RESUMO
Thyroid disruption is an increasingly recognized issue in the use and development of chemicals and new drugs, especially to help toxicologist to complement the reproductive and developmental toxicology information of chemicals. Still, adequate assessment methods are scarce and often suffer a trade-off between physiological relevance and labor- and cost-intensive assays. Here, we present a tiered approach for a medium-throughput screening of chemicals to identify their thyroid disrupting potential in zebrafish embryos as a New Approach Methodology (NAM). After identifying the maximum tolerated concentrations, we exposed zebrafish larvae to sub-adverse effect levels of the reference compounds benzophenone-2, bisphenol A, phenylthiourea, potassium perchlorate, propylthiouracil, and phloroglucinol to exclude any systemic toxicity. Applying the transgenic zebrafish line that carries a gene for the red fluorescence protein (Tg(tg:mCherry)) under the thyroglobulin promoter, we could identify the thyroid disrupting effects of the chemicals by a time and cost-effective image analysis measuring the fluorescence levels in the thyroid glands. Our observations could be confirmed by altered expression patterns of genes involved in the hypothalamus-pituitary-thyroid (HPT) axis. Finally, to anchor the observed thyroid disruption, we determined some changes in the Thyroid hormone levels of triiodothyronine (T3) and Thyroxine (T4) using a newly developed liquid chromatography mass spectrometric (LCMS) method. The presented approach carries the potential to extend the toolbox for legislative authorities and chemical producers for the assessment of thyroid-specific endocrine disruption and to overcome current challenges in the evaluation of endocrine disruptors.
RESUMO
INTRODUCTION: Therapeutic decisions and clinical events during the pretransplantation phase of stem cell transplantation (SCT) may influence survival, quality of life, and efficiency of health expenses. However, there is a lack of relevant published data. AIMS: The aims of this study were to identify reasons why the procedure was not performed and to know the waiting time for SCT candidates. PATIENTS AND METHODS: We collected pretransplantation data from 166 consecutive patients evaluated by the SCT Committee of a tertiary center between April 2005 and December 2006. RESULTS: One hundred fifty-two of 166 patients were referred for the first time. Additionally, 14 were reconsidered as candidates for a subsequent SCT due to relapse, graft failure, secondary malignancy, or a multiple-graft program. One hundred forty-one were accepted for transplantation, whereas 25 were not. At the time of analysis, 22 patients were still awaiting SCT, 8 were delayed because they required additional courses of treatment, and 32 were excluded because of death (34.4%), poor stem cell mobilization (21.9%), patient refusal (15.6%), relapse/progression (9.4%), comorbidity (6.3%), or absence of a donor (6.3%). The median time between inclusion in the program and transplantation was 3.6 months (range, 0.27-13.43), and 5.7 months (P < .05) for unrelated allogeneic transplantation. No significant differences were observed in the diagnosis or hospital of origin. CONCLUSIONS: SCT was not performed in 22% of transplant candidates, mainly due to death, insufficient stem cell mobilization, patient refusal, or disease progression/relapse. The median time between inclusion in the SCT program and transplantation was 3 months, but longer among the unrelated allogeneic transplantations.