ObjectiveAfter establishing the rabbit brain death model, TUNEL, western blotting, and immuno-histochemical methods were used to detect hepatocyte apoptosis to study hepatocyte apoptosis level from rabbit donors after brain death. MethodsSixty healthy male New Zealand rabbits were divided into brain death group (n=30) and sham group (n=30). The rabbits of brain death group were established by increasing intracranial pressure in a modified, slow, and intermittent way, collecting liver tissues after corresponding treatment respectively, using TUNEL to detect apoptosis rate, western blotting and immunohistochemical methods to detect the expression of Cleaved-caspase 3. ResultsThe hepatocyte apoptosis rate at each time point of brain death group were higher than those of the corresponding time point of sham group (P<0.05), and the rate of hepatocyte apoptosis increased gradually with the extension of brain death time (P<0.05). The results of Western blot assay and immunohistochemistry assay showed that the relative expression amount of Cleaved-caspase 3 protein increased gradually with the extension of brain death time (P<0.05), and relative expression amount of Cleaved-caspase 3 protein at each time point of brain death group were higher than those of the corresponding time point of sham group (P<0.05). ConclusionsThe relationship between brain death donor liver and cell apoptosis is closely related. Along with the extension of the brain death time in rabbits, the level of apoptosis of liver cells gradually increased, which affects the quality of liver donors after brain death.
Objective To set up and to evaluate an acute closed brain injury model in rats. Methods The acute closed brain injury was produced in rats by using an impactor consisting of a stand, a guide tube, a weight and a footplate. Ninetysix SD rats were divided into a control group(n＝32, no impact), a mild injury group(n＝32, impact once at force level of 400 g·cm) and a severe injury group(n＝32, impact once at force level of 800 g·cm) to elucidate the physiological responses, the pathophysiological changes and brain edema after brain injury at different injury levels. Results In the mild injury group and the severe injury group, a sudden rise or reduction of blood pressure, deep and fast breath apnea, and pain reflects inhibition were observed. The responses were more obvious in the severe injury group than in the mild injury group. The water content of the brain increased after 6 hours of injury. The pathological contusion and edema of brain were noted or above the impact force level of 800 g·cm. When the impact force rose to or over 1200g·cm, the animals died of persistent apnea mostly. Conclusion Although the established closed brain injury model with different biomechanical mechanisms as the clinical brain injury, it is in conformity with pathological changes and pathophysiological characteristics of acute clinical brain injury, it can be utilized extensively because of its convenient and practice.
Objective To study the effects of several neurotrophic factors and growth factors on the survival of human retinal ganglion cells(RGC)in vitro. Methods RGC were isolated from donor eyes and cultured.RGC in cell culture were identified by morphologic criteria and immunocytochemical staining.Various neurotrophic factors and growth factors were added individually to the cultures.Numbers of RGC in wells in which these agents had been added were compared with those from control wells(cultures without supplements). Results No or very few RGC were present in cell cultures containing medium without supplements or those supplemented with neurotrophin-3(NT-3),nerve growth factor (NGF),epidermal growth factor(EGF)amd plateletderived growth factor(PDGF).Numbers of RGC(per 10 fields)in cell cultures containing brain derived neurotrophic factor(BDNF),ciliary neurotrophic factor(CNTF),neurotrophin-4/5(NT-4/5)and basic fibroblast growth factor(bFGF)wer 4.08,1.23,2.63 and 2.65,respectively,significantly more than found in the control cultures. Conclusions BDNF,NT-4/5,bFGF,CNTF improve survival of human RGC in vitro,while NGF,NT-3,EGF and PDGF do not. (Chin J Ocul Fundus Dis, 1999, 15: 149-152)
Objective To investigate the value and significance of the changes of plasma level of brain natriuretic peptide（BNP） in evaluating ventricle performance of functional single ventricle after total cavopulmonary connection （TCPC）. Methods We studied 11 patients with functional single ventricle undergone TCPC procedure after 2.1 years, who were followed-up at our ward between April 2004 and November 2004, 7 of them were males and 4 of them were females （TCPC group）. The clinical heart function of patients was scored according to the modified scoring system described by Ross. We obtained 3ml blood samples from the extremital vein of all subjects. Blood was collected into chilled tubes containing EDTA and aprotinin （4.5mg and 1 500u/ml blood, respectively）. The blood samples were promptly centrifuged （-4℃, 3 000r/min for 10 min） and the plasma was separated. BNP concentration was determined using immunoradiometric assay kits. Magnetic resonance imaging （MRI） examination was undertaken in 6 patients of TCPC group to analyse the relative factors with the change of BNP. Control group included 9 healthy children. Results （1） Median plasma BNP level for TCPC group and control group was 400pg/ ml （IQR200-690） and 110 pg/ml （IQR90-190）, respectively. There was a significant difference in plasma BNP between them （P=0. 003）. （2） The results of the index of heart function of TCPC group determined by MRI were 65. 76±8. 65 ml/m2 in end-diastolic volume index, 31. 90±6. 36ml/m2 in end-systolic volume index, 39.09±11.76ml/m2 in stroke volume index, 0. 52± 0. 06 in ejection fraction（EF）, 2.38±0.58L/min·m2 in cardiac index （CI）, 103.49±21.57g/m2 in mass index and 1.57±0.24 in mass/EDV. （3） The plasma BNP level for TCPC group was significant correlation with operation ages（r=0.632, P=0.041 ）. There was no correlation between plasma BNP level with EF, CI, score of Ross, gender, ages, percutaneous oxygen saturation（SpO2） and the type of dominant ventricle, respectively. Conclusions Raised concentration of plasma BNP in patients 2 years after undertaken TCPC procedure indicates that nervous-endosecretory system is still under stress condition. This pattern suggests that neurohormonal activation is primarily related to the altered postoperative physiology. the significance of BNP in patients of functional single ventricle after undertaken TCPC is different from tat in biventricular physiology patiens. The plasma BNP level could not be correctly evaluated the cardiac function after TCPC operation.
Electroconvulsive therapy (ECT) is an interventional technique capable of highly effective neuromodulation in major depressive disorder (MDD), but its antidepressant mechanism remains unclear. By recording the resting-state electroencephalogram (RS-EEG) of 19 MDD patients before and after ECT, we analyzed the modulation effect of ECT on the resting-state brain functional network of MDD patients from multiple perspectives: estimating spontaneous EEG activity power spectral density (PSD) using Welch algorithm; constructing brain functional network based on imaginary part coherence (iCoh) and calculate functional connectivity; using minimum spanning tree theory to explore the topological characteristics of brain functional network. The results show that PSD, functional connectivity, and topology in multiple frequency bands were significantly changed after ECT in MDD patients. The results of this study reveal that ECT changes the brain activity of MDD patients, which provides an important reference in the clinical treatment and mechanism analysis of MDD.
High-frequency steady-state asymmetric visual evoked potential (SSaVEP) provides a new paradigm for designing comfortable and practical brain-computer interface (BCI) systems. However, due to the weak amplitude and strong noise of high-frequency signals, it is of great significance to study how to enhance their signal features. In this study, a 30 Hz high-frequency visual stimulus was used, and the peripheral visual field was equally divided into eight annular sectors. Eight kinds of annular sector pairs were selected based on the mapping relationship of visual space onto the primary visual cortex (V1), and three phases (in-phase[0o, 0o], anti-phase [0o, 180o], and anti-phase [180o, 0o]) were designed for each annular sector pair to explore response intensity and signal-to-noise ratio under phase modulation. A total of 8 healthy subjects were recruited in the experiment. The results showed that three annular sector pairs exhibited significant differences in SSaVEP features under phase modulation at 30 Hz high-frequency stimulation. And the spatial feature analysis showed that the two types of features of the annular sector pair in the lower visual field were significantly higher than those in the upper visual field. This study further used the filter bank and ensemble task-related component analysis to calculate the classification accuracy of annular sector pairs under three-phase modulations, and the average accuracy was up to 91.5%, which proved that the phase-modulated SSaVEP features could be used to encode high- frequency SSaVEP. In summary, the results of this study provide new ideas for enhancing the features of high-frequency SSaVEP signals and expanding the instruction set of the traditional steady state visual evoked potential paradigm.
Neurofeedback (NF) technology based on electroencephalogram (EEG) data or functional magnetic resonance imaging (fMRI) has been widely studied and applied. In contrast, functional near infrared spectroscopy (fNIRS) has become a new technique in NF research in recent years. fNIRS is a neuroimaging technology based on hemodynamics, which has the advantages of low cost, good portability and high spatial resolution, and is more suitable for use in natural environments. At present, there is a lack of comprehensive review on fNIRS-NF technology (fNIRS-NF) in China. In order to provide a reference for the research of fNIRS-NF technology, this paper first describes the principle, key technologies and applications of fNIRS-NF, and focuses on the application of fNIRS-NF. Finally, the future development trend of fNIRS-NF is prospected and summarized. In conclusion, this paper summarizes fNIRS-NF technology and its application, and concludes that fNIRS-NF technology has potential practicability in neurological diseases and related fields. fNIRS can be used as a good method for NF training. This paper is expected to provide reference information for the development of fNIRS-NF technology.
Increasing evidences show that a gradual trend away from deep hypothermia toward moderate hypothermic circulatory arrest, which has been proved to be safe and effective in clinic. By summarizing and analyzing the research progress and applying status of the moderate hypothermia circulatory arrest with selective antegrade cerebral perfusion, the article aims at promoting the application of this tenique as a cerebral protection strategy in aortic arch surgery for adults in China.
In recent years, exploring the physiological and pathological mechanisms of brain functional integration from the neural network level has become one of the focuses of neuroscience research. Due to the non-stationary and nonlinear characteristics of neural signals, its linear characteristics are not sufficient to fully explain the potential neurophysiological activity mechanism in the implementation of complex brain functions. In order to overcome the limitation that the linear algorithm cannot effectively analyze the nonlinear characteristics of signals, researchers proposed the transfer entropy (TE) algorithm. In recent years, with the introduction of the concept of brain functional network, TE has been continuously optimized as a powerful tool for nonlinear time series multivariate analysis. This paper first introduces the principle of TE algorithm and the research progress of related improved algorithms, discusses and compares their respective characteristics, and then summarizes the application of TE algorithm in the field of electrophysiological signal analysis. Finally, combined with the research progress in recent years, the existing problems of TE are discussed, and the future development direction is prospected.
Vagus nerve stimulation was first used in the treatment of refractory epilepsy and depression, and its indications have expanded in recent years. The brain-gut axis is a bidirectional communication network pathway connecting the gut to the brain, maintaining homeostatic balance of the gut microbiota and shaping brain function. The vagus nerve plays an important role in brain-gut axis mechanisms in neurological disorders, which may be an important rationale for vagus nerve stimulation in the treatment of related diseases. Recent studies have shown that vagus nerve stimulation modulates the intestinal microenvironment and the intestinal microbiota, but the specific mechanisms of this alteration need further investigation. Fecal transplants or oral probiotics combined with vagus nerve stimulation may become an important therapeutic tool in the future, especially to improve the efficacy of vagus nerve stimulation for epilepsy; the gut microbiota may also be a predictive target for the efficacy of vagus nerve stimulation for epilepsy.