Showing papers by "Yu Huang published in 2000"
TL;DR: In vitro effects of baicalin on the growth, viability, and induction of apoptosis in several human prostate cancer cell lines, including DU145, PC-3, LNCaP and CA-HPV-10 indicate that baical in has direct anti-tumor effects onhuman prostate cancer cells.
221 citations
TL;DR: It is suggested that berberine could act at both endothelium and the underlying vascular smooth muscle to induce relaxation, while Nitric oxide from endothelio may account primarily for the berberines-induced endothelia-dependent relaxation.
108 citations
TL;DR: The results suggest that cGMP via a protein kinase G-dependent mechanism may play a key role in the regulation of the store-operated Ca2+ entry in vascular endothelial cells.
106 citations
TL;DR: Measurements of vibrational excitation and deexcitation of NO (v = 2) scattering from a Au(111) surface show that the probability of both processes increases strongly with the kinetic energy of the incident NO.
Abstract: Measurements of vibrational excitation and deexcitation of NO (v = 2) scattering from a Au(111) surface show that the probability of both processes increases strongly with the kinetic energy of the incident NO. These results are qualitatively consistent with a vibrational energy transfer mechanism involving electron-hole pairs but not with competing adiabatic models. The form of the energy dependence, and other features of the measurements, are not in accord with existing calculations.
97 citations
TL;DR: It was found that CLA as a whole oxidized rapidly and more than 80% was degraded within 110 h in air at 50 degrees C and four c,c-CLA isomers were most unstable followed by four t,t- CLA isomers, which were relatively stable under the same experimental conditions.
Abstract: Conjugated linoleic acids (CLAs) have been shown to be a strong anticarcinogen in a number of animal models. Our previous study demonstrated that CLA as a whole was extremely unstable in air. The present study was undertaken further to examine the oxidative stability of individual CLA isomers using the combination of gas-liquid chromatography (GLC) and silver ion high-performance liquid chromatography (Ag-HPLC). It was found that CLA as a whole oxidized rapidly and more than 80% was degraded within 110 h in air at 50 degrees C. Four c,c-CLA isomers were most unstable followed by four c,t-CLA isomers. In contrast, four t,t-CLA isomers were relatively stable under the same experimental conditions. Both the oxygen consumption and the GLC analysis revealed that 200 ppm jasmine green tea catechins (GTCs) exhibited protection to CLA and were even stronger than 200 ppm butylated hydroxytoluene (BHT) when added to either CLA or canola oil containing 10% CLA. The present study emphasized that oxidative unstability of CLA should not be overlooked although CLA has many biological effects.
91 citations
TL;DR: In this paper, the authors tested whether four natural flavonoids (kempferol, morin, myricetin, and quercetin) would protect or regenerate α-tocopherol in human LDL.
Abstract: Oxidative modification of low density lipoprotein (LDL) may play an important role in the development of atherosclerosis. α-Tocopherol functions as a major antioxidant in human LDL. The present study was to test whether four natural flavonoids (kempferol, morin, myricetin, and quercetin) would protect or regenerate α-tocopherol in human LDL. The oxidation of LDL incubated in sodium phosphate buffer (pH 7.4, 10 mM) was initiated by addition of either 5.0 mM CuSO4 at 37°C or 1.0 mM of 2,2′-azo-bis (2-amidinopropane) dihydrochloride (AAPH) at 40°C. It was found that α-tocopherol was completely depleted within 1 hour. Under the same experimental conditions, all four flavonoids demonstrated a dose-dependent protecting activity to α-tocopherol in LDL at the concentration ranging from 1 to 20μM. All flavonoids showed a varying protective activity against depletion of α-tocopherol in LDL, with kempherol and morin being less effective than myricetin and quercetin. The addition of flavonoids to the incubation mixture after 5 minutes demonstrated a significant regeneration of α-tocopherol in human LDL. The protective activity of four flavonoids to LDL is related to the number and location of hydroxyl groups in the B ring as well as the stability in sodium phosphate buffer.
84 citations
TL;DR: A mechanosensitive Ca2+‐permeable channel is identified in vascular endothelial cells, suggesting that this channel is the primary pathway mediating flow‐induced Ca2 + entry into vascular endothelium cells.
Abstract: The hemodynamic force generated by blood flow is considered to be the physiologically most important stimulus for the release of nitric oxide (NO) and prostacyclin (PGI2) from vascular endothelial cells (1). NO and PGI2 then act on the underlying smooth muscle cells, causing vasodilation and thus lowering blood pressure (2, 3). One critical early event occurring in this flow-induced regulation of vascular tone is that blood flow induces Ca2+ entry into vascular endothelial cells, which in turn leads to the formation of NO (4, 5). Here we report a mechanosensitive Ca2+-permeable channel in vascular endothelial cells. The activity of the channel was inhibited by 8-Br-cGMP, a membrane-permeant activator of protein kinase G (PKG), in cell-attached membrane patches. The inhibition could be reversed by PKG inhibitor KT5823 or H-8. A direct application of active PKG in inside-out patches blocked the channel activity. Gd3+, Ni2+, or SK&F-96365 also inhibited the channel activity. A study of fluorescent Ca2+ entry...
56 citations
TL;DR: In contrast to LA, CLA significantly lowered hepatic cholesterol but it increased the level of adipose tissue cholesterol, suggesting that the hypocholesterolaemic mechanism of CLA is different from that of LA.
Abstract: The present study was designed to study the mechanisms by which dietary conjugated linoleic acids (CLA) decrease serum cholesterol. Hamsters were fed a semi-synthetic diet containing 1 g cholesterol/kg diet with or without supplementation with 20 g linoleic acid (LA) and 20 g CLA/kg diet. After 8 weeks, serum fasting total cholesterol (TC) and triacylglycerol (TG) were significantly lower in the LA-supplemented and CLA-supplemented groups compared with those of the control (CTL) hamsters. In contrast to LA, CLA significantly lowered hepatic cholesterol but it increased the level of adipose tissue cholesterol, suggesting that the hypocholesterolaemic mechanism of CLA is different from that of LA. CLA decreased the activity of intestinal acyl CoA:cholesterol acyltransferase (ACAT) whereas LA had no effect on this enzyme. Consequently, CLA supplementation increased the faecal excretion of total neutral sterols, but it had no or little effect on the faecal acidic sterols. If the ACAT is associated with cholesterol absorption, the part of mechanisms by which CLA decreases serum cholesterol may involve down-regulation of intestinal ACAT activity.
50 citations
TL;DR: In this paper, the authors examined the antioxidant activity in heated canola oil of hexane, acetone, and methanol extracts of dry roots of gansu huangqin (Scutellaria rehderiana) as well as six flavonoids isolated from the acetone and methenol extracts.
Abstract: The present study examined the antioxidant activity in heated canola oil of hexane, acetone, and methanol extracts of dry roots of gansu huangqin (Scutellaria rehderiana) as well as six flavonoids isolated from the acetone and methanol extracts. The oxidation was conducted at 95°C by monitoring oxygen consumption and decreases in both linoleic and α-linolenic acids. The acetone extract was most effective in inhibiting oxidation of canola oil, followed by the methanol extract. The antioxidant activity of gansu huangqin acetone extract was dose-dependent. Among the six flavonoids, baicalein and ganhuangenin were more effective than butylated hydroxytoluene (BHT) in protecting canola oil from oxidation. The present results suggest that the acetone extract of this root may be a potential source of natural antioxidants for use in processed foods.
41 citations
TL;DR: Results indicate that glibenclamide-induced endothelium-dependent relaxation involves nitric oxide release and this effect may be related to its stimulatory effect on endothelial Ca(2+) levels and on the protein kinase C-mediated contractile mechanism.
Abstract: Objectives: Glibenclamide was found to act as both a selective ATP-sensitive K+ channel blocker and a vasorelaxant. The exact mechanisms underlying the relaxant effect of glibenclamide are unknown. The present study was designed to examine the role of endothelium/nitric oxide in glibenclamide-induced relaxation in rat isolated aortic rings. Methods: A combination of experimental approaches including isometric force measurement, cell culture, Ca2+ fluorescence measurement and radioimmunoassay were used to examine the vascular effect of glibenclamide. Results: Glibenclamide induced a concentration-dependent relaxation more effectively in rings with endothelium (IC50 of 32±4 μM) than those without endothelium (IC50 of 365±29 μM). Incubation with N G-nitro-l-arginine methyl ester (L-NAME) or methylene blue significantly reduced and l-arginine (3 mM) potentiated the glibenclamide-induced relaxation. l-Arginine (3 mM) partially antagonized the effect of L-NAME. Glibenclamide (100 μM) increased the cyclic GMP content of endothelium-intact tissues. Pretreatment with N G-nitro-l-arginine (100 μM) or removal of endothelium significantly suppressed the effect of glibenclamide on cyclic GMP production. Glibenclamide elevated the intracellular Ca2+ levels in cultured rat aortic endothelial cells. Glibenclamide also inhibited the endothelium-independent contractile response to 60 mM K+ (IC50 of 137±21 μM) and caused a rightward shift in the concentration–contraction curve for CaCl2. Besides, glibenclamide inhibited phorbol-12,13-diacetate (1 μM)-induced contraction in Ca2+-free Krebs solution. Conclusion: These results indicate that glibenclamide-induced endothelium-dependent relaxation involves nitric oxide release and this effect may be related to its stimulatory effect on endothelial Ca2+ levels. However, the glibenclamide-induced endothelium-independent relaxation may be associated with its inhibitory effect on Ca2+ influx through Ca2+ channels and on the protein kinase C-mediated contractile mechanism.
34 citations
TL;DR: It is concluded that weight cycling in rats may promote body fatness if an HF diet is consumed and can significantly alter whole body fatty acid balance irrespective of whether they consumed an MF or HF diet.
Abstract: Epidemiological studies have suggested that repeated weight cycling over time may increase the risk of coronary heart disease. The mechanism involved remains poorly understood, but the change in li...
Journal Article•
TL;DR: The purified epicatechin derivatives from jasmine green tea relaxed the isolated rat arteries preconstricted by phenylephrine and inhibited aortic smooth muscle cell proliferation.
Abstract: "AIM:
The present study was aimed to examine the vasorelaxant and antiproliferative responses to purified green tea epicatechin mixture, (-)epicatechin and (-)epigallocatechin gallate on rat arterial smooth muscle cells.
METHODS:
Changes in isometric force were measured by Grass force transducer and effects on cell proliferation were evaluated using [3H]thymidine incorporation assay.
RESULTS:
Epicatechin mixture, (-)epicatechin and (-)epigallocatechin gallate, which we isolated and purified from jasmine green tea, concentration-dependently, reduced the contractile response to phenylephrine in rat isolated aortic rings with (-)epigallocatechin gallate being more effective. These three agents also inhibited [3H]thymidine incorporation into DNA in cultured rat aortic smooth muscle cells in a concentration-dependent manner.
CONCLUSION:
The purified epicatechin derivatives from jasmine green tea relaxed the isolated rat arteries preconstricted by phenylephrine and inhibited aortic smooth muscle cell proliferation."
TL;DR: In this article, the authors examined the antioxidant activity of heane, acetone, and methanol extracts, as well as Baicalein purified from the dry roots of Scutellaria baicalensis Georgi (common name: Huangqin), in heated canola oil.
Abstract: There is an increasing interest in natural antioxidants present in traditional Chinese herbal medicines. The present study examined the antioxidant activity of heane, acetone, and methanol extracts, as well as baicalein purified from the dry roots of Scutellaria baicalensis Georgi (common name: Huangqin), in heated canola oil. Oxygen consumption and decreases in linoleic acid linolenic acid content were monitored in canola oil held at 90–93°C. Among the three extracts, the acetone extract was most effective against oxidation of canola oil, followed by the methanol extract of the dry roots. The antioxidant activity of these three extracts correlated well with their content of baicalein, which provided strong protection to canola oil from oxidation. The antioxidant activity of Huangqin acetone extract was dose-dependent. The acetone extract at 100 ppm or above was even more effective than butylated hydroxytoluene at 200 ppm in protecting canola oil from oxidation. The present results suggest that the acetone extract of these roots should be further explored as a potential source of natural antioxidants for use in the processed foods.
Journal Article•
TL;DR: Baicalein and baicalin enhanced the phenylephrine-induced contraction most likely through inhibiting production or/and release of endothelial nitric oxide, whilst, cardamonin-, alpinetin- or (-)epicatechin-induced endothelium-dependent relaxation is primarily mediated through endothelialNitric oxide.
Abstract: "AIM:
To examine the role of endothelium in the vascular responses to flavonoids, baicalein, baicalin, cardamonin, alpinetin, and to purified jasmine green tea (-)epicatechin in the isolated rate mesenteric artery rings.
METHODS:
The isometric contraction was measured by Grass force-displacement transducers.
RESULTS:
Both baicalein and baicalin enhanced the phenylephrine-induced contractile response in the endothelium-intact rings. This enhancement was abolished by pretreatment with the nitric oxide inhibitor NG-nitro-L-arginine or in the absence of the endothelium. Both flavonoids also inhibited the acetylcholine-induced endothelial nitric oxide-dependent relaxation. In contrast, cardamonin, alpinetin or (-)epicatechin induced both endothelium-dependent and -independent relaxation. NG-nitro-L-arginine meyhyl ester or endothelium denudation attenuated the endothelium-dependent relaxation to the same extent.
CONCLUSION:
Baicalein and baicalin enhanced the phenylephrine-induced contraction most likely through inhibiting production or/and release of endothelial nitric oxide. Whilst, cardamonin-, alpinetin- or (-)epicatechin-induced endothelium-dependent relaxation is primarily mediated through endothelial nitric oxide."
TL;DR: Depletion of internal Ca(2+) stores with cyclopiazonic acid resulted in an increased efficacy of nifedipine to inhibit this contraction and the associated increase in [Ca(2+)](i), which promoted electromechanical coupling between full muscarinic stimulation and muscle contraction to the detriment of pharmacomechanical coupling.
Abstract: Full muscarinic stimulation in bovine tracheal smooth muscle caused a sustained contraction and increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) that was largely resistant to inhibition by nifedipine. Depletion of internal Ca(2+) stores with cyclopiazonic acid resulted in an increased efficacy of nifedipine to inhibit this contraction and the associated increase in [Ca(2+)](i). Thus internal Ca(2+) store depletion promoted electromechanical coupling between full muscarinic stimulation and muscle contraction to the detriment of pharmacomechanical coupling. A similar change in coupling mode was induced by ryanodine even when it did not significantly modify the initial transient increase in [Ca(2+)](i) induced by this stimulation, indicating that depletion of internal stores was not necessary to induce the change in excitation-contraction coupling mode. Blockade of the Ca(2+)-activated K(+) channel by tetraethylammonium, charybdotoxin, and iberiotoxin all induced the change in excitation-contraction coupling mode. These results suggest that in this preparation, Ca(2+) released from the ryanodine-sensitive Ca(2+) store, by activating Ca(2+)-activated K(+) channels, plays a central role in determining the expression of the pharmacomechanical coupling mode between muscarinic excitation and the Ca(2+) influx necessary for the maintenance of tone.
05 Nov 2000
TL;DR: The experimental results presented demonstrate that compared to earlier methods, the proposed method achieves the above objectives while also achieving higher fault coverages for most of the benchmark circuits considered.
Abstract: A method to select the lengths of functional sequences in a BIST scheme for scan designs is proposed in this paper. A functional sequence is a sequence of primary input vectors applied when the circuit operates as a sequential circuit, without using scan. These sequences can be applied at-speed, i.e., at the normal circuit clock speed. The objectives set for choosing the lengths of the functional sequences are to increase the number of vectors applied at-speed, and to reduce the number of settings of functional sequence lengths, without compromising the fault coverage achieved. The experimental results presented demonstrate that compared to earlier methods, the proposed method achieves the above objectives while also achieving higher fault coverages for most of the benchmark circuits considered.
TL;DR: Results indicate that thapsigargin produced complex vascular effects primarily by acting on the endothelial cells, and causes an endothelial nitric oxide-dependent relaxation; on the other hand, it inhibits nitricoxide-mediated relaxation at the similar concentrations.
TL;DR: Results indicate that both baicalin and baicalein potentiated the evoked contractile response, likely through inhibition of nitric oxide formation and/or release in the endothelium.
Abstract: The effects of purified baicalin and baicalein from the traditional Chinese herb, Huangqin, on contractions induced by phenylephrine, U46619, and high extracellular K+ were investigated in isolated rat mesenteric arteries. Both baicalin (1-100 microM) and baicalein (1-50 microM) potentiated the contractile response to phenylephrine in a concentration-related manner. Both flavonoids (10 microM) also enhanced the U46619- or 40 mM K+-induced contractions. Baicalein (100-300 microM) reduced the phenylephrine-induced tone. Prazosin at 1 microM did not affect U46619-induced contraction in the absence and presence of baicalein or baicalin. Neither baicalin (1-100 microM) nor baicalein (1-100 microM) affected the basal tension. Removal of the functional endothelium abolished the potentiating effects of baicalin and baicalein in arteries preconstricted by both constrictors. Pretreatment of endothelium-intact rings with 100 microM N(G)-nitro-L-arginine also potentiated phenylephrine- or U46619-induced contraction but completely inhibited the effects of baicalin and baicalein. Pretreatment with 1 mM L-arginine reversed the enhancing effect of baicalin but not of baicalein on phenylephrine-evoked contraction. Pretreatment with 10 microM baicalin or 10 microM baicalein significantly reduced the endothelium-dependent relaxation induced by acetylcholine or ionomycin. These results indicate that both baicalin and baicalein potentiated the evoked contractile response, likely through inhibition of nitric oxide formation and/or release in the endothelium.
30 Dec 2000
TL;DR: This paper uses the dominant motion model to calculate both the background and foreground motion in a robust estimation framework and then combines it with the result of static segmentation using the watershed algorithm to segment the foreground from the background.
Abstract: This paper addresses the problem of image segmentation using motion and luminance information. We use the dominant motion model to calculate both the background and foreground motion in a robust estimation framework and then combine it with the result of static segmentation using the watershed algorithm to segment the foreground from the background. In this paper, the previous pixelbased (or over a small neighborhood) motion measure is replaced by the patch-based motion measure in motion segmentation. Experimental results are given to show the efficiency of our method.
TL;DR: An approach of motion-based segmentation is proposed to realize the extraction of spatial-temporal features of gesturing, and based on the dominant motion model the gesturing region is extracted, i.e., the dominant object.
Abstract: One of the key problems in a vision-based gesture recognition system is the extraction of spatial-temporal features of gesturing. In this paper an approach of motion-based segmentation is proposed to realize this task. The direct method cooperated with the robust M-estimator to estimate the affine parameters of gesturing motion is used, and based on the dominant motion model the gesturing region is extracted, i.e., the dominant object. So the spatial-temporal features of gestures can be extracted. Finally, the dynamic time warping (DTW) method is directly used to perform matching of 12 control gestures (6 for “translation” orders, 6 for “rotation” orders). A small demonstration system has been set up to verify the method, in which a panorama image viewer can be controlled (set by mosaicing a sequence of standard “Garden” images) with recognized gestures instead of the 3-D mouse tool.
TL;DR: Comparing the efficacy of cromakalim and nifedipine to inhibit acetylcholine and pilocarpine-induced tonic contractions in control preparations and in tissues where a fraction of the muscarinic receptor population had been removed by alkylation with phenoxybenzamine is compared.
14 Jun 2000
TL;DR: This paper uses the dominant motion model to calculate both the background and foreground motion in a robust estimation framework and then combines it with the result of static segmentation using the watershed algorithm to segment the foreground from the background.
Abstract: This paper addresses the problem of image segmentation using motion and luminance information. We use the dominant motion model to calculate both the background and foreground motion in a robust estimation framework and then combine it with the result of static segmentation using the watershed algorithm to segment the foreground from the background. In this paper, the previous pixel-based (or over a small neighborhood) motion measure is replaced by the patch-based motion measure in motion segmentation. Experimental results are given to show the efficiency of our method.
TL;DR: The main aim of this study was to examine a unique role of endothelium in the vascular response to tetraoctylammonium ions (TOA+) in the isolated rat aorta.
Abstract: Quaternary ammonium ions are common pharmacological probes used to study the kinetic properties of K+ channels in smooth muscle cells. On the other hand, some ammonium compounds cause vasorelaxation through unknown mechanisms. The main aim of this study was to examine a unique role of endothelium in the vascular response to tetraoctylammonium ions (TOA+) in the isolated rat aorta. Changes in contractile force were measured by force transducers and total tissue content of cGMP was measured by radioimmunoassay. Endothelial cytosolic Ca2+ ([Ca2+]i) was assessed by laser scanning confocal microscopy.