Ultrafast Photochemistry of a Manganese-Tricarbonyl CO-Releasing Molecule (CORM) in Aqueous Solution.

Ultraviolet irradiation of a manganese-tricarbonyl CO-releasing molecule (CORM) in water eventually leads to the liberation of some of the carbon monoxide ligands. By ultraviolet pump/mid-infrared probe femtosecond transient absorption spectroscopy in combination with quantum chemical calculations, we could disclose for the exemplary compound [Mn(CO)3(tpm)](+) (tpm = tris(2-pyrazolyl)methane) that only one of the three carbonyl ligands is photochemically dissociated on an ultrafast time scale and that some molecules may undergo geminate recombination.

A comparative study on chirped-pulse upconversion and direct multichannel MCT detection.

A comparative study is carried out on two spectroscopic techniques employed to detect ultrafast absorption changes in the mid-infrared spectral range, namely direct multichannel detection via HgCdTe (MCT) photodiode arrays and the newly established technique of chirped-pulse up-conversion (CPU). Whereas both methods are meanwhile individually used in a routine manner, we directly juxtapose their applicability in femtosecond pump-probe experiments based on 1 kHz shot-to-shot data acquisition. Additionally, we examine different phase-matching conditions in the CPU scheme for a given mid-infrared spectrum, thereby simultaneously detecting signals which are separated by more than 200 cm(-1).

Ultrafast multisequential photochemistry of 5-diazo Meldrum's acid.

We disclose the light-induced dynamics and ultrafast formation of several photoproducts from the manifold of reaction pathways in the photochemistry of 5-diazo Meldrum's acid (DMA), a photoactive compound used in lithography, by femtosecond mid-infrared transient absorption spectroscopy covering several nanoseconds. After excitation of DMA dissolved in methanol to the second excited state S(2), 70% of excited molecules relax back to the S(0) ground state. In competing processes, they can undergo an intramolecular Wolff rearrangement to form ketene, which reacts with a solvent molecule to an enol intermediate and further to carboxylate ester, or they first relax to the DMA S(1) state, from where they can isomerize to a diazirine and via an intersystem crossing to a triplet carbene. For a reliable identification of the involved compounds, density functional theory calculations on the normal modes and Fourier transform infrared spectroscopy of the reactant and the photoproducts in the chemical equilibrium accompany the analysis of the transient spectra. Additional experiments in ethanol and 2-propanol lead to slight spectral shifts as well as elongated time constants due to steric hindrance in transient spectra connected with the ester formation channel, further substantiating the assignment of the occurring reaction pathways and photoproducts.

TRAF5 deficiency accelerates atherogenesis in mice by increasing inflammatory cell recruitment and foam cell formation.

RATIONALE: Tumor necrosis factor receptor-associated factors (TRAFs) are cytoplasmic adaptor proteins for the TNF/interleukin-1/Toll-like receptor superfamily. Ligands of this family comprise multiple important cytokines such as TNFα, CD40L, and interleukin-1ß that promote chronic inflammatory diseases such as atherosclerosis. We recently reported overexpression of TRAF5 in murine and human atheromata and that TRAF5 promotes inflammatory functions of cultured endothelial cells and macrophages. OBJECTIVE: This study tested the hypothesis that TRAF5 modulates atherogenesis in vivo. METHODS AND RESULTS: Surprisingly, TRAF5(-/-)/LDLR(-/-) mice consuming a high-cholesterol diet for 18 weeks developed significantly larger atherosclerotic lesions than did TRAF5(+/+)/LDLR(-/-) controls. Plaques of TRAF5-deficient animals contained more lipids and macrophages, whereas smooth muscle cells and collagen remained unchanged. Deficiency of TRAF5 in endothelial cells or in leukocytes enhanced adhesion of inflammatory cells to the endothelium in dynamic adhesion assays in vitro and in murine vessels imaged by intravital microscopy in vivo. TRAF5 deficiency also increased expression of adhesion molecules and chemokines and potentiated macrophage lipid uptake and foam cell formation. These findings coincided with increased activation of JNK and appeared to be independent of TRAF2. Finally, patients with stable or acute coronary heart disease had significantly lower amounts of TRAF5 mRNA in blood compared with healthy controls. CONCLUSIONS: Unexpectedly, TRAF5 deficiency accelerates atherogenesis in mice, an effect likely mediated by increased inflammatory cell recruitment to the vessel wall and enhanced foam cell formation.

Tumor necrosis factor receptor-associated factor 1 (TRAF1) deficiency attenuates atherosclerosis in mice by impairing monocyte recruitment to the vessel wall.

BACKGROUND: Members of the tumor necrosis factor superfamily, such as tumor necrosis factor-alpha, potently promote atherogenesis in mice and humans. Tumor necrosis factor receptor-associated factors (TRAFs) are cytoplasmic adaptor proteins for this group of cytokines. METHODS AND RESULTS: This study tested the hypothesis that TRAF1 modulates atherogenesis in vivo. TRAF1(-/-)/LDLR(-/-) mice that consumed a high-cholesterol diet for 18 weeks developed significantly smaller atherosclerotic lesions than LDLR(-/-) (LDL receptor-deficient) control animals. As the most prominent change in histological composition, plaques of TRAF1-deficient animals contained significantly fewer macrophages. Bone marrow transplantations revealed that TRAF1 deficiency in both hematopoietic and vascular resident cells contributed to the reduction in atherogenesis observed. Mechanistic studies showed that deficiency of TRAF1 in endothelial cells and monocytes reduced adhesion of inflammatory cells to the endothelium in static and dynamic assays. Impaired adhesion coincided with reduced cell spreading, actin polymerization, and CD29 expression in macrophages, as well as decreased expression of the adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in endothelial cells. Small interfering RNA studies in human cells verified these findings. Furthermore, TRAF1 messenger RNA levels were significantly elevated in the blood of patients with acute coronary syndrome. CONCLUSIONS: TRAF1 deficiency attenuates atherogenesis in mice, most likely owing to impaired monocyte recruitment to the vessel wall. These data identify TRAF1 as a potential treatment target for atherosclerosis.

CD40L induces inflammation and adipogenesis in adipose cells--a potential link between metabolic and cardiovascular disease.

CD40L figures prominently in atherogenesis. Recent data demonstrate elevated levels of sCD40L in the serum of patients with the metabolic syndrome (MS). This study investigated the role of CD40L in pro-inflammatory gene expression and cellular differentiation in adipose tissue to obtain insight into mechanisms linking the MS with atherosclerosis. Human adipocytes and preadipocytes expressed CD40 but not CD40L. Stimulation with recombinant CD40L or membranes over-expressing CD40L induced a time- and dose-dependent expression of IL-6, MCP-1, IL-8, and PAI-1. Supernatants of CD40L-stimulated adipose cells activated endothelial cells, suggesting a systemic functional relevance of our findings. Neutralising antibodies against CD40L attenuated these effects substantially. Signalling studies revealed the involvement of mitogen-activated protein kinases and NFkB. Furthermore, stimulation with CD40L resulted in enhanced activation of C/EBPa and PPARg and promoted adipogenesis of preadipose cells in the presence and absence of standard adipogenic conditions. Finally, patients suffering from the metabolic syndrome with high levels of sCD40L also displayed high levels of IL-6, in line with the concept that CD40L may induce the expression of inflammatory cytokines in vivo in this population. Our data reveal potent metabolic functions of CD40L aside from its known pivotal pro-inflammatory role within plaques. Our data suggest that CD40L may mediate risk at the interface of metabolic and atherothrombotic disease.