunctional reagents, ii) evaluate the in vivo efficacy of the resulting protein homo-/hetero-dimers and iii) determine the overall potential for efficient scaling of the process to make the desired protein homo-/hetero-dimers.
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