Biomedical subjects

F Zou

Publications and source records attributed to F Zou.

3 recordsLinked to original sources

PubMed1995

[Single channel properties of NMDA receptors in cortical neurons].

The cell-attached and inside-out configurations of the patch-clamp techniques were used to investigate single channel properties of NMDA receptors in cultured intact neurons mechanically isolated from rat cereberal cortex. Recordings were made in Mg(2+)-free solutions. A channel, with a conductance of 35 pS was studied in detail with either NMDA or L-aspartate in the patch pipette. NMDA channels were permeable to Na+ K+, but not to Cl-, the mean open times and open probabilities of these channels were decreased with increasing hyperpolarization. Distributions for the open times, closed times and burst durations required two-component fits. Channel openings were suppressed by APV. When Mg2+ was included in the pipette, the mean open times were significantly diminished in a concentration- and voltage-dependent manner. Decreasing the bath temperature prolonged channel open times and decreased current amplitudes. The results indicate that there is an intrinsic voltage dependence of NMDA channel kinetics in the intact neurons, suggesting that the normal function of the NMDA channel may be dependent on some intracellular biochemical processes.

Animals↗

PubMed1994

[Changes in the functional characteristics of acetylcholine activated channels of hippocampal neurons at different periods of culture].

Patch-clamp technique was used to examine activation of single acetylcholine receptor channels of hippocampal neurons of neonatal rat at different periods of culture. The conductance values showed substantial variation from patch to patch. Some of channels have the same conductance but are kinetically different. Changes in the electrophysiological behaviour of ACh-evoked channels were dependent on the duration of culture. In the earlier period (1-2 days), the 20-pS state was predominant. Isolated short openings were much more common with mean open times usually less than 2.0 ms. In the late period of culture (18-21 days), the 31-pS state was predominant. The channel openings displays either as single events (tau o1, 0.35 ms; tau o2, 1.29 ms) or as bursts of events (tau b1, 1.15 ms; tau b2, 9.6 ms) in different patches. However, 20-pS state in the late period of culture could also be observed mostly as constituting events during the long burst.

Animals↗

PubMed1994

ECG data compression with wavelet and discrete cosine transforms.

When applying transform techniques in data compression, an efficient approximation of the original signal using fewer transform coefficients is desired. The Discrete Cosine Transform (DCT) has been an effective tool in such applications. It decomposes a signal into a set of sinusoidal waveforms that are global in time. The DCT is not as efficient for signals with only local variations. The Wavelet Transform (WT) is a new technique that can decompose a signal into a set of small waveforms called wavelets. These wavelets possess local supports in the time domain, which makes the WT suitable for representing signals with local variations. Even though the ECG is dominated by low frequencies, its QRS complex exhibits strong localized characteristics. In this study, the effectiveness of the two transforms in compressing ECG data is investigated. Having noted the weakness of each transform, the two techniques are combined in two ways to compress the ECG data. It is observed that with the new techniques, better visualization quality can be achieved with the same total number of transform coefficients.

Electrocardiography↗