Organization, expression and polymorphism of the human persyn gene

Persyn is a recently identified member of the synuclein family with a distinct pattern of expression during pre- and postnatal development of the mouse peripheral and central nervous systems. As with other synucleins, persyn is believed to be involved in the pathogenesis of human neurodegenerative diseases. However, in contrast to other synucleins, high levels of persyn mRNA expression were also found in advanced breast carcinomas, suggesting an involvement of the encoded protein in breast tumour progression. Here we have used an antibody specific to human persyn to demonstrate that the level of this protein is increased in ageing cerebral cortex and in breast tumours. We cloned, characterized and sequenced the human persyn genomic locus and localized it to the long arm of chromosome 10 in the q23.2-q23.3 region. Sequence information was used to search for specific mutations in the protein coding regions of persyn mRNA and the persyn gene in breast tumours and tumour cell lines. No tumour-specific mutations were found, but two linked polymorphisms in the coding region were detected, both in mRNA and exons III and IV of the gene. These results suggest that development of breast tumours correlates with overexpression of the wild-type persyn protein. Detailed characterization of the human persyn locus is important for further studies of the involvement of persyn in neurodegeneration and malignancy.      

Human T cell IgD receptors react with O-glycans on both human IgD and IgA1

Previous studies on murine T cell IgD-R have shown that these receptors recognize N-glycans of murine IgD, and not of other Ig isotypes. We have now studied the specificity of IgD-R on human T cells. Human IgD digested with proteinase K to fragments of < 5 kDa inhibit the ability of T cells to form rosettes with IgD-coated ox erythrocytes. The same amount of digested IgG does not. We tested all the human Ig isotypes: IgG1, −2, −3, −4, IgA2, IgE and IgM fail to inhibit significantly at 20 μg/assay. However, IgA1 is as effective as IgD itself, showing approximately 60 % and 80 % inhibition at 5 μg and 10 μg/assay. Human IgA1 and IgD both contain Gal-1 → 3-GalNac-rich O-linked glycans, and on this basis are both bound to ricin and jacalin. The O-linked glycans may therefore also represent the common moiety binding to IgD-R. Disaccharides Gal-1 → 3-GalNac, and Gal-1 → 4-Glc at 10 μg/assay blocked IgD rosetting while Gal-1 → 6-Glc did not. We conclude that the human IgD-R is a lectin, differing from the murine IgD-R in that it has both IgA1 and IgD as ligands.     

Removal of ECG interference from the EEG recordings in small animals using independent component analysis.

In experiments involving small animals, the electroencephalogram (EEG) recorded during severe injury and accompanying resuscitation exhibit the strong presence of electrocardiogram (ECG). For improved quantitative EEG (qEEG) analysis, it is therefore imperative to remove ECG interference from EEG. In this paper, we validate the use of independent component analysis (ICA) to effectively suppress the interference of ECG from EEG recordings during normal activity, asphyxia and recovery following asphyxia. Two channels of EEG from five rats were recorded continuously for 2 h. Simultaneous recording of one channel ECG was also made. Epochs of 4 s and 1 min were selected from baseline, asphyxia and recovery (every 10 min) and their independent components and power spectra were calculated. The improvement in normalized power spectrum of EEG obtained for all animals was 7.71+/-3.63 db at the 3rd minute of recovery and dropped to 1.15+/-0.60 db at 63rd minute. The application of ICA has been particularly useful when the power of EEG is low, such as that observed during early brain hypoxic-asphyxic injury. The method is also useful in situations where accurate indications of EEG signal power and frequency content are needed.     

Fabrication of Screen-Printed Carbon Electrode Arrays for Sensing Neuronal Messengers

Deciphering the methods of communication between neurons and ensembles of neurons in the brain is a major area of interest in the field of neuroscience. An array of sensors designed to sense specific neuronal messengers or neurotransmitters should provide a better method to study their spatial and temporal activity across a tissue. Screen-printing is a simple and inexpensive technique for fabricating arrays of sensors that can be used to monitor neurotransmitter activity in the brain. One important neuronal messenger known to actively modulate neuronal excitability is nitric oxide (NO). Carbon has been shown to interact with NO in an oxidation-reduction reaction that produces a current proportional to the amount of NO present. The proposed design uses carbon polymer inks screen printed onto aluminum traces to form the sensors. A thick, photodefineable epoxy resin, known as SU-8, serves as an insulator and a mold for the carbon ink. A potentiostat is used to apply a 900 mV voltage between the carbon sensor and a reference electrode positioned in the bath of the experimental setup. The current produced indicates the concentration of NO in close proximity to the carbon site. The screen-printing technique provides an elegant way to produce an array of individual carbon sensors. The carbon sensor array promises a novel approach to mapping the distribution of neurotransmitters in brain tissue.     

Pathological analysis of myocardial cell under ventricular tachycardia and fibrillation based on symbolic dynamics.

Ventricular fibrillation (VF) is one of the most serious malignant arrhythmias usually resulting from immediate degeneration of ventricular tachycardia (VT). In order to analyse the nonlinear dynamics of the cardiac micro-mechanism under VT and VT rhythm, at the cellular level, myocardial cell action potentials are investigated under different rhythm, normal sinus rhythm, VT and VT. On the basis of nonlinear chaotic theory and symbolic dynamics, we put forward new definitions, complexity rate, etc, and obtained some useful properties for cellular electrophysiological analysis. The results of the experiments and computation show that the myocardial cellular signals under VT and VF rhythm are different kinds of chaotic signals in that the cardiac chaos attractor under VF is higher than that under VT. The analytical complexity theory has been promising in the clinical application.     

Design, Microfabrication and Analysis of a Microfluidic Chamber for the Perfusion of Brain Tissue Slices

Successful perfusion and survival of brain slices using a microfabricated fluidic interface chamber is demonstrated. Up to three chambers are fabricated on the same glass substrate using a standard photolithography process. Their base is filled with arrays of micropillars to replace the nylon mesh used in classical interface chambers. These micropillars confine the flow and also uphold slices at the interface between perfusate and oxygen. Enhanced exposure of the neural tissue to oxygen and to the nutritive substances is reached. Computational fluid dynamics and empirical tests are used to study the flow properties of the chambers. The influence of various micropillar arrangements on the flow is as well analyzed. In these flat perfusion chambers, the flow is laminar and remains confined within the chamber even though the side-walls are not higher than the micropillars (400 m). At comparable flow rate this small volume microfluidic chamber (about 100 l) has a perfusate exchange rate at least 4 times faster than conventional perfusion chambers, making experiments with dynamic control of the perfusion medium possible. Using a zero-Mg²⁺ model of epileptiform activity, spontaneous single and multi-spike bursts in the CA3 region of a rat hippocampal brain slice have been observed for more than 5 hours. Compatibility of brain slice perfusion chambers with micro- and nanotechnology is expected to open new avenues in neurophysiology research using multifunction perfusion systems with important integrated features (e.g., microfluidic channels for drug delivery, electrode or sensor arrays).     

Uncovering the mechanisms of deep brain stimulation for Parkinson's disease through functional imaging,neural recording,and neural modeling

High-frequency deep brain stimulation (DBS) of the thalamus or basal ganglia represents an effective clinical technique for the treatment of several medically refractory movement disorders, including Parkinson's disease. However, understanding of the mechanisms of action of DBS remains elusive. The goal of this review is to address our understanding of the effects of high-frequency stimulation within the central nervous system based on results from functional imaging, neural recording, and neural modeling experiments. Using these results, we address the main hypotheses on the mechanisms of action of DBS and conclude that stimulation-induced desynchronization of network oscillations represents the hypothesis that best explains the presently available data.