MALDI MS images

Professor Caprioli of Vanderbilt University (US), Professor Heeren s group (Europe), and our group (Japan) independently developed the MALDI-MS imaging and attained the expected resolution.1,2... 

Figure 12.5. (Top) MALDI-MS images of clozapine in rat brain slice as a function of laser fluence (bottom) relative MALDI responses of clozapine and norclozapine in rat brain slice as a function of laser fluence.

Figure 12.8. MALDI-MS images of letters (a) S and (b) P containing norclozapine and clozapine in rat brain sections, respectively. MALDI-MS/MS spectra of (c) clozapine and (d) norclozapine in rat brain sections (Hsieh et al., 2006a).

In addition, we also envisage MALDI-MS imaging becoming more mainstream in the area of carbohydrate research, offering the added dimension of spatial information on top of the specificity of the structural information that MS delivers. 

Beyond peptides and proteins, MALDI MS imaging of tissue section for the detection of low-molecular-weight compounds can also be achieved. Of particular interest is the posttreatment location of pharmaceutical compounds in targeted tissues or organs. Further, in parallel to location, the effects of a drug on the local proteome can be observed as a function of dose or time. Variations in the proteome are indicative of drug efficacy.116... 

Monroe E, Annangudi S, Hatcher N, Gutstein H, Rubakhin S, Sweedler J (2008) SIMS and MALDI MS imaging of the spinal cord. Proteomics 8 3746-3754. doi 10.1002/pmic.200800127... 

Goodwin R, Dungworth J, Cobb S, Pitt A (2008) Time-dependent evolution of tissue markers by MALDI-MS imaging. Proteomics 8 3801-3808. doi 10. 1002/pmic.2008002001... 

Jurchen J, Rubakhin S, Sweedler J (2005) MALDI-MS imaging of features smaller than the size of the laser beam. J Am Soc Mass Spectrom 6 1654-1659. doi 10.1016/j. jasms.2005.06.006... 

The acquisition of the mass spectra for peptide and protein imaging is done in our lab on commercial MALDI TOF instruments (Voyager sSTR, 4700 Proteomics Analyzer Applied Biosystems, Framingham, MA) equipped with a Nd YAG laser. The acquisition of the data is controlled by an in-house designed software (MALDI MS Imaging Tool, MMSIT). The area to be scanned is specified as a pattern of points, equidistant from each other. The distance is chosen referring to the diameter of the... 

FIGURE 11.2 General procedure for MALDI-MS imaging analysis and conventional quantitative HPLC/MS analysis. 

FIGURE 11.7 (a) MALDI-MS images of clozapine in rat brain slice as a function of laser... 

During the past several years, significant progress was made for the MALDI-MS imaging technique. It has been proven to be a valuable tool for studying drug distribution in animal tissues. MALDI-IMS is a simple, quick, and molecularly specific analytical platform that can distinguish small molecules from their metabolites on... 

Ohkawa, T. and Bunch, J., MALDI MS imaging to reveal distribution of benzodiazepine drug and metabolite molecules in rat brain, Proceedings of the 55th ASMS Conference, Indianapolis, IN, 2007. 

Today, M S imaging is perceived as a rather new - but very promising - approach, not only for the basic sciences but also for clinical diagnosis [156]. Although other MS imaging methods based on desorption electrospray-ionization (DESI) MS [157] or secondaryion mas s spectrometry (SIMS)are currently available (for a timely review, see Ref. [158]), attention here will be focused exclusively on MALDI-MS imaging. The same technique is also discussed comprehensively in Chapter 4 of this book. 

Whole-body MALDI MS imaging of proteins has also been performed and an example is presented in Fig. 1.3. Images from an embryonic day 14.5 mouse are shown one stained and optically imaged and the other imaged by MALDI MS. In the latter, each of the five colors shown represents a different protein (unpublished data courtesy Peggi Angel, Vanderbilt University). 

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