The Autoradiographs

While autoradiographic techniques can be quantitative, they must be used under carefully controlled conditions and shown in fact to be quantitative and reproducible. In detailed studies, we have found that the production of autoradiographic grains following receptor labeling is linear with time and also with tissue concentration of radioactivity. By using suitable standards in conjunction with receptor autoradiography, one can 

Since these radiohistochemical techniques can be used in a quantitative and reproducible way, a great deal of information regarding drug and neurotransmitter receptors has been provided. These radiohistochemical studies can be used as important complements to mapping neurotransmitter pathways. They can also be useful complements to various physiological experiments, and they often provide new hypotheses about the mechanisms of action of various drugs. 

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Bolognesi C, Taningher M, Parodi S, et al. 1986. Quantitative predictivity of carcinogenicity of the autoradiographic repair test (primary hepatocyte cultures) for a group of 80 chemicals belonging to different chemical classes. Environ Health Perspect 70 247-53. 

The accuracy of the results depends on many factors, including the type of radiohgand used (irreversible or reversible ligands), the autoradiographic method (in vivo or in vitro labehng) and the photographic... 

When radioactive lignin precursors are applied to resistant host plants infected with an avirulent pathogen, the autoradiographic localization of radioactivity in resistant reacting host cells may help to corroborate the participation of lignification in the resistance response. Thorough extraction of non-polymerized precursor with organic solvents and the removal of esterified phenolics by alkaline hydrolysis are important steps in these experiments (25,28,30,31). 

After the twenty-four hour period of contact, the solution in the fissures was rapidly withdrawn. The surfaces of the fissures were dried under vacuum at 25 °C and then dismantled. The distributions of americium on the fissure surfaces were determined first qualitatively using autoradiographs of the fissure surfaces with POLAROID LAND black and white 3000 ASA type 47 film. The autoradiographs are shown in Figures 5, 7, and 9. The lighter areas on the autoradiographs represent areas of americium adsorption. 

Model Predictions. The rate for desorption of americium from the fissure surfaces into solution was assumed to equal the rate for the adsorption of americium from solution by the fissure surfaces. The sorption rate and the equilibrium fractionation of americium that were determined in the static experiments were used to determine input parameters to the ARDISC model. The ARDISC model predictions for the distributions of americium on the fissure surfaces in both sets of experiments are presented in Figures 5 through 10 along with the autoradiographs and the experimental histograms representing the various distributions of americium on the fissure surfaces. 

A) Replication forks in the E. coli chromosome. The autoradiographic pattern was produced by a chromosome that initiated replication with [3H] thymine (5 Ci / mmol) and was subsequently labeled with [3H]thymidine (52 ci / mmol) for 6 min. 

Initiation of a second round of replication leads to a replication eye at the initiation site of replication (fig. 26.3). As synthesis proceeds the size of the replication eye becomes larger at this stage the replicating chromosome is referred to as a theta structure because it has the appearance of the Greek letter d. Semiconservative replication is consistent with the density of the autoradiographic tracks made by different parts of the chromosome after one and two rounds of replication in [3H]thymidine (see fig. 26.3). 

Simulated autoradiographs of the E. coli chromosome after one or more replications in the presence of [3H]thymidine. After one round of replication, the autoradiograph shows a circular structure that is uniformly labeled. The second round of replication begins with the formation of a replication eye. One branch in the replication eye is twice as strongly labeled as the remainder of the chromosome, indicating that this branch contains two labeled strands. This structure is consistent with semiconservative replication for the E. coli chromosome. 

Consistent data have been reported with respect to the autoradiographic localization of H3-receptor binding sites using various radioligands, i.e. [3H](R)a-methylhistamine [24, 58, 59], [3H]Na-methylhistamine [60, 61], [125l]iodophenpropit [29] and [125l]iodoproxyfan [26],... 

Unscheduled DNA Synthesis in Mammalian Cells. The principle of this test is that it measures the repair that follows DNA damage and is thus a reflection of the damage itself. It depends on the autoradiographic measurement of the incorporation of tritiated thymidine into the nuclei of cells previously treated with the test chemical. 

The autoradiographs of the rock and mineral thin sections (Figures 4 to 6) also confirm the importance of iron oxides although biotite.(K(Mg,Fe Si AlCLQ(0H) ) and hornblende ((Na,Ca2)(Mg,Fe )(Al,Fe )(Si AlO OH ) contain ferrous iron, sorption appears to take place solely on the small opaque (iron-oxide) inclusions. In the case of biotite, these oxides are located between the basal planes, and are randomly distributed in the hornblende. Similar distributions are observed for olivine, pyroxene, and epidote. The results for pyroxene further confirm the low sorption results obtained with gabbro, where it is one of the major minerals. 

The autoradiographs also show some sorption on the granite obtained from the Eye-Dashwa Lakes pluton (Figure 6). Even though the iron concentration is low, hydrothermal alteration of the granite has resulted in the infilling of the minute fractures in the microcline feldspar with iron oxides, which show technetium sorption, while there is no sorption on the biotite crystals. 

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