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Biomedical subjects

Huibi Xu

Publications and source records attributed to Huibi Xu.

30 records · Page 2Linked to original sources
PubMed2003

Antioxidant status and mineral contents in tissues of rutin and baicalin fed rats.

The versatile benefit effects of flavonoids lead some nutritionists to believe that they are micronutrients. However, excess intake of flavonoids may cause side effects. In this paper, the effects produced by a higher intake of rutin and baicalin on antioxidant status as well as trace minerals such as iron, copper and zinc in rat tissues were studied. When rats were fed a rutin or baicalin containing diet (1%) for 20 days, the body weight gain was lower than that of the control group. Both rutin and baicalin caused significant a decrease of catalase activity and a moderate increase of total superoxide dismutase activity in the liver. The total antioxidant status of flavonoid fed rats was increased in the liver but decreased in the serum. In comparison to the control group, the lipid peroxidation level in the liver of the rutin fed group was significantly decreased; however, there was no statistical significance in the liver of the baicalin fed group and the brain of both flavonoids groups. The liver homogenates of both flavonoid fed rats significantly inhibited alkyl radical-induced lipid peroxidation. The iron contents in the liver of flavonoid fed rats were significantly decreased; rutin also caused zinc and copper decrease in the liver. These results indicated that high flavonoid intake can improve rat antioxidant systems in the liver; while it can also cause a trace mineral decrease and, in turn, reduce the activities of some metal-containing enzymes and may cause harmful effects on health.

Animals↗
PubMed2003

Effects of long-term selenium deficiency on glutathione peroxidase and thioredoxin reductase activities and expressions in rat aorta.

The objective of this work was to determine whether long-term selenium (Se) deficiency might affect the antioxidant capacity of rat aorta, and the activities and expressions of glutathione peroxidase (GPx) and thioredoxin reductase (TR) in rat arterial walls. Weanling male Wister rats were fed Se-deficient or Se-adequate diets for 12 months. For the Se supplementation, sodium selenite was supplemented in drinking water (1 microg Se/ml) for 1 month. The aorta isolated from these groups were used to determine activities and mRNA levels. In comparison with the control, the activity and expression of GPx, superoxide dismutase activity and the total antioxidant capacity were significantly decreased in Se-deficient rats arterial walls. Following Se supplementation, they were restored to different extents. The content of malondialdehyde was increased markedly in Se-deficient rats. There seems an inverse relationship between the dietary Se and the activity and expression of TR. A positive relationship exists between dietary Se and the antioxidant capacity of rat arterial walls. The activities and expressions of GPx and TR in arterial walls were regulated by selenium by different mechanisms. Regulation of the expression of TR was mediated by reactive oxygen species, but of GPx by selenium status. The thioredoxin system may be the major cellular redox signaling system in rat arteries, rather than the glutathione system.

Animals↗
PubMed2003

Ameliorative effect of L-methionine on Pb-exposed mice.

The present investigation was carried out to study the ameliorative effects of L-Met (L-methionine) on Pb-exposed mice by the measurement of the weight gain, the weight of organs, the Hb content, the level of lipid peroxidation (LPO), and the Pb and Fe contents of selected organs and serum. Thirty mice were randomly divided into the healthy control group (A), the Pb control group (B), and the Pb+L-Met-treated group (C). Lead-induced depression of growth and Hb content was reversed when L-Met was added to the daily drinking water. The level of LPO of all the samples from group B was significantly higher than group A (p<0.05); however, in group C, it was lowered, especially that in the brain, kidney, and serum, which were not significantly different than normal (p>0.05). Significant enhancement of Pb content (p<0.05) and significant decrease of Fe content of all the samples in group B (p<0.05) were observed. However, dietary Met significantly lowered Pb concentration of all the samples (p<0.05) compared to that of the liver and kidney, reaching no significance in comparison to group A (p>0.05). The Fe concentration changed little (p>0.05). The result suggests that L-Met has an ameliorative effect on Pb-exposed mice.

Animals↗
PubMed2002

Mitochondrial permeability transition and cytochrome c release induced by selenite.

Cytochrome c release and mitochondrial permeability transition (MPT) play important roles in apoptosis. In this study, we found that selenium, an essential trace element, induced mitochondrial membrane potential (Delta psi(m)) loss, swelling, and cytochrome c release in isolated mitochondria. All of the above observations were blocked by cyclosporin A (CsA), which is a specific inhibitor to permeability transition pore (PTP), indicating selenite-induced mitochondrial changes were mediated through the opening of PTP. In physiological concentration, selenite could induce mitochondria at low-conductance PTP 'open' probability, which is correlated to regulate the physiological function, whereas in toxic concentration, induce mitochondria at high-conductance PTP 'open' probability and rapidly undergo a process of osmotic swelling following diffusion toward matrix as for inducer (Ca(2+)/P(i)). Selenite also induced other mitochondrial marker enzymes including monoamine oxidase (MAO) and mitochondria aspartate aminotransferase (mAST). Oligomycin inhibited the selenite-induced cytochrome c release and Delta psi(m) loss, showing that F(0)F(1)-ATPase was important in selenite or Ca(2+)/P(i)-induced MPT.

Animals↗
PubMed2002

DNA hydrolytic cleavage by the diiron(III) complex Fe(2)(DTPB)(mu-O)(mu-Ac)Cl(BF(4))(2): comparison with other binuclear transition metal complexes.

The binuclear structure of Fe(2)(DTPB)(mu-O)(mu-Ac)Cl(BF(4))(2) (DTPB = 1,1,4,7,7-penta (2'-benzimidazol-2-ylmethyl)-triazaheptane, Ac = acetate) was characterized by UV-visible absorption and infrared spectra and NMR and ESR. The binding interaction of DNA with the diiron complex was examined spectroscopically. Supercoiled and linear DNA hydrolytic cleavage by the diiron complex is supported by the evidence from anaerobic reactions, free radical quenching, high performance liquid chromatography experiments, and enzymatic manipulation such as T4 ligase ligation, 5'-(32)P end-labeling, and footprinting analysis. The estimation of rate for the supercoiled DNA double strand cleavage shows one of the largest known rate enhancement factors, approximately 10(10) against DNA. Moreover, the DNA hydrolysis chemistry needs no coreactant such as hydrogen peroxide. The poor sequence-specific DNA cleavage indicated by the restriction analysis of the pBR322 DNA linearized by the diiron complex might be due to the diiron complex bound to DNA by a coordination of its two ferric ions to the DNA phosphate oxygens, as suggested by spectral characterizations. The hydrolysis chemistry for a variety of binuclear metal complexes including Fe(2)(DTPB)(mu-O)(mu-Ac)Cl(BF(4))(2) is compared. It is established that the dominant factors for the DNA hydrolysis activities of the binuclear metal complexes are the mu-oxo bridge, labile and anionic ligands, and open coordination site(s). Concerning the hydrolytic mechanisms, the diiron complex Fe(2)(DTPB)(mu-O)(mu-Ac)Cl(BF(4))(2) might share many points in common with the native purple acid phosphatases.

Bacteriophage T4↗
PubMed2002

The metal site as a template for the metalloprotein structure formation.

Achieving a thorough explanation of the behavior of metal sites in the formation of native metalloprotein structures is an exciting challenge in the biochemistry of metallobiomacromolecules. This study presents a personal insight into the subject. It is proposed that a metal center and its exogenous ligand compose a template. A template may impose a clear stereochemical preference on the loose peptide chains, and organize them into natural stereospecificity via the metal-ligand interaction, a long-range and strong interaction. Therefore, the stable peptide conformation induced by the template effect surrounding a template polyhedron could be called a template-mediated structural motif (TMSM).

Animals↗
PubMed2002

Role of selenium in cytoprotection against cholesterol oxide-induced vascular damage in rats.

Wistar rats were fed Se-deficient (0.038 mg/kg diet) and adequate (0.326 mg/kg diet) diets for 13 weeks. The blood Se content, blood and vascular wall glutathione peroxidase (GPx) activity, serum high-density lipoprotein cholesterol (HDL-C) level and plasma prostacyclin (PGI(2)) concentration were decreased significantly, and the blood lipid peroxide (LPO) concentration, serum low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC) level and plasma thromboxane A(2) (TXA(2)), content were increased significantly in Se-deficient rats compared with Se-adequate group, respectively. Furthermore the Se-deficient and adequate rats were given 5 mg/kg of cholestane-3 beta, 5 alpha, 6 beta -triol (3-triol) or vehicle only. Twenty four hours after treatment, the plasma PGI(2) level was decreased in Se-adequate rats infused 3-triol (+3 triol), meanwhile, the level in Se- deficient +3-triol group was much lower than that in Se-adequate +3-triol group. Compared with Se-adequate group, plasma TXA(2) content in Se-adequate +3-triol group had no significantly difference, but in Se- deficient rats infused 3-triol, plasma TXA(2) content was much higher than that in Se-adequate +3-triol group. The plasma ET concentration in Se-deficient group decreased slightly, but the concentration in Se-adequate +3-triol group increased significantly with respect to Se-deficient group. Although plasma ET concentration in Se-deficient group +3-triol did not increase, it was significantly lower than that in Se-adequate +3-triol group. The luminal surfaces of aorta thoracica of experimental rats were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Observed by SEM, the luminal surface of aorta of Se-deficient rats showed few crater-like defects due to the disruption of endothelial cell. Se-adequate +3-triol group showed some crater-like defects on the their aorta luminal surface, but the luminal surface of Se-deficient +3-triol group exhibited numerous crater-like defects and appeared sponge-like as well as platelets adhering followed by thrombus formation in focal area of extensive endothelial damage. TEM studies also showed that the endothelium of aorta of Se deficient +3-triol group had more frequent lesion where endothelial cell plasma were swelling with profuse intracellular edema and some vacuoles were seen in cytoplasm. In severely injured areas, endothelial integrity was completely destroyed and smooth muscle cells were proliferating and migrated to the endomembrane. Thus, we can conclude that Se or selenoproteins in the vascular wall plays an important role in cytoprotection against cholesterol oxide-induced vascular damage in rats.

6-Ketoprostaglandin F1 alpha↗
PubMed2002

Protective effect of polysaccharide from the loach on the in vitro and in vivo peroxidative damage of hepatocyte.

Misgurnus anguillicaudatus polysaccharide (MAP), a type of natural neutral polysaccharide occurring in the mucus of Misgurnus anguillicaudatus C., was studied for antioxidant bioactivity. The preliminary research showed that MAP was able to remove O(2)*, HO., H(2)O(2) and other active compounds of oxygen and significantly protected DNA chains from being damaged by hydroxyl radicals. This antioxidant bioactivity was further evaluated using the model of peroxide-induced oxidative injury in rat primary hepatocytes and hepatotoxity in mice. The results demonstrated that MAP, at the concentrations of 0.10 approximately 0.40 mg/ml, significantly increased the activity of SOD and GSH-px, but decreased the consumption of reduced glutathione and the formation of malondialdehyde induced by a 30-min treatment of H(2)O(2) (2.0 mmol/L). The in vivo investigation showed that oral pretreatment of MAP (100, 200 and 300 mg/kg) for 7 days before a single dose of t-BHP (0.2 mmol/kg, ip) significantly lowered the serum levels of hepatic enzyme markers (alanine and aspartate aminotransferase) and reduced oxidative liver injury. The histopathological evaluation of the liver revealed that MAP reduced the incidence of liver lesions including inflammatory, leukocyte infiltration, and necrosis induced by t-BHP in mice. Based on the results described above, a conclusion can be drown that MAP may play an important role in the prevention of oxidative damage in living systems.

Journal Article↗
PubMed2002

Effects of rutin supplementation on antioxidant status and iron, copper, and zinc contents in mouse liver and brain.

The effect of rutin on total antioxidant status as well as on trace elements such as iron, copper, and zinc in mouse liver and brain were studied. Mice were administrated with 0.75 g/kg or 2.25 g/kg P. O. of rutin for 30 d consecutively. Following the treatment, the activity of total antioxidant status, catalase, Cu,Zn-superoxide dismutase, Mn-superoxide dismutase, zinc, copper, and iron were measured in mouse liver and brain. The results showed that rutin significantly increased the antioxidant status and Mn-superoxide dismutase activities in mouse liver, but it had no effect on these variables in the brain. Treatment with a higher concentration of rutin significantly decreased catalase activity and iron, zinc, and copper contents in mouse liver; it also resulted in a slower weight gain for the first 20 d. These results indicate that rutin taken in proper amount can effectively improve antioxidant status, whereas at an increased dosage, it may cause trace element (such as iron, zinc, and copper) deficiencies and a decrease in the activities of related metal-containing enzymes.

Animals↗
PubMed2002

[Study on effects of scutellarin on scavenging reactive oxygen].

OBJECTIVE: To study the antioxidative effects and its mechanism of scutellarin. METHODS: Scavenging effects of scutellarin on hydroxyl radical (OH.) produced from 0-phenathroline-ascorbic acid system, super oxide anion radical (O2-.) produced from xanthine-xanthine oxidase-luminol system and hydrogen peroxide was studied by a chemiluminescence assay. RESULTS: Scutellarin has a significant effect on scavenging hydroxyl radicals, super oxide anion radicals, hydrogen peroxide, their IC50 are 66 micrograms/ml, 1.3 micrograms/ml and 1.6 micrograms/ml respectively. CONCLUSION: Scutellarin is an efficiency antioxidant.

Apigenin↗