Biomedical subjects

Shu-Mei Guo

Publications and source records attributed to Shu-Mei Guo.

6 recordsLinked to original sources

PubMed2005

Resveratrol inhibits the electrical activity of subfornical organ neurons in rat.

The effects of resveratrol on the discharges of neurons in rat subfornical organ (SFO) slices were examined by using extracellular recording technique. The results are as follows: (1) In response to the application of resveratrol (1, 5, 10 mumol/L, n=65) into the superfusate for 2 min, the spontaneous discharge rate of 60/65 (92.3%) neurons was significantly decreased in a dose-dependent manner;(2) Application of L-glutamate (0.3 mmol/L) into the superfusate led to a marked increase in discharge rate of all 12 (100%) neurons in an epileptiform pattern. The increased discharges of 10/12 (83.3%) neurons were suppressed by application of resveratrol (5 mumol/L);(3) In 8 neurons, the selective L-type calcium channel agonist, Bay K8644 (0.1 mumol/L), induced a significant increase in discharge rate of all 8 (100%) neurons. The increased discharges of all 8 (100%) neurons were suppressed by resveratrol (5 mumol/L);(4) In 14 neurons, nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) 50 mumol/L significantly increased the discharge rate of 11/14 (78.6%) neurons. Resveratrol (5 ?mol/L) applied into the superfusate reduced the increased discharges of 9/11 (81.8%) neurons;(5) In 12 neurons, the large-conductance Ca(2+)-activated K(+) channel blocker tetraethylammonium chloride (TEA) 1 mmol/L significantly increased the discharge rate of 10/12 (83.3%) neurons. Resveratrol (5 mumol/L) inhibited the increased discharges of 9/10 (90%) neurons. These results suggest that resveratrol inhibits the electrical activity of SFO neurons. This effect may be related to its properties of blockade of L-type voltage-gated calcium channel and nitric oxide (NO) promoting, and probably has no association with large-conductance Ca(2+)-activated K(+) channel.

Journal Article↗

PubMed2005

3D localization of clustered microcalcifications using cranio-caudal and medio-lateral oblique views.

This paper presents a 3D localization method to register clustered microcalcifications on mammograms from cranio-caudal (CC) and medio-lateral oblique (MLO) views. The method consists of three major components: registration of clustered microcalcifications in CC and MLO views, 3D localization of clustered microcalcifications and 3D visualization of clustered microcalcifications. The registration is performed based on three features, gradient, energy and local entropy codes that are independent of spatial locations of microcalcifications in two different views and are prioritized by discriminability in a binary decision tree. The 3D localization is determined by a sequence of coordinate corrections of calcified pixels using the breast nipple as a controlling point. Finally, the 3D visualization implements a virtual reality modeling language viewer (VRMLV) to view the exact location of the lesion as a guide for needle biopsy. In order to validate our proposed 3D localization system, a set of breast lesions, which appear both in mammograms and in MR Images is used for experiments where the depth of clustered microcalcifications can be verified by the MR images.

Calcification, Physiologic↗

PubMed2005

Resveratrol inhibits neuronal discharges in rat hippocampal CA1 area.

The effects of resveratrol on the discharges of neurons in CA1 area of rat hippocampal slices were examined by using extracellular recording technique. The results are as follows: (1) In response to the application of resveratrol (0.05, 0.5, 5.0 micromol/L, n=52) into the superfusate for 2 min, the spontaneous discharge rate of 46/52 (88.5%) neurons was significantly decreased in a dose-dependent manner; (2) Application of L-glutamate (0.2 mmol/L) into the superfusate led to a marked increase in discharge rate of all 8 (100%) slices in an epileptiform pattern. The increased discharges were suppressed by application of resveratrol (5.0 micromol/L); (3) In 7 slices, perfusion of the selective L-type calcium channel agonist, Bay K8644 (0.1 micromol/L), induced a significant increase in the discharge rate of 6/7 (85.7%) slices. The increased discharges were suppressed by application of resveratrol (5.0 micromol/L); (4) In 9 slices, perfusion of nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 50 micromol/L) into the superfusate significantly augmented the discharge rate of 7/9 (77.8%) slices. Resveratrol (5.0 micromol/L) applied into the superfusate reduced the increased discharges of all 7/7 (100%) neurons; (5) In 10 units, the large-conductance Ca(2+)-activated K(+) channel blocker (tetraethylammonium chloride, TEA, 1 mmol/L) significantly increased the discharge rate of 9/10 (90%) slices. Resveratrol (5.0 micromol/L) applied into the superfusate inhibited the discharges of 8/9 (88.9%) slices. These results suggest that resveratrol inhibits the electrical activity of CA1 neurons. This effect may be related to the blockade of L-type calcium channel and a subsequent reduction of calcium influx, and probably has no association with large-conductance Ca(2+)-activated K(+) channel.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed2005

Genetic-based fuzzy image filter and its application to image processing.

In this paper, we propose a Genetic-based Fuzzy Image Filter (GFIF) to remove additive identical independent distribution (i.i.d.) impulse noise from highly corrupted images. The proposed filter consists of a fuzzy number construction process, a fuzz filtering process, a genetic learning process, and an image knowledge base. First, the fuzzy number construction process receives sample images or the noise-free image and then constructs an image knowledge base for the fuzzy filtering process. Second, the fuzzy filtering process contains a parallel fuzzy inference mechanism, a fuzzy mean process, and a fuzzy decision process to perform the task of noise removal. Finally, based on the genetic algorithm, the genetic learning process adjusts the parameters of the image knowledge base. By the experimental results, GFIF achieves a better performance than the state-of-the-art filters based on the criteria of Peak-Signal-to-Noise-Ratio (PSNR), Mean-Square-Error (MSE), and Mean-Absolute-Error (MAE). On the subjective evaluation of those filtered images, GFIF also results in a higher quality of global restoration.

Algorithms↗

PubMed2004

High-frequency electrical stimulation of femoral nerve reduces infarct size following myocardial ischemia-reperfusion in rats.

The effects of femoral nerve electrostimulation (FNES) on ischemia-reperfused myocardium were examined in the urethane- anesthetized rats to determine whether FNES may provide cardioprotection and to observe the possible mechanism. The area at risk (AR) and infarct area (IA) were determined using Evans blue and nitro-blue tetrazolium staining, respectively. Infarct size (IS) was defined as 100xIA/AR (%). The results are as follows: (1) During 30 min myocardial ischemia and subsequent 120 min reperfusion, the myocardial infarct size occupied (54.96+/-0.82)% of the area at risk. (2) FNES of high frequency (10 V, 100 Hz, 1 ms) significantly reduced myocardial infarct size to (36.94+/-1.34)% (P<0.01), indicating the cardioprotective effect FNES of high frequency on myocardial ischemia-reperfusion, while FNES of low frequency (10 V, 10 Hz, 1 ms) had no effect on myocardial infarct size. (3) Pretreatment with either naloxone (5 mg /kg, i.v), a nonselective opioid receptor antagonist, or glibenclamide (5 mg /kg, i.v), a K(ATP) channel antagonist, completely abolished the cardioprotection of FNES (100 Hz) from myocardial ischemia-reperfusion. It is suggested that FNES of high frequency can protect myocardium from ischemia-reperfusion injury. The possible mechanism is that FNES of high frequency may induce the release of opioids from the central nervous system, and the activation of opioid receptors in the heart results in an opening of myocardial K(ATP) channels which can protect myocardium.

Animals↗

PubMed2004

Digital redesign of analog smith predictor for systems with input time delays.

This paper presents a new methodology for digitally redesigning an existing analog Smith predictor control system, such that the cascaded analog controller with input delay can be implemented with a digital controller. A traditional analog Smith predictor system is reformulated into an augmented system, which is then digitally redesigned using the predicted intersampling states. The paper extends the prediction-based digital redesign method from a delay free feedback system to an input time-delay cascaded system. A tuning parameter v is optimally determined online such that in any sampling period, the output response error between the original analogously controlled time-delay system and the digitally controlled sampled-data time-delay system is significantly reduced. The proposed method gives very good performance in dealing with systems with delays in excess of several integer sampling periods and shows good robustness to sampling period selection.

Journal Article↗