Occurrence, distribution and ecological risks of antibiotics and pesticides in coastal waters around Liaodong Peninsula, China.

Mariculture activities and river inputs can lead to pollution of micropollutants (e.g., antibiotics and pesticides) in coastal seawater which is the base of the most dynamic ecosystems due to its hosting some of the highest biodiversity and biological production in the world. It is thus of importance to investigate the occurrence and risks of organic micropollutants in coastal waters. In this study, 13 antibiotics and 15 pesticides were screened in coastal waters around the Liaodong Peninsula, China. Among the targets, thirteen were detected with concentrations up to 64.8 ng L-1. Simazine, atrazine and triadimenol were found to be the predominant pesticides with detection frequencies of 100%, and sulfamethoxazole was the predominant antibiotic with a detection frequency of 62.5%. The total level of the pollutants in the Bohai Sea was generally higher than that in the Yellow Sea, and a seaward decreasing trend of the pollutants was observed. Terrestrial inputs and mariculture were distinguished as main pollution sources by principal component analysis. Finally, ecological risk quotients were calculated and atrazine and acetochlor showed relatively higher risks to aquatic organisms.

The Quantitative Imaging Network: NCI's Historical Perspective and Planned Goals.

The purpose of this editorial is to provide a brief history of National Institutes of Health National Cancer Institute (NCI) workshops as related to quantitative imaging within the oncology setting. The editorial will then focus on the recently supported NCI initiatives, including the Quantitative Imaging Network (QIN) initiative and its organizational structure, including planned research goals and deliverables. The publications in this issue of Translational Oncology come from many of the current members of this QIN research network.

Gadolinium-rhodamine nanoparticles for cell labeling and tracking via magnetic resonance and optical imaging.

A novel dual-labeled nanoparticle for use in labeling and tracking cells in vivo is described. We report the construction and characterization of these gadolinium-rhodamine nanoparticles. These particles are constructed from lipid monomers with diacetylene bonds that are sonicated and photolyzed to form polymerized nanoparticles. Cells are efficiently labeled with these nanoparticles. We have inoculated labeled tumor cells subcutaneouosly into the flanks of C3H mice and have been able to image these labeled tumor cells via MRI and optical imaging. Furthermore, the labeled tumor cells can be visualized via fluorescent microscopy after tissue biopsy. Our results suggest that these nanoparticles could be used to track cells in vivo. This basic platform can be modified with different fluorophores and targeting agents for studying metastisic cell, stem cell, and immune cell trafficking among other applications.

Detection and localization of proteinuria by dynamic contrast-enhanced magnetic resonance imaging using MS325.

After renal transplantation, persistent glomerular disease affecting the native kidneys typically causes albuminuria, at least for a period of time, making it difficult to determine in a noninvasive fashion whether proteinuria originates in the native kidneys or the renal allograft. To address this problem, dynamic contrast-enhanced magnetic resonance imaging (MRI) using gadolinium (Gd)-based albumin-bound blood pool contrast agent (MS325) to localize proteinuria was investigated. Glomerular proteinuria was induced in Sprague-Dawley rats by intravenous injection of puromycin aminonucleoside (PAN), whereas control rats received physiologic saline vehicle. Both groups of animals underwent a 40-min dynamic contrast-enhanced MRI using radio frequency spoiled gradient echo imaging sequence after injection of Gd-labeled MS325. Contrast uptake and clearance curves for cortex and medulla were determined from acquired MR images. Compared with controls, proteinuric rats exhibited significantly lower elimination rate constants. The use of gadopentetate dimeglumine (Gd-DTPA) as a contrast agent showed smaller and less specific differences between proteinuric and control groups. In rats with one proteinuric kidney (PAN-treated) and one normal kidney (transplanted from a normal rat), MRI using MS325 was able to differentiate between the two kidneys. The results suggest that MRI with an albumin-bound blood pool contrast agent may be a useful noninvasive way to localize proteinuria. If this technique can be successfully applied in human patients, it may allow for the localization of proteinuria after kidney transplant and thereby provide a noninvasive way to detect disease affecting the renal allograft.

Influence of body temperature on the BOLD effect in murine SCC tumors.

Changes in the blood oxygen level dependent (BOLD) enhancements in tumors (squamous cell carcinoma, (SCCVII)) implanted in mice maintained at core temperatures of 30 degrees C or 37 degrees C were measured using MRI and compared to tumor oxygen levels obtained using an oxygen-sensitive Eppendorf electrode. Tumors were implanted in a hindleg of the mice intramuscularly. Tumor-bearing mice were imaged by BOLD MRI, while first breathing air and then carbogen (95% O2, 5% CO2) for 15-min intervals at a core temperature of 30 degrees C. After an equilibration period, the identical regimen was conducted with the same animal maintained at 37 degrees C. This procedure was repeated with additional mice starting at 37 degrees C followed by imaging at 30 degrees C. Likewise, oxygen electrode measurements of the tumor were determined at core temperatures of 30 degrees C and 37 degrees C. The Eppendorf measurements showed that tumors in animals maintained at 30 degrees C were significantly more hypoxic than at 37 degrees C. MRI studies demonstrated stronger BOLD enhancement at 30 degrees C than at 37 degrees C, suggesting significant changes in hypoxia and/or blood flow in tumors at these temperatures. The findings of the study stress the importance of maintaining normal core temperature when assessing tumor oxygen status using functional imaging modalities or oxygen-sensitive electrodes.

Microarray gene expression analysis of murine tumor heterogeneity defined by dynamic contrast-enhanced MRI.

Current methods of studying angiogenesis are limited in their ability to serially evaluate in vivo function throughout a target tissue. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and pharmacokinetic modeling provide a useful method for evaluating tissue vasculature based on contrast accumulation and washout. While it is often assumed that areas of high contrast enhancement and washout comprise areas of increased angiogenesis and tumor activity, the actual molecular pathways that are active in such areas are poorly understood. Using DCE-MRI in a murine subcutaneous tumor model, we were able to perform pharmacokinetic functional analysis of a tumor, coregistration of MRI images with histological cross-sections, immunohistochemistry, laser capture microdissection, and genetic profiling of tumor heterogeneity based on pharmacokinetic parameters. Using imaging as a template for biologic investigation, we have not found evidence of increased expression of proangiogenic modulators at the transcriptional level in either distinct pharmacokinetic region. Furthermore, these regions show no difference on histology and CD31 immunohistochemistry. However, the expression of ribosomal proteins was greatly increased in high enhancement and washout regions, implying increased protein translation and consequent increased cellular activity. Together, these findings point to the potential importance of posttranscriptional regulation in angiogenesis and the need for the development of angiogenesis-specific contrast agents to evaluate in vivo angiogenesis at a molecular level.