Autoradiographic techniques

Physical methods Physical methods include photometric absorption and fluorescence and phosphorescence inhibition, which is wrongly referred to as fluorescence quenching [1], and the detection of radioactively labelled substances by means of autoradiographic techniques, scintillation procedures or other radiometric methods. These methods are nondestructive (Chapt. 2). 

Since these studies utilized autoradiographic techniques, it was important to determine the chemical nature of the material measured using radiochemical procedures. Using punch biopsies of the brain slices which were measured autoradiographically, it was shown using thin-layer chromatography that about 30% of the radioactivity was associated with unchanged BCNU (14). It was therefore concluded that the measurements described above accurately reflect brain concentrations of BCNU. 

Gude D. Autoradiographic Techniques, Prentice Hall, EngelwoodCliffs, NJ, 1968. 

Morel G. Electron microscopic autoradiographic techniques, in Electron Microscopy in Biology. A Practical Approach (Harris JR, ed.), IRL Press, Oxford, UK, 1994, pp. 83-123. 

Divalent mercury in rats has been reported to poorly penetrate the blood-brain barrier [23], However, there is an impairment of the blood-brain barrier within hours after mercury treatment [24, 25], By means of autoradiographic techniques, it was demonstrated [26] that after a single intravenous injection of labelled mercuric chloride, large portions of the radioactive mercury were detected in the cerebellar grey matter, area postrema, hypothalamus and areas near the lateral ventricle of mice. 

In 1958 Taylor demonstrated SCEs, using autoradiographic techniques to detect the disposition or labeled DNA following incorporation of [3H]-thymidine. 5-Bromo-2 -deoxyuridine (drdU) has now replaced [3H]-thymidine and various staining methods have been used to show the differential incorporation of BrdU between sister chromatids fluorescent Hoechst 33258 (Latt, 1973) combined fluorescent... 

Dosimetry is an autoradiographic technique to measure the total dose of radiation received by a worker ov -r a period of time. 

Radioactive isotopes provide a very convenient way of monitoring the fate or metabolism of compounds that contain the isotopes. When used in this way, the isotope is described as a tracer and compounds into which the radioactive atom has been introduced are said to be labelled or tagged. The labelled molecules need only comprise a very small proportion of the total amount of the unlabelled radioactive substance because they act in the same way as the non-radioactive substance but can be detected very much more easily. The varied applications of tracers in biochemistry range from studies of metabolism in whole animals or isolated organs to sensitive quantitative analytical techniques, such as radioimmunoassay. Phosphorus-32 is used in work with nucleic acids, particularly in DNA sequencing and hybridization techniques. In these instances the isotope is used as a means of visualizing DNA separations by autoradiographic techniques. 

Kunzle H, Akert K (1977) Efferent connections of cortical, area 8 (frontal eye field) in Macaca fascicularis. A reinvestigation using the autoradiographic technique. J Comp Neurol /7i 147-164. 

Wiksten B, Grant G (1986) Cerebellar projections from the cervical enlargement An experimental study with silver impregnation and autoradiographic techniques in the cat. Exp. Brain Res., 61, 513-518. 

Figure 10.7 Concentration profiles after implantation of a BCNU-releasing implant. Solutions to Equation 10-22 were compared to experiment data obtained by quantitative autoradiographic techniques. The solid lines in the three panels labeled 3, 7, and 14 days were all obtained using the following parameters i = 0.15 cm — 2.1 and q = 0.81 mM. The solid line in the panel labeled 1 day was obtained using the following parameters R = 0.15 cm (j) = 0.7 and q = 1.9 mM. Redrawn from [22].

Cell Division Inhibition. If the mitotic index (% of cells in mitosis) decreases to zero during the first few hours of treatment (approximately 8 h), the compound is inhibiting some metabolic process in interphase (Gi, S, or G2) The location and possible cause of the inhibition, which can be determined by autoradiographic techniques, involves treating root meristems with radioactive thymidine after herbicide treatment. The details of this procedure have been published by Van t Hof (33). An alternative to the above procedure is to treat root tissue with herbicide plus radioactive thymidine or uridine and follow the increase of radioactivity precipitable by trichloroacetic acid (34). 

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