Developmental toxicity from exposure to various forms of mercury compounds in medaka fish (Oryzias latipes) embryos.

This study examined developmental toxicity of different mercury compounds, including some used in traditional medicines. Medaka (Oryzias latipes) embryos were exposed to 0.001-10 µM concentrations of MeHg, HgCl2, α-HgS (Zhu Sha), and β-HgS (Zuotai) from stage 10 (6-7 hpf) to 10 days post fertilization (dpf). Of the forms of mercury in this study, the organic form (MeHg) proved the most toxic followed by inorganic mercury (HgCl2), both producing embryo developmental toxicity. Altered phenotypes included pericardial edema with elongated or tube heart, reduction of eye pigmentation, and failure of swim bladder inflation. Both α-HgS and β-HgS were less toxic than MeHg and HgCl2. Total RNA was extracted from survivors three days after exposure to MeHg (0.1 µM), HgCl2 (1 µM), α-HgS (10 µM), or β-HgS (10 µM) to examine toxicity-related gene expression. MeHg and HgCl2 markedly induced metallothionein (MT) and heme oxygenase-1 (Ho-1), while α-HgS and β-HgS failed to induce either gene. Chemical forms of mercury compounds proved to be a major determinant in their developmental toxicity.

Introduction of novel video-based tasks to clinical fMRI: Comparing traditional fMRI tasks with novel video-based tasks for mapping brain language areas

Recently, blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) has become a routine clinical procedure for localization of language and motor brain regions and has been replacing more invasive preoperative procedures. However, the fMRI results from these tasks are not always reproducible even from the same patient. Evaluating the reproducibility of language and speech mapping is especially complicated due to the complex brain circuitry that may become activated during the functional task. Non-language areas such as sensory, attention, decision-making, and motor brain regions may also be activated in addition to the specific language regions during a traditional sentence-completion task. In this study, I test a new approach, which utilizes 4-minute video-based tasks, to map language and speech brain regions for patients undergoing brain surgery. Results from 35 subjects have shown that the video-based task activates Wernicke’s area, as well as Broca’s area in most subjects. The computed laterality indices, which indicate the dominant hemisphere from that functional task, have indicated left dominance from the video-based tasks. This study has shown that the video-based task may be an alternative method for localization of language and speech brain regions for patients who are unable to complete the sentence-completion task.