Digital autoradiography

Radioactive zones can be detected on thin layers by film autoradiography, digital autoradiography with a multiwire proportional chamber, use of charged-coupled devices, or bioimaging/phosphor imaging techniques. These methods differ in terms of factors such as simplicity, speed, sensitivity, resolution, linear range, and accuracy and precision of quantification, and the method of choice depends on the available instrumentation, the type of experiment, and the information needed. 

Klebovich, 1., Application of planar chromatography and digital autoradiography in metabolism research, in Planar Chromatography, Nyiredy, Sz., Ed., Springer Scientific, Budapest, Hungary, 2001, pp. 293-311. 

Specific contact detection (x-ray film, digital autoradiography)... 

Fig. 3.1. Simultaneous bidirectional transport of phosphorus within mycelium of Hypholoma fasciculare demonstrated using doublelabelling and digital autoradiography, (a) Experimental design, (b) Imaging of isotope distribution 29 days after addition of labels. Microcosms are 20 cm long. Derived from Lindahl et al. (2001).

Fig. 2.7 Photograph left), autoradiography ( Cd, = 453 days) (center) and digitally contrast-enhanced version of cadmium...

Two-dimensional planar chromatography (2D-TLC) is frequently used in combination with autoradiography or digital autoradiography (DAR) in studies on metabolism. Examples of 2D-TLC-DAR will be given in the analysis of pharmaceutical products. Other applications generally use either different types of development, or utilise different interactions for separation, or different stationary phases, such as elution-displacement absorption-partition normal phase-reversed phase ion exchange-normal phase. 

It is also worthwhile to mention that FF-TLC can be used as a clean-up method before HPLC. Special detection techniques as well as direct coupling methods (such as on-line coupling to GC-MS. digital autoradiography, etc.) may afso be used with FF-TLC. 

Klebovich, I. Mincsovics, E. Szunyog, J. Ludanyi, K. Karancsi, T. Ujszaszy, K. Kiss, B.D. Vekey, K. Isolation and identification of metabolites of H- and C-deramci-clane by OPLC-digital autoradiography on-line sample collection and mass spectrometry. J. Planar Chromatogr.-Mod. TLC 1998, 11, 394-399. 

Digital autoradiography (DAR) can be used in combination with TLC for the analysis of radiolabeled compounds, most frequently and " C. The method is simple and requires reasonably priced instmmentation therefore it is widely used for biochemical and pharmacological appli-, cations. The instrumentation for TLC-DAR can scan a i 20 X 20 cm area, the radioactivity bands are visualized with a digital radiograph, and the digital data are processed with a high-capacity computer. 

The analysis of samples in biological matrices is extremely powerful compared with drawbacks such as narrow concentration range for quantitative measurements and long time required for spot detection. Digital autoradiography can be used in hyphenated off-line and... 

Figure 4.2 Estimation of diffusion coefficients by autoradiography of tissue sections, (a) Digitized autoradiographic image of radiolabeled NGF released from a polymeric implant in a rat brain, reproduced from [18]. (b) The resulting concentration profile, obtained by scanning intensities from the autoradiographic image, and using calibrated standards to determine the local concentration the solid line indicates Equation 3-58.

Autoradiography can be used to document chromatograms containing samples labeled with radioactive isotopes (see Chapter 13). Digital autoradiography combined with TLC-MS-MS was used for the structure determination of drug metabolites (Ludanyi, 1997). 

Digital autoradiography was applied to the study of testosterone metabolites (Vingler et al., 1993), deramciclane metabolism (Hazal et al., 1995), and sebaceous neutral C-lipids (Christelle et al., 1997). 

Vingler, P., Filthuth, H., Bague, A., Pruche, F., and Kermici, M. (1993). Direct quantitative digital autoradiography of testosterone metabolites in the pilosebaceous unit an environmentally advantageous trace radioactive technology. Steroids 58 429-438. 

Figure 22.7 Anuran limb development (Xenopus hind limb). A series of Nieuwkoop-Faber stages SI/2-S4/S whose chondrogenic patterning— which is similar to the bauplan in Figure 22.6—is revealed by 35S04 autoradiography. Compare with Figure 22.2. Note the digital arch (da) and numbered digit 4 (P=posterior) (bar=0.S mm).

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