Molecular PET Imaging of Cyclophosphamide Induced Apoptosis with 18F-ML-8.

In this paper, a novel small-molecular apoptotic PET imaging probe, (18)F-ML-8 with a malonate motif structure, is presented and discussed. After study, the small tracer that belongs to a member of ApoSense family is proved to be capable of imaging merely apoptotic regions in the CTX treated tumor-bearing mice. The experimental result is further confirmed by in vitro cell binding assays and TUNEL staining assay. As a result, (18)F-ML-8 could be used for noninvasive visualization of apoptosis induced by antitumor chemotherapy.

Highly sensitive and selective measurement of underivatized methylmalonic acid in serum and plasma by liquid chromatography-tandem mass spectrometry.

Methylmalonic acid (MMA) is a functional biomarker of vitamin B12 deficiency. Measurement of plasma MMA is challenging due to its small molecular weight and hydrophilic nature. Several liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods have been developed for measuring plasma MMA. However, these methods involve lengthy sample preparation, long chromatographic run time, inadequate sensitivity, or interference from succinic acid (SA). Here we report a novel LC-MS/MS method for quantitation of underivatized MMA in serum or heparinized plasma with high sensitivity and selectivity. Sample preparation involved only strong anion exchange solid phase extraction. The extract was purified by online turbulent flow and analyzed on an Organic Acids column. MS/MS analysis was performed in negative electrospray mode, and the analytical time was 6 min. The use of ion ratio confirmation in combination with chromatographic resolution from SA greatly enhanced the selectivity. No interference was observed. This method was linear from 26.2 to 26,010.0 nM with an accuracy of 98-111 %. Total coefficient of variation was less than 4.6 % for three concentration levels tested. Comparison with a reference laboratory LC-MS/MS method using leftover patient serum specimens (n = 48) showed a mean bias of -2.3 nM (-0.61 %) with a Deming regression slope of 1.016, intercept of -6.6 nM, standard error of estimate of 25.3 nM, and a correlation coefficient of 0.9945. In conclusion, this LC-MS/MS method offers highly sensitive and selective quantitation of MMA in serum and plasma with simple sample preparation.

An on-line solid phase extraction procedure for the routine quantification of urinary methylmalonic acid by liquid chromatography-tandem mass spectrometry.

BACKGROUND: The goal of this study was to develop and to validate an improved isotope-dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of methylmalonic acid (MMA) in urine. METHODS: A previously described sample preparation protocol requires two solvent extraction steps, including evaporation. The first extraction is to extract the analyte from the sample, and second occurs following derivatization of the extract. In the method described here, the second evaporation step was substituted by on-line solid phase extraction employing column-switching and a permanent co-polymer based extraction cartridge. A standard validation protocol was applied to investigate the performance of the method. RESULTS: The method was found to be linear in the clinically relevant range of concentrations (6-100 µmol/L). Total coefficients of variation were below 10% and inaccuracy was <10% for quality control samples at three concentrations. CONCLUSIONS: By omitting one evaporation step, the semi-automated method described in this article enables for more convenient work-flow in the quantification of urinary MMA compared to the previous protocol. This is of relevance for MMA measurement in the routine clinical laboratory setting. Validation demonstrated acceptable analytical performance.

Determination of serum methylmalonic acid by alkylative extraction and liquid chromatography coupled to tandem mass spectrometry.

Despite the new advances in bioanalytical techniques, the analysis of low-molecular-weight organic acids in complex matrices is still a challenge. Although new strategies applying liquid chromatography-tandem mass spectrometry (LC-MS/MS) seem to be promising, sample preparation methodologies hamper its application in most clinical laboratories. The quantitation of methylmalonic acid (MMA) in biological matrices is an emblematic example due to its low concentration, the need for derivatization to increase its molecular weight, and the presence of the physiologically more abundant isomer succinic acid. Here we present a new strategy for rapid and sensitive MMA quantitation by combining alkylative extraction and LC-MS/MS. Alkylative extraction conditions were optimized to allow endogenous detection of MMA using only 50 microL of serum with a short sample preparation procedure. The formation of a unique ion from the MMA dipentafluorobenzyl derivative in negative atmospheric pressure chemical ionization (APCI) allowed its detection with high sensitivity and with no interference from succinic acid, a more abundant physiologically present isomer.

Identification and effects of interaction phytotoxic compounds from exudate of Cistus ladanifer leaves.

Eleven allelochemicals (ferulic acid, cinnamic acid, 4-hydroxybenzoic acid, hydroxycinnamic acid, methyl propionate, oxalic acid, methylmalonic acid, p-anisic acid, butyric acid, 3-hydroxybutyric acid, and azulene) were identified in the exudate of Cistus ladanifer L. We studied the effect of each on germination, cotyledon emergence, root length, and cotyledon length of Rumex crispus. Three groups were distinguished with respect to phytotoxic activity: compounds with low activity (ferulic acid, 4-hydroxybenzoic acid, oxalic acid, methylmalonic acid, p-anisic acid, hydroxybutyric acid, and azulene), with intermediate activity (cinnamic acid and hydroxycinnamic acid), and with high activity (methyl propionate and butyric acid). The effect of the interaction of the compounds was studied. When acting conjointly, all combinations tested produced a more negative effect on both germination and seedling growth than when acting alone. The interaction affected cotyledon emergence and root length more negatively than germination and cotyledon length. When hydroxycinnamic acid and cinnamic acid were added to these mixtures there was an enhancement in the phytotoxic activity, accentuating the effect of the other allelochemicals.