On the Cellular Pharmacokinetics of 6-Thioguanine in Acute Myelogenous Leukemia

The pharmacokinetics of 6-thioguanine were studied in 10 patients with acute myelogenous leukemia treated with 25-100 mg/m(2) orally. The concentration of 6-thioguanine in plasma was determined with reversed phase high performance liquid chromatography (HPLC). After isolation of leukemic cells and erythrocytes by density centrifugation, HClO4 extraction of nucleotides and isolation of thiol containing substances on mercurial cellulose, the intracellular concentration of phosphorylated 6-thioguanine metabolites was measured by anion exchange HPLC. The plasma peak concentration of 6-thioguanine was significantly correlated (r(2) = 0.60) to the dose administered. In the leukemic cells, the 5'-mono-(TGMP) and 5'-triphosphates (TGTP) of 6-thioguanosine could be detected in nine of the patients. In one patient only TGMP was seen. The diphosphate could be detected in low concentrations in 6 patients. In all patients, the concentration of TGMP was higher than that of TGTP which was higher than the diphosphate. The interindividual variation in cellular TGMP and TGTP concentration was > 100-fold and independent of dose, while the variation in plasma 6-TG was < 15-fold. There was no correlation between dose or plasma area under the concentration versus time curve (AUC) of 6-TG and the cellular AUC of TGMP or TGTP. However, the AUC of TGMP and TGTP correlated significantly (r(2) = 0.64). The t1/2 of the intracellular metabolites and of 6-thioguanine in plasma were in the same order (4.4, 5.2 and 5.0 h for plasma 6-thioguanine, the intracellular mono- and triphosphate respectively). Phosphorylated metabolites of 6-thioguanine were detectable in erythrocytes from 8 patients. The kinetic pattern of the metabolites in erythrocytes was different from that in leukemic cells. While shortly after administration being eliminated according to first order kinetics in the leukemic cells, the concentration of intracellular metabolites in the erythrocytes was raising during the first 24 h after the treatment. The concentration of the metabolites were, however, much (100-fold) lower in erythrocytes compared to leukemic cells. Furthermore, the triphosphate was the predominant metabolite in the erythrocytes and considerable amounts of the diphosphate was seen while the concentration in the monophosphate was low. We conclude that there is a considerable interindividual variation in the cellular pharmacokinetics of TGMP and TGTP. The concentration of the phosphorylated metabolites in the leukemic cells cannot be predicted by determination of plasma 6-thioguanine concentration, nor by the concentration of the same metabolites in the erythrocytes.

Health and functioning in the everyday lives of young children with cancer: documenting with the International Classification of Functioning, Disability and Health--Children and Youth (ICF-CY)

BACKGROUND

Health care focus is shifting for children from surviving childhood cancer to living with it on a daily basis. There is a need to document health and function in the everyday lives of young children with cancer using the multidimensional framework and language of the International Classification of Functioning, Disability and Health--Children and Youth (ICF-CY).

AIMS

The aims of this study were (1) to document health and functioning in the everyday lives of young children with cancer using ICF-CY codes and (2) to identify a comprehensive code set that can aid clinical assessment.

METHOD

Interviews with children diagnosed with cancer and their parents, were transcribed, reviewed for content and coded to the ICF-CY using linking procedures.

RESULTS

A comprehensive code set (n = 70) for childhood cancer was identified. The majority of content identified to codes was related to activity and participation describing social relations with family, peers and professionals, preschool attendance and play, as well as issues related to support and independence.

CONCLUSIONS

The ICF-CY can be used to document the nature and range of characteristics and consequences of cancer experienced by children. The identified comprehensive code set could be helpful to health care professionals, parents and teachers in assessing and supporting young children's health and everyday life through the cancer trajectory. The comprehensive code set could be developed as a clinical assessment tool for those caring for young children with cancer. The universal language of the ICF-CY means that the utility of a clinical assessment tool based on identified codes can have wide reaching effects for the care of young children with cancer.

Polymorphisms in the ABCB1 gene and effect on outcome and toxicity in childhood acute lymphoblastic leukemia

The membrane transporter P-glycoprotein, encoded by the ABCB1 gene, influences the pharmacokinetics of anti-cancer drugs. We hypothesized that variants of ABCB1 affect outcome and toxicity in childhood acute lymphoblastic leukemia (ALL). We studied 522 Danish children with ALL, 93% of all those eligible. Risk of relapse was increased 2.9-fold for patients with the 1199GA variant versus 1199GG (P=0.001), and reduced 61% and 40%, respectively, for patients with the 3435CT or 3435TT variants versus 3435CC (overall P=0.02). The degree of bone marrow toxicity during doxorubicin, vincristine and prednisolone induction therapy was more prominent in patients with 3435TT variant versus 3435CT/3435CC (P=0.01/P<0.0001). We observed more liver toxicity after high-dose methotrexate in patients with 3435CC variant versus 3435CT/TT (P=0.03). In conclusion, there is a statistically significant association between ABCB1 polymorphisms, efficacy and toxicity in the treatment of ALL, and ABCB1 1199G>A may be a new possible predictive marker for outcome in childhood ALL.

Development, testing, and deployment of an air sampling manifold for spiking elemental and oxidized mercury during the Reno Atmospheric Mercury Intercomparison Experiment (RAMIX)

The Reno Atmospheric Mercury Intercomparison Experiment (RAMIX) was in Reno, NV from August 22, 2011 to September 16, 2011. The goals of the experiment were to compare existing and new methods for measurements of ambient elemental and oxidized Hg, and to test these with quantitative spikes of Hg(0), HgBr2, O3 and water vapor. In this paper we describe the design, testing, and deployment of a high flow manifold system designed to deliver ambient air and spiked compounds to multiple instruments simultaneously. The manifold was constructed of 1" OD PFA tubing and heated to 115 °C for the entire active zone. Manifold flow was controlled at ∼200 LPM using a blower and a velocity sensor in a feedback control system. Permeation tubes in controlled ovens were used to deliver Hg(0) and HgBr2. Ozone was generated from a small UV lamp in a flow of high purity O2. Water vapor was generated by pumping a flow of purified N2 through heated, high purity water. The spiking delivery for Hg(0), HgBr2, O3, and water vapor after dilution in the manifold ranged up to 20 ng m(-3), 0.64 ng m(-3), 100 ppbv, and 20 g kg(-1), respectively. During laboratory tests the average transmission efficiencies for Hg(0), HgBr2, and O3 were found to be 92%, 76%, and 93%, respectively.

Do we understand what the mercury speciation instruments are actually measuring? Results of RAMIX

From August 22 to September 16, 2012, atmospheric mercury (Hg) was measured from a common manifold in the field during the Reno Atmospheric Mercury Intercomparison eXperiment. Data were collected using Tekran systems, laser induced fluorescence, and evolving new methods. The latter included the University of Washington-Detector for Oxidized Mercury, the University of Houston Mercury instrument, and a filter-based system under development by the University of Nevada-Reno. Good transmission of total Hg was found for the manifold. However, despite application of standard protocols and rigorous quality control, systematic differences in operationally defined forms of Hg were measured by the sampling systems. Concentrations of reactive Hg (RM) measured with new methods were at times 2-to-3-fold higher than that measured by Tekran system. The low RM recovery by the latter can be attributed to lack of collection as the system is currently configured. Concentrations measured by all instruments were influenced by their sampling location in-the-manifold and the instrument analytical configuration. On the basis of collective assessment of the data, we hypothesize that reactions forming RM were occurring in the manifold. Results provide a new framework for improved understanding of the atmospheric chemistry of Hg.

The "E" word: epilepsy and perceptions of unfair treatment from the 2010 Australian Epilepsy Longitudinal Survey

AIM

The aim of the current study was to examine self-report data on perceptions of unfair treatment due to epilepsy.

METHOD

We analyzed data from the 2010 Australian Epilepsy Longitudinal Survey, distributed to 621 registrants on the Australian Epilepsy Research Register. A total of 343 responses were received (55% response rate), providing insight into experiences of life with epilepsy in Australia. Responses relating to perceptions of unfair treatment in areas of employment, education and community participation as a result of epilepsy are reported in this article.

RESULTS

Forty-eight percent of respondents reported perceptions of unfair treatment as a result of their epilepsy, with most providing details of their experiences. Discrimination in the workplace remains of key concern, with 47% citing examples of unfair treatment in this setting.

CONCLUSIONS

In spite of Australian anti-discrimination laws, findings indicate that full-time employment rates for people with epilepsy are lower than previously reported, with further mechanisms for support required to improve education and reduce experiences of stigma.

Attachment style as a piedictor of sexual attitudes and behavior in late Adolescence

Abstract This research applied attachment theory to the study of sexual attitudes and behaviors in a sample of late adolescents. Four hundred and seventy heterosexual undergraduate students completed questionnaires assessing attachment (discomfort with closeness; anxiety over relationships). relationship history, communication about sex. sexual self-efficacy and locus of control, and attitudes to condoms. Eight weeks later, participants reported on sexual behaviors occurring during the eight-week interval. and perceived risk of these activities. Both discomfort with closeness and anxiety over relationships were associated with external locus of control for sexual outcomes, and with use of drugs before sexual contact. Anxiety over relationships was linked to unsafe sex and to negative attitudes to condoms, but discomfort with closeness was associated with a more cautious approach to sexual risk-taking. Some results were qualified by gender differences. and by differences between the full sample and those who were sexually active. The findings arc discussed in terms of attachment style and its links with communication and affect regulation. SUMMARY AND CONCLUSIONS This study indicates that attachment dimensions are reliably related to many aspects of sexual attitudes and behaviors among late adolescents. Insecure attachment was linked to increased drug use before sexual contact. Anxiety over relationships was also linked to less safe sexual practice, but discomfort with closeness was associated with a tendency for males to be cautious about sexual risk-taking. The results support the utility of the attachment perspective on adolescent sexuality, but also highlight the complex relations between attachment dimensions and sexual outcomes. Future research would benefit from more detailed investigations of the attitudes, emotions, and cognitions which may mediate the link between attachment style and sexual behavior. For example, those who are highly anxious about their relationships may engage in more risky sexual practices because they fear that non-compliance with partners' wishes will jeopardize their relationship; the tendency to engage in drug use before sexual cpntact may reflect their attempts to boost self-confidence or to manage negative mood states. Research into these issues has the potential to explain how attachment insecurity is played out in patterns of sexual activity.

Testing the use of passive sampling systems for understanding air mercury concentrations and dry deposition across Florida, USA

This paper describes the use of passive sampling systems and surrogate surfaces for monitoring atmospheric mercury (Hg) concentrations and dry deposition, respectively, in Florida,USA. Although this area has been reported to have low air concentrations, wet deposition values, reported by the Mercury Deposition Network, are some of the highest in the United States, and little is known about the magnitude of dry deposition to the region. To address this uncertainty, dry deposition of gaseous oxidized mercury (GOM) was estimated based on data collected using surrogate surfaces and through the application of a dry deposition model that utilized Tekran® Mercury Analyzer data for three sites (Davie near Fort Lauderdale, Tampa and Pensacola) over a year (July 2009-July 2010). Passive sampler systems for monitoring GOM and total gaseous mercury (TGM) concentrations were also deployed. In general, higher surrogate surface deposition, and GOM and TGM passive sampler uptake were observed at the DVE location. Across all sites, empirically derived dry deposition was higher than that determined using modeled values. Tekran® Instrument derived GOM concentrations, as well as modeled deposition rates, followed the same seasonal and spatial patterns as that measured by the samplers, however there were some spatial and temporal trends captured by the samplers that were not seen in the Tekran® derived data. Results indicate that these samplers may be applied to identify spatial and temporal trends in air Hg concentrations and potential deposition at sites with low and fairly constant GOM concentrations as reported by the Tekran® system (2-8 pg m(-3)). When viewed collectively, trends in sampler and Tekran® derived data also suggest the potential for different forms of GOM in air. Using empirical and modeled values, dry deposition in Florida during the year of this study could account for 1.5 to 14% of total annual Hg deposition (wet+dry).