| 641. |
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| 642. |
- Lehmann, E. H., et al.
(författare)
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The energy-selective option in neutron imaging
- 2009
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 603:3, s. 429-438
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Tidskriftsartikel (refereegranskat)abstract
- In the past, neutron imaging investigations have been mostly performed in "integrating mode", which averages over the full applied neutron energy spectrum. This article describes four different methods and devices of obtaining energy selectivity in the thermal to cold energy range, which allow a new approach in neutron imaging. Two principles have been used and tested: (a) selection of neutrons by suppression of contribution of other spectral parts; (b) using the flight-time information in distance from the source. For the (a) option, three different devices have been exploited practically. Information about material properties can be revealed that cannot be obtained in integrating mode. The energy-dependent transmission measurements make use of the Bragg edges in the total cross-sections of materials. Energy-selective radiography has vast potential for contrast variation, and for mapping structural properties such as crystallographic texture and residual strains with high spatial resolution. The obtained images highlight new opportunities in materials and engineering research, in comparison and complementary to what can be obtained by neutron scattering. There is likely to be an increasing need for implementing time-of-flight neutron imaging at present and future pulsed spallation sources, where the energy range can be selected almost without limitations. In this paper we attempt to give an overview over the current state of the art of energy-selective imaging and the experimental configurations required. (C) 2009 Elsevier B.V. All rights reserved.
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| 643. |
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| 644. |
- Lehmann, I., et al.
(författare)
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Vacuum predictions and measurements for an internal Pellet Target at a storage ring
- 2008
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Ingår i: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 82:6, s. 645-650
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Tidskriftsartikel (refereegranskat)abstract
- Measurements with low Z targets at internal experiments typically imply a gas load which deteriorates the vacuum of a storage ring. Future experiments need reliable estimates for the expected vacuum conditions in order to design 4π detectors closely surrounding the interaction area. We present a method for the calculation of the resulting vacuum of such a complex system using a Pellet Target. In order to test the method, a vacuum system with diagnostic tools has been set-up and a Pellet Target was operated under realistic conditions. The results for the absolute vacuum agree within factors of two with the expected pressures.
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| 645. |
- Lehmann, Jean, et al.
(författare)
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Folding of small RNAs displaying the GNC base-pattern : implications for the self-organization of the genetic system
- 2004
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Ingår i: Journal of Theoretical Biology. - : Elsevier BV. - 0022-5193 .- 1095-8541. ; 227:3, s. 381-395
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical arguments and statistical analyses of present-day coding sequences have long suggested the existence of primitive patterns in RNA sequences, which were thought to have been predominant at the time of the origin of the genetic code. The main propositions were centered around the base-patterns GNC and RNY, where R = A or G, Y = C or U and N = A, G, C or U. A theoretical model of the primitive process of translation explaining the origin of this type of pattern was recently published in the Journal of Theoretical Biology. On the basis of this previous analysis.. and on physico-chemical evidence supporting the idea of the GNC base-pattern as the most primitive one, the present paper shows the results of folding simulations of small RNA strands displaying this pattern, which enabled us to specify the characteristics of the suggested primitive form of tRNA. This analysis is notably based on a conjecture of Eigen and Schuster of an early structural (or pattern) similarity between mRNA and tRNA, and, more specifically, of a "joint function of messenger and adaptor". Working with this conjecture, we show that the convergence of the primitive pool of RNAs toward a system containing a high proportion of sequences displaying the GNC base-pattern (according to the evolutionary model) is accompanied by a significant gain in stability of the translation process. In particular, it is demonstrated how the reading frame would be automatically discriminated without the presence of a start codon.
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| 646. |
- Lehmann, O. J., et al.
(författare)
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Novel anterior segment phenotypes resulting from forkhead gene alterations: Evidence for cross-species conservation of function
- 2003
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Ingår i: Investigative Ophthalmology & Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 44:6, s. 2627-2633
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE. Mutations in murine and human Versions of an ancestrally related gene usually result in similar phenotypes. However, interspecics differences exist, and in the case of two forkhead transcription factor genes (FOXC1 and FOXC2), these differences include corneal or anterior segment phenotypes, respectively. This study was undertaken to determine whether such discrepancies provide an opportunity for identifying novel human-murine ocular phenotypes. METHODS. Four pedigrees with early-onset glaucoma phenotypes secondary to segmental chromosomal duplications or deletions encompassing FOXC1 and 18 individuals from 9 FOXC2 mutation pedigrees underwent detailed ocular phenotyping. Subsequently, mice with mutations in Foxc1 or a related forkhead gene, Foxe3, were assessed for features of the human phenotypes. RESULTS. A significant increase in central corneal thickness was present in affected individuals from the segmental duplication pedigrees compared with their unaffected relatives (mean increase 13%, maximum 35%, P < 0.05). Alterations in corneal thickness were present in mice heterozygous and homozygous for Foxe3 mutations but neither in Foxc1 heterozygotes nor the small human segmental deletion pedigree. Mutations in FOXC2 resulted in ocular anterior segment anomalies. These were more severe and prevalent with mutations involving the forkhead domain. CONCLUSIONS. Normal corneal development is dependent on the precise dose and levels of activity of certain forkhead transcription factors. The altered corneal thickness attributable to increased forkhead gene dosage is particularly important, because it may affect the clinical management of certain glaucoma subtypes and lead to excessive treatment. The FOXC1 and Foxe3 data, taken together with the novel ocular phenotypes of FOXC2 mutations, highlight the remarkable cross-species conservation of function among forkhead genes.
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| 647. |
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| 648. |
- Lehmann, S, et al.
(författare)
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Targeting p53 in vivo : a first-in-man study with the p53-targeting compound APR-246 in refractory hematologic malignancies and prostate cancer
- 2012
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Ingår i: Journal of Clinical Oncology. - : American Society of Clinical Oncology. - 0732-183X .- 1527-7755. ; 30:29, s. 3633-3639
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: APR-246 (PRIMA-1MET) is a novel drug that restores transcriptional activity of unfolded wild-type or mutant p53. The main aims of this first-in-human trial were to determine maximum-tolerated dose (MTD), safety, dose-limiting toxicities (DLTs), and pharmacokinetics (PK) of APR-246.PATIENTS AND METHODS: APR-246 was administered as a 2-hour intravenous infusion once per day for 4 consecutive days in 22 patients with hematologic malignancies and prostate cancer. Acute myeloid leukemia (AML; n = 7) and prostate cancer (n = 7) were the most frequent diagnoses. Starting dose was 2 mg/kg with dose escalations up to 90 mg/kg.RESULTS: MTD was defined as 60 mg/kg. The drug was well tolerated, and the most common adverse effects were fatigue, dizziness, headache, and confusion. DLTs were increased ALT/AST (n = 1), dizziness, confusion, and sensory disturbances (n = 2). PK showed little interindividual variation and were neither dose nor time dependent; terminal half-life was 4 to 5 hours. Tumor cells showed cell cycle arrest, increased apoptosis, and upregulation of p53 target genes in several patients. Global gene expression analysis revealed changes in genes regulating proliferation and cell death. One patient with AML who had a p53 core domain mutation showed a reduction of blast percentage from 46% to 26% in the bone marrow, and one patient with non-Hodgkin's lymphoma with a p53 splice site mutation showed a minor response.CONCLUSION: We conclude that APR-246 is safe at predicted therapeutic plasma levels, shows a favorable pharmacokinetic profile, and can induce p53-dependent biologic effects in tumor cells in vivo.
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| 649. |
- Lehmann, Sören, et al.
(författare)
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Targeting p53 in Vivo : a First-in-Human Study With p53-Targeting Compound APR-246 in Refractory Hematologic Malignancies and Prostate Cancer
- 2012
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Ingår i: Journal of Clinical Oncology. - 0732-183X .- 1527-7755. ; 30:29, s. 3633-3639
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSEAPR-246 (PRIMA-1MET) is a novel drug that restores transcriptional activity of unfolded wild-type or mutant p53. The main aims of this first-in-human trial were to determine maximum-tolerated dose (MTD), safety, dose-limiting toxicities (DLTs), and pharmacokinetics (PK) of APR-246.PATIENTS AND METHODSAPR-246 was administered as a 2-hour intravenous infusion once per day for 4 consecutive days in 22 patients with hematologic malignancies and prostate cancer. Acute myeloid leukemia (AML; n = 7) and prostate cancer (n = 7) were the most frequent diagnoses. Starting dose was 2 mg/kg with dose escalations up to 90 mg/kg.RESULTSMTD was defined as 60 mg/kg. The drug was well tolerated, and the most common adverse effects were fatigue, dizziness, headache, and confusion. DLTs were increased ALT/AST (n = 1), dizziness, confusion, and sensory disturbances (n = 2). PK showed little interindividual variation and were neither dose nor time dependent; terminal half-life was 4 to 5 hours. Tumor cells showed cell cycle arrest, increased apoptosis, and upregulation of p53 target genes in several patients. Global gene expression analysis revealed changes in genes regulating proliferation and cell death. One patient with AML who had a p53 core domain mutation showed a reduction of blast percentage from 46% to 26% in the bone marrow, and one patient with non-Hodgkin's lymphoma with a p53 splice site mutation showed a minor response.CONCLUSION We conclude that APR-246 is safe at predicted therapeutic plasma levels, shows a favorable pharmacokinetic profile, and can induce p53-dependent biologic effects in tumor cells in vivo.
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