We investigated the ability of targeted immunomicelles to detect and assess macrophages in atherosclerotic plaque using MRI in vivo. There is a large clinical need for a noninvasive tool to assess atherosclerosis from a molecular and cellular standpoint. Macrophages play a central role in atherosclerosis and are associated with plaques vulnerable to rupture. Therefore, macrophage scavenger receptor (MSR) was chosen as a target for molecular MRI. MSR-targeted immunomicelles, micelles, and gadolinium-diethyltriaminepentaacetic acid (DTPA) were tested in ApoE؊/؊ and WT mice by using in vivo MRI. Confocal laser-scanning microscopy colocalization, macrophage immunostaining and MRI correlation, competitive inhibition, and various other analyses were performed. In vivo MRI revealed that at 24 h postinjection, immunomicelles provided a 79% increase in signal intensity of atherosclerotic aortas in ApoE؊/؊ mice compared with only 34% using untargeted micelles and no enhancement using gadolinium-DTPA. Confocal laser-scanning microscopy revealed colocalization between fluorescent immunomicelles and macrophages in plaques. There was a strong correlation between macrophage content in atherosclerotic plaques and the matched in vivo MRI results as measured by the percent normalized enhancement ratio. Monoclonal antibodies to MSR were able to significantly hinder immunomicelles from providing contrast enhancement of atherosclerotic vessels in vivo. Immunomicelles provided excellent validated in vivo enhancement of atherosclerotic plaques. The enhancement seen is related to the macrophage content of the atherosclerotic vessel areas imaged. Immunomicelles may aid in the detection of high macrophage content associated with plaques vulnerable to rupture. macrophage scavenger receptor ͉ molecular imaging ͉ vulnerable plaque ͉ immunomicelles ͉ gadolinium

Using genetic inactivation in the mouse, PURA, encoding Pur alpha, is demonstrated to be essential for developmentally-timed dendrite formation in the cerebellum and hippocampus. Comparison of RNA species bound by Pur alpha prompts the hypothesis that Pur alpha functions with non-coding RNA in transport of certain mRNA molecules to sites of translation in dendrites. Pur alpha binds to human BC200 RNA, implicated in dendritic targeting, and this has homologies to 7SL RNA, implicated in compartmentalized translation. Results using hippocampal rat neurons in situ show that Pur alpha binds to BC1 RNA, implicated in dendritic targeting as a mouse counterpart of BC200, and to mRNA molecules translated in dendrites; Pur alpha is specifically located in dendrites, where it is colocalized with Map2, but not in axons, where it fails to colocalize with Ankyrin G. Pur alpha and Staufen are colocalized at dendritic sites of mRNA translation. Microtubule disruptors inhibit Pur alpha dendritic targeting and allow its mislocalization to axons. Using mouse brain, double-RNA immunoprecipitation places Pur alpha together with Staufen or FMRP on BC1 RNA and specific mRNA species in vivo. These results help define a mechanism by which Pur alpha targets specific mRNA molecules to sites of dendritic translation.

Evaluating the effects of diagenesis on the isotopic compositions of Sr, O, and C in marine carbonates is critical to their use as proxies in reconstructing information on the salinity, temperature and dissolved inorganic carbon of ancient oceans. We have analyzed a series of samples of mollusk shells from the Baculites compressus zone (late Campanian) of the Pierre Shale of South Dakota. Samples included outer shell material and septa of cephalopods collected inside and outside concretions. Preservation was evaluated using light microscopy, scanning electron microscopy (SEM), trace element analysis and X-ray diffraction. All of the material consists of aragonite based on X-ray diffraction. An SEM preservation index (PI) was established based on comparison of the microstructure of the fossil material with that of modern Nautilus. Excellent preservation (PI ‫؍‬ 5) was characterized by well-defined nacreous plates with discrete, angular boundaries. In contrast, samples showing fused nacreous plates with indistinct boundaries were rated poor (PI ‫؍‬ 1). 87 Sr/ 86 Sr ratios vary with preservation and average 0.707648 ؎ .000021 (n ‫؍‬ 10) for excellent preservation (PI Ϸ 5), 0.707615 ؎ .000028 (n ‫؍‬ 5) for good preservation (PI Ϸ 3), 0.707404 ؎ .000074 (n‫)7؍‬ for fair preservation (PI Ϸ 2), and 0.707261 ؎ .000053 (n‫)8؍‬ for poor preservation (PI Ϸ 1). These data suggest that as the quality of the preservation declines, the mean 87 Sr/ 86 Sr ratio decreases and the standard error of the mean increases. Oxygen and carbon isotope analyses of the same specimens also show decreases with preservation, and ␦ 18 O, ␦ 13 C and 87 Sr/ 86 Sr are well correlated, suggesting that these tracers are all altered as the PI decreases. The Sr/Ca ratio increases as preservation decreases, indicating that Sr is added to the shell material during diagenesis. In contrast, Mg/Ca shows no trend with preservation. If the increasing Sr concentration (and decreasing 87 Sr/ 86 Sr) of the shell material with decreasing preservation represents the addition of Sr to the shell during diagenesis, we calculate that the added Sr had 87 Sr/ 86 Sr ranging from 0.707582 to 0.707032. Potential sources of the added Sr include older marine carbonates and weathering of volcanic ash layers present in the shale. The mechanisms of alteration likely include epitaxial growth of strontianite on the original shell aragonite and isotopic exchange of C and O between alteration fluids and shell carbonate. We conclude that SEM preservation criteria are effective in screening shell material that records original isotopic values and that variations in Sr, O and C isotope composition in well-preserved material can be used to assess paleoenvironmental parameters, such as salinity and temperature. Our results also indicate that assessing preservation is a critical prerequisite to the determination of numerical ages of shell material using strontium isotope stratigraphy.

Purpose:To evaluate the capability of P947, a magnetic resonance (MR) imaging contrast agent that molecularly targets matrix metalloproteinases (MMPs), to aid detection and imaging of MMPs in atherosclerotic lesions in vivo; its specificity compared with that of P1135; expression and distribution of MMPs in atherosclerotic vessels; and in vivo distribution and molecular localization of fluorescent europium (Eu) P947. Materials and Methods:The Animal Care and Use Committee approved all experiments. P947 was synthesized by attaching a gadolinium chelate (1,4,7,10-tetraazacyclododecane-N,NЈ,NЉ,Nٞ-tetraacetic acid) to a peptide that specifically binds MMPs. Scrambled form of P947 (P1135) was synthesized by replacing the targeting moiety of P947 with a scrambled peptide lacking the ability to bind MMPs. P947, P1135, and gadoterate meglumine were injected into atherosclerotic apolipoprotein E-deficient and wild-type mice. The aortic MR imaging enhancement produced by the contrast agents was measured at different times and was compared by using one-way analysis of variance. MMP expression was investigated in the aortas by using MMP immunostaining and in situ MMP zymography. A fluorescent form of P947 (Eu-P947) was synthesized to compare the in vivo distribution of the contrast agent (Eu-P947) with specific MMP immunofluorescent staining. Results:MMP-targeted P947 facilitated a 93% increase (P Ͻ .001) in MR image signal intensity (contrast-to-noise ratio [CNR], 17.7 compared with 7.7; P Ͻ .001) of atherosclerotic lesions in vivo. Nontargeted P1135 (scrambled P947) provided 33% MR image enhancement (CNR, 10.8), whereas gadoterate meglumine provided 5% (CNR, 6.9). Confocal laser scanning microscopy demonstrated colocalization between fluorescent Eu-P947 and MMPs in atherosclerotic plaques. Eu-P947 was particularly present in the fibrous cap region of plaques. Conclusion:P947 improved MR imaging for atherosclerosis through MMP-specific targeting. The results were validated and provide support for further assessment of P947 as a potential tool for the identification of unstable atherosclerosis. RSNA, 2009 Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, use the Radiology Reprints form at the end of this article. Despite great advances in cardiovascular medicine, atherosclerosis remains the foremost cause of death in developed industrialized societies (1,2) and has become the leading cause of death globally (3,4). We do not currently possess clinical tools capable of accurately evaluating atherosclerosis directly or at early stages of disease when interventions may have the greatest effect on altering disease progression.The rapidly evolving field of molecular imaging will ultimately allow us to accurately assess molecular, cellular, and compositional components of atherosclerotic lesions. This information will be clinically vital to identify vulnerable patients (5,6) and facilitate personalized medical management. Molecular ...