Synthesis, Characterization of Low Molecular Weight Chitosan Selenium Nanoparticles and Its Effect on DSS-Induced Ulcerative Colitis in Mice.

Selenium nanoparticles have attracted extensive attention due to their good bioavailability and activity. In the present study, a new form of selenium nanoparticle (Low molecular weight chitosan selenium nanoparticles (LCS-SeNPs)) were synthesized in a system of sodium selenite and acetic acid. The size, element state, morphology and elementary composition of LCS-SeNPs were characterized by using various spectroscopic and microscopic measurements. The protection of LCS-SeNPs against dextran sulfate sodium (DSS)-induced intestinal barrier dysfunction and the inherent mechanisms of this process were investigated. The results showed that LCS-SeNPs, with an average diameter of 198 nm, zero-valent and orange-red relatively uniform spherical particles were prepared. LCS-SeNPs were mainly composed of C, N, O and Se elements, of which Se accounted for 39.03% of the four elements C, N, O and Se. LCS-SeNPs reduced colon injury and inflammation symptoms and improved intestinal barrier dysfunction. LCS-SeNPs significantly reduced serum and colonic inflammatory cytokines TNF-α and IL-6 levels. Moreover, LCS-SeNPs remarkably increased antioxidant enzyme GSH-Px levels in serum and colonic tissue. Further studies on inflammatory pathways showed that LCS-SeNPs alleviated DSS-induced colitis through the NF-κB signaling pathway, and relieved inflammatory associated oxidative stress through the Nrf2 signaling pathway. Our findings suggested that LCS-SeNPs are a promising selenium species with potential applications in the treatment of oxidative stress related inflammatory intestinal diseases.

[Development and Design of Portable Sleep Electroencephalogram Monitoring System].

The growing rate of public health problem for increasing number of people afflicted with poor sleep quality suggests the importance of developing portable sleep electroencephalogram (EEG) monitoring systems. The system could record the overnight EEG signal, classify sleep stages automatically, and grade the sleep quality. We in our laboratory collected the signals in an easy way using a single channel with three electrodes which were placed in frontal position in case of the electrode drop-off during sleep. For a test, either silver disc electrodes or disposable medical electrocardiographic electrodes were used. Sleep EEG recorded by the two types of electrodes was compared to each other so as to find out which type was more suitable. Two algorithms were used for sleep EEG processing, i. e. amplitude-integrated EEG (aEEG) algorithm and sample entropy algorithm. Results showed that both algorithms could perform sleep stage classification and quality evaluation automatically. The present designed system could be used to monitor overnight sleep and provide quantitative evaluation.

A study of sleep staging based on a sample entropy analysis of electroencephalogram.

In this paper we report a detection method for different sleep stages and it is based on a single-channel electroencephalogram (EEG) system. The system is simple and can be easily setup in homes to perform sleep EEG recording, overnight sleep EEG automatic staging, and sleep quality evaluation. EEG data of 14 sleeping subjects were recorded through the entire night. All subjects were within the age group of 20-30 years and having no significant sleep disorders. To analyze the EEG data, it is segmented into equal time intervals. This is followed by calculation of Sample Entropy (SampEn) for each section, and the SampEn's statistical characteristics, such as the median, upper quartile, lower quartile and inter-quartile range. The sleep data were divided into training group (7 cases) and test group (7 cases). Sleep stages' quantitative ranges of training group referring to ZEO results were extracted and the quantization range used to sleep staging EEG data. Both the training group and test group results were close to ZEO results. It suggested that the statistical characteristics of Sample Entropy could be used as a criterion for sleep staging and evaluation.

Temporal integration reflected by frequency following response in auditory brainstem.

Auditory temporal integration (ATI) has been widely described in psychoacoustic studies, especially for loudness perception. Loudness increases with increasing sound duration for durations up to a time constant about 100 ~ 200 ms, and then loudness becomes saturated with more duration increase. However, the electrophysiological mechanism underlying the ATI phenomenon has not been well understood. To investigate ATI at the brainstem level of auditory system and its relationship to cortical and behavioral ATI, frequency follow response (FFR) was acquired in our study. Simultaneously, ATI in auditory cortex was evaluated by cortical response P1. Behavioral loudness and electrophysiological measures were estimated from normal-hearing young adults for vowel /a/ whose durations varied from 50 ms to 175 ms. Significant effects of stimulus duration were found both on FFR and P1 amplitudes. Linear regression analysis revealed that as stimulus duration increased, brainstem FFR amplitude was significantly associated with cortical P1 amplitude and behavioral loudness, which confirmed the existence of temporal integration in auditory brainstem. Moreover, behavioral loudness ATI was better predicted using brainstem and cortical measures together than merely using each one separately, indicating an interplay and coordination for ATI across the three levels along auditory pathway.

Pitch perception of concurrent harmonic tones with overlapping spectra.

Fundamental frequency difference limens (F0DLs) were measured for a target harmonic complex tone with nominal fundamental frequency (F0) of 200 Hz, in the presence and absence of a harmonic masker with overlapping spectrum. The F0 of the masker was 0, ± 3, or ± 6 semitones relative to 200 Hz. The stimuli were bandpass filtered into three regions: 0-1000 Hz (low, L), 1600-2400 Hz (medium, M), and 2800-3600 Hz (high, H), and a background noise was used to mask combination tones and to limit the audibility of components falling on the filter skirts. The components of the target or masker started either in cosine or random phase. Generally, the effect of F0 difference between target and masker was small. For the target alone, F0DLs were larger for random than cosine phase for region H. For the target plus masker, F0DLs were larger when the target had random phase than cosine phase for regions M and H. F0DLs increased with increasing center frequency of the bandpass filter. Modeling using excitation patterns and "summary autocorrelation" and "stabilized auditory image" models suggested that use of temporal fine structure information can account for the small F0DLs obtained when harmonics are barely, if at all, resolved.

Curvelet processing of MRI for local image enhancement.

Magnetic resonance imaging provides very good contrast between different soft tissues; however, in some cases, this technique is not so suitable to image calcified structures like bones. The quality of images is often degraded by blur edges or noises, which makes it difficult to accurately identify bone structures. In this paper, we proposed a new curvelet preprocessing method for local image enhancement to especially improve the quality of spinal MRI. Our objective is to both sharpen boundaries and smoothen the intensity variation of the vertebra. In the first phase, we extract features through curvelet coefficients and the gradient of the original image, then we utilize fuzzy cluster method to classify the whole image scope into the 'edge' region and the 'nonedge' region. In the second phase, we locally sharpen or smoothen the image by adaptive adjustment of curvelet coefficients and Gaussian smoothing method in different subregions. To evaluate the effect of the preprocessing method, we examine the gradient of the image and its segmentation results as the assessments. The experiment results show that the feature extraction method is effective for classification and the vertebra performs higher contrast on boundaries and less noises after the enhancement, which indeed helps increase the accuracy of further segmentation.

A statistical study of the factors influencing the extent of respiratory motion blur in PET imaging.

Respiratory motion results in significant motion blur in thoracic and abdomen PET imaging. The extent of respiratory motion blur is mainly correlated with breathing amplitude, tumor size and location. In this paper we introduce a statistical study to quantitatively show the factors influencing the extent of respiratory motion blur in thoracic PET images. The study is centered on two regression models, one is linked with motion blur induced loss of mean intensity(LMI), tumor motion magnitude and tumor size, and another is to investigate the influence of tumor location, patient gender and patient height on tumor motion magnitude. We use the blur identification and image restoration technique to estimate the tumor motion and compute the LMI. The regression model was validated by simulation and phantom data before extended to 39 cases of clinical lung tumor PET images corrupted with blurring artifact. Results show that the motion magnitude of lung tumor during breathing is 10.9±3.7mm in transaxial plane, and it is significantly greater in lower lung lobes than in upper lobes. The LMI is 7.1±2.4% in the region of interest (ROI) above 40% of the image's maximum intensity. The least-square estimate of regression equations demonstrates that LMI is proportional to tumor motion magnitude and is inversely proportional to tumor size; the two factors play the same role in determining the extent of respiratory motion blur in thoraco-abdominal PET imaging. The location of tumor was shown as the major factor determining its motion magnitude, while the influencing of patient gender and height on tumor motion was not shown significant.

Cochlear-implant spatial selectivity with monopolar, bipolar and tripolar stimulation.

Sharp spatial selectivity is critical to auditory performance, particularly in pitch-related tasks. Most contemporary cochlear implants have employed monopolar stimulation that produces broad electric fields, which presumably contribute to poor pitch and pitch-related performance by implant users. Bipolar or tripolar stimulation can generate focused electric fields but requires higher current to reach threshold and, more interestingly, has not produced any apparent improvement in cochlear-implant performance. The present study addressed this dilemma by measuring psychophysical and physiological spatial selectivity with both broad and focused stimulations in the same cohort of subjects. Different current levels were adjusted by systematically measuring loudness growth for each stimulus, each stimulation mode, and in each subject. Both psychophysical and physiological measures showed that, although focused stimulation produced significantly sharper spatial tuning than monopolar stimulation, it could shift the tuning position or even split the tuning tips. The altered tuning with focused stimulation is interpreted as a result of poor electrode-to-neuron interface in the cochlea, and is suggested to be mainly responsible for the lack of consistent improvement in implant performance. A linear model could satisfactorily quantify the psychophysical and physiological data and derive the tuning width. Significant correlation was found between the individual physiological and psychophysical tuning widths, and the correlation was improved by log-linearly transforming the physiological data to predict the psychophysical data. Because the physiological measure took only one-tenth of the time of the psychophysical measure, the present model is of high clinical significance in terms of predicting and improving cochlear-implant performance.

Respiratory motion blur identification and reduction in ungated thoracic PET imaging.

Respiratory motion results in significant motion blur in thoracic positron emission tomography (PET) imaging. Existing approaches to correct the blurring artifact involve acquiring the images in gated mode and using complicated reconstruction algorithms. In this paper, we propose a post-reconstruction framework to estimate respiratory motion and reduce the motion blur of PET images acquired in ungated mode. Our method includes two steps: one is to use minmax directional derivative analysis and local auto-correlation analysis to identify the two parameters blur direction and blur extent, respectively, and another is to employ WRL, à trous wavelet-denoising modified Richardson-Lucy (RL) deconvolution, to reduce the motion blur based on identified parameters. The mobile phantom data were first used to test the method before it was applied to 32 cases of clinical lung tumor PET data. Results showed that the blur extent of phantom images in different directions was accurately identified, and WRL can remove the majority of motion blur within ten iterations. The blur extent of clinical images was estimated to be 12.1 ± 3.7 mm in the direction of 74 ± 3° relative to the image horizontal axis. The quality of clinical images was significantly improved, both from visual inspection and quantitative evaluation after deconvolution. It was demonstrated that WRL outperforms RL and a Wiener filter in reducing the motion blur with one to two more iterations. The proposed method is easy to implement and thus could be a useful tool to reduce the effect of respiration in ungated thoracic PET imaging.

Reference values for amplitude-integrated EEGs in infants from preterm to 3.5 months of age.

OBJECTIVES: Amplitude-integrated electroencephalogram (aEEG) is a valuable tool for the continuous evaluation of functional brain maturation in infants. The amplitudes of the upper and lower margins of aEEGs are postulated to change with maturation and correlate with postmenstrual age (PMA). In this study we aimed to establish reliable reference values of aEEG amplitudes, which provide quantitative guidelines for assessing brain maturation as indicated by aEEG results in neonates and young infants. METHODS: aEEGs from healthy infants (n = 274) with PMAs that ranged from 30 to 55 weeks were divided into 10 groups according to their PMAs. Two 5-minute segments were selected from each aEEG and were used to automatically calculate the upper and lower margins and bandwidths of the aEEG tracings. RESULTS: Interobserver agreement was achieved with an overall correlation of 0.99. The upper and lower margins of the aEEGs in both active and quiet sleep clearly rose in infants after the neonatal period. The bandwidth defined as the graphic distance decreased almost monotonically throughout the PMA range from 30 to 55 weeks. The lower margin of the aEEG was positively correlated with PMA, with a larger rank correlation coefficient during quiet sleep (r = 0.89) than during active sleep (r = 0.49). CONCLUSIONS: Reference values of aEEG amplitudes were obtained for infants with a wide range of PMAs and constituted the basis for the quantitative assessment of aEEG changes with maturation in neonates and young infants. The normative amplitudes of aEEG margins, especially of the lower margin in quiet sleep, are recommended as a source of reference data for the identification of potentially abnormal aEEG results.

Partial transfection of cells using laminar flows in microchannels.

This manuscript describes a convenient method for partial transfection using a Y-shaped microchannel polydimethylsiloxane (PDMS)-glass chip and on-chip cationic lipid-mediated transfection. Enhanced green fluorescent protein genes (pEGFP-N2) were introduced into the COS-7 cells cultured in half of the channel, while red fluorescent protein genes (pDsRed-N1) were introduced into the cells cultured in another half of the channel. This on-chip partial transfection technique provides an avenue for the spatial control of transfection. It is possible to use this technique to perform parallel transfection on chips in order to study cell behaviors under two or more gene transfections in the same culture.

[Mathematical model of bursting spike train and its spectrum features].

Bursting is an important firing mode of neurons. To propose a stochastic model of bursting spike train, the interspike interval (ISI) characteristics of single-spiking train and bursting spike train were analyzed and compared. In contrast with the exponential distribution of ISI in single-spiking train, normal distribution is supposed to be the ISI model of bursting spike train. Simulated neural spike trains were produced to investigate the spectrum features of the ISI model. The results showed that: (1) bursting spike train with normally distributed ISI held a low-pass spectrum while the spectrum of single-spiking train was flat; (2) the coefficient of variation of ISI in bursting train decided the bandwidth of its low-pass spectrum. Then neural activities from anesthetized rodent were used to check the validity of the model. 10 simultaneously recorded bursting spike trains and 10 single-spiking trains were selected during anesthesia and after pure-oxygen-washout period respectively. The spectrograms of these neural spike trains were analyzed and the results were matched with our mathematical model. It is believed that the bursting spike train model established in this paper will help to theoretically study the statistical characters of neural spike train and to add mathematical foundation in neural coding schemes.

Application of Tsallis entropy to EEG: quantifying the presence of burst suppression after asphyxial cardiac arrest in rats.

Burst suppression (BS) activity in EEG is clinically accepted as a marker of brain dysfunction or injury. Experimental studies in a rodent model of brain injury following asphyxial cardiac arrest (CA) show evidence of BS soon after resuscitation, appearing as a transitional recovery pattern between isoelectricity and continuous EEG. The EEG trends in such experiments suggest varying levels of uncertainty or randomness in the signals. To quantify the EEG data, Shannon entropy and Tsallis entropy (TsEn) are examined. More specifically, an entropy-based measure named TsEn area (TsEnA) is proposed to reveal the presence and the extent of development of BS following brain injury. The methodology of TsEnA and the selection of its parameter are elucidated in detail. To test the validity of this measure, 15 rats were subjected to 7 or 9 min of asphyxial CA. EEG recordings immediately after resuscitation from CA were investigated and characterized by TsEnA. The results show that TsEnA correlates well with the outcome assessed by evaluating the rodents after the experiments using a well-established neurological deficit score (Pearson correlation = 0.86, p << 0.01 ). This research shows that TsEnA reliably quantifies the complex dynamics in BS EEG, and may be useful as an experimental or clinical tool for objective estimation of the gravity of brain damage after CA.

[Evaluating fatigue resistance effect of health food by near-infrared tissue oximeter].

Currently, chronic fatigue syndrome (CFS) seriously affects people's normal living and work. In the present paper, the physiological parameters, such as tissue oxygenation saturation and heart rate, were used to evaluate the subjects' fatigue degree, and the fatigue resistance capsule and coffee were taken as a measure to adjust the fatigue. Human tissue oxygen saturation (rSO2) can be monitored noninvasively and in real time by near infrared spectroscopy (NIRS) based on spatially-resolved spectroscopy. Aiming at those brainworkers who need to work in an office for a long time; two static experiments were designed to evaluate the fatigue degree of the subjects who either take the fatigue resistance capsules/coffee or not. The rSO2 and heart rate (HR) of the subjects in the experiment group and contrast group were measured respectively for fatigue evaluation. This work particularly analyzed the changes in rSO2 in these two groups. The results show that the rSO2 of subjects in the experiment group evidently increased compared to that in the contrast group when the subjects took the fatigue resistance capsule or coffee, thereby show that the health food can reduce the fatigue to a certain extent.

[An overview of the studies on combined electric and acoustic stimulation of auditory system].

This paper discusses the technology of combined electric and acoustic stimulation (EAS) of the auditory system, which is a new therapy for the patients suffering from severe to profound high- and mid-frequency hearing loss but still having their low-frequency hearing. EAS uses hearing aid and cochlear implant technology together in the same ear. The hearing aid acoustically amplifies at low-frequencies, while the cochlear implant electrically stimulates at mid- and high-frequencies. The inner ear processes acoustic and electric stimuli simultaneously. This technique can provide substantial benefit in speech understanding for individuals with severe high-frequency hearing loss and can maintain their residual lower-frequency acoustic hearing. The study of EAS would significantly enhance the conventional cochlear implant therapy and benefit the patients afflicted with severe to profound hearing loss.

An easy protocol for on-chip transfection of COS-7 cells with a cationic lipid-based reagent.

The microchip has become a miniaturized and integrated platform for cell research and gene analysis. Traditional biological experiments are being performed on chips with greater frequency. Transfection, which is the process of introducing foreign DNA (or RNA) into cultured mammalian cells, is an important tool for basic and applied life science research. Therefore, on-chip transfection is a critical requirement for a fully comprehensive lab-on-chip system. In this study, a microchip made of polydimethylsiloxane (PDMS) and glass was fabricated for continuous cell culture and transfection. Enhanced green fluorescent protein genes (pEGFP) were introduced into COS-7 cells using a cationic lipid-based reagent, Lipofectamine 2000. The optimal concentration of Lipofectamine 2000 was also studied. This on-chip transfection protocol with cationic lipid-based reagent is expected to add to the emerging use of microchip-based life science and drug discovery research.

Self-organizing map-based multi-thresholding on neural stem cells images.

Automatic segmentation and tracking systems can be useful tools for biologists to monitor and understand the proliferation and the differentiation of neural stem cells. This paper applied the self-organizing map-based multi-thresholding on the neural stem cells images. Using local variance as the local spatial feature and quadtree decomposition as the sub-sampling method, inner-cell regions, cell borders and background can be roughly classified. Based on these results, proper foreground and background seeds were constructed for the seeded watershed segmentation and every single cell in a cell cluster can be segmented correctly. The results were also compared to the seeded watershed segmentation based on regional maxima method.

Neurodevelopment in newborns: a sample entropy analysis of electroencephalogram.

The present paper investigates the neural ontogeny of newborns in view of electroencephalogram (EEG) complexity during active sleep (AS) and quiet sleep (QS). Sample entropy (SampEn) is applied to EEG recordings from 168 newborns with postmenstrual age (PMA) ranging from 25 to 60 weeks. The relationship between neurodevelopment and PMA is then explored according to the statistical analysis of the median and interquartile range of SampEn curves. It is found that SampEn of EEG during AS is higher than that during QS. SampEn increases during both AS and QS before about 42 weeks in PMA while it ceases its increase in QS and even decreases in AS after newborns reaching term age. A distinct decrease in the interquartile range of SampEn is found with increasing PMA (from 25 to about 50 weeks), followed by maintenance of low fluctuation in SampEn curves. The study in this paper sets the stage for exhaustive investigation of the SampEn of EEG during brain maturation in newborns. And it could be hoped that SampEn in sleep EEG might be a useful parameter against which delays and aberrations in brain maturation might be tested. The SampEn changes during brain maturation also offer functional clues about neurodevelopment, based on which further explorations could be done. The significance of this paper is the discovery of the decrease in EEG complexity after newborns reaching term. Although some potential neurophysiologic reasons are given, this new discovery might require more study to investigate. In addition, the fluctuation of EEG complexity is analyzed for the first time, which helps to understand the EEG maturation in neurodevelopment.

[Advances in the study of virtual channels of cochlear implant].

This paper discusses virtual channels of cochlear implant, which is produced by simultaneous or sequential activation of adjacent cochlear implant electrodes. Virtual channels create and transfer more available spectral pitch information with the limited number of fixed electrodes, which can be recognized as pitch percepts intermediate to those produced by each electrode separately. This technique not only utilizes the interaction of electrodes but also increases the number of place-pitch steps available to cochlear implant listeners. Virtual channels could be used to realize speech recognition in noisy environment, in enjoying music, and in understanding Chinese language. The study of virtual channels would significantly enhance the traditional cochlear implant therapy and benefit people suffering severe to profound hearing loss.

[The application of amplitude-integrated EEG in the cerebral function monitoring of neonates].

Amplitude-integrated electroencephalogram (aEEG) which is a simplified form of standard EEG has been increasingly used in neonates. The aEEG method is easy to apply and to interpret and the simplicity of the method makes it feasible for "round the clock" recording. The present paper briefly introduces the signal acquisition, data analysis and clinical applications of aEEG. Then we propose a number of possible research directions in light of the domestic research in this field, in the future.