Genetic and metabolic determinants of methotrexate-induced mucositis in pediatric acute lymphoblastic leukemia.

Methotrexate (MTX) is an effective and toxic chemotherapeutic drug in the treatment of pediatric acute lymphoblastic leukemia(ALL). In this prospective study, we aimed to identify metabolic and genetic determinants of MTX toxicity. One hundred and thirty-four Dutch pediatric ALL patients were treated with four high infusions MTX (HD-MTX: 5 g m(-2)) every other week according to the DCOG-ALL-10 protocol. Mucositis (National Cancer Institute grade ⩾ 3) was the most frequent occurring toxicity during the HD-MTX phase (20%) and occurred especially after the first MTX course. Mucositis was not associated with plasma MTX, plasma folate or plasma homocysteine levels. Patients with mucositis had higher erythrocyte folate levels at the start of protocol M than patients without mucositis (median 1.4 vs 1.2 µmol l(-1), P<0.008), this could reflect an increased MTX uptake in mucosal cells of patients with mucositis. From 17 single-nucleotide polymorphisms in the MTX pathway, only patients with the wild-type variant of rs7317112 SNP in the ABCC4 gene had more mucositis (AA (39%) vs AG/GG (15%), P=0.016). We found no evidence that erythrocyte folate levels mediate in the association between the rs7317112 and mucositis.

Measuring methotrexate polyglutamates in red blood cells: a new LC-MS/MS-based method.

The folate antagonist methotrexate (MTX) is the anchor drug in the treatment of rheumatoid arthritis. The therapeutic effects of MTX are attributed to the intracellular levels of MTX, present in the cell as polyglutamates (MTXPGn). We developed a new liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS)-based assay to separately quantitate MTXPGn in red blood cells using stable-isotope-labelled internal standards. Samples were analyzed by LC-ESI-MS/MS using a Waters Acquity UPLC BEH C18 column with a 5-100% organic gradient of 10 mM ammonium bicarbonate (pH 10) and methanol. The analysis consisted of simple sample preparation and a 6-min run time. Detection was done using a Waters Acquity UPLC coupled to a Waters Quattro Premier XE with electrospray ionization operating in the positive ionization mode. Assay validation was performed following recent Food and Drug Administration guidelines. The method was linear from 1-1,000 nM for all MTXPGn (R(2) > 0.99). The coefficient of variation ranged from 1-4% for intraday precision and 6-15% for interday precision. Samples were stable for at least 1 month at -80 °C. Recovery ranged from 98-100%, and the relative matrix-effect varied from 95-99%. The lower limit of quantitation was 1 nM for each MTXPGn. Fifty patient samples from the tREACH study were analyzed. The MTXPGn concentration and distribution of these samples were comparable with values reported in literature. The developed LC-ESI-MS/MS method for the quantitative measurement of MTXPGn in red blood cells is both sensitive and precise within the clinically relevant range. The method can be easily applied in clinical laboratories due to the combination of simple pre-treatment with robust LC-ESI-MS/MS.

LCA-IWM: a decision support tool for sustainability assessment of waste management systems.

The paper outlines the most significant result of the project 'The use of life cycle assessment tools for the development of integrated waste management strategies for cities and regions with rapid growing economies', which was the development of two decision-support tools: a municipal waste prognostic tool and a waste management system assessment tool. The article focuses on the assessment tool, which supports the adequate decision making in the planning of urban waste management systems by allowing the creation and comparison of different scenarios, considering three basic subsystems: (i) temporary storage; (ii) collection and transport and (iii) treatment, disposal and recycling. The design and analysis options, as well as the assumptions made for each subsystem, are shortly introduced, providing an overview of the applied methodologies and technologies. The sustainability assessment methodology used in the project to support the selection of the most adequate scenario is presented with a brief explanation of the procedures, criteria and indicators applied on the evaluation of each of the three sustainability pillars.

The calibration of rabbit tissue thromboplastins: experience of the Dutch Reference Laboratory for anticoagulant control.

A number of commercial rabbit tissue thromboplastins used in oral anticoagulant control have been calibrated against the first International Reference Preparation for thromboplastins. This was done in a three-stage procedure by one laboratory, each stage representing a different level of thromboplastin comparability. The calibration model recently recommended by ICTH and ICSH was tested. This model proved to be suitable, although a statistically significant aberration was observed for some of the thromboplastins. The bias introduced by using the model in these non-ideal cases was small compared to the overall variation of the International Normalized Ratio, being the universal scale for reporting the prothrombin time during oral anticoagulant control. Batch-to-batch calibration using lyophilized pooled plasmas could be reliably performed for several commercial thromboplastins.

Clinical biochemical and haemodynamic correlates of sodium sensitivity in essential hypertension.

Factors contributing to the blood pressure (BP) response to changes in dietary sodium intake were studied in 25 patients with essential hypertension (EH). Relevant clinical, biochemical and haemodynamic variables were measured after two weeks on a low sodium diet (LS, 50 mmol) and after two weeks on a high sodium diet (HS, 300 mmol). BP was significantly higher during HS. The difference in mean arterial pressure between HS and LS (delta MAP) was taken as a measure of sodium sensitivity. delta MAP was directly related to age, initial BP, plasma noradrenaline during HS and changes in forearm vascular resistance. It was indirectly related to plasma aldosterone during LS. No correlation was found with renin or with the excretion of urinary kallikrein. It is concluded that sodium sensitivity in EH is related to age and blood pressure and is predominantly mediated by changes in vascular resistance to which aldosterone and adrenergic mechanisms are likely to contribute.