Parahydrogen-Polarized [1-13 C]Pyruvate for Reliable and Fast Preclinical Metabolic Magnetic Resonance Imaging

Hyperpolarization techniques increase nuclear spin polarization by more than four orders of magnitude, enabling metabolic MRI. Even though hyperpolarization has shown clear value in clinical studies, the complexity, cost and slowness of current equipment limits its widespread use. Here, a polarization procedure of [1-13 C]pyruvate based on parahydrogen-induced polarization by side-arm hydrogenation (PHIP-SAH) in an automated polarizer is demonstrated. It is benchmarked in a study with 48 animals against a commercial dissolution dynamic nuclear polarization (d-DNP) device. Purified, concentrated (≈70-160 mM) and highly hyperpolarized (≈18%) solutions of pyruvate are obtained at physiological pH for volumes up to 2 mL within 85 s in an automated process. The safety profile, image quality, as well as the quantitative perfusion and lactate-to-pyruvate ratios, are equivalent for PHIP and d-DNP, rendering PHIP a viable alternative to established hyperpolarization techniques.

Simultaneous magnetic resonance imaging of pH, perfusion and renal filtration using hyperpolarized 13C-labelled Z-OMPD

pH alterations are a hallmark of many pathologies including cancer and kidney disease. Here, we introduce [1,5-13C2]Z-OMPD as a hyperpolarized extracellular pH and perfusion sensor for MRI which allows to generate a multiparametric fingerprint of renal disease status and to detect local tumor acidification. Exceptional long T1 of two minutes at 1 T, high pH sensitivity of up to 1.9 ppm per pH unit and suitability of using the C1-label as internal frequency reference enables pH imaging in vivo of three pH compartments in healthy rat kidneys. Spectrally selective targeting of both 13C-resonances enables simultaneous imaging of perfusion and filtration in 3D and pH in 2D within one minute to quantify renal blood flow, glomerular filtration rates and renal pH in healthy and hydronephrotic kidneys with superior sensitivity compared to clinical routine methods. Imaging multiple biomarkers within a single session renders [1,5-13C2]Z-OMPD a promising new hyperpolarized agent for oncology and nephrology.

ANGI-05. VASCULAR NORMALIZATION IN MURINE GLIOBLASTOMA IS CONTROLLED BY APLN-SIGNALING AND CAN BE MONITORED BY DCE-MR IMAGING IN VIVO

OBJECTIVE

Glioblastoma (GBM) expansion is accompanied by aberrant tumor vascularization. We demonstrated that the peptide hormone Apelin (APLN) controls GBM neo-vascularization and that the APLN-receptor antagonist Apelin-F13A improved the efficiency and reduced the invasive side effect of established antiangiogenic therapy. Here we investigated if Apelin-F13A blunts the formation of vasogenic edema, which can be monitored by MRI in vivo.

METHODS

To investigate the role of APLN -signaling in regulating the tightness of the tumor vasculature we performed in vivo leakage assays using Evans-Blue dye and fluorescent dextran. By confocal immunofluorescence, we characterized the maturation of the tumor vasculature with respect to pericyte-coverage and established a dynamic contrast enhanced (DCE) MR imaging protocol to follow vascular edema formation.

RESULTS

We found that Evans-Blue extravasation is significantly increased by 3-fold in APLNKO tumors compared to controls. Uptake of fluorescent Dextran by CD31+ endothelia was quantified and increased massively from 200μm2 per high magnification field (HMF) in wildtype to 3500μm2 per HMF in APLNKO tumors. Interestingly, intracerebral infusion of Apelin-F13A enhanced pericyte coverage of the tumor vasculature by 50%, decreased Evans-Blue extravasation from 25 μg/ml in controls to 8 μg/ml in treated tumors significantly and efficiently reversed the APLN-dependent vasogenic edema assessed by comparison of T2w-MRI to HE tumor volumes. To follow vasogenic edema formation in vivo, T1w 3D FLASH images were acquired every second over a 360s time course after gadolinium-based MR-contrast agent injection and demonstrated a delayed washout of the contrast in APLN-deficient GBM.

CONCLUSION

Together, our study shows that DCE-MRI can document APLN-dependent intratumoral vascular normalization and allows inspecting vasogenic edema formation in vivo. In addition to its anti-angiogenic / anti-invasive effect, Apelin-F13A can potently reduce vasogenic edema and might thus serve as a multimodal therapy for the treatment of human GBM in the future.

Bioaccumulation and depuration of Escherichia coli in the tropical clam Anomalocardia brasiliana at different salinities

ABSTRACT Anomalocardia brasiliana is an intertidal filter-feeding clam that can accumulate enterobacteria, such as Escherichia coli, and consequently affect human health. Shellfish depuration is a procedure which reduces microbiological contaminants; however, salinity and depuration time can vary across species to adequately reduce bacteria load. To analyze the effect of salinity on the bioaccumulation and depuration of E. coli by A. brasiliana, this study evaluated salinity and depuration time in animals artificially contaminated with E. coli. Each experimental group of clams were acclimated for 6 hours in a recirculating aquaculture system (RAS) and then exposed to E. coli for 18 hours. Following exposure, clams were then held at one of four salinities (35, 30, 25 e 20) for a period of one of four depuration times (0, 12, 24, 36 and 48h). The highest bioaccumulation of E. coli in A. brasiliana was observed in clams held at salinities of 35, 30 and 25. The greatest reduction of E. coli in A. brasiliana was observed in clams held at 25 for 48 hours. A salinity of 20 showed low bioaccumulation and depuration of E. coli. The results of this study will contribute to developing a protocol for depurating A. brasiliana to mitigate human health concerns.

Growth and survival of the native oyster Crassostrea gasar cultured under different stocking densities in two grow-out systems in tropical climate

ABSTRACT Survival and growth of the native oyster Crassostrea gasar along the juvenile and adult phases were evaluated in three different stocking densities [low (D), medium (2D) and high (3D)] and in two grow-out systems (fixed and floating system). The fixed system consisted of a rack made with PVC, fixed from the bottom with wood sticks. The floating system consisted of floating bags suspended by a rack made with PVC and maintained submerged from the seawater surface by eight floats. Survival and shell height of oysters cultured after 30, 60 and 90 days were registered in each phase and in each grow-out system. Results showed that the grow-out system did not affect survival and growth of C. gasar in the juvenile and adult phases. The tested densities affected the survival of oysters cultured over time in both phases but did not affect oyster growth. At times analyzed, it was observed positive growth in juvenile oysters grow after 90 days of culture. However, in the adult phase, no growth was observed after 90 days of culture. Oyster yield was higher in the density 3D, in both juvenile and adult phases. These findings contributed to the development of the oyster C. gasar culture.

Sexual stages of the female portion in the scallop Nodipecten nodosus (Linné, 1758) and astaxanthin quantity in each stage

This work describes the gametogenic cycle of the scallop Nodipecten nodosus kept in a culture system. To this end, during one year, samples were taken from the broodstocks every 30 days to be submitted to macroscopic and microscopic analyses and to measure the amount of astaxanthin. To perform the microscopic evaluation, 5 micro slices from the median portion of the female part of the gonad were submitted to the pattern methodology for histological analyses with paraffin and HE coloration. The remaining portion of the female gonad was lyophilised to extract and quantify the levels of astaxanthin using HPLC. The microscopic analyses revealed four well defined stages for the reproductive cycle. Analyses of data taken throughout the year indicated preferential spawning periods from December to January and from July to September. The astaxanthin analyses showed higher amounts of this carotenoid during the advanced pre-spawning and the initial spawning periods than during gametogenesis, initial pre-spawning, advanced spawning, and the spent stages. According to these results, it was possible to establish a descriptive table of the sexual stages of the female portion of the gonad and the amount of astaxanthin in the sexual stage of the scallop Nodipecten nodosus.