Parahydrogen hyperpolarization of minimally altered urine samples for sensitivity enhanced NMR metabolomics.

Parahydrogen hyperpolarization has been shown to enhance NMR sensitivity in urine analysis by several orders of magnitude if urine samples are prepared by solid phase extraction (SPE). We present a different approach, developed for minimal sample alteration before analysis. Removing SPE from the workflow allows to retain a wider range of metabolites and paves the way towards more universal hyperpolarized NMR metabolomics of low abundance metabolites.

Zinc and copper complexes with azacrown ethers and their comparative stability in vitro and in vivo.

Copper-based radiopharmaceuticals are of high interest these days owing to the decay properties of copper radioisotopes. In contrast, labeled zinc compounds have been less studied for applications in nuclear medicine. In this study, the stability of labeled zinc and copper complexes with two azacrown ether ligands was investigated and compared. Then, the in vitro and in vivo stability of the studied zinc complexes was demonstrated, with the complexes showing promise for biomedical applications. In contrast, analogous copper complexes quickly dissociated in the presence of serum proteins. Furthermore, a simple method for the production of radiochemically pure 65Zn was proposed, and the opportunity for its use as a surrogate radionuclide for research into potential zinc-containing radiopharmaceuticals was demonstrated.

Critical analysis of reference studies on the toxicokinetics of aluminum-based adjuvants.

We reviewed the three toxicokinetic reference studies commonly used to suggest that aluminum (Al)-based adjuvants are innocuous. A single experimental study was carried out using isotopic 26Al (Flarend et al., Vaccine, 1997). This study used aluminum salts resembling those used in vaccines but ignored adjuvant uptake by cells that was not fully documented at the time. It was conducted over a short period of time (28days) and used only two rabbits per adjuvant. At the endpoint, Al elimination in the urine accounted for 6% for Al hydroxide and 22% for Al phosphate, both results being incompatible with rapid elimination of vaccine-derived Al in urine. Two theoretical studies have evaluated the potential risk of vaccine Al in infants, by reference to an oral "minimal risk level" (MRL) extrapolated from animal studies. Keith et al. (Vaccine, 2002) used a high MRL (2mg/kg/d), an erroneous model of 100% immediate absorption of vaccine Al, and did not consider renal and blood-brain barrier immaturity. Mitkus et al. (Vaccine, 2011) only considered solubilized Al, with erroneous calculations of absorption duration. Systemic Al particle diffusion and neuro-inflammatory potential were omitted. The MRL they used was both inappropriate (oral Al vs. injected adjuvant) and still too high (1mg/kg/d) regarding recent animal studies. Both paucity and serious weaknesses of reference studies strongly suggest that novel experimental studies of Al adjuvants toxicokinetics should be performed on the long-term, including both neonatal and adult exposures, to ensure their safety and restore population confidence in Al-containing vaccines.

Differences in protein binding and excretion of Triapine and its Fe(III) complex.

Triapine has been investigated as anticancer drug in multiple clinical phase I/II trials. Although promising anti-leukemic activity was observed, Triapine was ineffective against solid tumors. The reasons are currently widely unknown. The biological activity of Triapine is strongly connected to its iron complex (Fe-Triapine) which is pharmacologically not investigated. Here, novel analytical tools for Triapine and Fe-Triapine were developed and applied for cell extracts and body fluids of treated mice. Triapine and its iron complex showed a completely different behavior: for Triapine, low protein binding was observed in contrast to fast protein adduct formation of Fe-Triapine. Notably, both drugs were rapidly cleared from the body (serum half-life time <1h). Remarkably, in contrast to Triapine, where (in accordance to clinical data) basically no renal excretion was found, the iron complex was effectively excreted via urine. Moreover, no Fe-Triapine was detected in serum or cytosolic extracts after Triapine treatment. Taken together, our study will help to further understand the biological behavior of Triapine and its Fe-complex and allow the development of novel thiosemicarbazones with pronounced activity against solid tumor types.

[Absorption, distribution and elimination of (59)Fe- corn polysaccharide iron complex in rats: a study with radioactivity isotope tracing].

OBJECTIVE: To establish a method for detecting plasma concentration of corn polysaccharide iron complex (CPIC) and investigate its absorption, distribution and elimination in rats. METHODS: Using radioactivity isotope tracing method, we detected the radioactivity of (59)Fe-CPIC in the plasma of rats at different time points by gavages of 3 doses (28.0, 14.0, and 7.0 mg/kg) (59)Fe-CPIC in SD rats. The pharmacokinetic parameters was obtained using DAS 2.0 program for analysis of tissue distribution and elimination of (59)Fe-CPIC. RESULTS: The standard curve was linear within the range of 0.14-141 µg/ml (r=0.9999, n=5). The average recovery was 95% with a relative standard deviation no more than 15%. The pharmacokinetic parameters at 3 doses obtained, namely t1/2 and AUC (0-), were 214∓104, 231∓110, and 181∓81 min, and 1986.3∓513.3, 737.0∓467.0, and 315.1∓226.1 mg·min-1·L(-)1, respectively. (59)Fe-CPIC were detected in all the 13 tissues types examined and high radioactivity intensity was found in the gastrointestinal tract, hematogenic organs and other organs rich in blood. (59)Fe-CPIC was eliminated after intragastric administration primarily via the feces in rats. CONCLUSION: The method we established is easy and specific, and the pharmacokinetic parameters of (59)Fe-CPIC fit the two- compartment open model.

Chemical speciation of trivalent actinides and lanthanides in biological fluids: the dominant in vitro binding form of curium(III) and europium(III) in human urine.

Radionuclides represent a serious health risk to humans in the case of incorporation. To elucidate the potential of time-resolved laser-induced fluorescence spectroscopy (TRLFS) to determine the dominant radionuclide species in natural biofluids, we investigated the in vitro speciation of curium(III) in human urine samples. Because in speciation studies trivalent lanthanides are often used as analogues for trivalent actinides, we also probed the suitability of this theory by investigating the speciation of europium(III) in human urine. Comparison with reference spectra of both heavy metals in model urine and of their complexes with single organic and inorganic urine constituents then allowed for the determination of the dominant species. Furthermore, the chemical composition of all urine samples was analyzed, and the parameters affecting the speciation of the metals were determined. The pH was found to be the most important parameter because for both, the actinide and the lanthanide, two analogue species were identified in dependence on the pH. In samples with slightly acidic pH a curium(III) and europium(III) citrate complex dominates, respectively, whereas in samples with near-neutral pH a higher complex with phosphate and calcium as the main ligands and the additional participation of citrate and/or carbonate is formed in each case. Comparison with thermodynamic modeling yields some discrepancies, especially at higher pH, which is due to a lack of data for the complex formation of the higher species for both heavy metals. Nevertheless, TRLFS has proven to be a suitable method for the direct determination of the dominant heavy metal species in untreated natural human urine samples.