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Bergman A, Carlberg T, Fredriksson H, Stjerndahl J. The Influence of Gravity on the Solidification of Monotectic and Near Monotectic Cu-Pb Alloys. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-9-579] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTUnidirectional solidification experiments with monotectic and near monotectic Cu-Pb alloys have been performed with the growth direction both parallel and antiparallel to the gravity vector. It was found that a more regular composite structure was possible to achieve in the samples solidified parallel to the gravity vector. It was also found that the amount of lead rich phase, regularily incorporated in the structure, was less than one would expect theoretically. It is proposed that monotectic alloys can solidify to two different kinds of composite structures. One, which can be described by the theory of coupled growth of a rod eutecticum, and the other similar to the growth of primary rods.
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Balleyguier C, Sala E, Da Cunha T, Bergman A, Brkljacic B, Danza F, Forstner R, Hamm B, Kubik-Huch R, Lopez C, Manfredi R, McHugo J, Oleaga L, Togashi K, Kinkel K. Staging of uterine cervical cancer with MRI: guidelines of the European Society of Urogenital Radiology. Eur Radiol 2010; 21:1102-10. [PMID: 21063710 DOI: 10.1007/s00330-010-1998-x] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/29/2010] [Accepted: 10/01/2010] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To design clear guidelines for the staging and follow-up of patients with uterine cervical cancer, and to provide the radiologist with a framework for use in multidisciplinary conferences. METHODS Guidelines for uterine cervical cancer staging and follow-up were defined by the female imaging subcommittee of the ESUR (European Society of Urogenital Radiology) based on the expert consensus of imaging protocols of 11 leading institutions and a critical review of the literature. RESULTS The results indicated that high field Magnetic Resonance Imaging (MRI) should include at least two T2-weighted sequences in sagittal, axial oblique or coronal oblique orientation (short and long axis of the uterine cervix) of the pelvic content. Axial T1-weighted sequence is useful to detect suspicious pelvic and abdominal lymph nodes, and images from symphysis to the left renal vein are required. The intravenous administration of Gadolinium-chelates is optional but is often required for small lesions (<2 cm) and for follow-up after treatment. Diffusion-weighted sequences are optional but are recommended to help evaluate lymph nodes and to detect a residual lesion after chemoradiotherapy. CONCLUSIONS Expert consensus and literature review lead to an optimized MRI protocol to stage uterine cervical cancer. MRI is the imaging modality of choice for preoperative staging and follow-up in patients with uterine cervical cancer.
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Asp V, Cantillana T, Bergman A, Brandt I. Chiral effects in adrenocorticolytic action of o,p'-DDD (mitotane) in human adrenal cells. Xenobiotica 2010; 40:177-83. [PMID: 20044879 DOI: 10.3109/00498250903470230] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Adrenocortical carcinoma (ACC) is a rare malignant disease with poor prognosis. The main pharmacological choice, o,p'-DDD (mitotane), produces severe adverse effects. Since o,p'-DDD is a chiral molecule and stereoisomers frequently possess different pharmacokinetic and/or pharmacodynamic properties, we isolated the two o,p'-DDD enantiomers, (R)-(+)-o,p'-DDD and (S)-(-)-o,p'-DDD, and determined their absolute structures. The effects of each enantiomer on cell viability and on cortisol and dehydroepiandrosterone (DHEA) secretion in the human adrenocortical cell line H295R were assessed. We also assayed the o,p'-DDD racemate and the m,p'- and p,p'-isomers. The results show small but statistically significant differences in activity of the o,p'-DDD enantiomers for all parameters tested. The three DDD isomers were equally potent in decreasing cell viability, but p,p'-DDD affected hormone secretion slightly less than the o,p'- and m,p'-isomers. The small chiral differences in direct effects on target cells alone do not warrant single enantiomer administration, but might reach importance in conjunction with possible stereochemical effects on pharmacokinetic processes in vivo.
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Wahl M, Guenther R, Yang L, Bergman A, Straehle U, Strack S, Weiss C. Polybrominated diphenyl ethers and arylhydrocarbon receptor agonists: Different toxicity and target gene expression. Toxicol Lett 2010; 198:119-26. [PMID: 20566336 DOI: 10.1016/j.toxlet.2010.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 05/29/2010] [Accepted: 06/01/2010] [Indexed: 10/19/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) accumulate in the environment and in humans. PBDEs are developmental neurotoxicants, disturb the endocrine system and induce tumors in rodents. However, underlying mechanisms of PBDE toxicity are still insufficiently understood. Some reports demonstrated activation but also inhibition of the aryl hydrocarbon receptor (AhR) by PBDEs based on expression of its target gene cyp1A1. In the present study, we used different PBDE congeners (BDE47, 99, 153 and 209) and analyzed their effects on AhR signaling in various cell lines and zebrafish embryos. Furthermore, we performed microarray experiments in rat hepatoma cells to compare changes in gene expression induced by either BDE47 or the AhR agonist 2,3,7,8-tetrabromo-dibenzofuran (TBDF). PBDEs did not activate but rather inhibited AhR signaling and specifically induced malformations in zebrafish embryos, which differ from those provoked by AhR agonists. Furthermore, BDE47 and TBDF differentially regulated global gene expression in hepatoma cells. Hence, PBDEs and AhR agonists trigger different toxicity and target gene expression. Several novel target genes of BDE47 and TBDF were identified and verified by RT-PCR. TBDF induced expression of the transcriptional regulators Sim2 and RevErbbeta whereas BDE47 specifically deregulated expression of two subunits of the cytochrome c oxidase complex, cox6a2 and cox4i2, which might be linked to its toxicity.
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Hellgren J, Cervin A, Nordling S, Bergman A, Cardell LO. Allergic rhinitis and the common cold--high cost to society. Allergy 2010; 65:776-83. [PMID: 19958315 DOI: 10.1111/j.1398-9995.2009.02269.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UNLABELLED The common cold and allergic rhinitis constitute a global health problem that affects social life, sleep, school and work performance and is likely to impose a substantial economic burden on society because of absence from work and reduced working capacity. This study assesses the loss of productivity as a result of both allergic rhinitis and the common cold in the Swedish working population. METHODS Four thousand questionnaires were sent to a randomized adult population, aged 18-65 years, in Sweden, stratified by gender and area of residence (metropolitan area vs rest of the country). The human capital approach was used to assign monetary value to lost productivity in terms of absenteeism (absence from work), presenteeism (reduced working capacity while at work) and caregiver absenteeism (absence from work to take care of a sick child). RESULTS Thousand two hundred and thirteen individuals responded, response rate 32%. The mean productivity loss was estimated at 5.1 days or euro 653 per worker and year, yielding a total productivity loss in Sweden of euro 2.7 billion a year. Of the total costs, absenteeism (44%) was the dominant factor, followed by presenteeism (37%) and caregiver absenteeism (19%). Poisson regression analyses revealed that women, people in the 18-29 year age group, and respondents with 'doctor-diagnosed asthma' reported more lost days than the rest of the group. CONCLUSION In Sweden, the cost of rhinitis is euro 2.7 billion a year in terms of lost productivity. A reduction in lost productivity of 1 day per individual and year would potentially save euro 528 million.
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Yin L, Bergman A, Shcherbinin S, Celler A, Liu M, Wu J, Duzenli C, Gill B, Moiseenko V. SU-GG-T-486: Sparing of Lung Function Using Perfusion SPECT Guided IMRT Treatment Planning for Lung Cancer Patients. Med Phys 2010. [DOI: 10.1118/1.3468884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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82
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Ekman S, Frodin J, Harmenberg J, Bergman A, Hedlund A, Dahg P, Bergstrom S, Bergqvist M. Clinical phase I/II study with the insulin-like growth factor-1 receptor inhibitor AXL1717: Future implications for patients with squamous non-small cell lung carcinoma? J Clin Oncol 2010. [DOI: 10.1200/jco.2010.28.15_suppl.e13019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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83
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Teke T, Bergman A, Kwa W, Gill B, Duzenli C, Popescu IA. Sci-Wed PM: Delivery-08: Monte Carlo Based RapidArc QA Using LINAC Log Files. Med Phys 2009. [DOI: 10.1118/1.3244100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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84
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Cantillana T, Sundström M, Bergman A. Synthesis of 2-(4-chlorophenyl)-2-(4-chloro-3-thiophenol)-1,1-dichloroethene (3-SH-DDE) via Newman-Kwart rearrangement - a precursor for synthesis of radiolabeled and unlabeled alkylsulfonyl-DDEs. CHEMOSPHERE 2009; 76:805-810. [PMID: 19447466 DOI: 10.1016/j.chemosphere.2009.04.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 04/14/2009] [Accepted: 04/20/2009] [Indexed: 05/27/2023]
Abstract
For the first time, a pathway for synthesis of 2-(4-chlorophenyl)-2-(4-chloro-3-thiophenol)-1,1-dichloroethene (3-SH-DDE), is presented. The compound is of particular interest as a precursor for synthesis of alkylsulfonyl-DDE containing different alkyl groups to discover structural activity relationships, and to promote synthesis of radiolabeled methylsulfonyl-DDE. 2-Chloro-5-methylphenol was first methylated and further oxidized to the corresponding benzoic acid. The acid was reduced to the corresponding aldehyde (4-chloro-3-methoxy benzaldehyde) via 4-chloro-3-methoxy-benzene methanol. A lead/aluminium bimetal system was used to carry out the reductive addition of tetrachloromethane to 4-chloro-3-methoxy benzaldehyde to obtain 2,2,2-trichloro-1-(4-chloro-3-methoxyphenyl)ethanol, the desired starting material to synthesize the DDT-analogue (2-(4-chlorophenyl)-2-(4-chloro-3-methoxy-phenyl)-1,1,1-trichloroethane). Elimination of hydrochloric acid and removal of the methyl group led to the 3-OH-DDE. The Newman-Kwart rearrangement was applied to convert 3-OH-DDE to 3-SH-DDE via the dimethylcarbamothioate derivative. 3-SH-DDE is then used as a precursor for the radiolabel synthesis. The overall yield to acquire 3-SH-DDE after 11 steps was 3%. The step with the lowest yield was the DDT-analog synthesis with a yield of 30%. All other step had a yield of >50%. 3-SH-DDE was methylated with (14)C-labeled iodomethane and oxidized by hydrogen peroxide to obtain 3-[(14)C]MeSO(2)-DDE in an overall yield of 30%.
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Cantillana T, Lindström V, Eriksson L, Brandt I, Bergman A. Interindividual differences in o,p'-DDD enantiomer kinetics examined in Göttingen minipigs. CHEMOSPHERE 2009; 76:167-172. [PMID: 19394667 DOI: 10.1016/j.chemosphere.2009.03.050] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2008] [Revised: 02/20/2009] [Accepted: 03/25/2009] [Indexed: 05/27/2023]
Abstract
Five minipigs were given a single oral dose of a racemic mixture of o,p'-DDD (30 mg kg(-1)b.w., EF=0.49). Blood plasma and subcutaneous adipose tissue were collected for analysis, at different time-points over 180 d. At the end of the experiment also liver, kidney and brain tissue were collected. Low concentrations of o,p'-DDD still remained after 180 d in plasma (mean 0.5+/-0.3 ng g(-1)f.w.) and in adipose tissue (mean 40+/-40 ng g(-1)f.w.). The mean concentrations in liver and kidney were 500+/-300 pg g(-1)f.w. and 90+/-50 pg g(-1)f.w., respectively. The enantiomers of o,p'-DDD were isolated by HPLC and the absolute configuration of the enantiomers were determined by X-ray crystallography and polarimetry as R-(+)-o,p'-DDD and S-(-)-o,p'-DDD. The enantiomer fractions (EFs) of o,p'-DDD were determined in plasma, adipose tissue and kidney using GC/ECD equipped with a chiral column. The EFs of o,p'-DDD in the individual minipigs showed large variability, ranging from 0.2 to 0.6 after 24h in plasma and from 0.2 to 0.7 after 90 d in adipose tissue. Hence in two of the minipigs, the S-(-)-o,p'-DDD enantiomer was dominating while the other enantiomer, R-(+)-o,p'-DDD was dominating in three minipigs. We propose that a yet not identified factor related to polymorphism, regulating the metabolism and/or elimination of the enantiomeric o,p'-DDD, is responsible for the differences in enantiomeric retention of the compound in the minipigs.
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Gibson CR, Bergman A, Lu P, Kesisoglou F, Denney WS, Mulrooney E. Prediction of Phase I single-dose pharmacokinetics using recombinant cytochromes P450 and physiologically based modelling. Xenobiotica 2009; 39:637-48. [DOI: 10.1080/00498250902954296] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Cohen Freue G, Lin D, Imai C, Ignaszewski A, Mancini J, Hollander Z, Bergman A, Sasaki M, Wilson-McManus J, Balshaw R, Ng R, Borchers C, Keown P, McManus B, McMaster R. 341: Proteomic Biomarkers of Chronic Heart Allograft Rejection. J Heart Lung Transplant 2009. [DOI: 10.1016/j.healun.2008.11.348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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88
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Zamir R, Athanasiadou M, Nahar N, Mamun MIR, Mosihuzzaman M, Bergman A. Persistent organohalogen contaminants in plasma from groups of humans with different occupations in Bangladesh. CHEMOSPHERE 2009; 74:453-459. [PMID: 18996566 DOI: 10.1016/j.chemosphere.2008.09.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 09/06/2008] [Accepted: 09/12/2008] [Indexed: 05/27/2023]
Abstract
The present study is aimed to assess persistent organic halogenated pollutants in humans living in Bangladesh. The results are compared to other similar studies in the region and globally. Human blood plasma were collected from groups of men and women with different occupations, i.e. being students, garment industry workers, employees at the Power Development Board (PDB), all groups in Dhaka, fishermen and fishermen wife's from Dhaka and another group from Barisal district. The plasma was analysed for hexachlorobenzene (HCB), the hexachlorocyclohexane isomers, alpha-HCH, beta-HCH, gamma-HCH and delta-HCH, the DDT group of chemicals, chlordane compounds, trans-chlordane, cis-chlordane, oxychlordane, trans-nonachlor, trans-heptachlorepoxide, methoxychlor and mirex. The most abundant contaminant, in all groups studied, p,p'-DDE is dominating, with p,p'-DDT/Sigma DDT ratios indicating recent and ongoing DDT exposure. Among the other pesticides analysed beta-HCH is the most abundant indicating the use of technical HCH products instead of Lindane (gamma-HCH). While the Sigma DDT is present in the low ppm range the beta-HCH is detected in up to approx. 400 ppb, lipid basis. The beta-HCH is most abundant in the groups of students. In contrast to the pesticides analysed very low concentrations of polychlorinated biphenyls (PCB) are present in all study groups, with e.g. CB-153 in the range of 5-30 ng g(-1) fat. The concentrations of the DDT group of chemical differ significantly between fishermen and fishermen's wives living and working in the Dhaka area versus those living and working in Barisal. Also, fishermen and their wives had significantly different concentrations of DDT compared to garment industry workers.
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Malmberg T, Hoogstraate J, Bergman A, Klasson Wehler E. Pharmacokinetics of two major hydroxylated polychlorinated biphenyl metabolites with specific retention in rat blood. Xenobiotica 2008; 34:581-9. [PMID: 15277017 DOI: 10.1080/00498250410001713078] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
1. Hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) are, depending on their structure, strongly retained in mammalian, fish and bird blood. This is due to strong, though reversible, binding to the thyroxine binding and transporting protein transthyretin. 2,3,3',4',5-Pentachloro-4-biphenylol (4-OH-CB 107) and 2,2',3,4',5,5',6-heptachloro-4-biphenylol (4-OH-CB 187) are two of five major OH-PCB congeners in human plasma. 2. The relative amounts of OH-PCB congeners vary between species and also between human populations, in spite of similar PCB congener patterns, and may depend on different pharmacokinetic parameters of the OH-PCBs. In the present study, the pharmacokinetic parameters of 4-OH-CB 107 and 4-OH-CB 187 were determined in the rat after a single intravenous dose of 1 micromol kg(-1). Plasma samples were analysed by gas chromatography/mass spectrometry. 3. 4-OH-CB 107 had a half-life of 3.8 days; 4-OH-CB 187 had a half-life of 15 days. Volumes of distribution were 0.07 and 0.11 l kg(-1), respectively; clearances (ml h(-1)) were 0.67 and 0.22, respectively; and the areas under the curve were estimated as approximately 1500 and 4450 nmol h ml(-1). 4. The pharmacokinetic parameters thus determined help to explain the observed differences in the relative amounts of OH-PCBs in humans and other mammals exposed to environmental PCBs.
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Moiseenko V, Popescu IA, Liu M, Kristensen S, Gill B, Teke T, Bergman A. SU-GG-T-348: Monte Carlo Calculations of Dose Distribution in NSCLC Patients Planned for Stereotactic Body Radiation Therapy. Med Phys 2008. [DOI: 10.1118/1.2962100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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91
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Harkonen T, Bäcklin BM, Barrett T, Bergman A, Corteyn M, Dietz R, Harding KC, Malmsten J, Roos A, Teilmann J. Mass mortality in harbour seals and harbour porpoises caused by an unknown pathogen. Vet Rec 2008; 162:555-6. [DOI: 10.1136/vr.162.17.555] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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92
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Bergman A, Fernandez V, Holmström KO, Claesson BEB, Enroth H. Rapid identification of pathogenic yeast isolates by real-time PCR and two-dimensional melting-point analysis. Eur J Clin Microbiol Infect Dis 2007; 26:813-8. [PMID: 17680284 DOI: 10.1007/s10096-007-0369-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
There is a need in the clinical microbiological laboratory for rapid and reliable methods for the universal identification of fungal pathogens. Two different regions of the rDNA gene complex, the highly polymorphic ITS1 and ITS2, were amplified using primers targeting conserved regions of the 18S, 5.8S and 28S genes. After melting-point analysis of the amplified products, the T(m) of the two PCR-products were plotted into a spot diagram where all the 14 tested, clinically relevant yeasts separated with good resolution. Real-time amplification of two separate genes, melting-point analysis and two-dimensional plotting of T(m) data can be used as a broad-range method for the identification of clinical isolates of pathogenic yeast such as Candida and Cryptococcus spp.
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Belbin TJ, Bergman A, Brandwein-Gensler M, Chen Q, Childs G, Garg M, Haigentz M, Hogue-Angeletti R, Moadel R, Negassa A, Owen R, Prystowsky MB, Schiff B, Schlecht NF, Shifteh K, Smith RV, Zheng X. Head and neck cancer: reduce and integrate for optimal outcome. Cytogenet Genome Res 2007; 118:92-109. [PMID: 18000360 DOI: 10.1159/000108290] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Accepted: 02/09/2007] [Indexed: 01/14/2023] Open
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Kamali-M S, Bergman A, Andersson G, Stanciu V, Häggström L. Local magnetic effects of interface alloying in Fe/Co superlattices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2006; 18:5807-5824. [PMID: 21690798 DOI: 10.1088/0953-8984/18/26/002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Effects of interface alloying and the thickness dependence of magnetic properties of Fe/Co(001) multilayers have been investigated. The thicknesses of the Fe layers have been varied between two and 14 monolayers while the Co layers have been held constant at 7 ML. From conversion electron Mössbauer spectroscopy (CEMS) measurements and electronic structure calculations it is found that the magnitude of the Fe magnetic hyperfine field is larger close to the interface and smaller in the middle of thick (≥9 ML) Fe layers. For a thinner Fe layer (≤5 ML) the largest field is found in the centre of the Fe layer. By modelling the effects of interface alloying from earlier data for bulk Fe-Co alloys, and comparing with the experimental results, the degree of interface alloying is estimated to be 2-3 ML at each interface.
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Peters AK, Leonards PE, Zhao B, Bergman A, Denison MS, Van den Berg M. Determination of in vitro relative potency (REP) values for mono-ortho polychlorinated biphenyls after purification with active charcoal. Toxicol Lett 2006; 165:230-41. [PMID: 16750337 PMCID: PMC3032053 DOI: 10.1016/j.toxlet.2006.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 04/23/2006] [Accepted: 04/24/2006] [Indexed: 11/22/2022]
Abstract
The TEF system for dioxin-like compounds has included assignment of TEF values for mono-ortho polychlorinated biphenyls (MO-PCBs). Small traces of aryl hydrocarbon receptor (AhR)-active impurities could result in artifactually higher relative potency (REP) values. MO-PCBs -105, -118, -156, and -167 were purified on an active charcoal column to remove AhR agonists that could be present as impurities. Activation or inhibition of AhR-dependent gene expression by purified MO-PCBs was studied in stably transfected cell lines (H1G1.1c3 mouse, H4G1.1c2 rat hepatoma), containing an AhR-responsive (AhR-EGFP) reporter gene. In addition, EROD activity was used as marker for CYP1A1 activity in these cell lines. MO-PCBs -105, -118, -156 induced AhR-EGFP expression in both rodent cell lines, with PCB-156 (10microM) being most effectively; inducing gene expression to approximately 27% of TCDD (mouse cells) and 62.5+/-3.4% (rat cells) of TCDD. This concurred with increased EROD activity in both cell lines to maxima of 20.5+/-1.5% and 68+/-3.2% of TCDD, respectively. No induction was observed for PCB-167. In the H1G1.1c3 mouse cells, PCB-105, -118 and -156 (10microM) significantly reduced TCDD-induced AhR-EGFP expression to 50.9+/-2.9%, 58.3+/-2.2% and 70.8+/-1.3% of TCDD. Reduced EROD activity was also observed, of 39.3+/-2.8%, 67+/-5% and 48.3+/-4% compared to TCDD. PCB-167 did not result in significant reduction. In rat cells, only PCB-156 resulted in significant decrease in TCDD-induced AhR-EGFP expression of 35%, suggesting species differences play a role. Our results suggest that purification of MO-PCBs is an essential step in determining accurate REP values, and could very likely lead to lower TEF values than those presently assigned by the WHO.
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Peters AK, Nijmeijer S, Gradin K, Backlund M, Bergman A, Poellinger L, Denison MS, Van den Berg M. Interactions of polybrominated diphenyl ethers with the aryl hydrocarbon receptor pathway. Toxicol Sci 2006; 92:133-42. [PMID: 16601081 PMCID: PMC3032055 DOI: 10.1093/toxsci/kfj186] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants that have been in use as additives in various consumer products. Structural similarities of PBDEs with other polyhalogenated aromatic hydrocarbons that show affinity for the aryl hydrocarbon receptor (AhR), such as some polychlorinated biphenyls, raised concerns about their possible dioxin-like properties. We studied the ability of environmentally relevant PBDEs (BDE-47, -99, -100, -153, -154, and -183) and the "planar" congener BDE-77 to bind and/or activate the AhR in stably transfected rodent hepatoma cell lines with an AhR-responsive enhanced green fluorescent protein (AhR-EGFP) reporter gene (H1G1.1c3 mouse and H4G1.1c2 rat hepatoma). 7-Ethoxyresorufin-O-deethylation (EROD) was used as a marker for CYP1A1 activity. Dose- and bromination-specific inhibition of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced responses was measured by their ability to inhibit the induction of AhR-EGFP expression and EROD activity. Individual exposure to these PBDEs did not result in any increase in induction of AhR-EGFP or CYP1A1 activity. The lower brominated PBDEs showed the strongest inhibitory effect on TCDD-induced activities in both cell lines. While the highest brominated PBDE tested, BDE-183, inhibited EROD activity, it did not affect the induction of AhR-EGFP expression. Similar findings were observed after exposing stably transfected human hepatoma (xenobiotic response element [XRE]-HepG2) cells to these PBDEs, resulting in a small but statically significant agonistic effect on XRE-driven luciferase activity. Co-exposure with TCDD resulted again in antagonistic effects, confirming that the inhibitory effect of these PBDEs on TCDD-induced responses was not only due to direct interaction at receptor level but also at DNA-binding level. This antagonism was confirmed for BDE-99 in HepG2 cells transiently transfected with a Gal4-AhR construct and the corresponding Gal4-Luc reporter gene. In addition, a chromatin immunoprecipitation assay further confirmed that BDE-99 could bind to the AhR and activate the AhR nuclear translocation and dioxin responsive element (DRE) binding in the context of the CYP1A1 promoter. However, the transactivation function of the BDE-99-activated AhR seems to be very weak. These combined results suggest that PBDEs do bind but not activate the AhR-AhR nuclear translocator protein-XRE complex.
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Migoya EM, Bergman A, Hreniuk D, Matthews N, Yi B, Roadcap B, Valesky R, Liu L, Riffel K, Groff M, Zhao JJ, Musson DG, Gambale J, Kosoglou T, Statkevich P, Lasseter KC, Laurent A, Johnson-Levonas AO, Murphy G, Gottesdiener K, Paolini JF. Bioequivalence of an ezetimibe/simvastatin combination tablet and coadministration of ezetimibe and simvastatin as separate tablets in healthy subjects. Int J Clin Pharmacol Ther 2006; 44:83-92. [PMID: 16502768 DOI: 10.5414/cpp44083] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVE To assess the bioequivalence of an ezetimibe/simvastatin (EZE/SIMVA) combination tablet compared to the coadministration of ezetimibe and simvastatin as separate tablets (EZE + SIMVA). METHODS In this open-label, randomized, 2-part, 2-period crossover study, 96 healthy subjects were randomly assigned to participate in each part of the study (Part I or II), with each part consisting of 2 single-dose treatment periods separated by a 14-day washout. Part I consisted of Treatments A (EZE 10 mg + SIMVA 10 mg) and B (EZE/SIMVA 10/10 mg/mg) and Part II consisted of Treatments C (EZE 10 mg + SIMVA 80 mg) and D (EZE/SIMVA 10/80 mg/mg). Blood samples were collected up to 96 hours post-dose for determination of ezetimibe, total ezetimibe (ezetimibe + ezetimibe glucuronide), simvastatin and simvastatin acid (the most prevalent active metabolite of simvastatin) concentrations. Ezetimibe and simvastatin acid AUC(0-last) were predefined as primary endpoints and ezetimibe and simvastatin acid Cmax were secondary endpoints. Bioequivalence was achieved if 90% confidence intervals (CI) for the geometric mean ratios (GMR) (single tablet/coadministration) of AUC(0-last) and Cmax fell within prespecified bounds of (0.80, 1.25). RESULTS The GMRs of the AUC(0-last) and Cmax for ezetimibe and simvastatin acid fell within the bioequivalence limits (0.80, 1.25). EZE/ SIMVA and EZE + SIMVA were generally well tolerated. CONCLUSIONS The lowest and highest dosage strengths of EZE/SIMVA tablet were bioequivalent to the individual drug components administered together. Given the exact weight multiples of the EZE/SIMVA tablet and linear pharmacokinetics of simvastatin across the marketed dose range, bioequivalence of the intermediate tablet strengths (EZE/SIMVA 10/20 mg/mg and EZE/SIMVA 10/40 mg/mg) was inferred, although these dosages were not tested directly. These results indicate that the safety and efficacy profile of EZE + SIMVA coadministration therapy can be applied to treatment with the EZE/SIMVA tablet across the clinical dose range.
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Peters AK, Sanderson JT, Bergman A, van den Berg M. Antagonism of TCDD-induced ethoxyresorufin-O-deethylation activity by polybrominated diphenyl ethers (PBDEs) in primary cynomolgus monkey (Macaca fascicularis) hepatocytes. Toxicol Lett 2006; 164:123-32. [PMID: 16448790 DOI: 10.1016/j.toxlet.2005.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Accepted: 12/09/2005] [Indexed: 11/30/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) are widespread environmental pollutants, and the levels of certain congeners have been increasing in biota and abiota in recent decades. Some PBDEs are lipophilic and persistent, resulting in bioaccumulation in the environment. Their structural similarity to other polyhalogenated aromatic hydrocarbons (PHAHs) such as polychlorinated biphenyls (PCBs) has raised concerns that PBDEs might act as agonists for the aryl hydrocarbon receptor (AhR). Recent studies in our laboratory with human and rat cell lines indicated no AhR mediated CYP1A1 induction for PBDEs. However, an earlier in vitro study by Van der Burght et al. (1999) [Van der Burght, A.S., Clijsters, P.J., Horbach, G.J., Andersson, P.L., Tysklind, M., van den Berg, M., 1999. Structure-dependent induction of CYP1A by polychlorinated biphenyls in hepatocytes of cynomolgus monkeys (Macaca fascicularis). Toxicol. Appl. Pharmacol. 155, 13-23] indicated that in cynomolgus monkey (M. fascicularis) hepatocytes PCBs with a non-planar configuration could induce CYP1A. As PBDEs show a structural similarity with non-planar (ortho substituted) PCBs, our present study focused on the possible CYP1A induction by PBDEs (BDE-47, -99, -100, -153, -154, -183, and -77) in individual preparations (n=4) of primary hepatocytes of cynomolgus monkeys (M. fascicularis). 7-Ethoxyresorufin-O-deethylase (EROD) was used as a marker for CYP1A-mediated catalytic activity. Cells were exposed for 48 h to various PBDE concentrations (0.01-10 microM), positive controls 2,3,7,8-TCDD (0.001-2.5 nM) and PCB-126 (0.01-10nM), and negative control (DMSO vehicle alone). No statistically significant induction of CYP1A was observed in the hepatocytes after 48 h of exposure to all environmentally relevant PBDEs. After exposing hepatocytes to PBDEs in combination with TCDD, a concentration-dependent decrease in TCDD-induced EROD activity was observed. All PBDEs tested showed a similar reduction in each of four experiments, though quantitative differences were observed. The observed antagonism of TCDD-induced EROD activity by PBDEs occurred in both male (n=3) and female (n=1) hepatocytes and was not due to catalytic inhibition of EROD activity or cytotoxicity. However, based on the results of this study we do not expect these antagonistic effects of PBDEs on CYP1A induction at environmental relevant levels, since these in vitro interactive effects with TCDD were observed only at relatively high concentrations that are normally not seen, e.g. in the human body.
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Bergman A, Bush K, Milette M, Popescu I, Otto K, Duzen C. 223 Implementation of Monte Carlo calculated beamlet dose distributions in a direct aperture optimization algorithm for IMRT. Radiother Oncol 2005. [DOI: 10.1016/s0167-8140(05)81200-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Depré M, Van Hecken A, Oeyen M, De Lepeleire I, Laethem T, Rothenberg P, Petty KJ, Majumdar A, Crumley T, Panebianco D, Bergman A, de Hoon JN. Effect of aprepitant on the pharmacokinetics and pharmacodynamics of warfarin. Eur J Clin Pharmacol 2005; 61:341-6. [PMID: 15983826 DOI: 10.1007/s00228-005-0907-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2004] [Accepted: 01/19/2005] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To examine the effect of aprepitant on the pharmacokinetics and pharmacodynamics of warfarin. Aprepitant is a neurokinin-1 (NK1)-receptor antagonist developed as an antiemetic for chemotherapy-induced nausea and vomiting. METHODS This was a double-blind, placebo-controlled, randomized, two-period, parallel-group study. During period 1, warfarin was individually titrated to a stable prothrombin time (expressed as international normalized ratio, INR) from 1.3 to 1.8. Subsequently, the daily warfarin dose remained fixed for 10-12 days. During period 2, the warfarin dose was continued for 8 days, and on days 1-3 administered concomitantly with aprepitant (125 mg on day 1, and 80 mg on days 2 and 3) or placebo. At baseline (day -1 of period 2) and on day 3, warfarin pharmacokinetics was investigated. INR was monitored daily. During period 2, warfarin trough concentrations were determined daily. RESULTS The study was completed by 22 healthy volunteers (20 men, 2 women). On day 3, steady-state pharmacokinetics of warfarin enantiomers after aprepitant did not change, as assessed by warfarin AUC(0-24 h) and C(max). However, compared with placebo, trough S(-) warfarin concentrations decreased on days 5-8 (maximum decrease 34% on day 8, P<0.01). The INR decreased after aprepitant with a mean maximum decrease on day 8 of 11% versus placebo (P=0.011). CONCLUSION These data are consistent with a significant induction of CYP2C9 metabolism of S(-) warfarin by aprepitant. Subsequently, in patients on chronic warfarin therapy, the clotting status should be monitored closely during the 2-week period, particularly at 7-10 days, following initiation of the 3-day regimen of aprepitant with each chemotherapy cycle.
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