A real-time spike sorting method based on the embedded GPU.

Microelectrode arrays with hundreds of channels have been widely used to acquire neuron population signals in neuroscience studies. Online spike sorting is becoming one of the most important challenges for high-throughput neural signal acquisition systems. Graphic processing unit (GPU) with high parallel computing capability might provide an alternative solution for increasing real-time computational demands on spike sorting. This study reported a method of real-time spike sorting through computing unified device architecture (CUDA) which was implemented on an embedded GPU (NVIDIA JETSON Tegra K1, TK1). The sorting approach is based on the principal component analysis (PCA) and K-means. By analyzing the parallelism of each process, the method was further optimized in the thread memory model of GPU. Our results showed that the GPU-based classifier on TK1 is 37.92 times faster than the MATLAB-based classifier on PC while their accuracies were the same with each other. The high-performance computing features of embedded GPU demonstrated in our studies suggested that the embedded GPU provide a promising platform for the real-time neural signal processing.

Expression and clinical significance of TGF-β1,Smad-3 and Smad-7 in the serum of colorectal cancer patients / 安徽医科大学学报

Objective To provide clinical evidence for the relationship between epithelial-mesenchymal transition (EMT) and colorectal cancer(CRC) by detecting the expression of TGF-β, Smad-3 and Smad-7 in serum from CRC patients. Methods We detected the expression levels of TGF-β1 , Smad-3 and Smad-7 by ELISA method. Results The expression levels of TGF-β1 , Smad-3 were significantly higher and the Smad-7 was significantly lower in CRC patients than those in control group(P<0. 01). The expression levels of TGF-β1 and Smad-3 were signifi-cantly higher in Dukes D than those in Dukes B,C. The Smad-7 was significantly lower in Dukes D than that in Dukes B,C(P<0. 01). Conclusion TGF-β1 and Smad-3 and Smad-7 may play an important role in the develop-ment of CRC.

Electrocorticographic signals comparison in sensorimotor cortex between contralateral and ipsilateral hand movements.

Brain machine interfaces (BMIs) have emerged as a technology to restore lost functionality in motor impaired patients. Most BMI systems employed neural signals from contralateral hemisphere. But many studies have also demonstrated the possibility to control hand movement using signals from ipsilateral one. However, the relationship of neural signals in sensorimotor cortex between contralateral and ipsilateral hand movement control is still unclear. In this study, the electrocorticographic signals (ECoG) of sensorimotor cortex were analyzed in two epilepsy participants when they performed a visual guided rock-scissors-paper task by using contralateral and ipsilateral hand respectively. Although typical beta suppression followed increased gamma were observed during the movements of each individual hands, the stronger responses were found in two participants when their contralateral hands were used during the task. We further extracted the power spectrum of high gamma frequency band (70-135Hz) of ECoG signals as neural features to decode the hand movements. The results showed that the classification accuracy of contralateral decoding and ipsilateral decoding were 81% and 78% for participator one (P1) and 84% and 77% for participator two (P2). The accuracy of ipsilateral decoding was only slightly lower than that of contralateral one. The hand movement information contained in ipsilateral sensorimotor cortex suggested that the ipsilateral hemisphere might be also involved in neural modulation as well as contralateral hemisphere did when performing unimanual movement, which would expand the clinical application of BMIs.

Localizing seizure onset zone by convolutional transfer entropy from iEEG.

Automatic localization of the seizure onset zone (SOZ) is able to output an objective result and help clinical doctors greatly in epilepsy therapy. Transfer entropy is one of the most frequently used measures based on information theory to localize the SOZ. However, if only using transfer entropy to localize the SOZ, different results can be obtained during different periods, thus humans still need to identify which one is most reasonable. This paper proposes a new method to output only a few (e.g. 1 or 2) results along a long time slot. Based on the results of traditional transfer entropy, we use a 3D convolution method to enhance the connection between the spatial channels and also between different temporal positions. After that, a connected component method is used to extract the stable blocks that indicate the SOZ. To evaluate the effectiveness of our method, preliminary experiments on a short iEEG signals are conducted. The experimental results show that our method can achieve a sensitivity of 100% and a false positive rate of 1.79% for SOZ localization.

Free cholesterol overloading induced smooth muscle cells death and activated both ER- and mitochondrial-dependent death pathway.

OBJECTIVE: Smooth muscle cells (SMCs) death promotes atherosclerotic lesion necrosis and plaque destabilization. We investigated the potential mechanisms of rat SMCs death in response to excess free cholesterol (FC). METHODS AND RESULTS: Rat aortic SMCs were incubated with "water soluble cholesterol" and acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor Sandoz58035 to establish FC-overloading cell model. Disruption of mitochondrial network and endoplasmic reticulum (ER) was observed after 12h incubation by transient transfection. After treated for 24h, enhanced cell death was noted as detected by propidium iodide (PI) staining/flow cytometry (P<0.001 vs. control). SMCs death was associated with markedly decreased mitochondrial transmembrane potential (Deltaphim), as well as upregulation of cellular reactive oxygen species (ROS) and ER stress. We also investigated possible signaling pathways involved in excess FC-initiated cell death and found that unfolded protein response (UPR) was activated, with increased cellular Bax expression and release of mitochondrial cytochrome c. CONCLUSION: Our findings suggested that FC-overloading might trigger SMCs death. Both ER- and mitochondria-based signals might be implicated in these lethal events.

Effects of serum containing oral liquid of Guilu-Erxian on the therapy of osteoporosis at the cellular level / 生物医学工程学杂志

This study sought to assess the effects of serum containing Guilu-Erxian (GLEX) on treating osteoporosis at the cellular level. First, Enzyme-digestion was used to obtain osteoblasts from newborn SD rats. Alkaline phosphatase staining was used to identify osteoblasts. The proliferation and the secretion of Insulin Like Growth Factor-1 (IGF-1) of osteoblasts were examined. Second, osteoclasts were generated by inducing bone marrow cells of SD male rat (6-9 weeks) with 1,25(OH)2D3. The osteoclasts were identified through tartrate-resistant acid phosphatase (TRAP) staining. Bone pits of osteoclasts were observed through Electron Scanning Microscope. At the same time, TRAP(+) cells with more than two nuclei and TRAP activity of osteoclasts were examined. Last, serum containing Guilu-Erxian was made through serum pharmacology. And we observed the effects of serum containing Guilu-Erxian on the function of osteoblasts and osteoclasts. We found that high doses of serum containing Guilu-Erxian had obvious effects on stimulating the multiplication and capability of secreting IGF-1 of osteoblasts cultured in vitro. Middle doses obviously inhibited the formation of osteoclasts and bone pits; TRAP activity of osteoclasts was also lowered clearly. This study indicated that Guilu-Erxian has positive effects on treating osteoporosis.

Analysis of rat 24h heart rate variability based on telemetry technology / 生物医学工程学杂志

In this study ECG signal of unstrained rat was recorded by telemetry device, and heart rate variability (HRV) was analyzed in order to evaluate 24h autonomic nervous activity. The results demonstrated an obvious circadian rhythm in the autonomic nervous activity: sympathetic activity being dominant during wake phase, and parasympathetic activity, dominant during sleep phase. The ratio of the low frequency to high frequency components in HRV power spectrum (LF/HF) fluctuates with the change in the sleep stages. It is concluded that 24h HRV analyses may reveal plentiful information about the behavior of autonomic nervous system and thus facilitate the investigation of its regulating role in physiological and pathological processes.

The effects of embryonic bodies on differentiation of mouse embryonic stem cells to neuronal cells in vitro / 生物医学工程学杂志

This study was directed at assessing the effects of embryonic bodies on differentiation of the embryonic stem cells. The embryonic bodies of different days gained by means of hanging, suspending and hung-suspended were processed by all-trans retinotic acids for 4 days. Then they were detected by immunocytochemistry methods and were measured to detect the fluorescence intensity changes of calcium after Glu stimulation. During this period, we observed the differentiation process and compared the differentiation ratio of embryonic stem cells processed by means of hanging, suspending for several days. It was found that the differentiation ratio of EBs obtained by suspending for 3 days, or by hanging for 3 days and suspending for 1 day, is relatively higher, which can help us find out the intrinsic differentiation mechanism of embryonic stem cells.

A Potential Excitability Was Induced by Basic Fibroblast Growth Factor during Early Differentiation of Neurons from Mouse Embryonic Stem Cells in vitro.

We report that basic fibroblast growth factor (bFGF) induces the release of glutamate in ES-derived neurons during early stages of differentiation. Changes of Ca2+concentration labeled by fluorescence intensity occurred in response to minimal concentrations of glutamate. The Ca2+concentration was changed more rapidly by bFGF than by glutamate during the early stages of differentiation of ES-derived neurons. High concentrations of the inhibitor MK801, a N-methyl-D-aspartate (NMDA) receptor antagonist applied before bFGF stimulation caused a dramatic decrease of fluorescence intensity in neurons derived from both hippocampal and ES cells. These results showed that bFGF induces glutamate release and an increase of [Ca2+] in neurons during early stages of differentiation, and that the increase of [Ca2+] can be inhibited by MK801. Therefore, we concluded that bFGF serves not only as a neurotrophin but also as a stimulator of excitability during the differentiation of ES cells into neurons.

Application of Overexcitation Model Induced by Penicillin Sodium in the Study of Inhibitory Effect of Sedative-Hypnotic Drugs.

Excessive release of glutamate can cause many nervous system disorders. It has been reported that when a high dose of penicillin sodium is administered into the rat's brain, epilepsy, accompanied with glutamate elevation, will result. In this experiment, a low dose of penicillin sodium (1000 kIU/l) was microinjected into the rat's lateral ventricle to set up an overexcitation model, in which the concentration of ipsilateral hippocampal glutamate was monitored in vivo. by microdialysis-HPLC method as an indicator of the rat's excitatory state. Influences of sedative-hypnotic drugs on this model were verified by coadministration of diazepam or phenobarbital with Na-PCN intracerebroventricularly. In models, hippocampal glutamate concentration was elevated to 307% compared with its baseline level (p < 0.05), and this increase of glutamate was inhibited completely when different doses of diazepam or phenobarbital were administered (p < 0.05). The sedative effect of jujuboside A and trifluoperazine were then studied with this model. Jujuboside A (JuA) 0.1 g/l also reduced the glutamate level significantly (p < 0.05). Calmodulin antagonist trifluoperazine showed similar inhibitory effect as JuA, which may indicate that the effect of JuA is correlated with its anticalmodulin action. This model can be used to investigate the inhibitory effect of central nervous system drugs.

Regulative Effects of Hawthorn Leave Flavonoids on Cytotoxicity,NO and Ca2+in Hypoxia-treated Human Umbilical Vein Endothelial Cells / 航天医学与医学工程

Objective To evaluate the potential effect of HLF (Hawthorn leave flavonoids, w/w, 80% flavonoids) against thrombus formation, effect of HLF on hypoxia-treated human umbilical vein endothelial cell (HUVECs) was studied. Method The levels of cytotoxicity and NO upon HUVECs were studied by flow cytometry. Moreover, the level of calcium ion in HUVECs was examined through laser scanning confocal microscopy. Result Data from this study showed that HLF at concentrations of 5 μg/ml and 10 μg/ml decreased the cytotoxicity of hypoxia to HUVECs (P<0.05, P<0.01). The intracellular levels of NO and calcium ion were downregulated by HLF at concentrations of 5 μg/ml (P<0.01; P<0.01) and 10 μg/ml (vs control, P<0.01; P<0.01) too. Conclusion Results observed suggest that HLF protect HUVECs from hypoxia partly through its regulative effect on NO and calcium ion levels.

Establishment of a system for measuring blood flow velocity of rat microvessel using dark background fluorescent image analysis method / 生物医学工程学杂志

Autologous red blood cells (RBC) labeled with fluorescence were immitted into microvessel of SD rat and observed under microscope. The movement of each individual labeled RBC was recorded by microscope video camera system. The recorded videotape is replayed to sample dark background fluorescent images through frame grabber. Sampled frame images were separated into odd and even field sequence images. Then these sequence images were analyzed to get the flow rate. The error between the actual flow velocity value and the flow velocity value of fluorescent globules in the chamber measured under the same system was below 7%. The upper limit was 9.6 mm/s. There are no obvious differences (P > 0.05). This system has been applied in the research of rat microcirculatory disturbance, and the temporal flow rate change in microvessel was obtained.

Modulation of Baroreflex Activity by Exogenous and Endogenous NO in SD Rats / 航天医学与医学工程

Objective To assess the modulation of baroreflex activity by exogenous and endogenous nitric oxide (NO) in SD rats. Method The normal baroreflex sensitivity of SD rat was evaluated by intravenous (I.v.) administration of Phenylephrine (PE, 30 μg·kg-1) to elevate blood pressure. Exogenous and endogenous nitric oxide (NO) were respectively produced by I.v. Infusion of sodium nitroprusside (SNP, 10.2 μg·kg-1) and L-arginine (L-Arg, 25 mg·kg-1). And NG-nitro-L-arginine methylester (L-NAME, 10 mg·kg-1) was infused to inhibit the generation of NO. Meanwhile, baroreflex sensitivity fluctuations caused by PE were estimated. Result Compared with the normal state, L-Arg significantly reduced the baroreflex sensitivity (Gmax) and the slope coefficient τ of the blood pressure-heart rate curve [Gmax=-1.469±0.120 beats/(min·mmHg) vs. -0.664±0.080 beats/(min·mmHg), P<0.01; τ=0.0860.005 vs. 0.0490.007, P<0.05]. SNP also led to attenuation of Gmax and τ [Gmax=-1.277±0.392 beats/(min·mmHg) vs. -0.943±0.297 beats/(min·mmHg); τ=0.074豹0.027 vs. 0.071±0.023] but the changes were not significant. In contrast to L-Arg and SNP, L-NAME induced raise of Gmax and τ [Gmax=-0.705±0.231 beats/(min·mmHg) vs. -1.065±0.200 beats/(min·mmHg); τ=0.0450.011 vs. 0.0590.026], however, they were statistically insignificant. Conclusion The results demonstrated that NO imposes effect on baroreflex activity, and the behaviors of exogenous and endogenous NO are different. Endogenous NO may be involved in the regulation of autonomic nervous system via central nervous system or carotid sinus, and inhibits the baroreflex sensitivity.

Effect of Puerarin on calcium overload in cultured human umbilical vascular endothelial cells / 中国药理学通报

Aim To examine the effect of Puerarin on calcium overload in human umbilical vascular endothelial cells(HUVECs).Methods The HUVECs were incubated with Puerarin,then were exposed to H_2O_2,ATP and high K~+.The changes of intracellular free calcium([Ca~(2+)]i) in HUVECs were determined using fluorescent Ca~(2+)-indicator fluo-3/AM with confocal laser scanning microscope.Results Puerarin inhibited the elevation of [Ca~(2+)]i induced by H_2O_2,ATP and high K~+,and the inhibition ratio were 72.2%,56.5% and 78.2% respectively.The effect of Puerarin inhibiting the elevation of [Ca~(2+)]i induced by high K~+ was similar to that of verapamil.Conclusion The mechanism of puerarin reducing the overload of calcium in HUVECs may be related with blocking both voltage-dependent calcium channels and the release of calcium pool in endoplasm.

Protective effect of ginsenoside Rb1 against H_2O_2-induced apoptosis in neonatal rat cardiomyocytes / 中国药理学通报

Aim To investigate the protective effect of ginsenoside Rb1 against apoptosis induced by H_2O_2. Methods H_2O_2 was used to build an oxidative stress-induced injury model in neonatal rat cardiomyocytes. After treated with gensenoside Rb1(20, 40, 80 mg?L -1),the apoptosis rate, the content of malondialdehyde (MDA), and the activity of superoxide dimutase (SOD) of the cardiomyocytes were examined. The intracellular calcium indicated by the fluorescence in cells were measured by the laser confocal microscope. Results Compared with the model group, the apoptosis rate and the content of MDA of the cardiomyocytes decreased greatly (P

Soring the sleep stages of rat based on the gravity frequency and complexity measure / 中国药理学通报

AIM To compare the new methods which can be used fo r soring the stages of rat sleep. METHODS Cortical EEG and hippocampal potential(HP) were collected by implanted electrodes in freely moving rats. Gravity frequency (f g) and the complexities(Kc,C 1), were calculated. According to the characteristics of each stage and by studying the histogram of f g, Kc and C 1, the stages of rat sleep were distinguished. RESULTS The methods of f g, Kc and C 1 can distinguish the Waking, nonrapid eye movement(NREM) and REM sleep well. Comparing the results of visual and our analysis, the rate of accordance is above 85%, and the analysis based on the complexity measure is more believable than that based on the f g. CONCLUSION The gravity frequency and the complexities of Kc,C 1 can be used to distinguish the different stages of rat sleep.

A Novel Method of Normal Estimation for Visualization of Medical Images / 航天医学与医学工程

Objective Normal estimation is the key step for volume visualization. Commonly used methods for normal estimation are based on interpolation and derivative. A novel normal estimation algorithm based on approximation for visualization of medical images was presented in this paper. Method It approximated the density function in local neighborhood with a second-degree polynomial function. The coefficients of the polynomial function were solved by minimizing the error of the approximation and the gradient vector at arbitrary point was obtained directly from the analytical derivative of the density function without interpolation. Because of symmetry, the solution of this equation was simplified.This method was tested in several volume data sets. The results and the generation time by different methods were obtained and compared. Result The results showed that this algorithm produced satisfactory quality images while the computational complexity was not increased. Conclusion This approach is preferable for most applications, especially for medical images reconstruction.

Effects of sampling parameter variation on the complexity analysis of EEG / 生物医学工程学杂志

The algorithmic complexity and the approximate entropy of EEG were calculated and analyzed with different data points, different sample frequencies and different sample time duration. The results showed that under fixed sample frequency, the longer the data was, the more stable the complexity values were. With fixed sample time duration or fixed data point, lower sample frequency would be better both for EEG distinguishing and for computing time saving.

An experimental study of interventional therapy by direct puncture for the treatment of hormone-induced necrosis of femoral head / 介入放射学杂志

Objective To evaluate the clinical efficacy of interventional therapy by direct puncture for the treatment of avascular necrosis of the femoral head. Methods 24 experimental rabbits were undertaken and divided randomly into 3 groups, B, C groups as the models of hormone induced necrosis of femoral head, and A group as the control one. B group was followed up later with interventional therapy by direct puncture. Thromolytic agents, drugs improving microcirculation, and repairing bone tissue were infused directly into the femoral head; and then microscopic observations were conducted to study the pathology. Results The results showed: in group B, the number of vacant bony lacunae in femoral head, the average diameter of fat cells in marrow cavity and the number of blood vessel in subchondral areas showed significant improvement, approaching group A. Conclusions Treatment of femoral head necrosis through interventional method of direct puncture has commenced a solid foundation for clinical therapy.

Effects of total isoflavones of Pueraria DC. on bone mineral density and bone strength in ovariectomized rats / 中草药

Object To observe the protective effect of total isoflavones of pueraria DC (TIP) on osteoporosis induced by estrogen deficient rat Methods 42 10 month old female SD rats were bilaterally ovariectomized and 10 animals were made sham operation (Sham) under anesthesia. After 7 d, the ovariectomized rats were divided into 4 groups: untreated control (OVX) group (n=12); 2 treated groups (n= 10 each), one with 100 mg/kg TIP ig and the other with 20 mg/kg TIP ig, and a niylestrol group (E 3) (n= 10) The total body bone mineral content (BMC), and bone mineral density (BMD) and bone biodynamics were detected at 4th and 7th month Results 1 Compared with OVX group, BMC and BMD in TIP 100 mg/kg group were increased by 14 6% and 12.1% at 4th month, by 6 8% and 14 2% at 7th month, while in TIP 20 mg/kg group by 7 8% and 6 9% at 4th month, by 8 6% and 14 9% at 7th month 2 The densities of femur in TIP 100 and 20 mg/kg groups were respectively increased by 3 8% and 3 4%, while those of tibia by 6 8% and 6 3% than that of OVX control group The Ca contents were increased by more than 15% in the TIP treated groups 3 The maximum load and structural strength of femur were increased by 16 1% and 19 4% in TIP 100 mg/kg group and 9 1% and 12 5% in TIP 20 mg/kg group than OVX control group These parameters in tibia were also improved 4 Uterine weights both in TIP 100 and 20 mg/kg groups were almost increased by one fold than OVX group Conclusion TIP can protect osteoporosis induced by ovariectomized rats and these effect may be attributable to its week estrogen like action