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Radioactive Tracer (radioactive + tracer)
Selected AbstractsMeasurement of specific radioactivity in proteins separated by two-dimensional gel electrophoresisELECTROPHORESIS, Issue 5-6 2006Shaobo Zhou Abstract We report a method to quantify the specific radioactivity of proteins that have been separated by 2-DE. Gels are stained with SyproRuby, and protein spots are excised. The SyproRuby dye is extracted from each spot using DMSO, and the fluorescence is quantified automatically using a plate reader. The extracted gel piece is then dissolved in hydrogen peroxide and radioactivity is quantified by liquid scintillation counting. Gentle agitation with DMSO for 24,h was found to extract all the SyproRuby dye from gel fragments. The fluorescence of the extract was linearly related to the amount of BSA loaded onto a series of 1-D gels. When rat muscle samples were run on 2-DE gels, the fluorescence extracted from 54,protein spots showed a good correlation (r = 0.79, p < 0.001) with the corresponding spot intensity measured by conventional scanning and image analysis. DMSO extraction was found not to affect the amount of radioactive protein left in the gel. When a series of BSA solutions of known specific radioactivity were run on 2-DE gels, the specific radioactivity measured by the new method showed a good correlation (r = 0.98, p < 0.01, n = 5) with the specific radioactivity measured directly before loading. Reproducibility of the method was measured in a series of 2-DE gels containing proteins from the livers of rats and mice that had been injected with [35S]methionine. Variability tended to increase when the amount of radioactivity in the protein spot was low, but for samples containing at least 10,dpm above background the CV was around 30%, which is comparable to that obtained when measuring protein expression by conventional image analysis of SyproRuby-stained 2-DE gels. Similar results were obtained whether spots were excised manually or using a spot excision robot. This method offers a high-throughput, cost-effective and reliable method of quantifying the specific radioactivity of proteins from metabolic labelling experiments carried out in,vivo, so long as sufficient quantities of radioactive tracer are used. [source] Decreasing the Sampling Time Interval in Radioactive Particle TrackingTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2003Navid Mostoufi Abstract The study of the movement of solids in multiphase reactors using radioactive particle tracking is currently limited to fairly modest particle velocities because of count-rate limitations of the detection system. In this work, this restriction was overcome by increasing the activity of the radioactive tracer, by decreasing the sampling time interval and by modifying the particle tracking software to recognize which detectors were saturated and to use only the data from the remaining unsaturated detectors. Higher tracer activity resulted in lower standard deviation of the calculated tracer coordinates. L'étude du mouvement des solides par traçage avec des particules radioactives dans un réacteur polyphasique est actuellement limitée à des vitesses de particules relativement modestes à cause des limites de comptage du système de détection. Dans ce travail, on contourne cette restriction en accroissant l'activité du traceur radioactif, en diminuant l'intervalle de temps d'échantillonnage et en modifiant le logiciel de traçage des particules de façon à reconnaître les détecteurs qui sont saturés et à utiliser uniquement les données venant des détecteurs non saturés restants. Une plus grande activité du traceur donne un écart type plus petit pour les coordonnées de traceur calculées. [source] Characteristics of sentinel lymph nodes' metastatic involvement in early stage of vulvar cancerAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 6 2009Jaroslav KLÁT Background:, Nodal involvement is one of the most significant prognostic factors in early-stage vulvar cancer. Aims:, To determine the diagnostic accuracy of sentinel lymph node (SLN) detection in early-stage vulvar cancer and to describe the characteristics of metastatic lymph node involvement. Methods:, Of 23 women with early-stage squamous cell vulvar cancer included in the study, five had lateral lesions and 18 had midline lesions. SLN detection was performed by using a radioactive tracer and blue dye, followed by radical vulvectomy or radical wide excision with uni/bilateral inguinofemoral lymphadenectomy, depending on tumour size and localization. SLNs were subsequently examined with haematoxylin,eosin and immunohistochemistry. Results:, The SLN detection was successful in all 23 women (100%) and in 38 of 41 groins (92.3%) tested. The total number of SLNs was 67, with an average of 1.76 per groin. In total, 20 positive SLNs were detected in 14 of 23 patients. From a total of 20 positive SLNs, micrometastases were found in five SLNs and isolated tumour cells in one SLN. We experienced one case with a false negativity of SLN. Sensitivity, negative predictive value, accuracy and false negativity of SLN detection were 93.3%, 88.8%, 95.6% and 7.1% respectively. Conclusion:, The SLN biopsy performed by an experienced team is a feasible method, with high accuracy in patients with early-stage vulvar cancer. Prognostic value of micrometastases should be confirmed in further studies. [source] The early history of 32P as a radioactive tracer in biochemical research: A personal memoirBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 3 2005Howard Gest The concept of using radioactive isotopes as "tracers" of chemical conversions was conceived and developed by inorganic chemist Georg de Hevesy (Nobel Laureate in Chemistry 1943). In 1935, he began to apply the technique to various biological processes using 32P, and his experiments revealed the dynamic character of physiology and metabolism. Following de Hevesy's lead, Samuel Ruben (University of California, Berkeley) exploited 32P in 1937,38 for investigation of phospholipid metabolism. Between 1937 and 1940, Ruben and colleague Martin Kamen spearheaded tracer studies in various biological systems using 32P, short-lived 11C, and other radioactive isotopes. During this period, Kamen was responsible for cyclotron-produced radioactive tracers and was able to sustain de Hevesy's research by supplying him with 32P. In 1940, Ruben and Kamen discovered long-lived 14C, which later proved to be a very powerful tool for analysis of complex biochemical processes, such as the path of carbon in photosynthesis. Between 1946 and 1950, 32P was used in studies of bacteriophage replication and photosynthetic metabolism. This memoir surveys the history of these early investigations. [source] Degradation of the sulfonylurea herbicide LGC-42153 in flooded soilPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2003Jin Kim Abstract LGC-42153, 2-fluoro-1-[3-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)pyridin-2-yl]propyl methoxyacetate, is a new sulfonylurea herbicide for use in rice. Its breakdown and metabolism were studied in soil under flooded condition using radioactive tracers labelled at either the propyl group or the pyrimidine ring. The half-life of LGC-42153 was approximately 3.0 days. The mass balance over 120 days ranged from 94.0 to 104.2% of applied radiocarbon, and no significant amount of volatiles or [14C]carbon dioxide were observed. Solvent non-extractable radiocarbon reached 11 , 14% of applied radiocarbon at 120 days after treatment. The major metabolic reaction was the cleavage of the carboxyl ester bond to give 1-(4,6-dimethoxypyrimidin-2-yl)-3-[2-(1-hydroxy-2-fluoropropyl)pyridine-3-sulfonyl]urea, which underwent hydrolysis of the sulfonylurea bridge giving 2-(1-hydroxy-2-fluoro)propyl-3-pyridinesulfonamide and 4,6-dimethoxy-2-aminopyrimidine. Copyright © 2003 Society of Chemical Industry [source] Comparative dynamics of gestalt odour formation in two ant species Camponotus fellah and Aphaenogaster senilis (Hymenoptera: Formicidae)PHYSIOLOGICAL ENTOMOLOGY, Issue 3 2001Alain Lenoir Abstract. Ant colonies experience continuous shifts in worker populations, which may affect odour composition in the nest. A major question regarding the dynamics of gestalt formation is that of the speed at which the scent of a new individual will be incorporated into the gestalt. It is predicted from the gestalt model of colony odour that workers have to exchange recognition cues continuously to maintain themselves within the gestalt and become well integrated within their colony. Using radioactive tracers the rates of transfer were measured between a labelled donor ant and one or 10 recipient ants, as a close approximation to the within-nest situation. The labelled hydrocarbons were first transferred to a small number of individuals and progressively to all the individuals of the group so that the distribution of hydrocarbon transfer rate approached a normal distribution. Furthermore, in Camponotus fellah Dalla Torre, which performs trophallaxis, homogeneity was reached more rapidly than in Aphaenogaster senilis Mayr, which does not show this behaviour. In the latter species, the gestalt seems to be maintained mainly by allogrooming. These experiments were accompanied by behavioural observations to ascertain the respective importance of trophallaxis and allogrooming in the behavioural time-budget of the ants. In A. senilis, allogrooming was more frequent than in ants that trophallax, which corroborates the role of allogrooming in the establishment of the gestalt in this species. [source] The early history of 32P as a radioactive tracer in biochemical research: A personal memoirBIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION, Issue 3 2005Howard Gest The concept of using radioactive isotopes as "tracers" of chemical conversions was conceived and developed by inorganic chemist Georg de Hevesy (Nobel Laureate in Chemistry 1943). In 1935, he began to apply the technique to various biological processes using 32P, and his experiments revealed the dynamic character of physiology and metabolism. Following de Hevesy's lead, Samuel Ruben (University of California, Berkeley) exploited 32P in 1937,38 for investigation of phospholipid metabolism. Between 1937 and 1940, Ruben and colleague Martin Kamen spearheaded tracer studies in various biological systems using 32P, short-lived 11C, and other radioactive isotopes. During this period, Kamen was responsible for cyclotron-produced radioactive tracers and was able to sustain de Hevesy's research by supplying him with 32P. In 1940, Ruben and Kamen discovered long-lived 14C, which later proved to be a very powerful tool for analysis of complex biochemical processes, such as the path of carbon in photosynthesis. Between 1946 and 1950, 32P was used in studies of bacteriophage replication and photosynthetic metabolism. This memoir surveys the history of these early investigations. [source] | |||||||||||||