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Relevant bibliographies by topics / Alpha Autoradiography

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Academic literature on the topic 'Alpha Autoradiography'

Author: Grafiati

Published: 25 May 2024

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Journal articles on the topic "Alpha Autoradiography"

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Takekawa, Shoichi, Yoshihiko Ueda, Yoshihiko Ueda, Yoshihiro Hiramatsu, Hirotsugu Munechika, and Fumio Shishido. "Imaging of Beta-Rays from Tissue Blocks with Thorotrast Deposition by Autoradiography using Fuji Computed Radiography." Jurnal Radiologi Indonesia 1, no. 2 (September 1, 2015): 58–64. http://dx.doi.org/10.33748/jradidn.v1i2.7.

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Background: Autoradiography of tissue with radioactive substance such as Thorotrast by Fuji Computed Radiography (FCR) has been available. We obtained autoradiographs from Thorotrast-deposited tissue by FCR. However, the nature of radiation from tissue with Thorotrast was not certain, because alpha particles are shielded by the plastic front of the FCR cassette. Therefore, we undertook investigation to clearly explain the nature of radiation from Thorotrast in case of autoradiography.Materials and Methods: Tissue blocks of liver and spleen with Thorotrast deposition were imaged by autoradiography using FCR, and radioactivity of tissue blocks was measured by a GM survey meter. Measurement was carried out by both with and without an aluminum plate between the tissue and the surface of GM survey meter to shield beta-rays.Results: Autoradiographs of the liver and spleen with Thorotrast were successful. It took only one day to obtain autoradiograph of the spleen, and 14 days for the liver. The radioactivity count decreased dramatically when an aluminum plate was inserted between the specimen and GM survey meter, but some radiation remained. The tissue blocks were contained in a plastic bag and the front of the Cassette of Imaging Plate is covered by a thin plastic board, so alpha-rays from Thorium dioxide in Thorotrast had been shielded from the beginning.Conclusion: We concluded that the radiation from the tissue blocks with Thorotrast in a plastic bag was mostly from beta-rays and less than 5% of radiation was from gamma-rays from the daughter nuclei of Thorium dioxide.

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Carpentier, J. L., D. Brown, B. Iacopetta, and L. Orci. "Detection of surface-bound ligands by freeze-fracture autoradiography." Journal of Cell Biology 101, no. 3 (September 1, 1985): 887–90. http://dx.doi.org/10.1083/jcb.101.3.887.

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This article describes a new freeze-fracture autoradiographic technique for the detection of radioactive ligands associated with the surface of cells in monolayer or suspension culture. Since freeze-fracture replicas are produced in the conventional way, all membrane features normally seen in freeze-fracture are retained, and autoradiographic grains produced by the labeled ligands are seen superimposed on unaltered exoplasmic membrane fracture faces. To assess the feasibility and resolution of this technique, we compared the surface distribution of alpha 2-macroglobulin and cholera toxin, labeled either with 125I or with colloidal gold, on 3T3-L1 fibroblasts. Both by autoradiography and cytochemical gold labeling, alpha 2-macroglobulin was associated specifically with coated pits, whereas cholera toxin was preferentially found over smaller, apparently non-coated membrane invaginations. Together with data on the surface localization of 125I-transferrin on HL-60 myelomonocytic cells, these results demonstrate the application of this technique for the accurate determination of ligand distribution over large areas of plasma membrane. The simplicity and reproducibility of the method should now allow freeze-fracture autoradiography to become a standard technique for investigating the distribution of both endogenous and exogenous cell surface-associated molecules, as well as the redistribution of such molecules under different experimental conditions.

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Stumpf, W. E., J. K. Morin, B. W. Ennis, J. E. Zielinski, and R. B. Hochberg. "Utility of [16 alpha-125I] iodoestradiol for autoradiography for the study of cellular and regional distribution of receptors." Journal of Histochemistry & Cytochemistry 35, no. 1 (January 1987): 87–92. http://dx.doi.org/10.1177/35.1.3794310.

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We demonstrate the utility of [16 alpha-125I]iodoestradiol for thaw-mount autoradiography with 2 micron and 4 micron thick sections of rat and mouse uterus, pituitary, and brain after in vivo administration. Under the conditions of the experiments, short-term autoradiography with exposure times between 3 and 14 days provides optimal cellular resolution, whereas long-term autoradiography with 1-2 months of exposure may be used to obtain topographic-regional surveys of distribution.

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Maltier, J. P., I. Petit, and C. Legrand. "Autoradiographic visualization of alpha 1-adrenergic receptors in cervix of early pregnant rat." Journal of Histochemistry & Cytochemistry 37, no. 5 (May 1989): 703–7. http://dx.doi.org/10.1177/37.5.2539410.

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alpha 1-Adrenergic receptors were identified, characterized, and localized in rat cervix on Day 6 of pregnancy by autoradiography. Autoradiographic study was performed in slide-mounted rat cervix sections using [3H]-prazosin ([3H]-PRAZ) as ligand. Binding was time dependent and specific. Pharmacological study indicated that specific [3H]-PRAZ binding was inhibited with high affinity by prazosin and phenylephrine and low affinity by yohimbine and clonidine. In cervix, the alpha 1-adrenergic receptors were localized mainly to the inner circular layer of the myometrium. Binding to the outer longitudinal layer of myometrium was moderate, and binding was absent in the endometrium. The regional distribution of alpha 1-adrenergic receptors strongly suggests that the circular layer of myometrium may function as an important modulator of contractile response of the cervix, probably involved in the retention of blastocysts at the utero-cervical end of the horn.

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AL Darwish, Ruqaya, Alexander Hugo Staudacher, Eva Bezak, and Michael Paul Brown. "Autoradiography Imaging in Targeted Alpha Therapy with Timepix Detector." Computational and Mathematical Methods in Medicine 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/612580.

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There is a lack of data related to activity uptake and particle track distribution in targeted alpha therapy. These data are required to estimate the absorbed dose on a cellular level as alpha particles have a limited range and traverse only a few cells. Tracking of individual alpha particles is possible using the Timepix semiconductor radiation detector. We investigated the feasibility of imaging alpha particle emissions in tumour sections from mice treated with Thorium-227 (using APOMAB), with and without prior chemotherapy and Timepix detector. Additionally, the sensitivity of the Timepix detector to monitor variations in tumour uptake based on the necrotic tissue volume was also studied. Compartmental analysis model was used, based on the obtained imaging data, to assess the Th-227 uptake. Results show that alpha particle, photon, electron, and muon tracks were detected and resolved by Timepix detector. The current study demonstrated that individual alpha particle emissions, resulting from targeted alpha therapy, can be visualised and quantified using Timepix detector. Furthermore, the variations in the uptake based on the tumour necrotic volume have been observed with four times higher uptake for tumours pretreated with chemotherapy than for those without chemotherapy.

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Koseki, C., Y. Hayashi, S. Torikai, M. Furuya, N. Ohnuma, and M. Imai. "Localization of binding sites for alpha-rat atrial natriuretic polypeptide in rat kidney." American Journal of Physiology-Renal Physiology 250, no. 2 (February 1, 1986): F210—F216. http://dx.doi.org/10.1152/ajprenal.1986.250.2.f210.

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To determine the intrarenal localization of receptors for atrial natriuretic polypeptide (ANP) in the rat, we performed autoradiography and binding assay by using 125I-labeled alpha-rat ANP (alpha-rANP). Autoradiography at the slice and microscopic level in the kidney and binding assay in isolated glomeruli demonstrated that receptors in the renal cortex were distributed mainly in glomeruli. Although dense silver grains were distributed diffusely both in inner medulla and outer stripe of outer medulla, a marked displacement of the grains was observed only in the inner medulla. Autoradiography at the microscopic level also showed that silver grains were distributed in the renal artery, renal pelvis, and inner medullary collecting tubule (IMCT) prepared by the microdissection method, but not in the arcuate artery, interlobular artery, and afferent or efferent arterioles. Specific binding was demonstrated in the isolated glomeruli and the preparation was rich in fragments of IMCT. Apparent binding affinity (Kd) and receptor density (R) for 125I-labeled alpha-rANP in isolated glomeruli and IMCT were Kd = 3.2 and 21 X 10(-9) M, and R = 320 and 420 fmol/mg protein, respectively. These observations suggest that alpha-rANP has a physiological action on glomeruli and possibly on the inner medullary collecting tubules in addition to the renal artery.

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Dvorak, A. M., R. A. Monahan-Earley, H. F. Dvorak, and S. J. Galli. "Ultrastructural cytochemical and autoradiographic demonstration of nonspecific esterase(s) in guinea pig basophils." Journal of Histochemistry & Cytochemistry 35, no. 3 (March 1987): 351–60. http://dx.doi.org/10.1177/35.3.3819377.

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We used ultrastructural autoradiographic and cytochemical methods to localize esterase activities in unstimulated guinea pig basophils and in basophils undergoing degranulation or recovery from degranulation. We used tritium-labeled diisopropylfluorophosphate (DFP) as a probe for serine enzymes and localized this probe by ultrastructural autoradiography to cytoplasmic granules of immature or mature unstimulated basophils, as well as to granules released by degranulating basophils. Ultrastructural cytochemistry using alpha naphthyl acetate (ANA) as substrate localized nonspecific esterase activity to extruded granules, either within the interiors of degranulation sacs or within granules completely separated from degranulating basophils. Extruded granules retained their esterase activity for as long as 24 hr after antigen-induced degranulation. The plasma membranes of unstimulated or degranulating basophils, as well as of basophils recovering from degranulation, displayed prominent cell surface ANA esterase ectoenzyme activity. Lipid bodies, organelles present in the cytoplasm of both control and recovering basophils, were also alpha naphthyl acetate esterase (ANAE)-positive. Thus, cytochemical and autoradiographic techniques localized esterase and/or [3H]-DFP-binding activities to cytoplasmic granules, lipid bodies, and cell surface of basophils, and these enzyme activities persisted during both degranulation and recovery from degranulation.

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Kalnins, Christopher A. G., Nigel A. Spooner, Michael J. P. Clarke, and David Ottaway. "Alpha particle autoradiography for high spatial resolution mapping of radionuclides." Journal of Environmental Radioactivity 197 (February 2019): 9–15. http://dx.doi.org/10.1016/j.jenvrad.2018.11.008.

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Healy, D. P., and D. D. Fanestil. "Localization of atrial natriuretic peptide binding sites within the rat kidney." American Journal of Physiology-Renal Physiology 250, no. 3 (March 1, 1986): F573—F578. http://dx.doi.org/10.1152/ajprenal.1986.250.3.f573.

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Although synthetic atrial natriuretic peptides (ANP) have potent natriuretic/diuretic properties, the renal mechanisms underlying these effects are not yet clearly defined. To determine the possible sites of action for ANP within the kidney, we have localized 125I-ANP binding sites by in vitro autoradiography. Slices of rat kidney were incubated with 150 pM 125I-ANP [alpha-rat ANP (alpha-rANP), 28 amino acids] alone or in the presence of 10 nM or 1 microM unlabeled ANP. Autoradiography was performed using LKB Ultrofilm or emulsion-coated cover slips together with histochemical/immunohistochemical staining of specific tubular segments. High-affinity 125I-ANP binding sites were concentrated over glomeruli and to a lesser extent over the arterial vasculature. Lower-affinity binding sites were seen over proximal tubules and inner medullary collecting ducts. The remainder of the nephron was unlabeled. The localization of high-affinity 125I-ANP binding sites in rat kidney is consistent with a glomerular filtration/hemodynamic mechanism as the principal means by which ANP promotes natriuresis/diuresis.

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Verdurand, Mathieu, Elise Levigoureux, Sophie Lancelot, Waël Zeinyeh, Thierry Billard, Isabelle Quadrio, Armand Perret-Liaudet, Luc Zimmer, and Fabien Chauveau. "Amyloid-Beta Radiotracer [18F]BF-227 Does Not Bind to Cytoplasmic Glial Inclusions of Postmortem Multiple System Atrophy Brain Tissue." Contrast Media & Molecular Imaging 2018 (2018): 1–7. http://dx.doi.org/10.1155/2018/9165458.

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The accumulation of aggregated alpha-synuclein (α-syn) in multiple brain regions is a neuropathological hallmark of synucleinopathies. Multiple system atrophy (MSA) is a synucleinopathy characterized by the predominant cerebral accumulation of aggregated α-syn as cytoplasmic glial inclusions (CGI). A premortem diagnosis tool would improve early diagnosis and help monitoring disease progression and therapeutic efficacy. One Positron Emission Tomography (PET) study suggested [11C]BF-227 as a promising radiotracer for monitoring intracellular α-syn deposition in MSA patients. We sought to confirm the binding of this radiotracer to α-syn using state-of-the-art autoradiography. Medulla sections were obtained from 9 MSA patients and 9 controls (London Neurodegenerative Diseases Brain Bank). [18F]BF-227, chemically identical to [11C]BF-227, was used at nanomolar concentrations to perform in vitro autoradiography assays. Autoradiograms were superimposed on fluorescent staining from the conformational anti-α-syn antibody 5G4 and quantified after immunofluorescence-driven definition of regions of interest. Autoradiography showed no specific signals in MSA patients in comparison to controls despite widespread pathology detected by immunofluorescence. Autoradiography does not support a significant binding of [18F]BF-227 to CGI at concentrations typically achieved in PET experiments.

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Dissertations / Theses on the topic "Alpha Autoradiography"

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Hudson, Alan Leslie. "Characterisation and comparative autoradiography of #alpha#â†2-adrenoceptors and Iâ†2-sites in mammalian brain." Thesis, University of Bristol, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388036.

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Oyedepo, Aderonke Caroline. "Human skeletal uptake of natural alpha radioactivity from '2'1'0Pb-supported '2'1'0Po." Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297922.

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Schneider, Nathaniel R. "Comparison of the measured biodistribution of 212Pb-radiolabeled monoclonal antibodies (Trastuzumab) in mice with 232Th and progeny in human reticuloendothelial tissue measured using alpha particle track autoradiographic microdosimetry from Thorotrast." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1573572379726605.

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4

Besançon, Clémence. "Étude de la mobilité du radium-226 en milieu naturel anthropisé par approches expérimentales et modélisation géochimique." Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS048.

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Le 226Ra, descendant radioactif de l’238U et isotope majoritaire naturellement présent sur Terre, suscite de nombreuses problématiques environnementales en raison de sa demi-vie de 1600 ans dans des industries variées : hydrothermalisme, désalinisation de l’eau de mer et production de zircon par exemple ; mais surtout dans les industries extractives : pétrole et gaz de schiste, charbon, phosphate et uranium. Le 226Ra est retenu au sein des résidus de traitement des mines d’U et sa mobilité est contrôlée par les mécanismes de sorption à la surface de minéraux (oxy-hydroxydes de fer, phyllosilicates, zéolithes), ou de la matière organique ou par la formation de solutions solides (minéraux sulfatés comme la barytine et minéraux carbonatés). La concentration moyenne dans les roches lithosphériques étant de 32 Bq/kg, soit 1 ppt, l’identification des mécanismes de rétention de ce radionucléide à l’échelle du matériau échantillonné sur le terrain est rendue difficile par son caractère ultra-trace. Les extractions séquentielles, technique classique pour le suivi des éléments traces, peuvent être sujettes à de nombreux artefacts exacerbés pour les éléments ultra-traces. Dans le cadre de ce travail, une modélisation géochimique d’expériences de lixiviations séquentielles a en effet montré que cette technique conduit à des interprétations biaisées en particulier dans le cas du 226Ra, soumis à de nombreux mécanismes de remobilisation aux différentes étapes de lixiviation. Afin de mieux comprendre les processus de rétention du 226Ra et la distribution de celui-ci dans les matériaux hétérogènes et finement divisés, dont font partie les résidus de traitement de l’extraction minière, une nouvelle approche a été développée couplant autoradiographie alpha, cartographies chimiques élémentaires et caractérisations minéralogiques obtenues entre autres par MEB/EDS sur lames minces pétrographiques. Une analyse globale directe de l’ensemble de l’activité de l’échantillon à l’échelle de la lame mince pétrographique est ainsi possible. Cette méthode a été qualifiée tout d’abord sur des échantillons de référence contenant un seul minéral synthétique ou naturel jouant un rôle important dans la rétention du 226Ra en milieu naturel, puis à un assemblage de trois des principaux minéraux responsables de la rétention, à savoir : barytine, minéraux argileux et oxy-hydroxydes de fer. Enfin, elle a été directement appliquée à des résidus de traitement. Un premier corpus est issu des sites français de stockage post-miniers de Bellezane, où les résidus de traitement sont stockés sous couverture solide, et de Bois Noirs Limouzat, qui utilise une couverture liquide. Sont également considérés des résidus du site en activité de traitement de minerai de McClean Lake, au Canada, qui utilise un processus de neutralisation des résidus par précipitation de barytine
226Ra, a radioactive decay product of 238U and the most prevalent naturally occurring isotope of radium leads to many environmental issues in various industries due to its half-life of 1600 years: hydrothermal energy, seawater desalination and zircon production among others. The most impacted industries are the extractive ones: shale oil and gas production, coal, phosphate and uranium extraction. 226Ra remains in tailings from U mines and its mobility is controlled by retention mechanisms: sorption on mineral surfaces (iron oxy-hydroxydes, phyllosilicates, zeolites) and organic matter, or by the formation of solid solutions (sulfate minerals such as barite and carbonate minerals). The average concentration in lithospheric rocks being 32Bq / kg, or 1ppt, the identification of the retention mechanisms of this radionuclide at the scale of the material sampled in the field is made difficult because it is an ultra-trace element. Sequential extractions are commonly used to assess the retention of trace elements, but this technique is subject to experimental and analytical artefacts which are exacerbated in the case of an ultra-trace element. In this work, geochemical modeling of sequential extractions experiments has indeed shown that this technique leads to biased interpretations, particularly in the case of 226Ra which is remobilized during the different extraction steps. In order to have a better understanding of the retention of 226Ra and its distribution in heterogeneous and fine-grained materials, including mine tailings, a new approach has been developed. This approach combines alpha autoradiography, chemical elemental cartographies and mineralogical characterizations obtained on petrographic thin sections. A direct global analysis of the activity of the sample at the petrographic thin section scale is thus possible. This method was first qualified on model samples containing a single synthetic or natural mineral playing an important role in the retention of 226Ra in the natural environment. It was then tested on an assemblage of three of the main minerals responsible for the retention, namely: barite, clay minerals and iron oxy-hydroxydes. Finally, it was applied to U-mine tailings. A first set of samples comes from the French post-mining storage sites of Bellezane, where the tailings are stored under a solid cover, and from Bois Noirs Limouzat, which uses a liquid cover. A second set of tailings sample comes from the on-going ore processing facility of McClean Lake, Canada, which uses a tailings neutralization process by barite precipitation. The results show that barite is the main trap of 226Ra via the formation of a solid solution (Ba, Ra)SO4 in all these tailings from different sites. Over a few years, with or without neutralization by barite precipitation, it appears that this solid solution tends towards a recrystallization equilibrium which controls the concentration of 226Ra in solution. These results will subsequently be integrated into reactive transport type modeling to predict the long-term behavior of these tailings

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PEREIRA, MARCO A. S. "Radiografia com partículas alfa induzida por nêutrons." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11619.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

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Book chapters on the topic "Alpha Autoradiography"

1

Örbom, Anders, Brian W. Miller, and Tom Bäck. "Beta and Alpha Particle Autoradiography." In Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 563–87. New York: CRC Press, 2021. http://dx.doi.org/10.1201/9780429489556-30.

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Woollard, Jeffrey E., Yirun Jiang, James F. Curran, Thomas E. Blue, and Rolf F. Barth. "Determination of Boron Concentration in Tissues by Means of Alpha Autoradiography." In Progress in Neutron Capture Therapy for Cancer, 317–20. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3384-9_69.

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Yanagie, Hironobu, Koichi Ogura, Yasumasa Nonaka, Toshio Matumoto, Yoshinori Sakurai, Tooru Kobayashi, Kouji Ono, Masazumi Eriguchi, and Hisao Kobayashi. "Alpha-Autoradiographic Determination of 10B Concentrations in Cancer Bearing Mice for Boron Neutron-Capture Therapy." In Frontiers in Neutron Capture Therapy, 945–51. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1285-1_143.

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Jiang, Yirun, Sherry Ng, Thomas E. Blue, Joan Rotaru, and Rolf F. Barth. "The Application of an Alpha Autoradiographic Technique for Determination of Boron-10 Concentrations in a Study of Intratumoral Injection of BSH and CBU-2’." In Advances in Neutron Capture Therapy, 449–51. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2978-1_92.

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Conference papers on the topic "Alpha Autoradiography"

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Tanguay, Jesse, Francois Benard, Anna Celler, Thomas J. Ruth, and Paul Schaffer. "Spatial resolution properties of digital autoradiography systems for pre-clinical alpha particle imaging (Conference Presentation)." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor Gimi and Andrzej Krol. SPIE, 2017. http://dx.doi.org/10.1117/12.2252282.

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Walsh, P. N., D. Sinha, F. Kueppers, F. S. Seaman, and K. B. Blanketein. "THE REGULATION OF FACTOR XIa ACTIVITY BY PLATELETS AND ALPHA-1-PROTEASE INHIBITOR." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642805.

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Since activated platelets bind factor XI (FXI), FXIa and high molecular weight kininogen (HMWK), promote the proteolytic activation of FXI, release an inhibitor of FXIa, and may protect FXIa from inactivation by plasma protease inhibitors, we have studied the complex interrelationships between platelets, FXIa, alpha-l-protease inhibitor (α1PI) and F-IX activation. Purified FXIa was incubated in the presence or absence of thrombin-treated gel-filtered platelets (GFP) or a platelet releasate and FXIa activity assayed by the release of a H-labeled activation peptide from H-FIX. Our results confirm the report of Soons et al (Blood 68:140, 1986) that platelets secrete an inhibitor of FXIa (PXIaI). The presence of intact GFP partially protected FXIa from inactivation by the PXIaI. The presence of GFP also partially protected FXIa from inactivation in the presence of both α1PI and the PXIaI. Purified HMWK had no effect on FXIa inactivation by α1PI or by the PXIaI. Both platelet-bound FXIa and unbound FXIa in the presence of thrombin-activated platelets were protected from inactivation by α1PI. Thrombin-treated GFP had no effect on the capacity of cxjPI to inactivate trypsin or elastase. Thus the protection of FXIa from inactivation by α1PI and/or the PXIaI did not arise from a) the binding of FXIa to platelets, b) the presence of HMWK, or c) the inactivation of α1PI by platelets. When 125I-labeled FXIa was incubated with α1PI and examined by autoradiography of SDS polyacrylamide gels a complex (Mr 85,000) was observed between the active-site-containing FXIa light chain (Mr 30,000) and α1PI (Mr 54,000). The formation of this complex was inhibited in the presence of activated platelets or platelet releaseates, but was not affected by HMWK. These results support the hypothesis that platelets can regulate FXIa catalyzed F-IX activation by secreting an inhibitor of FXIa that may act primarily outside the platelet microenvironment and by protecting FXIa from inhibition, thereby localizing F-IX activation to the platelet plug.

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Kanzaki, M., H. Kimura, and J. Ochi. "IMMUNOHISTOCHEMICAL LOCALISATION OF SEROTONIN IN RABBIT PLATELETS." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644884.

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Although it has been accepted that the dense bodymay be the most predominant storage site of serotonin (5HT), some literatures suggested that 5KT was localized more abundantly in the alpha-granules or theplasma membrane than in the dense body. The discrepancy may be due to different methods used.For example, the former dense body theory is mostly based on biochemical measurements of 5HT which may easily diffusible among subcellular fractions, and the latter hypothesis is proposed by autoradiographic demonstration of exogenously applied 5HT. In the present study, endogenous 5HT has been visualized by immunoelectron microscopy using monoclonal antibody against 5HT.Platelet rich plasma (PRP) of rabbits was suspended for 30 min in a fixative containing 0.5% glutaraldehyde, 4% paraformaldehyde and 0.5% picric acid in 0.1M phosphate buffer (PB; pH 7.4), and resuspended overnight in the glutaraldehyde-free fixative. After wash the PRP was incubated for 3 days with PB containing saline and 0.03% Triton X-100 (PBST), and reacted for 3 days with monoclonal 5HT antibody ( 1μg/ml). The immunoreactive sites were rendered visible byABC immunohistochemistry (ABC from Vector Co. USA) with DAB precipitation. The colorized PRP was osmificated (1%) for 30 min, dehydrated with alcohol, embedded in Spurr and cut into ultrathin sections for electron microscopic observation. For immunohistochemical controls monoclonal 5HT antibody preabsorbed with O.lmM 5HT or non-immune normal mouse serum was used as the primary antibody, and no specific reaction was observed. Very fine 5HT-positive immunoreaction products were clearly localized in some granules with different staining intensity. These positive granules were mostly round or ovoid in shape with variousdiameters. The present immunohistochemical results appears to support previous results suggesting that 5HT is located in such granules as alpha-granules anddense bodies.

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