Miniature Fluorescence Microscopy for Imaging Brain Activity in Freely-Behaving Animals / 神经科学通报·英文版

An ultimate goal of neuroscience is to decipher the principles underlying neuronal information processing at the molecular, cellular, circuit, and system levels. The advent of miniature fluorescence microscopy has furthered the quest by visualizing brain activities and structural dynamics in animals engaged in self-determined behaviors. In this brief review, we summarize recent advances in miniature fluorescence microscopy for neuroscience, focusing mostly on two mainstream solutions - miniature single-photon microscopy, and miniature two-photon microscopy. We discuss their technical advantages and limitations as well as unmet challenges for future improvement. Examples of preliminary applications are also presented to reflect on a new trend of brain imaging in experimental paradigms involving body movements, long and complex protocols, and even disease progression and aging.

Miniature Fluorescence Microscopy for Imaging Brain Activity in Freely-Behaving Animals / 神经科学通报·英文版

An ultimate goal of neuroscience is to decipher the principles underlying neuronal information processing at the molecular, cellular, circuit, and system levels. The advent of miniature fluorescence microscopy has furthered the quest by visualizing brain activities and structural dynamics in animals engaged in self-determined behaviors. In this brief review, we summarize recent advances in miniature fluorescence microscopy for neuroscience, focusing mostly on two mainstream solutions - miniature single-photon microscopy, and miniature two-photon microscopy. We discuss their technical advantages and limitations as well as unmet challenges for future improvement. Examples of preliminary applications are also presented to reflect on a new trend of brain imaging in experimental paradigms involving body movements, long and complex protocols, and even disease progression and aging.

Alterations of the Ca²⁺ signaling pathway in pancreatic beta-cells isolated from db/db mice

Upon glucose elevation, pancreatic beta-cells secrete insulin in a Ca(2+)-dependent manner. In diabetic animal models, different aspects of the calcium signaling pathway in beta-cells are altered, but there is no consensus regarding their relative contributions to the development of beta-cell dysfunction. In this study, we compared the increase in cytosolic Ca(2+) ([Ca(2+)]i) via Ca(2+) influx, Ca(2+) mobilization from endoplasmic reticulum (ER) calcium stores, and the removal of Ca(2+) via multiple mechanisms in beta-cells from both diabetic db/db mice and non-diabetic C57BL/6J mice. We refined our previous quantitative model to describe the slow [Ca(2+)]i recovery after depolarization in beta-cells from db/db mice. According to the model, the activity levels of the two subtypes of the sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) pump, SERCA2 and SERCA3, were severely down-regulated in diabetic cells to 65% and 0% of the levels in normal cells. This down-regulation may lead to a reduction in the Ca(2+) concentration in the ER, a compensatory up-regulation of the plasma membrane Na(+)/Ca(2+) exchanger (NCX) and a reduction in depolarization-evoked Ca(2+) influx. As a result, the patterns of glucose-stimulated calcium oscillations were significantly different in db/db diabetic beta-cells compared with normal cells. Overall, quantifying the changes in the calcium signaling pathway in db/db diabetic beta-cells will aid in the development of a disease model that could provide insight into the adaptive transformations of beta-cell function during diabetes development.

A comparative study of intra-arterial thrombolysis combined with mechanical adjuvant in the treatment of ischemic stroke patients with acute large artery occlusion in either anterior circulation or posterior circulation / 中国神经精神疾病杂志

Objective To study the effect and safety of intra-arterial thrombolysis combined with mechanical ad-juvant in the treatment of acute large artery occlusive infarction of anterior circulation and posterior circulation. Methods Fourty-tow patients were divided into anterior circulation group (24 cases) and posterior circulation group(18 cases). The recanalization rate, NIHSS score (National Institute of Health stroke scale), GCS score ( Glasgow coma score,GCS), BI ( Barthel Index) excellent rate, symptomatic intracranial hemorrhage rate and mortality was analyzed after intra-arterial thrombolysis combined with mechanical aids therapy. Results The anterior circulation group was mainly caused by car-diogenic embolism (15/24, 62.5%) and posterior circulation group was mainly caused by atherosclerosis thrombosis (5/18, 72.2%). The NIHSS score was significantly lower after treatment (8.3±4.9 vs. 8.1±5.7) than before treatment(15.1±5.3 vs. 16.8±7.8)(P=0.001 vs. P=0.001), the GCS score was significantly higher after treatment(13.9±4.4 vs. 12.8±4.2)than be-fore treatment(9.5 ± 3.8 vs. 9.6 ± 3.7)(P=0.001 vs. P=0.021). The symptomatic intracranial hemorrhage rate was signifi-cant higher in anterior circulation group (5/24, 20.8%) than in posterior circulation group (0,0%) (P<0.05). Compared with the anterior circulation group, the recanalization rate trended to increase in posterior circulation group (P=0.830).The symptomatic intracranial hemorrhage rate in anterior circulation group (5/24,20.8%) was significant higher than in pos-terior circulation group (0,0%) (P<0.05), the mortality was similar between these two groups. Conclusions Intra-arterial thrombolysis combined with mechanical adjuvant therapy can improve neurological deficit in acute large artery occlusive infarction and increase the recanalization rate,which is more suitable for the treatment of posterior circulation infarction.

Ultrafast, accurate, and robust localization of anisotropic dipoles

The resolution of single molecule localization imaging techniques largely depends on the precision of localization algorithms. However, the commonly used Gaussian function is not appropriate for anisotropic dipoles because it is not the true point spread function. We derived the theoretical point spread function of tilted dipoles with restricted mobility and developed an algorithm based on an artificial neural network for estimating the localization, orientation and mobility of individual dipoles. Compared with fitting-based methods, our algorithm demonstrated ultrafast speed and higher accuracy, reduced sensitivity to defocusing, strong robustness and adaptability, making it an optimal choice for both two-dimensional and three-dimensional super-resolution imaging analysis.

Individualized endovascular treatment of intracranial vein sinous thrombosis based on the stage of disease / 中华神经科杂志

Objective To discuss the individualizing schedule of endovascular treatment for intracranial venous sinus thrombosis based on the clinical feature and the stage of the disease.Methods Forty-three patients diagnosed with intracranial venous sinus thrombosis in Xuanwu Hospital,Capital University of Medical Sciences and in Zhongshan Hospital Xiamen University during period of August 2010 to August 2011 were treated with endovascular therapy designed individually based on the clinical stage of the disease development.Of all 43 cases,22 cases with acute onset (＜ 1 week after the onset) were treated with standard anticoagulant therapy ; 11 cases who failed to respond to anticoagulant therapy and 8 cases with subacute onset (1 week to 1 month) received intravenous thrombolysis and mechanical thrombus maceration;and 13 cases with chronic course (＞ 1 month) were given mechanical thrombus maceration combined with balloon dilation vascular surgery or stent-assisted venous sinus surgery,with taking anticoagulant for 12months.The patients were followed up for 3 to 6 months (mean 4.5 months).Results Their symptoms and signs were all significantly improved,with headache relief in 29 cases(67.4％),vision improvement in 28cases (28/31,90.3％),cerebrospinal fluidpressure decrease to normal level in 32 cases(32/43,74.4％) ;no improvement in 1 case,and a complication of subdural hematoma in 1 case.Three months follow-up of 39 patients,symptoms disappeared,the pressure cerebrospinal fluid in 36 cases returned to normal (94.3％),the papilledema in 37 cases subsided (94.9％).After 6 months,16 patients were followed up with an angiography; 8 of them were found venous sinus clear,5 were found partial recanalization of venous sinus trunk,cortical veins and deep venous was partially compensation,and 3 cases with stent-assisted venous sinus surgery were found the stent not shifted or collapsed,and venous sinuses maintained patency.Conclusions Endovascular treatment for patients with intracranial venous sinus thrombosis should be treated with individually designed therapy based on their clinical features and the stage of the disease.The individualized treatment was effective and safe.

Bulk-like endocytosis plays an important role in the recycling of insulin granules in pancreatic beta cells

Although bulk endocytosis has been found in a number of neuronal and endocrine cells, the molecular mechanism and physiological function of bulk endocytosis remain elusive. In pancreatic beta cells, we have observed bulk-like endocytosis evoked both by flash photolysis and trains of depolarization. Bulk-like endocytosis is a clathrin-independent process that is facilitated by enhanced extracellular Ca(2+) entry and suppressed by the inhibition of dynamin function. Moreover, defects in bulk-like endocytosis are accompanied by hyperinsulinemia in primary beta cells dissociated from diabetic KKAy mice, which suggests that bulk-like endocytosis plays an important role in maintaining the exo-endocytosis balance and beta cell secretory capability.

Protective effects of Ginkgo biloba extract on rats during cerebral ischemia/reperfusion / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To study the effect of Ginkgo biloba extract on rats during ischemia/reperfusion and its influence on intracellular calcium in hippocampal neurons.</p><p><b>METHODS</b>Model of intraluminal occlusion of the middle cerebral artery (MCAO) was used to prepare the ischemia/reperfusion cortex tissue. Concentration of MDA was determined by measuring thiobarbituric acid-reactive substance. GSH-PX was quantified using the thiobarbituric acid (TBA) technique. SOD was assayed througha xanthine method. Endogenous amino acids were quantified by high performance liquid chromatographic (HPLC) analysis. Primary culturs of hippocampal neurons were prepared for a free intracellular calcium ([Ca(2+)]I) assay by Fura-2 based single cell microfluoremetric technique.</p><p><b>RESULTS</b>Comparing control and treatment groups, the concentration of SOD and GSH-PX were higher, whereas that of MDA was much lower; the concentration of glutamate and aspartate decreased and that of GABA increased markedly at all time point (P < 0.01), Gly also decreased at some time points (P < 0.05). The differences were significant between the groups of 10 mg/kg, 15 mg/kg and the groups of 5 mg/kg. When 1 x 10(-5) mol/L glutamate was applied with 25 micro g/ml ginkgo biloba extract to cultured neurons, the increase in [Ca(2+)]I was lower than that caused by applying glutamate alone. Its peak value was much lower and increased phase was longer, its declining phase was shorter. After returning to baseline, the application of 1 x 10(-5) mol/L glutamate could induce the reaction to recover.</p><p><b>CONCLUSIONS</b>Ginkgo biloba extract could protect damaged neurons by keeping the balance of inhibitory/excitatory aminoacids, enhancing the free radical scavengers system, and inhibiting the effect of glutamate on [Ca(2+)]I.</p>