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Maisa U, Jacob T, Nagel J, Hagen R. Objektivierung und Visualisierung von Stimmparametern zur Verbesserung der Stimmrehabilitation nach Laryngektomie. Laryngorhinootologie 2004. [DOI: 10.1055/s-2004-823370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Nagel J, Molerus O, Wirth KE. Ein neues Verfahren zur Handhabung feinster Partikel und Herstellung dünnster Schichten am Beispiel der Pulverlackierung mit Flüssigstickstoff. CHEM-ING-TECH 2004. [DOI: 10.1002/cite.330690965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Conradi S, Smolenski UC, Bak P, Biskupek H, Frey M, Galeazzi A, Klaas T, Kluge K, Müller K, Nagel J, Psczolla M, Schröder N, Sturm C, Wagner W, Wilde W. Reliabilität der manualmedizinischen Tests bei Low Back Pain (LBP) Patienten. MANUELLE MEDIZIN 2003. [DOI: 10.1007/s00337-003-0236-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ericson K, Halvarsson B, Nagel J, Rambech E, Planck M, Piotrowska Z, Olsson H, Nilbert M. Defective mismatch-repair in patients with multiple primary tumours including colorectal cancer. Eur J Cancer 2003; 39:240-8. [PMID: 12509957 DOI: 10.1016/s0959-8049(02)00584-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Individuals with an inherited predisposition to cancer development are at an increased risk of developing multiple tumours. Hereditary non-polyposis colorectal cancer (HNPCC) is one of the most common hereditary cancer syndromes and is estimated to account for approximately 2% of colorectal cancers. However, HNPCC individuals are at an increased risk of developing other tumour types such as cancers of the endometrium, urothelium and small intestine. We have utilised a population-based regional cancer registry to identify all patients with double primary colorectal cancers and at least one additional malignancy and characterised the tumour spectrum in this patient group. We subsequently selected those 47 individuals who had developed at least four malignancies, including two colorectal cancers, for studies of the tumour characteristics associated with HNPCC. In total, these individuals developed 209 tumours, 156 of which were successfully retrieved. Microsatellite instability (MSI), a phenomenon caused by defective mismatch-repair (MMR), was identified in 63/154 (41%) evaluable tumours with a MSI-high pattern in 59 and a MSI-low pattern in four tumours. All tumours were immunohistochemically stained for the MMR proteins MLH1 and MSH2, with loss of expression in 55/63 (87%) MSI tumours and in 2/89 (2%) microsatellite stable (MSS) tumours. This loss affected MLH1 in 24 tumours and MSH2 in 33 tumours. A concordant loss of expression for the same MMR protein in several tumours from the same individual, a pattern that strongly suggests an underlying germline MMR gene mutation, was found in 17/45 (38%) patients and affected MLH1 in 8 patients and MSH2 in 9 patients. We conclude that the development of multiple primary tumours, including synchronous or metachronous colorectal cancers, is associated with an increased frequency of MSI and loss of immunohistochemical expression of MLH1 and MSH2.
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Nagel J, Hauber W. Effects of salient environmental stimuli on extracellular adenosine levels in the rat nucleus accumbens measured by in vivo microdialysis. Behav Brain Res 2002; 134:485-92. [PMID: 12191835 DOI: 10.1016/s0166-4328(02)00062-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In the nucleus accumbens (NAc), the neuromodulator adenosine plays a major role in control of behaviour. The NAc subserves behaviour governed by salient stimuli in the environment, however, it is unknown whether such stimuli and the behavioural effects elicited are associated with changes in NAc extracellular adenosine levels. In order to further characterise the neuromodulatory actions of adenosine, the present study investigated for the first time the effects of four prototypical stimuli known to involve NAc processing on extracellular levels of adenosine in the NAc. Using in vivo microdialysis, the following stimuli were examined: (1) an appetitive, unfamiliar stimulus (palatable food), (2) an appetitive, familiar stimulus (standard laboratory food), (3) an aversive stimulus (handling) and (4) a novelty stimulus (cage change). Results revealed that neither of these stimuli significantly changed extracellular adenosine levels in the NAc. These findings demonstrate that NAc extracellular adenosine is not responsive to a number of prototypical salient stimuli in the environment. Thus the data provide no clues to suggest that transient changes of extracellular adenosine in the NAc modulate behavioural responses governed by these stimuli.
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Pretzsch H, Biber P, ursky J, von Gadow K, Hasenauer H, Kandler G, Kenk G, Kublin E, Nagel J, Pukkala T, Skovsgaard JP, Sodtke R, Sterba H. Recommendations for Standardized Documentation and Further Development of Forest Growth Simulators. Empfehlungen fur die standardisierte Beschreibung und Weiterentwicklung von Waldwachstumssimulatoren. ACTA ACUST UNITED AC 2002. [DOI: 10.1046/j.1439-0337.2002.00138.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hamhaber U, Grieshaber FA, Nagel J, Klose U. [Illustration of elasticity differences using MR-elastography]. Z Med Phys 2002; 11:236-44. [PMID: 11820180 DOI: 10.1016/s0939-3889(15)70523-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Differences of elasticity in tissue phantoms with inclusions of different elasticity were mapped by means of MR elastography (MRE). This new magnetic resonance imaging technique is based on the phase shift of the MR signal by switching a motion sensitizing magnetic field gradient simultaneously with the coupling of a shear wave. Wave patterns showing snapshots of the shear wave that propagates through the investigated substance were depicted in tomographic phase images. It was investigated wether a visualization of differences in elasticity of soft tissues was possible on the basis of differences in the wavelength. For this purpose, tissue phantoms with cylindrical inclusions were produced from agar gels, with agar concentrations between 1.0 and 1.5%. The diameters of the inclusions were of the order of a few centimetres. For diameters as small as 4 cm, there were still distinct differences in the wavelength between the matrix and the inclusion. The results of our study suggest that this technique has the potential for future application as an additional imaging method for tumor detection.
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Gardella L, Viruega A, Rojas H, Nagel J. A case of a patient with SUNCT syndrome treated with Jannetta procedure. Cephalalgia 2001; 21:996-9. [PMID: 11843874 DOI: 10.1046/j.1468-2982.2001.00252.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hauber W, Neuscheler P, Nagel J, Müller CE. Catalepsy induced by a blockade of dopamine D1 or D2 receptors was reversed by a concomitant blockade of adenosine A(2A) receptors in the caudate-putamen of rats. Eur J Neurosci 2001; 14:1287-93. [PMID: 11703457 DOI: 10.1046/j.0953-816x.2001.01759.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The present study sought to determine, in more detail, the effects of an unselective and a selective adenosine A(2A) receptor blockade on catalepsy induced by a blockade of dopamine D1 or D2 receptors in rats. The results demonstrated that systemic administration of the unselective A1/A2 receptor antagonist, theophylline and the selective A(2A) receptor antagonist, CSC potently reversed catalepsy induced by a systemic D2 receptor blockade with raclopride or by a bilateral blockade of D2 receptors in the caudate-putamen (CPu) with S(-)sulpiride. Likewise, systemic administration of theophylline and CSC reversed catalepsy induced by a systemic D1 receptor blockade with SCH23390; theophylline also counteracted catalepsy after an intra-CPu D1 receptor blockade with SCH23390. Intracerebral co-microinfusions of the selective A(2A) receptor antagonist, MSX-3 together with a D1 (SCH23390) or D2 receptor [S(-) sulpiride] antagonist revealed that catalepsy due to intra-CPu D1 or D2 receptor blockade can be potently reversed by an intra-CPu A2A receptor blockade. In conclusion, our results with systemic and intra-CPu drug administration demonstrate that D1 and D2 receptor-mediated catalepsy can both be reversed by a concomitant blockade of A(2A) receptors. Our results implicate that the CPu is a critical neural substrate for antagonistic interactions of a D1/D2 receptor blockade and an A(2A) receptor blockade in control of motor activity. The present results provide further support for the view that A(2A) receptor antagonists may be potential therapeutics for the treatment of Parkinson's disease.
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Petty M, Pearson C, Monkman A, Casalini R, Capaccioli S, Nagel J. Application of impedance spectroscopy to the study of organic multilayer devices. Colloids Surf A Physicochem Eng Asp 2000. [DOI: 10.1016/s0927-7757(99)00559-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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von Deimling A, Fimmers R, Schmidt MC, Bender B, Fassbender F, Nagel J, Jahnke R, Kaskel P, Duerr EM, Koopmann J, Maintz D, Steinbeck S, Wick W, Platten M, Müller DJ, Przkora R, Waha A, Blümcke B, Wellenreuther R, Meyer-Puttlitz B, Schmidt O, Mollenhauer J, Poustka A, Stangl AP, Lenartz D, von Ammon K. Comprehensive allelotype and genetic anaysis of 466 human nervous system tumors. J Neuropathol Exp Neurol 2000; 59:544-58. [PMID: 10850867 DOI: 10.1093/jnen/59.6.544] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Brain tumors pose a particular challenge to molecular oncology. Many different tumor entities develop in the nervous system and some of them appear to follow distinct pathogenic routes. Molecular genetic alterations have increasingly been reported in nervous system neoplasms. However, a considerable number of affected genes remain to be identified. We present here a comprehensive allelotype analysis of 466 nervous system tumors based on loss of heterozygosity (LOH) studies with 129 microsatellite markers that span the genome. Specific alterations of the EGFR, CDK4, CDKN2A, TP53, DMBT1, NF2, and PTEN genes were analyzed in addition. Our data point to several novel genetic loci associated with brain tumor development, demonstrate relationships between molecular changes and histopathological features, and further expand the concept of molecular tumor variants in neuro-oncology. This catalogue may provide a valuable framework for future studies to delineate molecular pathways in many types of human central nervous system tumors.
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Port J, Nagel J, Faust U. Dynamisches Zustandsmodell spannungsgesteuerter Ionenkanäle. BIOMED ENG-BIOMED TE 2000. [DOI: 10.1515/bmte.2000.45.s1.375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Newman S, Pitcairn G, Steed K, Harrison A, Nagel J. Deposition of fenoterol from pressurized metered dose inhalers containing hydrofluoroalkanes. J Allergy Clin Immunol 1999; 104:S253-7. [PMID: 10588986 DOI: 10.1016/s0091-6749(99)70042-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The imaging technique of gamma scintigraphy has been used to quantify the total amount of drug deposited in the lungs and the pattern of regional lung deposition, for formulations of Berodual (Boehringer Ingelheim GmbH) delivered from pressurized metered dose inhalers formulated with chlorofluorocarbons, and with hydrofluoroalkane-134a or -227. Data were expressed as the mass of fenoterol deposited in the lungs from the Berodual formulations. All the formulations tested gave a whole lung deposition less than 20% of the metered (exvalve) dose. The mass of fenoterol deposited in the lungs for a solution formulation containing hydrofluoroalkane-134a was inversely proportional to the actuator nozzle diameter. The data suggest that the total and regional lung deposition of hydrofluoroalkane-based pressurized aerosol formulations is highly product-specific and that changes in bioavailability can be brought about by varying both the constituents of the formulation and the design of the actuator.
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Li JH, Joppek C, Faust U, Nagel J. [Imaging cardiac impedance changes in the human thorax using impedance tomography]. BIOMED ENG-BIOMED TE 1998; 43 Suppl:52-3. [PMID: 9859253 DOI: 10.1515/bmte.1998.43.s1.52] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Wilde J, Wigman A, Nagel J, Oertel U, Beeby A, Tanner B, Petty M. Structural and optical properties of Langmuir—Blodgett films of a Schiff base coordination polymer: A material for hydrocarbon vapor sensing. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1521-4044(199806)49:6<294::aid-apol294>3.0.co;2-m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Hauber W, Nagel J, Sauer R, Müller CE. Motor effects induced by a blockade of adenosine A2A receptors in the caudate-putamen. Neuroreport 1998; 9:1803-6. [PMID: 9665604 DOI: 10.1097/00001756-199806010-00024] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Motor effects mediated through adenosine A2A receptors within the caudate-putamen were investigated in rats using bilateral microinfusions of MSX-3 (9 microg in 1 microl per side), a water-soluble phosphate prodrug of the selective A2A receptor antagonist MSX-2. Blockade of striatal A2A receptors produced a significant motor stimulation measured by an enhanced sniffing activity. Furthermore, catalepsy induced by systemic dopamine D1 (0.75 mg/kg SCH23390, i.p.) or dopamine D2 receptor blockade (1.5 mg/kg raclopride, i.p.) was potently reversed. These findings suggest that A2A receptors within the caudate-putamen are tonically activated by endogenous adenosine and that a striatal A2A receptor blockade produces motor stimulant effects, in particular in animals with dopamine hypofunction. The present results support the view that A2A receptor antagonists may be potentially useful therapeutics for the treatment of Parkinson's disease.
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Ploetz R, Benscher D, Vázquez A, Colls A, Nagel J, Schaffer B. MANGO DECLINE: RESEARCH IN FLORIDA ON AN APPARENTLY WIDE-SPREAD DISEASE COMPLEX. ACTA ACUST UNITED AC 1997. [DOI: 10.17660/actahortic.1997.455.72] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Nagel J, Edholm O, Berger O, Jähnig F. Investigation of the proton release channel of bacteriorhodopsin in different intermediates of the photo cycle. A molecular dynamics study. Biochemistry 1997; 36:2875-83. [PMID: 9062117 DOI: 10.1021/bi962427h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Molecular dynamics simulations on bacteriorhodopsin were performed starting from a conformation based on electron cryomicroscopy studies [Henderson, R., et al. (1990) J. Mol. Biol. 213, 899-929]. We examined the proton release channel in different intermediates of the bacteriorhodopsin photocycle. In the simulations of the ground state, two stable sets of conformations were observed differing in the distance of the guanidinium group of Arg82 to the Schiff base. The set of conformations in which Arg82 is located closer to the Schiff base has a lower potential energy and agrees better with experimental data than the other set. With both sets, we performed a series of simulations in which the chromophore was isomerized to different states using purposive and nonpurposive methods. The energetic consideration of the different states argues for the location of the guanidinium group of Arg82 close to the Schiff base. The results also show that no C13-C14, C14-C15 dicis conformation of the retinal occurs in the K/L-intermediate of the photocycle instead supporting the occurrence of C13-C14 cis in these intermediates. In a last series of simulations, we modeled the M-intermediate of the bacteriorhodopsin photocycle. Again, comparison to different experimental data indicates that Arg82 points toward the Schiff base. We conclude that the guanidinium group of Arg82 is located close to the Schiff base at a distance of approximately 4.5 A and stays there at least up to the M-intermediate of the photocycle.
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Roberts WW, Nagel J. First-order projections activated by stimulation of hypothalamic sites eliciting attack and flight in rats. Behav Neurosci 1997. [PMID: 8888997 DOI: 10.1037//0735-7044.110.3.509] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
14C-deoxyglucose autoradiographs of attack rats were compared densitometrically with those of control rats whose electrodes were located nearby and elicited nonaggressive behaviors like those that accompanied the attack. Most closely associated with attack was the path from the ventromedial hypothalamus through the ventral supraoptic commissural pathway to the peripeduncular area, subparafascicular nucleus, zona incerta, and cuneiform area. Moderately correlated with attack were 4 visual areas: the dorsal and ventral lateral geniculate nuclei, pretectal area, and superior colliculus. Activity in the periaqueductal gray was unrelated to attack ipsilaterally and only weakly related contralaterally. In an orthogonal analysis, upward-oriented flight thresholds were significantly correlated with medial activation extending anteriorly to the lateral septal nucleus, dorsally to the thalamic paraventricular-parataenial region, and posteriorly to the periaqueductal gray.
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Olea E, Gil MC, Tomicic M, Araya G, Chandía M, Quintana JC, Pinto L, Orellana P, Nagel J, Ortíz V. [Nationally produced 153SmEDTMP in the palliative treatment of metastatic bone cancer pain]. Rev Med Chil 1996; 124:805-12. [PMID: 9138368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
153SmEDTMP was obtained from enriched 152Sm irradiated at the 5 MW Chilean Research Reactor and labelled at a molar ratio of 15:1 pH 7.5. Biodistribution, autoradiography, radiochemical purity tests were done for evaluation. 40 patients were treated with 37-55 MBq/kg weight. Bone scans using 99mTcHMDP were obtained prior and after treatment. Bone marrow depression was observed in 37% of them and normal liver function in all of them. In 45% the pain dissapear completely, in 22.5% significantly decreased and partially in 30%. In 17 patients more than one dosis was injected. Our preliminary results indicate that 153SmEDTMP is a promising radiotherapeutic agent for palliative treatment of metastatic bone cancer pain and encourage its use specially because it can be produced in countries with low economic resources, thus a large number of patients can get the benefits of this new procedure.
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Roberts WW, Nagel J. First-order projections activated by stimulation of hypothalamic sites eliciting attack and flight in rats. Behav Neurosci 1996; 110:509-27. [PMID: 8888997 DOI: 10.1037/0735-7044.110.3.509] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
14C-deoxyglucose autoradiographs of attack rats were compared densitometrically with those of control rats whose electrodes were located nearby and elicited nonaggressive behaviors like those that accompanied the attack. Most closely associated with attack was the path from the ventromedial hypothalamus through the ventral supraoptic commissural pathway to the peripeduncular area, subparafascicular nucleus, zona incerta, and cuneiform area. Moderately correlated with attack were 4 visual areas: the dorsal and ventral lateral geniculate nuclei, pretectal area, and superior colliculus. Activity in the periaqueductal gray was unrelated to attack ipsilaterally and only weakly related contralaterally. In an orthogonal analysis, upward-oriented flight thresholds were significantly correlated with medial activation extending anteriorly to the lateral septal nucleus, dorsally to the thalamic paraventricular-parataenial region, and posteriorly to the periaqueductal gray.
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Grimberg SJ, Nagel J, Aitken MD. Kinetics of phenanthrene dissolution into water in the presence of nonionic surfactants. ENVIRONMENTAL SCIENCE & TECHNOLOGY 1995; 29:1480-1487. [PMID: 22276867 DOI: 10.1021/es00006a008] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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49
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Olea E, Ortiz V, Nagel J, Arenas L. Bone seeking agent uptake in abdominal muscle after exercise. Clin Nucl Med 1995; 20:561-2. [PMID: 7648752 DOI: 10.1097/00003072-199506000-00027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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50
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Spangenberg G, Vallés MP, Wang ZY, Montavon P, Nagel J, Potrykus I. Asymmetric somatic hybridization between tall fescue (Festuca arundinacea Schreb.) and irradiated Italian ryegrass (Lolium multiflorum Lam.) protoplasts. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 1994; 88:509-519. [PMID: 24186103 DOI: 10.1007/bf01240911] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/1993] [Accepted: 09/09/1993] [Indexed: 06/02/2023]
Abstract
Intergeneric asymmetric somatic hybrids have been obtained by the fusion of metabolically inactivated protoplasts from embryogenic suspension cultures ofFestuca arundinacea (recipient) and protoplasts from a non-morphogenic cell suspension ofLolium multiflorum (donor) irradiated with 10, 25, 50, 100, 250 and 500 Gy of X-rays. Regenerating calli led to the recovery of genotypically and phenotypically different asymmetric somatic hybridFestulolium plants. The genome composition of the asymmetric somatic hybrid clones was characterized by quantitative dot-blot hybridizations using dispersed repetitive DNA sequences specific to tall fescue and Italian ryegrass. Data from dot-blot hybridizations using two cloned Italian ryegrass-specific sequences as probes showed that irradiation favoured a unidirectional elimination of most or part of the donor chromosomes in asymmetric somatic hybrid clones obtained from fusion experiments using donor protoplasts irradiated at doses ≤ 250 Gy. Irradiation of cells of the donor parent with 500 Gy prior to protoplast fusion produced highly asymmetric nuclear hybrids with over 80% elimination of the donor genome as well as clones showing a complete loss of donor chromosomes. Further information on the degree of asymmetry in regenerated hybrid plants was obtained from chromosomal analysis including in situ hybridizations withL. multiflorum-specific repetitive sequences. A Southern blot hybridization analysis using one chloroplast and six mitochondrial-specific probes revealed preferentially recipient-type organelles in asymmetric somatic hybrid clones obtained from fusion experiments with donor protoplasts irradiated with doses higher than 100 Gy. It is concluded that the irradiation of donor cells before fusion at different doses can be used for producing both nuclear hybrids with limited donor DNA elimination or highly asymmetric nuclear hybrid plants in an intergeneric graminaceous combination. For a wide range of radiation doses tested (25-250Gy), the degree of the species-specific genome elimination from the irradiated partner seems not to be dose dependent. A bias towards recipient-type organelles was apparent when extensive donor nuclear genome elimination occurred.
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