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Biomedical subjects

Hong Sun

Publications and source records attributed to Hong Sun.

At least 73 records · Page 4Linked to original sources
PubMed2005

The effects of Ananas comosus L. leaves on diabetic-dyslipidemic rats induced by alloxan and a high-fat/high-cholesterol diet.

The aim of this study is to demonstrate the effects of Ananas comosus L. leaves on diabetic-dyslipidemic rats. Hypoglycemic and hypolipidemic activities of the ethanolic extract of Ananas comosus L. leaves (EEACL) were evaluated in normal and alloxan-induced diabetic rats by oral glucose tolerance test and an olive oil load test. Anti-diabetic, anti-hyperlipidemic and anti-oxidative activities of EEACL were also investigated in diabetic-dyslipidemic rats induced by alloxan and a high-fat/high-cholesterol diet. EEACL at the dose of 0.40 g/kg significantly inhibited the increase in blood glucose in diabetic rats in oral glucose tolerance test, but did not cause any hypoglycerimic activity in normal rats. It also significantly inhibited the increase in postprandial triglycerides (TG) levels in both normal and diabetic rats in olive oil load test. After 15 days of treatment of diabetic dyslipidemic rats, EEACL significantly decreased blood glucose (-51.0%, P < 0.01), TG (-50.1%, P < 0.01), TC (-23.3%, P < 0.01), LDL-c (-47.9%, P < 0.01) and glycated albumin (-25.4%, P < 0.01) levels, significantly increased serum high-density lipoprotein cholesterol levels (66.2%, P < 0.01) and prevented lower body weight of diabetes (11.8%, P < 0.05), significantly lowered lipid peroxidation productions of blood (-27.8%, P < 0.01), brain (-31.6%, P < 0.05), liver (-44.5%, P < 0.01) and kidneys (-72.2%, P < 0.05) compared with those in untreated diabetic dyslipidemic rats. These data suggest that EEACL has anti-diabetic, anti-dyslipidemic and anti-oxidative activities, which may be developed into a new plant medicine for treatment of diabetes and its complications.

Ananas↗
PubMed2005

[Effects of the polysaccharides isolated from ganoderma applanatum (PGA) on the level of PGE2 and gastric mucosal blood flow (GMBF) and gastric mucus secretion of rats with gastric mucosa injury].

OBJECTIVE: To investigate the protective effects of the polysaccharides isolated from ganoderma applanatum (PGA) on gastric mucosal injury in rats and the underlying mechanism. METHOD: Gastric ulcer was induced by either acetic acid or pylorus ligation in the rats. The level of PGE2 and GMBF, and gastric mucus secretion were examined respectively. RESULT: After oral administration of PGA (250-1000 mg x kg(-1)) repeatedly, the level of PGE2 and GMBF were obviously increased in gastric mucosa of rats as compared with the model group. The secretions of both free mucus in stomach and mucus of gastric wall were enhanced apparently by PGA in a dose-dependent manner. CONCLUSION: PGA could strengthen gastric mucosa barrier by improving the level of PGE2, GMBF and the secretion of gastric mucus, which may be one of the mechanisms underlying the protective effect of PGA on the gastric mucosa during the gastric ulcer.

Animals↗
PubMed2004

Electroactive layer-by-layer films of heme protein-coated polystyrene latex beads with poly(styrene sulfonate).

In this work, a novel two-step construction strategy for protein layer-by-layer assembly films was proposed. In the first step, positively charged hemoglobin (Hb) or myoglobin (Mb) at pH 5.0 was adsorbed on the negatively charged surface of 500 nm diameter-sized polystyrene (PS) latex beads, forming core-shell structured PS-protein particles. In the next step, the PS-protein particles were further assembled layer by layer with oppositely charged poly(styrene sulfonate)(PSS) on various solid surfaces under suitable conditions. Cyclic voltammetry (CV), quartz crystal microbalance (QCM), and UV-vis spectroscopy were used to monitor the growth of {(PS-protein)/PSS}(n) films. The stable {(PS-protein)/PSS}(n) films modified on pyrolytic graphite (PG) electrodes demonstrated good electroactivity in protein-free buffer, which was originated from protein heme Fe(III)/Fe(II) redox couples, and the electroactivity extended to six (PS-protein)/PSS bilayers. UV-vis spectroscopy showed that Hb and Mb in the films retained their near-native structure in the medium pH range. {(PS-protein)/PSS}(n) films catalyzed electrochemical reduction of oxygen, hydrogen peroxide, trichloroacetic acid (TCA) and nitrite with a significant lowering of overpotential, and displayed better catalytic activity than corresponding cast PS-protein films.

Animals↗
PubMed2004

Superhard cubic BC2N compared to diamond.

Recent experiments claimed successful synthesis of cubic boron-carbonitride compounds BC2N with an extreme hardness second only to diamond. In the present Letter, we examine the ideal strength of cubic BC2N using first-principles calculations. Our results reveal that, despite the large elastic parameters, compositional anisotropy and strain dependent bonding character impose limitation on their strength. Consequently, the hardness of the optimal BC2N structure is predicted to be lower than that of cubic BN, the second hardest material known. The measured extreme hardness of BC2N nanocomposites is most likely due to the nanocrystalline size effect and the bonding to the surrounding amorphous carbon matrix. This may prove to be a general rule useful in the quest for new superhard covalent materials.

Journal Article↗
PubMed2004

Voltammetric studies of hemoglobin-coated polystyrene latex bead films on pyrolytic graphite electrodes.

A novel hemoglobin (Hb)-coated polystyrene (PS) latex bead film was deposited on pyrolytic graphite (PG) electrode surface. In the first step, positively charged Hb molecules in pH 5.0 buffers were adsorbed on the surface of negatively charged, 500 nm diameter PS latex beads bearing sulfate groups by electrostatic interaction. The aqueous dispersion of Hb-coated PS particles was then deposited on the surface of PG electrodes and, after evaporation of the solvent, Hb-PS films were formed. The Hb-PS film electrodes exhibited a pair of well-defined, quasi-reversible cyclic voltammetric (CV) peaks at about -0.36 V vs. SCE in pH 7.0 buffers, characteristic of Hb heme Fe(III)/Fe(II) redox couples. Positions of Soret absorption band of Hb-PS films suggest that Hb retains its near-native structure in the films in its dry form and in solution at medium pH. The Hb in PS films was also acted as a catalyst to catalyze electrochemical reduction of various substrates such as trichloroacetic acid (TCA), nitrite, oxygen and hydrogen peroxide.

Animals↗
PubMed2004

Effects of uremic toxins on hepatic uptake and metabolism of erythromycin.

Hepatic clearance of erythromycin (Ery) is significantly reduced in patients with end stage renal disease. Since Ery is primarily eliminated via excretion of unchanged drug in the bile, we suspect that this change could be due to the effect of uremic toxins on hepatic uptake and/or efflux transporters. Using rat hepatocytes and microsomes as model proof of concept systems, we examined six uremic toxins, 3-carboxy-4-methyl-5-propyl-2-furan-propanoic acid (CMPF), indoxyl sulfate (IS), hippuric acid (HA), indole acetic acid (IA), guanidinosuccinic acid (GSA), and indoxyl-beta-D-glucuronide (IG), for their effects on Ery uptake and metabolism. Ery and the metabolite N-demethyl-Ery were measured by liquid chromatography/tandem mass spectrometry. The uptake of Ery by rat hepatocytes was markedly inhibited by rifampin and digoxin, but not by quinidine, suggesting that Oatp2 plays a major role in the uptake of Ery. At 50 microM, CMPF significantly (p < 0.05) reduced hepatocyte accumulation of Ery and N-demethyl-Ery. At higher concentrations (>200 microM), CMPF appears to also inhibit the enzymatic metabolism of Ery. In contrast, IS did not significantly inhibit the hepatocyte uptake of Ery, even at the highest concentration (800 microM) tested, but reduced metabolite generation (p < 0.001). The other uremic toxins, HA, IA, IG, and GSA, did not affect either hepatic uptake or microsomal metabolism of Ery. CMPF, IS, and HA were shown not to inhibit differential P-glycoprotein transport of Ery in cellular systems. Our results suggest that CMPF can directly inhibit the uptake of Ery by inhibiting Oatp2, whereas IS is more likely to inhibit the enzymatic metabolism of Ery.

Animals↗
PubMed2004

Ca2+-binding protein-1 facilitates and forms a postsynaptic complex with Cav1.2 (L-type) Ca2+ channels.

Ca2+-binding protein-1 (CaBP1) is a Ca2+-binding protein that is closely related to calmodulin (CaM) and localized in somatodendritic regions of principal neurons throughout the brain, but how CaBP1 participates in postsynaptic Ca2+ signaling is not known. Here, we describe a novel role for CaBP1 in the regulation of Ca2+ influx through Ca(v)1.2 (L-type) Ca2+ channels. CaBP1 interacts directly with the alpha1 subunit of Ca(v)1.2 at sites that also bind CaM. CaBP1 binding to one of these sites, the IQ domain, is Ca2+ dependent and competitive with CaM binding. The physiological significance of this interaction is supported by the association of Ca(v)1.2 and CaBP1 in postsynaptic density fractions purified from rat brain. Moreover, in double-label immunofluorescence experiments, CaBP1 and Ca(v)1.2 colocalize in numerous cell bodies and dendrites of neurons, particularly in pyramidal cells in the CA3 region of the hippocampus and in the dorsal cortex. In electrophysiological recordings of cells transfected with Ca(v)1.2, CaBP1 greatly prolonged Ca2+ currents, prevented Ca2+-dependent inactivation, and caused Ca2+-dependent facilitation of currents evoked by step depolarizations and repetitive stimuli. These effects contrast with those of CaM, which promoted strong Ca2+-dependent inactivation of Ca(v)1.2 with these same voltage protocols. Our findings reveal how Ca2+-binding proteins, such as CaM and CaBP1, differentially adjust Ca2+ influx through Ca(v)1.2 channels, which may specify diverse modes of Ca2+ signaling in neurons.

Animals↗
PubMed2004

Molecularly imprinted copolymer membranes functionalized by phase inversion imprinting for uracil recognition and permselective binding.

Uracil (URA) was selected as a template for preparing molecularly imprinted membranes of poly(acrylonitrile-co-methylacrylic acid) [P(AN-co-MAA)] using the phase inversion technique. This study used Fourier transform infra-red (FT-IR) and (1)H nuclear magnetic resonance (NMR) spectroscopic studies to characterize the polymer-template interaction and scanning electron microscopy (SEM) and atomic force microscopy (AFM) for morphology of the URA imprinted membrane. Resultant membranes had typical ultrafiltration structure with porous morphology and showed a permeation flux of 3.5 x 10 9-5)m(3)/(m(2)s) for 32 microM URA aqueous solution. Permselective binding to the target molecule was observed in permeation experiments with 7.9 micromol/g binding capacity of URA. Binding selectivity was discussed for URA and its analogs, dimethyluracil (DMURA) and caffeine (CAF), with 0.6 and 0.8 micromol/g binding capacity, respectively.

Binding Sites↗
PubMed2004

[Formation mechanisms of the fibrous capsule around hepatic and splenic hydatid cyst].

OBJECTIVE: To investigate the formative mechanisms of the fibrous capsule around hepatic and splenic hydatid cyst. METHODS: HE stain was used to observe the histopathologic changes of the fibrous capsules around hepatic and splenic hydatid cysts and the adjacent parenchyma. The expression of collagen IV, fibronectin (FN), laminin (LN), transforming growth factor-beta1 (TGF-beta1) and tumor necrosis factor-alpha (TNF-alpha) were detected by using immunohistochemistry or in situ hybridization in fibrous capsules around 40 hepatic hydatid cysts and 15 splenic hydatid cysts including adjacent parenchyma. RESULTS: A special delaminated phenomenon was observed in the fibrous capsules around hepatic hydatid cysts. Granuloma-like pathologic changes were found in the fibrous capsules near worm and there were many depressed Glisson capsules and hepatic vein system in the fibrous capsules near hepatic parenchyma while these phenomena could not be observed in splenic hydatid cysts. All parameters were highly expressed in the fibrous capsules near hepatic parenchyma and the difference between the two fibrous capsules was significant (P<0.01). CONCLUSION: The mechanisms of forming fibrous capsule around hepatic and splenic hydatid cysts are different. The fibrous capsule around hepatic hydatid cyst is a granuloma-like structure, covered by the pressed Glisson system and hepatic vein system with a small gap between them; while the fibrous capsule around splenic hydatid cyst is formed by granuloma-like tissue covering the worm and there is no gap between the capsule and the splenicparenchyma.

Echinococcosis↗
PubMed2004

Determination of the role of the human RNase H1 in the pharmacology of DNA-like antisense drugs.

Although ribonuclease H activity has long been implicated as a molecular mechanism by which DNA-like oligonucleotides induce degradation of target RNAs, definitive proof that one or more RNase H is responsible is lacking. To date, two RNase H enzymes (H1 and H2) have been cloned and shown to be expressed in human cells and tissues. To determine the role of RNase H1 in the mechanism of action of DNA-like antisense drugs, we varied the levels of the enzyme in human cells and mouse liver and determined the correlation of those levels with the effects of a number of DNA-like antisense drugs. Our results demonstrate that in human cells RNase H1 is responsible for most of the activity of DNA-like antisense drugs. Further, we show that there are several additional previously undescribed RNases H in human cells that may participate in the effects of DNA-like antisense oligonucleotides.

Adenoviridae↗
PubMed2004

Influence of exercise on dilatation of the basilar artery during diabetes mellitus.

Our goal was to examine whether exercise training alleviates impaired nitric oxide synthase (NOS)-dependent dilatation of the basilar artery in Type 1 diabetic rats. To test this hypothesis, we measured in vivo diameter of the basilar artery in sedentary and exercised nondiabetic and diabetic rats in response to NOS-dependent (acetylcholine) and -independent (nitroglycerin) agonists. To determine the potential role for nitric oxide in vasodilatation in sedentary and exercised nondiabetic and diabetic rats, we examined responses after NG-monomethyl-l-arginine (l-NMMA). We found that acetylcholine produced dilatation of the basilar artery that was similar in sedentary and exercised nondiabetic rats. Acetylcholine produced only minimal vasodilatation in sedentary diabetic rats. However, exercise alleviated impaired acetylcholine-induced vasodilatation in diabetic rats. Nitroglycerin produced dilatation of the basilar artery that was similar in sedentary and exercised nondiabetic and diabetic rats. l-NMMA produced similar inhibition of acetylcholine-induced dilatation of the basilar artery in sedentary and exercised nondiabetic and diabetic rats. Finally, we found that endothelial NOS (eNOS) protein in the basilar artery was higher in diabetic compared with nondiabetic rats and that exercise increased eNOS protein in the basilar artery of nondiabetic and diabetic rats. We conclude that 1) exercise can alleviate impaired NOS-dependent dilatation of the basilar artery during diabetes mellitus, 2) the synthesis and release of nitric oxide accounts for dilatation of the basilar artery to acetylcholine in sedentary and exercised nondiabetic and diabetic rats, and 3) exercise may exert its affect on cerebrovascular reactivity during diabetes by altering levels of eNOS protein in the basilar artery.

Acetylcholine↗
PubMed2004

L-arginine prevents impaired endothelium-dependent cerebral arteriolar dilatation during acute infusion of nicotine.

Exogenous treatment with L-arginine has been shown to restore impaired nitric oxide synthase (NOS)-dependent dilatation of peripheral blood vessels during disease states. We have shown that nicotine impairs NOS-dependent arteriolar dilatation in the cerebral circulation. However, the role of L-arginine in impaired responses of cerebral arterioles during infusion of nicotine has not been examined. Thus the goal of the present study was to examine the role of L-arginine in nicotine-induced impairment of cerebral arteriolar reactivity. We measured the diameter of pial arterioles in response to NOS-dependent (5'-adenosine diphosphate [ADP] and acetylcholine) and NOS-independent (nitroglycerin) agonists before and after infusion of vehicle or nicotine (2 microg/kg/min intravenously for 30 min followed by a maintenance dose of 0.35 microg/kg/min) in the absence or presence of L-arginine (10(-3) M). We found that topical application of L-arginine to cerebral microvessels during infusion of nicotine could prevent impaired NOS-dependent vasodilatation. We suggest that exogenous L-arginine may have a beneficial role in preventing cerebral microvascular dysfunction during exposure to nicotine.

Animals↗
PubMed2004

Inward rectifier potassium channels in the basilar artery during chronic alcohol consumption.

BACKGROUND: The goals of this study were to determine whether chronic alcohol consumption alters potassium channel-mediated reactivity in the basilar artery and to determine a potential mechanism that might account for the effects of alcohol on the basilar artery. METHODS: Sprague-Dawley rats were fed liquid diets with or without alcohol for 2 to 3 months. We measured diameter of the basilar artery in response to potassium channel inhibitors and activators. Protein level of inward rectifier potassium channel subunit Kir2.1 in the basilar artery was determined by Western blot. RESULTS: Topical application of glibenclamide (1 and 10 microM) significantly constricted the basilar artery at high dose; iberiotoxin (10 and 100 nM), 4-AP (0.1 and 1 mM), and BaCl2 (1 and 10 microM) produced dose-related constriction in both non-alcohol-fed and alcohol-fed rats. However, the magnitude of constriction in response to BaCl2 was significantly less in alcohol-fed rats compared with non-alcohol-fed rats. Topical application of KCl (1 and 3 mM), cromakalim (0.1 and 0.3 microM), and NS1619 (10 and 30 microM) induced dose-related dilation in non-alcohol-fed and alcohol-fed rats. However, the magnitude of vasodilation in response to KCl was significantly less in alcohol-fed rats compared with non-alcohol-fed rats. In addition, Kir2.1 protein level in the basilar artery was significantly reduced in alcohol-fed compared with non-alcohol-fed rats. CONCLUSIONS: These findings suggest that chronic alcohol consumption reduces expression of inward rectifier potassium channels and inhibits KIR channel-mediated dilation in the basilar artery.

Alcohol Drinking↗
PubMed2004

[Expression of thymidine phosphorylase in human colorectal carcinoma and its clinical significance].

BACKGROUND & OBJECTIVE: Angiogenesis has been well known to be a factor related to the tumor growth and metastasis. Recent studies have reported that thymidine phosphorylase (TP) is identical with platelet-derived endothelial cell growth factor. It not only plays a role in the induction of the tumor angiogenesis, but also enhances the chemotherapeutical sensitivity of the tumor cells to prodrug of 5-fluorouracil. However, until now, the complete identity of view about the function of TP expression in colorectal carcinoma and its prognostic significance has not been reached. The present study was to explore the TP expression level in human colorectal carcinoma and its clinical significance. METHODS: Seventy archived samples of the patients with colorectal carcinoma were detected by immunohistochemical staining. These patients had undergone radical surgical treatment at the First Hospital of Xi'an Jiaotong University and had been followed up for 5 years after operation. RESULTS: TP expression was predominantly observed in the cytoplasm of the tumor cells. The positive rate was 57.14%(40/70). TP expression levels in the patients with different Dukes, stages and histopathological grades showed obvious difference (P=0.007 and 0.002, respectively). By Kaplan-Meier methods, the survival of TP positive expression group was shorter than that of TP negative expression group, and the five-year survival rates of TP positive expression group and TP negative expression group were 33.33% and 73.33% (P=0.000). The results indicated that the prognosis of the patients with TP positive expression was poorer than that of patients with TP negative expression. CONCLUSION: These findings suggest that TP expression might be one of the important prognostic indicators for colorectal carcinoma patients, and TP detection in colorectal carcinoma patients might served as a parameter for designing therapeutic schedule and choosing prodrug of 5-fluorouracil.

5'-Nucleotidase↗
PubMed2004

[Inhibitory effect of hyaluronic acid, hyaluronidase and RGD on adhesion and invasion of human gastric cancer cell line SGC7901].

OBJECTIVE: To investigate the inhibitory effect of hyaluronic acid (HA), hyaluronidase (Hase) and arg-gly-asp tripeptide (RGD) on adhesion and invasion of human gastric cancer cell line SGC7901. METHODS: Expression of CD44 and integrin beta1 protein on cell surface was determined by indirect fluorescence. After SGC7901 cells were treated with HA, Hase and RGD alone or in various combinations, their adhesion and invasion to ECM were measured by MTT and Boyden chamber method. Cell morphology was also observed. RESULTS: Expression of CD44 and integrin beta1 protein on cell surface was detected in human gastric cancer cell line SGC7901. Hase or RGD alone could block the adhesion and invasion of SGC7901 cells to ECM in contrast to the control (P < 0.001, P < 0.05); their blocking effect was stronger than HA (P < 0.05). The inhibitory effect of Hase + HA or a combination of the three agents was stronger than any single agent (P < 0.001). Morphologically, the untreated cells adhered onto the matrigel had spread out presenting a fibroblast feature with variously shaped pseudopods, while the treated ones were kept round with relatively fewer pseudopods. CONCLUSION: HA, Hase and RGD can inhibit the adhesion and invasion of SGC7901 cells expressing functional CD44 and integrin beta1 protein to ECM, and a combination of the three agents may achieve the best inhibitory effect.

Adenocarcinoma↗
PubMed2004

[Effect of estrogen and progesterone on the expression of VEGF mRNA in epithelial ovarian cancer cell line].

OBJECTIVE: To study the effect of 17beta-estradiol (17beta-E(2)) and medroxyprogesterone acetate (MPA) on the expression of VEGF mRNA in epithelial ovarian carcinoma cell line in vitro. METHODS: Human epithelial ovarian carcinoma cell line SKOV3 cells were exposed to 17beta-E(2) (10(-12) approximately 10(-8) mol/L) or MPA (10(-9) approximately 10(-5) mol/L), the expression level of VEGF mRNA was determined by RT-PCR. RESULTS: The PCR products of VEGF were mainly 606 bp and 474 bp. The expression of VEGF mRNA in the 17beta-E(2)-treated cells was significantly higher than in the untreated control (P < 0.05), the expression level of VEGF mRNA increased with the increase in 17beta-E(2) concentration. The expression of VEGF mRNA in SKOV3 cells treated with MPA (10(-9) approximately 10(-5) mol/L) was significantly lower than in the untreated control (P < 0.05), especially that of 606 bp. CONCLUSION: Estrogen can up-regulate, while progesterone can down-regulate mRNA expression of VEGF. Further studies are needed to elucidate the mechanism.

Adenocarcinoma↗
PubMed2004

[Research of plasma adsorption and action of platelet adhesion of Dacron modified by plasma surface modification].

In this paper, polyethylene glycol (PEG) of different molecular weight was grafted on the polyethylene terephthalate (PET, Dacron) films by plasma surface grafting modification. The competitive adsorption relation of plasma (fibrinogen and albumin) adsorbing on materials surface was analyzed in light of surface energy and interface free energy. The results indicated that the PET films grafted PEG long chain molecular possesses the characteristic of preferentially adsorbing albumin and this adsorption tendency of grafted PEG6000 sample is most distinct. The platelet adhesion tests of the PET films whose surfaces were pre-set in contact with fibrinogen and albumin indicated that the surface adsorbing albumin can distinctly inhibit platelet adhesion and aggregation and possess favorable blood compatibility, but the surface adsorbing fibrinogen can enhance platelet adhesion and aggregation.

Adsorption↗