Enhancement of Classification Accuracy of a Time-frequency Approach for an EEG-based Brain-computer Interface

Objectives : The aim of this paper is to develop a new algorithm to enhance the performance of EEG-based brain-computer interface (BCI).

Methods : We improved our time-frequency approach of classification of motor imagery (MI) tasks for BCI applications. The approach consists of Laplacian filtering, band-pass filtering and classification by correlation of time-frequency-spatial patterns.

Results and Conclusions : Through off-line analysis of data collected during a “cursor control" experiment, we evaluated the capability of our new method to reveal major features of the EEG control for enhancement of MI classification accuracy. The pilot results in a human subject are promising, with an accuracy rate of 96.1%.

Cortical dipole imaging of movement-related potentials by means of parametric inverse filters incorporating with signal and noise covariance

OBJECTIVE

The objective of this study is to explore suitable spatial filters for inverse estimation of cortical equivalent dipole layer imaging from the scalp electroencephalogram. We utilize cortical dipole source imaging to locate the possible generators of scalp-measured movement-related potentials (MRPs) in human.

METHODS

The effects of incorporating signal and noise covariance into inverse procedures were examined by computer simulations and experimental study. The parametric projection filter (PPF) and parametric Weiner filter (PWF) were applied to an inhomogeneous three-sphere head model under various noise conditions.

RESULTS

The present simulation results suggest that the PWF incorporating signal information provides better cortical dipole layer imaging results than the PPF and Tikhonov regularization under the condition of moderate and high correlation between signal and noise distributions. On the other hand, the PPF has better performance than other inverse filters under the condition of low correlation between signal and noise distributions. The proposed methods were applied to self-paced MRPs in order to identify the anatomic substrate locations of neural generators. The dipole layer distributions estimated by means of PPF are well-localized as compared with blurred scalp potential maps and dipole layer distribution estimated by Tikhonov regularization. The proposed methods demonstrated that the contralateral premotor cortex was preponderantly activated in relation to movement performance.

CONCLUSIONS

In cortical dipole source imaging, the PWF has better performance especially when the correlation between the signal and noise is high. The proposed inverse method was applicable to human experiments of MRPs if the signal and noise covariances were obtained.

Genome-wide scan for type 1 diabetic nephropathy in the Finnish population reveals suggestive linkage to a single locus on chromosome 3q

Diabetic nephropathy (DN) is the primary cause of morbidity and mortality in patients with type 1 as well as type 2 diabetes, and accounts for 40% of end-stage renal disease in the Western world. Familial clustering of DN suggests importance of genetic factors in the development of the disease. In the present study, we performed a two-stage genome-wide scan to search for chromosomal loci containing susceptibility genes for nephropathy in patients with type 1 diabetes. In total, 83 discordant sib pairs (DSPs), sibs concordant for type 1 diabetes but discordant for nephropathy, were collected from Finland, a homogeneous population with one of the highest incidences of type 1 diabetes. To map loci for DN, we applied DSP analysis to detect linkage. In the initial scan, 73 DSPs were typed using 900 markers with an average intermarker distance of approximately 4 cM. Multipoint DSP analysis identified five chromosome regions (3q, 4p, 9q, 16q, and 22p) with maximum logarithm of odds (LOD) score (MLS) >or=1.0 (corresponding to a nominal P-value <or=0.015). In the second stage, additional 43 markers flanking these five loci were genotyped in all 83 DSPs. Using simulations, we determined the empirical threshold with LOD score of 1.76 and 3.12 for suggestive and significant linkage, respectively. No locus reached the genome-wide significance of 5%. However, one locus on 3q reached suggestive linkage with MLS of 2.67 (P=4.4 x 10(-4)). These results, together with data from others, suggest that the locus on 3q most likely has a susceptibility gene for DN.

Three-Dimensional Microchannels in Biodegradable Polymeric Films for Control Orientation and Phenotype of Vascular Smooth Muscle Cells

The poor mechanical strength and vasoactivity of current small-diameter tissue engineered blood vessels (TEBVs) remain unsolved problems. Given the plasticity of smooth muscle cells (SMCs), 1 of the main limitations of current scaffolding techniques is the difficulty in controlling SMC phenotype shifts in vitro. A synthetic phenotype allows the cells to rapidly proliferate and produce extracellular matrix (ECM), whereas a shift to contractile phenotype with organized ECM ultimately provides a functional blood vessel. In this study, 3D deep (65 microm) and wide microchannels separated by high-aspect ratio (8) microwalls were successfully ultraviolet (UV) microembossed using a liquid UV polymerizable biodegradable macromer (poly(epsilon-caprolactone-r-L-lactide-r-glycolide) diacrylate) and the in vitro guidance effects of varying channel width (40-160 microm) on SMCs were verified. The results show that SMCs cultured in the wider microchannels (80-160 microm wide) switch from fibroblast morphology and random orientation to spindle-shaped morphology, and align along the direction of the microchannel nearing confluence achieved with similar cell density to unpatterned film. Further, an enhanced expression of smooth muscle alpha-actin of SMCs grown on micropatterns was found nearing confluence, which demonstrates a phenotype shift to a more contractile phenotype. These films are flexible and can be folded into tubular and lamellar structures for tissue engineering of small-diameter TEBVs as well as other organs such as esophagus or intestine. These results suggest that these micropatterned synthetic biodegradable scaffolds may be useful for guiding SMCs to grow into functional, small-diameter vascular grafts.

Effect of an increase in coronary perfusion on transmural ventricular repolarization

The effect of increased coronary flow on transmural ventricular repolarization was investigated in six pentobabital-anesthetized sheep. Fresh blood at 10 ml/min was injected into the left circumflex coronary artery (LCX) in addition to the normal coronary flow. Unipolar electrocardiograms were simultaneously registered from epicardium, mid-myocardium and endocardium with fine plunge needles. Activation-recovery interval (ARI) was measured from the unipolar electrocardiograms and was used for estimating the ventricular repolarization duration. It was found that intracoronary blood injection (n=3) prolonged ARI in the epicardium, mid-myocardium and endocardium by an average of 34 +/- 16, 28 +/- 18 and 25 +/- 13 ms, respectively (p<0.01). Pretreatment with nitro-L-arginine (n=3), a nitric synthase inhibitor, diminished the flow-induced ARI prolongation across the ventricular wall. In conclusion, an increase in coronary flow lengthens the duration of transmural ventricular repolarization. These effects appear to be mediated by nitric oxide from the coronary endothelium.

An osteopontin splice variant induces anchorage independence in human breast cancer cells

In malignant tumors, metastasis genes are typically deregulated by aberrant expression or splicing. Osteopontin is expressed at high levels by various cancers and contributes importantly to their invasive potential. In contrast, osteopontin derived from host cells induces cellular immunity and could bolster antitumor protection by cytotoxic T lymphocytes. Here we show that breast cancer cells express multiple splice variants of osteopontin. According to RT-PCR analysis of human breast tissue specimens, the splice variant osteopontin-c is a highly specific marker for transformed cells, which is not expressed in their surrounding normal tissue. The full-length form of osteopontin aggregates in the presence of physiologic amounts of calcium and, in this state, leads to enhanced cell adhesion. Ostensibly, this effect is inhibitory for tumor cell dissemination. The shortest splice variant, osteopontin-c, does not aggregate in the presence of calcium and enhances clone formation in soft agar. According to microarray analysis, osteopontin-c induces the expression of oxidoreductases, consistent with protection from anoikis during anchorage-independent growth. These studies define a third functional domain of osteopontin, beside the C-terminal CD44-binding site and the central integrin-binding site. They also provide evidence for a bifunctional character of osteopontin, with the soluble form supporting invasiveness and the aggregated form promoting adhesion.

Viruses, endoplasmic reticulum stress, and interferon responses

Viral infection induces endoplasmic reticulum (ER) stress and interferon responses. While viral double-stranded RNA intermediates trigger interferon responses, viral polypeptides synthesized during infection stimulate ER stress. Among the interferon-regulated gene products, the double-stranded RNA-dependent protein kinase (PKR) plays a key role in limiting viral replication. Thus, to establish productive infection, viruses have evolved mechanisms to overcome the deleterious effects of PKR. It has become clear that ER stress causes translational attenuation and transcriptional upregulation of genes encoding proteins that facilitate folding or degradation of proteins. Notably, prolonged ER stress triggers apoptosis. Therefore, viruses are confronted with the consequences of ER stress. Emerging evidence suggests that viruses not only interfere with the interferon system involving PKR but also manipulate the programs emanating from the ER in a complex way, which may facilitate viral replication or pathogenesis. This review highlights recent progress in these areas.

Imaging 3-dimensional cardiac electrical activity from intra-cavity potentials

We propose a novel approach to image 3- dimensional (3-D) cardiac electrical activity from intra-cavity electrical potentials. The 3-D cardiac electrical activity is estimated by minimizing the difference between the recorded and model-generated intra-cavity potential distributions. The feasibility of the proposed concept is tested by a computer simulation.

Ectopic galanin expression and normal galanin receptor 2 and galanin receptor 3 mRNA levels in the forebrain of galanin transgenic mice

The functional interactions of the neuropeptide galanin (GAL) occur through its binding to three G protein-coupled receptor subtypes: galanin receptor (GALR) 1, GALR2 and GALR3. Previously, we demonstrated that GALR1 mRNA expression was increased in the CA1 region of the hippocampus and discrete hypothalamic nuclei in galanin transgenic (GAL-tg) mice. This observation suggested a compensatory adjustment in cognate receptors in the face of chronic GAL exposure. To evaluate the molecular alterations to GALR2 and GALR3 in the forebrain of GAL overexpressing mice, we performed complementary quantitative, real-time PCR (qPCR), in situ hybridization, and immunohistochemistry in select forebrain regions of GAL-tg mice to characterize the neuronal distribution and magnitude of GAL mRNA and peptide expression and the consequences of genetically manipulating the neuropeptide GAL on the expression of GALR2 and GALR3 receptors. We found that GAL-tg mice displayed dramatic increases in GAL mRNA and peptide in the frontal cortex, posterior cortex, hippocampus, septal diagonal band complex, amygdala, piriform cortex, and olfactory bulb. Moreover, there was evidence for ectopic neuronal GAL expression in forebrain limbic regions that mediate cognitive and affective behaviors, including the piriform and entorhinal cortex and amygdala. Interestingly, regional qPCR analysis failed to reveal any changes in GALR2 or GALR3 expression in the GAL-tg mice, suggesting that, contrary to GALR1, these receptor genes are not under ligand-mediated regulatory control. The GAL-tg mouse model may provide a useful tool for the investigation of GAL ligand-receptor relationships and their role in normal cognitive and affective functions as well as in the onset of neurological disease.

Estimation of in vivo human brain-to-skull conductivity ratio from simultaneous extra- and intra-cranial electrical potential recordings

OBJECTIVE

The present study aims to accurately estimate the in vivo brain-to-skull conductivity ratio by means of cortical imaging technique. Simultaneous extra- and intra-cranial potential recordings induced by subdural current stimulation were analyzed to get the estimation.

METHODS

The effective brain-to-skull conductivity ratio was estimated in vivo for 5 epilepsy patients. The estimation was performed using multi-channel simultaneously recorded scalp and cortical electrical potentials during subdural electrical stimulation. The cortical imaging technique was used to compute the inverse cortical potential distribution from the scalp recorded potentials using a 3-shell head volume conductor model. The brain-to-skull conductivity ratio, which leads to the most consistent cortical potential estimates with respect to the direct intra-cranial measurements, is considered to be the effective brain-to-skull conductivity ratio.

RESULTS

The present estimation provided consistent results in 5 human subjects studied. The in vivo effective brain-to-skull conductivity ratio ranged from 18 to 34 in the 5 epilepsy patients.

CONCLUSIONS

The effective brain-to-skull conductivity ratio can be estimated from simultaneous intra- and extra-cranial potential recordings and the averaged value/standard deviation is 25+/-7.

SIGNIFICANCE

The present results provide important experimental data on the brain-to-skull conductivity ratio, which is of significance for accurate brain source localization using piece-wise homogeneous head models.

Estimation of the cortical functional connectivity with the multimodal integration of high-resolution EEG and fMRI data by directed transfer function

Nowadays, several types of brain imaging device are available to provide images of the functional activity of the cerebral cortex based on hemodynamic, metabolic, or electromagnetic measurements. However, static images of brain regions activated during particular tasks do not convey the information of how these regions communicate with each other. In this study, advanced methods for the estimation of cortical connectivity from combined high-resolution electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data are presented. These methods include a subject's multicompartment head model (scalp, skull, dura mater, cortex) constructed from individual magnetic resonance images, multidipole source model, and regularized linear inverse source estimates of cortical current density. Determination of the priors in the resolution of the linear inverse problem was performed with the use of information from the hemodynamic responses of the cortical areas as revealed by block-designed (strength of activated voxels) fMRI. We estimate functional cortical connectivity by computing the directed transfer function (DTF) on the estimated cortical current density waveforms in regions of interest (ROIs) on the modeled cortical mantle. The proposed method was able to unveil the direction of the information flow between the cortical regions of interest, as it is directional in nature. Furthermore, this method allows to detect changes in the time course of information flow between cortical regions in different frequency bands. The reliability of these techniques was further demonstrated by elaboration of high-resolution EEG and fMRI signals collected during visually triggered finger movements in four healthy subjects. Connectivity patterns estimated for this task reveal an involvement of right parietal and bilateral premotor and prefrontal cortical areas. This cortical region involvement resembles that revealed in previous studies where visually triggered finger movements were analyzed with the use of separate EEG or fMRI measurements.

Assessing cortical functional connectivity by linear inverse estimation and directed transfer function: simulations and application to real data

OBJECTIVE

To test a technique called Directed Transfer Function (DTF) for the estimation of human cortical connectivity, by means of simulation study and human study, using high resolution EEG recordings related to finger movements.

METHODS

The method of the Directed Transfer Function (DTF) is a frequency-domain approach, based on a multivariate autoregressive modeling of time series and on the concept of Granger causality. Since the spreading of the potential from the cortex to the sensors makes it difficult to infer the relation between the spatial patterns on the sensor space and those on the cortical sites, we propose the use of the DTF method on cortical signals estimated from high resolution EEG recordings, which exhibit a higher spatial resolution than conventional cerebral electromagnetic measures. The simulation study was followed by an analysis of variance (ANOVA) of the results obtained for different levels of Signal to Noise Ratio (SNR) and temporal length, as they have been systematically imposed on simulated signals. The whole methodology was then applied to high resolution EEG data recorded during a visually paced finger movement.

RESULTS

The statistical analysis performed returns that during simulations, DTF is able to estimate correctly the imposed connectivity patterns under reasonable operative conditions, i.e. when data exhibit a SNR of at least 3 and a length of at least 75 s of non-consecutive recordings at 64 Hz of sampling rate, equivalent, more generally, to 4800 data samples.

CONCLUSIONS

Functional connectivity patterns of cortical activity can be effectively estimated under general conditions met in any practical EEG recordings, by combining high resolution EEG techniques, linear inverse estimation and the DTF method.

SIGNIFICANCE

The estimation of cortical connectivity can be performed not only with hemodynamic measurements, by using functional MRI recordings, but also with modern EEG recordings treated with advanced computational techniques.

Evaluation of mollusks as biomonitors to investigate heavy metal contaminations along the Chinese Bohai Sea

Two gastropod species (Rapana venosa and Neverita didyma) and three bivalve species (Mytilus edulis, Crassostrea talienwhanensis and Ruditapes philippinarum) were collected from eight sites along the coastline of the Chinese Bohai Sea for the investigation of heavy metal contaminations. Cd, Co, Cu, Ni, Pb and Zn were analyzed by using pressure nebulization-inductively coupled plasma-mass spectrometer. Two certified reference materials Dogfish mussel (DORM-2) and Mussel (GBW 08571) were used to validate the methods and the obtained results proved to be in good agreement with the certified values. The results of the present study showed that Crassostrea talienwhanensis possessed a much greater ability for bioaccumulation of Cu and Zn than did the other species. Rapana venosa manifested the most bioaccumulation capacity of Cd. Among the five species, the Ruditapes philippinarum possessed the highest content of Ni. Furthermore, Cd, Cu and Zn contents in some gastropods and oysters samples exceeded the maximum permissible levels established by WHO. Due to their special bioaccumulation capacity of Cd and Ni, Rapana venosa and Ruditapes philippinarum had the potential of being used as biomonitors to control the aquatic contaminations of heavy metals.

Characterisation of Fasciola species from Mainland China by ITS-2 ribosomal DNA sequence

Isolates of Fasciola (Platyhelminthes: Trematoda: Digenea) from different host species and geographical locations in Mainland China were characterised genetically. The second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) was amplified from individual trematodes by polymerase chain reaction (PCR), and the representative amplicons were cloned and sequenced. The length of the ITS-2 sequences was 361-362bp for all Chinese Fasciola specimens sequenced. While there was no variation in length or composition of the ITS-2 sequences among multiple specimens from France, Sichuan and Guangxi, sequence difference of 1.7% (6/362) was detected between specimens from France and Sichuan, and those from Guangxi. Based on ITS-2 sequence data, it was concluded that the Fasciola from Sichuan represented Fasciola hepatica, the one from Guangxi represented Fasciola gigantica and the one from sheep from Heilongjiang may represent an "intermediate genotype", as its ITS-2 sequences were unique in that two different ITS-2 sequences exist in the rDNA array within a single Fasciola worm. One of the sequences is identical to that of F. hepatica, and the other is almost identical to that of F. gigantica in that nucleotides at five of the six polymorphic positions represent F. gigantica. This microheterogeneity is possibly due to sequence polymorphism among copies of the ITS-2 array within the same worm. Based on the sequence differences, a PCR-linked restriction fragment length polymorphism (PCR-RFLP) assay was established for the unequivocal delineation of the Fasciola spp. from Mainland China using restriction endonuclease Hsp92II or RcaI. This assay should provide a valuable tool for the molecular identification and for studying the ecology and population genetic structures of Fasciola spp. from Mainland China and elsewhere.

Non-invasive estimation of myocardial infarction by means of a heart-model-based imaging approach: A simulation study

In the study, a new myocardial infarction (MI) estimation method was developed for estimating MI in the three-dimensional myocardium by means of a heart-model-based inverse approach. The site and size of MI are estimated from body surface electrocardiograms by minimising multiple objective functions of the measured body surface potential maps (BSPMs) and the heart-model-generated BSPMs. Computer simulations were conducted to evaluate the performance of the developed method, using a single-site MI and dual-site MI protocols. The simulation results show that, for the single-site MI, the averaged spatial distance (SD) between the weighting centres of the 'true' and estimated MIs, and the averaged relative error (RE) between the numbers of the 'true' and estimated infarcted units are 3.0 +/- 0.6/3.6 +/- 0.6 mm and 0.11 +/- 0.02/0.14 +/- 0.02, respectively, when 5 microV/10 microV Gaussian white noise was added to the body surface potentials. For the dual-site MI, the averaged SD between the weighting centres of the 'true' and estimated MIs, and the averaged RE between the numbers of the 'true' and estimated infarcted units are 3.8 +/- 0.7/3.9 +/- 0.7mm and 0.12 +/- 0.02/0.14 +/- 0.03, respectively, when 5 microV/10 microV Gaussian white noise was added to the body surface potentials. The simulation results suggest the feasibility of applying the heart-model-based imaging approach to the estimation of myocardial infarction from body surface potentials.

Cortical potential imaging of brain electrical activity by means of parametric projection filter

OBJECTIVES

The objective of this study was to explore suitable spatial filters for inverse estimation of cortical potentials from the scalp electroencephalogram. The effect of incorporating noise covariance into inverse procedures was examined by computer simulations and tested in human experiment.

METHODS

The parametric projection filter, which allows inverse estimation with the presence of information on the noise, was applied to an inhomogeneous three-concentric-sphere model under various noise conditions in order to estimate the cortical potentials from the scalp potentials. The method for determining the optimum regularization parameter, which can be applied for parametric inverse techniques, is also discussed.

RESULTS

Human visual evoked potential experiment was carried out to examine the performance of the proposed restoration method. The parametric projection filter gave more localized inverse solution of cortical potential distribution than the truncated SVD and Tikhonov regularization.

CONCLUSION

The present simulation results suggest that incorporation of information on the noise covariance allows better estimation of cortical potentials, than inverse solutions without knowledge about the noise covariance, when the correlation between the signal and noise is low.

High-resolution EEG: cortical potential imaging of interictal spikes

BACKGROUND

It is of clinical importance to localize pathologic brain tissue in epilepsy. Noninvasive localization of cortical areas associated with interictal epileptiform spikes may provide important information to facilitate presurgical planning for intractable epilepsy patients.

METHODS

A cortical potential imaging (CPI) technique was used to deconvolve the smeared scalp potentials into the cortical potentials. A 3-spheres inhomogeneous head model was used to approximately represent the head volume conductor. Five pediatric epilepsy patients were studied. The estimated cortical potential distributions of interictal spikes were compared with the subsequent surgical resections of these same patients.

RESULTS

The areas of negativity in the reconstructed cortical potentials of interictal spikes in 5 patients were consistent with the areas of surgical resections for these patients.

CONCLUSIONS

The CPI technique may become a useful alternative for noninvasive mapping of cortical regions displaying epileptiform activity from scalp electroencephalogram recordings.

High-resolution spatio-temporal functional neuroimaging of brain activity

The past decades have shown extraordinary progress in our ability to noninvasively image the functions of the human brain. Of particular interest is the recent trend in combining information from electrophysiological and magnetic resonance imaging, which we termed eMRI, to achieve high-resolution functional neuroimaging in both space and time domains. In this article, we review the recent progress in high-resolution functional neuroimaging, in particular the multimodal integration of electroencephalography (EEG) and magnetic resonance imaging (MRI). The state-of-the-art EEG inverse solutions based on different brain electric source models and various approaches to integrate the information from MRI are reviewed. The remaining challenges, future trends, and potential applications of the high-resolution functional neuroimaging research are discussed.

Body surface Laplacian mapping of atrial depolarization in healthy human subjects

In the present study, we report body surface Laplacian mapping of atrial depolarization under sinus rhythm in 8 healthy male subjects. For each subject, 95 unipolar disk electrodes with inter-electrode distance of 2 cm were used to record simultaneously potential ECGs over the anterior chest. The Laplacian ECG was then estimated during the P wave using a novel spline Laplacian technique. The body surface potential map (BSPM) and body surface Laplacian map (BSLM) at different time instants or time intervals of the P wave were constructed and compared. The present results showed that the BSPMs during the P wave were characterized by the rotation of a pair of positive/negative potential distribution from right to left around the anterior torso. On the other hand, the corresponding BSLMs revealed more spatial details, including two positive activities (denoted as P1 and P2, appeared in all 8 subjects), and three negative activities (denoted as N1, N2, and N3, appeared in 7, 7, and 4 subjects, respectively). The separation of these activities and their evolving patterns were also compared and confirmed by computer simulation using a realistic geometry heart-torso model. The above findings may be directly related to the underlying activation sequence during atrial depolarization in healthy subjects, suggesting the potential clinical applications of the Laplacian ECG technique.

The murine gene encoding parathyroid hormone: genomic organization, nucleotide sequence and transcriptional regulation

The type 1 parathyroid hormone receptor (PTHR1) binds, with equal affinity, two ligands with distinct biological functions: PTH, the major peptide hormone controlling calcium homeostasis, and the paracrine factor, PTH-related peptide (PTHrP), a local regulator of cellular proliferation and differentiation. To clarify the complexity of possible interactions between two distinct ligands, PTH and PTHrP, and their common receptor in the intact organism, and to identify as yet unrecognized roles for PTH in normal physiology, we have cloned and characterized the structural organization, nucleotide sequence and transcriptional regulation of the murine gene encoding PTH. One recombinant clone isolated from a mouse genomic library contained 14 kb of DNA, encompassing the entire Pth gene. The transcriptional unit spans 3.2 kb of genomic DNA and, analogous to the human PTH gene, it is interrupted by two introns. The deduced mRNA encodes the 115-amino acid precursor, preproPTH. Comparison of the murine preproPTH sequence with other mammalian forms of the protein shows it to be highly conserved and to share limited structural similarity to PTHrP at the amino-terminal region, a domain critical for binding and activation of their common receptor. Putative binding motifs for the transcription factors sex-determining region Y gene product, transcriptional repressor CDP, hepatic nuclear factor 3beta, GATA-binding factor 1, glucocorticoid receptor, SRY-related high mobility group box protein 5 and cAMP response element binding protein were identified in the 5' flanking region of the Pth gene. When placed upstream of a reporter gene, these sequences failed to confer transcriptional regulation in response to 1,25(OH)(2) vitamin D(3), but responded positively to the addition of isoproterenol and forskolin. Mutational analysis identified a cAMP-response element in the Pth promoter.

A role for CCN3 (NOV) in calcium signalling

AIMS

In animals and humans increased expression of CCN3 (NOV) is detected in tissues where calcium is a key regulator, such as the adrenal gland, central nervous system, bone and cartilage, heart muscle, and kidney. Because the multimodular structure of the CCN proteins strongly suggests that these cell growth regulators are metalloproteins, this study investigated the possible role of CCN3 in ion flux and transport during development, control of cell proliferation, differentiation, and pathobiology.

METHODS

The isolation of CCN3 partners was performed by means of the two hybrid system. Yeasts were cotransfected with an HL60 cDNA library fused to the transactivation domain of the GAL4 transcription factor, and with a plasmid expressing CCN3 fused to the DNA binding domain of GAL4. Screening of the recombinant clones selected on the basis of leucine, histidine, and tryptophan prototrophy was performed with a beta-galactosidase assay. After the interaction between CCN3 and its putative partners was checked with a GST (glutathione S-transferase) pull down assay, the positive clones were identified by cloning. To establish whether the CCN3 protein affected calcium ion flux, a dynamic imaging microscopy system was used, which allowed the fluorometric measurement of the intracellular calcium concentration. The proteins used in the assays were GST fused with either CCN3 or CCN2 (CTGF) and GST alone as a control.

RESULTS

The two hybrid system identified the S100A4 (mts1) calcium binding protein as a partner of CCN3 and the use of the GST fusion proteins showed that the addition of CCN3 and CCN2 to G59 glioblastoma and SK-N-SH neuroblastoma cells caused a pronounced but transient increase of intracellular calcium, originating from both the entry of extracellular calcium and the mobilisation of intracellular stores.

CONCLUSIONS

The interaction of CCN3 with S100A4 may account, in part, for the association of CCN3 with carcinogenesis and its pattern of expression in normal conditions. The increased intracellular calcium concentrations induced by CCN3 and CCN2 both involve different processes, among which voltage independent calcium channels might be of considerable importance in regulating the calcium flux associated with cell growth control, motility, and spreading. These observations assign for the first time a biological function to the CCN3 protein and point out a broader role for the CCN proteins in calcium ion signalling.

Boundary element method-based cortical potential imaging of somatosensory evoked potentials using subjects' magnetic resonance images

A boundary element method-based cortical potential imaging technique has been developed to directly link the scalp potentials with the cortical potentials with the aid of magnetic resonance images of the subjects. First, computer simulations were conducted to evaluate the new approach in a concentric three-sphere inhomogeneous head model. Second, the corresponding cortical potentials were estimated from the patients' preoperative scalp somatosensory evoked potentials (SEPs) based on the boundary element models constructed from subjects' magnetic resonance images and compared to the postoperative direct cortical potential recordings in the same patients. Simulation results demonstrated that the cortical potentials can be estimated from the scalp potentials using different scalp electrode configurations and are robust against measurement noise. The cortical imaging analysis of the preoperative scalp SEPs recorded from patients using the present approach showed high consistency in spatial pattern with the postoperative direct cortical potential recordings. Quantitative comparison between the estimated and the directly recorded subdural grid potentials resulted in reasonably high correlation coefficients in cases studied. Amplitude difference between the estimated and the recorded potentials was also observed as indexed by the relative error, and the possible underlying reasons are discussed. The present numerical and experimental results validate the boundary element method-based cortical potential imaging approach and demonstrate the feasibility of the new approach in noninvasive high-resolution imaging of brain electric activities from scalp potential measurement and magnetic resonance images.

[Progress in the research of bone substitutes]

This is a review of the researches on bone substitutes including their institutes, mechanisms, existing problems and some synthetic methods.

The putative androgen receptor-A form results from in vitro proteolysis

Activation domains in the 114 kDa androgen receptor (AR) NH(2)- and carboxyl-terminal regions are thought to contribute to different extents to AR-mediated transactivation. We investigated using anti-peptide antibodies whether smaller AR forms that migrate like the previously described 87 kDa AR-A occur in vivo resulting in constitutive or increased gene activation. Immunoblots of prostate cancer and fibroblast cell culture extracts revealed 114 and 84 kDa AR forms. Antibody mapping indicated the 84 kDa AR lacked the ligand-binding domain and comigrated with the constitutively active AR fragment AR1-660. AR expressed in COS cells was 114 and 92 kDa. Migration of the 92 kDa AR was slightly slower than that of a 90 kDa expressed fragment that was designed to initiate at the second methionine (residue 189) and lacked the NH(2)-terminal FxxLF interaction sequence. The 92 kDa AR did not result from alternative initiation since it was observed when the second methionine was changed to alanine. Optimization of extraction conditions indicated that both 84 and 92 kDa forms resulted from in vitro proteolytic cleavage and that cleavage by caspase-3 could account for the 92 kDa form. The results suggest that AR forms with gel mobility similar to that of the previously described 87 kDa AR-A result from in vitro proteolytic cleavage of NH(2)- or carboxyl-terminal regions during cell extraction and storage and that smaller forms with increased transcriptional activity do not occur in vivo.

[Activation of transcription factors and induction of cytokines from macrophages in chronic obstructive pulmonary disease]

OBJECTIVE

To investigate the activation of transcription factors and induction of cytokines from alveolar macrophages in chronic obstructive pulmonary disease (COPD).

METHODS

Alveolar macrophages were collected by fibrobronchoscopy from 8 patients with chronic bronchitis, 8 patients with COPD, and 8 healthy volunteers. All patients were at stable stage. The macrophages thus collected were cultured and stimulated with lipopolysaccharide (LPS, 10 micrograms/ml). The IL-8, IL-1 beta, TNF alpha and IL-6 thus produced were measured by ELISA in the supernatant. Nuclear factor-kappa B (NF kappa B), activator protein-1 (AP-1), AP-2 and AP-3 were detected by electrophoretic mobility shift assay.

RESULTS

The concentration of IL-8 released from macrophages of patients with COPD at stable stage before LPS stimulation was about 3 times higher than that in the healthy control (F = 4.34, P < 0.05). The concentration of IL-8 released from macrophages in patients with COPD was increased further after LPS stimulation in comparison to that in healthy controls(F = 3.56, P < 0.05). The concentration of IL-1 beta and that of TNF alpha released from macrophages of COPD patients were further increased after LPS stimulation (P < 0.05) in the COPD patients, but there was no difference in the concentration of IL-1 beta and between the control and COPD patients before LPS stimulation. The constitutive activity of AP-1 and the activity of NF kappa B induced by LPS were higher in the patients with COPD than in the controls.

CONCLUSION

The alverlar macrophages of patients with COPD at stable stage may release higher concentration of IL-8 and IL-1 beta. LPS stimulation increases the release of IL-1 beta and TNF alpha of alveolar macrophages. Enhancement of activity of NF kappa B and AP-1 may positively regulate the production of IL-8 and IL-1 beta in the airflow obstruction.

Val193 and Phe195 of the gamma 1 34.5 protein of herpes simplex virus 1 are required for viral resistance to interferon-alpha/beta

Herpes simplex viruses (HSV) are resistant to the antiviral action of interferon. However, the underlying mechanisms are not well understood. In this report, we show that unlike that of wild-type HSV-1, replication of the gamma 1 34.5 null mutants was significantly inhibited by exogenous interferon-alpha in cells devoid of interferon-alpha/beta genes. Using a series of gamma 1 34.5 deletion mutants, the domain required for interferon resistance was mapped to the region containing amino acids 146 to 263 in the gamma 1 34.5 protein. Interestingly, Val193 Glu and Phe195 Leu substitutions in the protein phosphatase 1 interacting motif of the gamma 1 34.5 protein rendered HSV-1 sensitive to interferon-alpha. Furthermore, gamma 1 34.5 null mutants were sensitive to interferon-alpha/beta in PKR+/+ but not in PKR-/- mouse embryo fibroblasts. These findings provide evidence that the gamma 1 34.5 protein contributes to HSV-1 resistance to interferon-alpha/beta by inhibiting PKR function.

Androgen-induced NH2- and COOH-terminal Interaction Inhibits p160 coactivator recruitment by activation function 2

The androgen receptor undergoes an androgen-specific NH(2)- and COOH-terminal interaction between NH(2)-terminal motif FXXLF and activation function 2 in the ligand binding domain. We demonstrated previously that activation function 2 forms overlapping binding sites for the androgen receptor FXXLF motif and the LXXLL motifs of p160 coactivators. Here we investigate the influence of the NH(2)- and COOH-terminal interaction on androgen receptor function. Specificity and relative potency of the motif interactions were evaluated by ligand dissociation rate and the stability of chimeras of transcriptional intermediary factor 2 with full-length and truncated androgen or glucocorticoid receptor. The results indicate that the androgen receptor activation function 2 interacts specifically and with greater avidity with the single FXXLF motif than with the LXXLL motif region of p160 coactivators, whereas this region of the glucocorticoid receptor interacts preferentially with the LXXLL motifs. Expression of the LXXLL motifs as a fusion protein with the glucocorticoid receptor resulted in loss of agonist-induced receptor destabilization and increased half-time of ligand dissociation. The NH(2)- and COOH-terminal interaction inhibited binding and activation by transcriptional intermediary factor 2. We conclude that the androgen receptor NH(2)- and COOH-terminal interaction reduces the dissociation rate of bound androgen, stabilizes the receptor, and inhibits p160 coactivator recruitment by activation function 2.

Human acyl-CoA:diacylglycerol acyltransferase is a tetrameric protein

Acyl-CoA:diacylglycerol acyltransferase (DGAT) is an integral membrane enzyme that catalyses the last step of triacylglycerol synthesis from diacylglycerol and acyl-CoA. Here we provide experimental evidence that DGAT is a homotetramer. Although the predicted molecular mass of human DGAT protein is 55 kDa, CHAPS-solubilized recombinant human DGAT was eluted in fractions over 150 kDa on gel-filtration chromatography. Cross-linking of recombinant DGAT in membranes with disuccinimidyl suberate yielded bands corresponding to the dimer (108 kDa) and the tetramer (214 kDa) in SDS/PAGE. Finally, when two differently epitope-tagged forms of DGAT were co-transfected into mammalian cells, they could be co-immunoprecipitated. From a human adipose tissue cDNA library we cloned a cDNA encoding a novel splice variant of DGAT (designated DGATsv) that contained a 77 nt insert of unspliced intron with an in-frame stop codon. This resulted in a truncated form of DGAT that terminated at Arg-387, deleting 101 residues from the C-terminus containing the putative active site. DGATsv was enzymically inactive when transfected in HEK-293E cells but was still able to form dimer and tetramer on cross-linking, indicating that the ability to form tetramers resides in the N-terminal region. When co-expressed in HEK-293E cells, DGATsv did not inhibit the activity of full-length DGAT, suggesting that the subunits of DGAT catalyse triacylglycerol synthesis independently.

A self-coherence enhancement algorithm and its application to enhancing three-dimensional source estimation from EEGs

In this paper a new algorithm is proposed to enhance the spatial resolution of solutions of the underdetermined EEG inverse problem. Termed the self-coherence enhancement algorithm (SCEA), the present algorithm provides a self-coherence solution, which is a function of the high order self-coherence estimate of an unbiased smooth estimate of the underdetermined EEG inverse solution. The order of the high order self-coherence function is determined by the blurring level of the actual source distribution as represented by a normalized blurring index. The proposed SCEA algorithm may be used to enhance the spatial resolution of an inverse solution obtained by any inverse reconstruction algorithm. Computer simulation studies have been conducted to evaluate the performance of the SCEA and to compare its performance to that of the LORETA and the FOCUSS algorithms.

Comparative observation with MRI and pathology of brain edema at the early stage of severe burn

OBJECTIVE

To investigate the correlation between MRI features and pathology in brain edema at the early stage of severe burn (5 0% TBSA III degree) in dogs.

METHODS

Fifty-two dogs were randomized into control, simple b urn (SB), burn plus sodium lactate (BSL), and burn plus glucose solution groups (BGS). The manifestation of the brain of control group was compared with that of burn groups at 6, 12, 18 and 24 hours postburn with MRI and pathological examination (gross appearance, electron microscopy and light microscopy).

RESULTS

The earliest findings of brain edema were seen at 12 h ours after burn in BGS group, in which brain swelling was the main feature of MR I. The decrease of SIR on T(1)WI was not observed until it was exceeded 10%. Sig nal of T(2)WI increased by 8.29% at 24 hours after burn. It was difficult to distinguish the gray matter from the white matter at the boundary line, which became blurred later. Histological changes of brain edema were observed as early as 6 hours after burn, being accompanied by swelling of endothelial cells and peri-vescular astrocytes, and vacuolation took place in neurons at 12 hours after burn, with different degrees of necrosis of capillary endothelium, neurons, and axons. These changes became more marked with elapse of time. The BGS group showed the most obvious changes mentioned above at 24 hours after burn.

CONCLUSIONS

The model of the brain edema after severe burn has the feature of both vasogenic edema and cytotoxic edema on the MRI and pathology. Positive MRI findings lagged behind that of the pathomorphological changes.

Nationality differences in distributions of serum lipids, lipoproteins and apolipoproteins levels in Xinjiang China

OBJECTIVE

To reveal the distribution characteristics of serum lipids, lipoproteins, and apolipoproteins levels in different nationalities.

METHODS

Quantitative levels of those traits mentioned above were determined and body height (H), weight (W) and body mass index (BMI = W/H2) were assessed in 773 Kazaks (men 360 and women 413) and 911 Han nationality (men 466 and women 445) from the Xinjiang Autonomous Region of China.

RESULTS

Kazaks men and women, respectively, had significantly higher serum levels of HDL-c and ApoA1 (all P < 0.001) and significantly lower serum levels of TG (men P < 0.01, women P < 0.001), Lp(a) (all P < 0.005), ApoB (men P < 0.005, women P < 0.001) and ApoB/A1 (men P < 0.01, women P < 0.001) than their Han nationality controls. The threshold points of ApoA1 (< 1.2 g/L) and ApoB (> 1.2 g/L) are higher in Hans than in Kazaks for ApoA1 (20.7 vs 9.8%) and ApoB (18.6 vs 14.3%); the serum levels of TG, HDL-c, Lp(a), ApoA1 and ApoB/A1 are all closely correlated with nationality (P < 0.001, P = 0.001, and P < 0.05, respectively).

CONCLUSION

The results suggest that the nationality differences exist in serum levels of lipids, lipoproteins, and apolipoproteins, and Kazaks have a superior serum lipid pedigree to Hans. This differences may come from genetic differences, which affect the serum levels of lipids, lipoproteins, and apolipoproteins by controlling lipid metabolism patterns. Future study will be needed to dissect to the role of genetic factors on serum lipids.