Yunqi Zhu

Identification of microcystins in waters used for daily life by people who live on Tai Lake during a serious cyanobacteria dominated bloom with risk analysis to human health

Tai Lake is the third largest freshwater lake in China with annual cyanobacteria blooms. Microcystins produced by these blooms have serious health risks for populations surrounding the lake, especially for people living on Tai Lake, because they usually drink raw lake water after a simple alum treatment. This study presents data on the detection and identification of microcystins in waters used for daily life by people living on Tai Lake, during the cyanobacterial blooming in July 2007. The health risks from drinking these microcystin‐polluted waters were also calculated. The main microcystins detected by high‐performance liquid chromatography‐electrospray ionization mass spectrometry in the water samples collected from two parts of Tai Lake (Wuli Lake and Meiliang Bay) were MC‐LR (4.33–12.27 μg/L), MC‐RR (8.36–16.91 μg/L) and MC‐YR (1.41–5.57 μg/L). Risk assessment showed that the drinking water simply treated by alum was not safe. The lowest calculated hazards ratios in all water samples was 6.4, which indicated that the risk of microcystins exposure from drinking water was over six times higher than the tolerable daily intake (TDI) recommended by The World Health Organization (WHO). Further studies should be conducted to elucidate the relationships between the epidemiology of people living on Tai Lake and microcystins exposure from drinking water.

Molecular, Functional, and Structural Imaging of Major Depressive Disorder

AbstractMajor depressive disorder (MDD) is a significant cause of morbidity and mortality worldwide, correlating with genetic susceptibility and environmental risk factors. Molecular, functional, and structural imaging approaches have been increasingly used to detect neurobiological changes, analyze neurochemical correlates, and parse pathophysiological mechanisms underlying MDD. We reviewed recent neuroimaging publications on MDD in terms of molecular, functional, and structural alterations as detected mainly by magnetic resonance imaging (MRI) and positron emission tomography. Altered structure and function of brain regions involved in the cognitive control of affective state have been demonstrated. An abnormal default mode network, as revealed by resting-state functional MRI, is likely associated with aberrant metabolic and serotonergic function revealed by radionuclide imaging. Further multi-modal investigations are essential to clarify the characteristics of the cortical network and serotonergic system associated with behavioral and genetic variations in MDD.

Molecular and Functional Imaging of Internet Addiction

Maladaptive use of the Internet results in Internet addiction (IA), which is associated with various negative consequences. Molecular and functional imaging techniques have been increasingly used for analysis of neurobiological changes and neurochemical correlates of IA. This review summarizes molecular and functional imaging findings on neurobiological mechanisms of IA, focusing on magnetic resonance imaging (MRI) and nuclear imaging modalities including positron emission tomography (PET) and single photon emission computed tomography (SPECT). MRI studies demonstrate that structural changes in frontal cortex are associated with functional abnormalities in Internet addicted subjects. Nuclear imaging findings indicate that IA is associated with dysfunction of the brain dopaminergic systems. Abnormal dopamine regulation of the prefrontal cortex (PFC) could underlie the enhanced motivational value and uncontrolled behavior over Internet overuse in addicted subjects. Further investigations are needed to determine specific changes in the Internet addictive brain, as well as their implications for behavior and cognition.

PET Mapping of Neurofunctional Changes in a Posttraumatic Stress Disorder Model

Posttraumatic stress disorder (PTSD) is an anxiety disorder that occurs after exposure to a traumatic event. This study aimed to investigate the neurobiologic changes before and after exposure-based therapy by PET in a rat model of PTSD. Methods: Serial 18F-FDG PET imaging studies were performed under the control (tone presentation), fear-conditioning, and extinction retrieval phases. Neuroactivity marker c-Fos protein was used for immunostaining. Results: Increased glucose metabolism was observed in the bilateral amygdala after fear-conditioning (P < 0.001) and in the right posterior insular cortex under extinction retrieval (P < 0.001) compared with the control phase. Increased c-Fos expression in the posterior insular cortex under extinction retrieval was positively correlated to the glucose metabolism (P < 0.01). Conclusion: Our results indicated that the amygdala plays a key role in fear memory formation and, most importantly, the insular cortex is related to the retrieval of extinction memory. 18F-FDG PET may provide a promising in vivo approach for evaluating exposure-based therapy of PTSD.

PET Mapping for Brain–Computer Interface Stimulation of the Ventroposterior Medial Nucleus of the Thalamus in Rats with Implanted Electrodes

Brain–computer interface (BCI) technology has great potential for improving the quality of life for neurologic patients. This study aimed to use PET mapping for BCI-based stimulation in a rat model with electrodes implanted in the ventroposterior medial (VPM) nucleus of the thalamus. Methods: PET imaging studies were conducted before and after stimulation of the right VPM. Results: Stimulation induced significant orienting performance. 18F-FDG uptake increased significantly in the paraventricular thalamic nucleus, septohippocampal nucleus, olfactory bulb, left crus II of the ansiform lobule of the cerebellum, and bilaterally in the lateral septum, amygdala, piriform cortex, endopiriform nucleus, and insular cortex, but it decreased in the right secondary visual cortex, right simple lobule of the cerebellum, and bilaterally in the somatosensory cortex. Conclusion: This study demonstrated that PET mapping after VPM stimulation can identify specific brain regions associated with orienting performance. PET molecular imaging may be an important approach for BCI-based research and its clinical applications.

Spatiotemporal PET Imaging of Dynamic Metabolic Changes After Therapeutic Approaches of Induced Pluripotent Stem Cells, Neuronal Stem Cells, and a Chinese Patent Medicine in Stroke

This study aimed to use spatiotemporal PET imaging to investigate the dynamic metabolic changes after a combined therapeutic approach of induced pluripotent stem cells (iPSCs), neuronal stem cells (NSCs), and Chinese patent medicine in a rat model of cerebral ischemia–reperfusion injury. Methods: Cerebral ischemia was established by the middle cerebral artery occlusion approach. Thirty-six male rats were randomly assigned to 1 of the 6 groups: control phosphate-buffered saline (PBS), Chinese patent medicine (Qing-kai-ling [QKL]), induced pluripotent stem cells (iPSCs), combination of iPSCs and QKL, neuronal stem cells (NSCs), and combination of NSCs and QKL. Serial 18F-FDG small-animal PET imaging and neurofunctional tests were performed weekly. Autoradiographic imaging and immunohistochemical and immunofluorescent analyses were performed at 4 wk after stem cell transplantation. Results: Compared with the PBS control group, significantly higher 18F-FDG accumulations in the ipsilateral cerebral infarction were observed in 5 treatment groups from weeks 1–4. Interestingly, the most intensive 18F-FDG accumulation was found in the NSCs + QKL group at week 1 but in the iPSCs + QKL group at week 4. The neurofunctional scores in the 5 treatment groups were significantly higher than that of the PBS group from week 3 to 4. In addition, there was a significant correlation between the PET imaging findings and neurofunctional recovery (P < 0.05) or glucose transporter-1 expression (P < 0.01). Immunohistochemical and immunofluorescence studies found that transplanted iPSCs survived and migrated to the ischemic region and expressed protein markers for cells of interest. Conclusion: Spatiotemporal PET imaging with 18F-FDG demonstrated dynamic metabolic and functional recovery after iPSCs or NSCs combined with QKL in a rat model of cerebral ischemia–reperfusion injury. iPSCs or NSCs combined with Chinese medicine QKL seemed to be a better therapeutic approach than these stem cells used individually.

In vivo Dynamic Metabolic Changes after Induced Pluripotent Stem Cells for Ischemia Injury

This study aimed to investigate in vivo dynamic metabolic changes after transplantation of induced pluripotent stem cells (iPSCs) and iPSC-derived enriched cardiomyocytes (iPSC-CMs) in a rat model of ischemic injury. Methods: Serial 18F-FDG PET, echocardiographic, immunohistochemical, and immunofluorescence studies were performed after transplantation of iPSCs and iPSC-CMs and compared with embryonic stem cells (ESCs), ESC-CMs, and a phosphate-buffered saline control group of rats with myocardial infarction. Results: Increased glucose metabolism in periinfarct areas and improved myocardial function were observed in the stem cell transplantation groups compared with the control group, and serial immunofluorescence and immunohistochemical results exhibited the survival and migration of stem cells during the study period. Conclusion: Serial 18F-FDG PET and echocardiographic imaging studies demonstrated the dynamic metabolic changes and recovery of myocardial function after stem cell transplantation. 18F-FDG PET could be a potential approach to evaluating spatiotemporal dynamic metabolic changes in vivo after transplantation of iPSCs or iPSC-CMs for ischemic injury.