RESUMO
We have developed laser desorption ionization mass spectrometry (LDI-MS) of organic molecules encapsulated in a crystalline sponge (CS). Cyclic organic compounds 1,2,3,4,5-pentamethylcyclopentadiene, zerumbone, and muscone were encapsulated in CS as guest regardless of guest crystallization. Single-crystal X-ray analysis closely scrutinized the position of the guest in the pore and the interaction between the guest and the CS framework. After single-crystal X-ray analysis, the same single crystal was subjected to LDI-MS. Ionization efficiency differed markedly depending on whether π-π interaction existed or not. It is obvious that π-π interaction is the key to transferring laser energy from the CS framework to the guest for the ionization of molecule encapsulated in CS. The results suggest the importance of controlling the positions of analyte and matrix as well as noncovalent interactions, such as hydrogen bonding interaction, electrostatic interaction, and so on.
RESUMO
The crystalline sponge (CS) method, which employs single-crystal X-ray diffraction to determine the structure of an analyte present as a liquid or an oil and having a low melting point, was used in combination with laser desorption ionization mass spectrometry (LDI-MS). 1,3-Benzodioxole derivatives were encapsulated in CS and their structures were determined by combining X-ray crystallography and MS. After the X-ray analysis, the CS was subjected to imaging mass spectrometry (IMS) with an LDI spiral-time-of-flight mass spectrometer (TOF-MS). The ion detection area matched the microscopic image of the encapsulated CS. In addition, the accumulated 1D mass spectra showed that fragmentation of the guest molecule (hereafter, guest) can be easily visualized without any interference from the fragment ions of CS except for two strong ion peaks derived from the tridentate ligand TPT (2,4,6-tris(4-pyridyl)-1,3,5-triazine) of the CS and its fragment. X-ray analysis clearly showed the presence of the guest as well as the π-π, CH-halogen, and CH-O interactions between the guest and the CS framework. However, some guests remained randomly diffused in the nanopores of CS. In addition, the detection limit was less than sub-pmol order based on the weight and density of CS determined by X-ray analysis. Spectroscopic data, such as UV-vis and NMR, also supported the encapsulation of the guest through the interaction between the guest and CS components. The results denote that the CS-LDI-MS method, which combines CS, X-ray analysis and LDI-MS, is effective for structure determination.
RESUMO
BACKGROUND/AIMS: Blocking of adhesion molecules is considered to be one of the therapeutic strategies inflammatory diseases, although it remains unclear whether this strategy is beneficial. METHODS: We used CD44-deficient mice to assess whether inhibition of CD44 could control liver injury caused by carbon tetrachloride (CCl(4)). RESULTS: CD44-deficient mice exhibited suppressed liver inflammation during the early phase (within 6h) after CCl(4) injection due to reduced inflammatory cell infiltration and cytokine production, but showed severe liver inflammation with increased numbers of apoptotic hepatocytes at the late phase (after 12h). The induction of hepatocyte apoptosis was triggered by reduced NF-kappaB activity, which was induced by the low inflammatory cytokine concentrations. Furthermore, macrophages contributed to the induction of hepatocyte apoptosis, since neutralization by an anti-CD11b antibody significantly protected against hepatocyte apoptosis. Finally, we found that blocking of MIP-2 and TNF-alpha reduced hepatocyte apoptosis with decreased numbers of intrahepatic leukocytes and reduced inflammatory cytokine production. CONCLUSIONS: These findings suggest that targeting of CD44 as a therapeutic approach for inflammatory liver diseases may require caution for particular immune systems in the liver.
