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Biomedical subjects

Zhixin Guo

Publications and source records attributed to Zhixin Guo.

13 recordsLinked to original sources
PubMed2026

Liver transcriptome analysis revealed multiple immune processes and lipid metabolism pathways involved in the defense response of the turbot (Scophthalmus maximus) against Aeromonas salmonicida.

Aeromonas salmonicida is a significant pathogen causing notable economic losses in Scophthalmus maximus aquaculture. This study utilized Illumina sequencing technology to examine the transcriptional response characteristics of S. maximus liver at 24 h following A. salmonicida infection. A total of 2363 differentially expressed genes (DEGs) were identified when compared to the negative control group. The immunity-related Toll-like receptor signaling pathway, NOD-like receptor signaling pathway, as well as metabolism-related PPAR signaling pathway and insulin signaling pathway, were notably enriched. Significant differences exist in the expression of key genes within the PPAR pathway, particularly cd36, acsl4a, pparαa, and plin2, all of which mediate the interaction between lipid metabolism and the immune response. These results offer valuable insights into the immunometabolic regulatory mechanism of S. maximus response to A. salmonicida infection.

Animals↗
PubMed2006

Downregulation of NADPH oxidase, antioxidant enzymes, and inflammatory markers in the heart of streptozotocin-induced diabetic rats by N-acetyl-L-cysteine.

We investigated the effect of N-acetyl-l-cysteine (NAC) on the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, antioxidant enzymes, and inflammatory markers in diabetic rat hearts. Metabolic parameters, free 15-F(2t)-isoprostane level, protein expression of NADPH oxidase, superoxide dismutase (SOD), heme oxygenase (HO-1), interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2) were analyzed in control and streptozotocin-induced diabetic rats treated with or without NAC in drinking water for 8 wk. The cardiac protein expression of p67(phox) and p22(phox) was increased in diabetic rats, accompanied by increased NADPH-dependent superoxide production. As a compensatory response to the increased NADPH oxidase, the protein expression of Cu-Zn-SOD and HO-1 and the total SOD activity were also increased in diabetic rat hearts. Consequently, cardiac free 15-F(2t)-isoprostane, an index of oxidative stress, was increased in diabetic rats, indicating that the production of reactive oxygen species becomes excessive in diabetic rat hearts. Cardiac inflammatory markers IL-6 and COX-2 were also increased in diabetic rats. NAC treatment prevented the increased expression of p22(phox) and translocation of p67(phox) to the membrane in diabetic rat hearts. Subsequently, the levels of cardiac free 15-F(2t)-isoprostane, HO-1, Cu-Zn-SOD, total SOD, IL-6, and COX-2 in diabetic rats were decreased by NAC. Consequently, cardiac hypertrophy was attenuated in diabetic rats treated with NAC. The protective effects of NAC on diabetic rat hearts may be attributable to its protection of hearts against oxidative damage induced by the increased NADPH oxidase and to its reduction in cardiac inflammatory mediators IL-6 and COX-2.

Acetylcysteine↗
PubMed2006

Antioxidant N-acetylcysteine restores myocardial Mn-SOD activity and attenuates myocardial dysfunction in diabetic rats.

Manganese-containing superoxide dismutase (Mn-SOD) plays a critical role in guarding against mitochondrial oxidative stress. Abnormal myocardial mitochondrial metabolism of reactive oxygen species plays an important role in the pathogenesis of diabetic cardiac dysfunction. We hypothesised that chronic treatment with N-acetylcysteine, an antioxidant and glutathione (GSH) precursor, would normalize hyperglycemia induced inactivation of Mn-SOD and attenuate myocardial dysfunction. Control and streptozotozin-induced diabetic rats were treated or untreated with N-acetylcysteine in drinking water for 8 weeks, initiated 1 week after streptozotozin injection. Myocardial performance was determined using the isolated perfused working heart preparation. Myocardial Mn-SOD activity, but not Mn-SOD protein expression, in diabetic rats was significantly reduced while levels of oxidative stress as determined by myocardial free 15-F2t-isoprostane were increased in diabetic rats and were normalized by N-acetylcysteine treatment. However, compensatory increases in myocardial Cu/Zn-SOD and GSH content were seen in diabetic rats accompanied by an increase in tissue antioxidant capacity as compared to control. N-acetylcysteine abolished the compensatory increase in myocardial Cu/Zn-SOD. The left ventricular developed pressure and rates of left ventricular pressure development and relaxation were decreased in diabetic rats as compared to control. These effects were attenuated, but not prevented by N-acetylcysteine treatment. N-acetylcysteine attenuation of diabetic myocardial dysfunction could be attributed to the restoration of myocardial Mn-SOD activity.

Acetylcysteine↗
PubMed2006

Antioxidant N-acetylcysteine restores systemic nitric oxide availability and corrects depressions in arterial blood pressure and heart rate in diabetic rats.

Increased oxidative stress and reduced nitric oxide (NO) bioactivity are key features of diabetes mellitus that eventually result in cardiovascular abnormalities. We assessed whether N-acetylcysteine (NAC), an antioxidant and glutathione precursor, could prevent the hyperglycaemia induced increase in oxidative stress, restore NO availability and prevent depression of arterial blood pressure and heart rate in vivo in experimental diabetes. Control (C) and streptozotocin-induced diabetic (D) rats were treated or not treated with NAC in drinking water for 8 weeks, initiated 1 week after induction of diabetes. At termination, plasma levels of free 15-F2t-isoprostane, a specific marker of oxygen free radical induced lipid peroxidation, was increased while the plasma total antioxidant concentration was decreased in untreated diabetic rats as compared to control rats (P<0.05). This was accompanied by a significant reduction of plasma levels of nitrate and nitrite, stable metabolites of NO, (P<0.05, D vs. C) and a reduced endothelial NO synthase protein expression in the heart and in aortic and mesenteric artery tissues. Systolic, diastolic and mean arterial blood pressures (SBP, DBP and MAP) and heart rate (HR) were reduced in diabetic rats (P<0.05 vs. C) and NAC normalised the changes that occurred in the diabetic rats. The protective effects may be attributable to restoration of NO bioavailability in the circulation.

Acetylcysteine↗
PubMed2005

Derivatized fullerenes bearing multiple electron donors: synthesis and charge transfer properties.

A series of methano-C60 adducts bearing up to six electron donating N,N-dimethylaniline units (denoted as D compounds), along with their analogues without the dimethylamino groups as references (R compounds), were synthesized. The redox properties of the D compounds in solutions were evaluated spectroscopically in reference to the R compounds. According to UV/vis absorption results, there are obviously ground-state intramolecular charge-transfer complexes in the D series, and the charge-transfer effects apparently become saturated with only two donor units in the molecule. The photoinduced intramolecular electron-transfer properties of the D compounds were investigated via fluorescence measurements. The emission from intramolecular exciplexes can be found only in the D molecule with two electron donor units. Throughout the D series, the fluorescence properties are highly sensitive to the solvent polarity, with the emission completely quenched for all of the molecules in a polar solvent like methylene chloride. Mechanistic implications of the results are discussed.

Journal Article↗
PubMed2005

Salt effect on the complex formation between polyelectrolyte and oppositely charged surfactant in aqueous solution.

The complex formation between sodium carboxymethylcellulose (NaCMC) and dodecyltrimethylammonium bromide (DTAB) at various sodium bromide concentrations (C(NaBr)) has been studied by microcalorimetry, turbidimetric titration, steady-state fluorescence measurements, and the fluorescence polarization technique. The addition of salt is found to influence the formation of NaCMC/DTAB complexes markedly. At C(NaBr) = 0.00, 0.01, 0.02, 0.10, and 0.20 M, DTAB monomers form micelle-like aggregates on NaCMC chains to form NaCMC/DTAB complexes above the critical surfactant concentration (C1). At C(NaBr) = 0.23 M, DTAB molecules first form micelles above a 2.46 mM DTAB concentration prompted by the added salt, and then, above C1 = 4.40 mM, these micelles can aggregate with NaCMC chains to form NaCMC/DTAB complexes. However, at C(NaBr) = 0.25 M, there is no NaCMC/DTAB complex formation because of the complete salt screening of the electrostatic attraction between DTAB micelles and NaCMC chains. It is also surprisingly found that the addition of NaBr can bring out a decrease in C1 at C(NaBr) < 0.20 M. Moreover, the addition of NaBr to a mixture of 0.01 g/L NaCMC and 3.6 mM DTAB can directly induce the formation of NaCMC/DTAB complexes. This salt-enhancing effect on the complex formation is explained as the result of competition between the screening of interaction of polyelectrolyte with surfactant and the increasing of polyelectrolyte/surfactant interaction owing to the growth of micelles by added salt. When the increasing of polyelectrolyte/surfactant interaction exceeds the screening of interaction, the complex formation can be enhanced.

Journal Article↗
PubMed2005

DNA-directed self-assembling of carbon nanotubes.

Multicomponent structures were constructed by DNA-directed self-assembling of multiple carbon nanotubes and gold nanoparticles. The work presented here represents an important advance in constructing many multicomponent nanotube structures for multifunctional material and device applications.

DNA, Single-Stranded↗
PubMed2005

Effects of a Chinese herbal preparation on vascular cells in culture: mechanisms of cardiovascular protection.

1. The use of traditional Chinese medicinal herbs or their pharmaceutical products for disease prevention and management is becoming increasingly popular in Western countries. Mixtures of various Chinese herbs have been used for the treatment of syndromes clinically overlapping Western cardiovascular syndromes. One modern preparation, known as the 'Cardiotonic Pill' (CP), is a pharmaceutical product derived mainly from a medicinal herb, Salvia miltiorrhiza bunge, and recently widely used in Chinese hospitals for the prevention and management of ischaemic cardiovascular diseases. Although the CP is believed to confer an extensive range of benefits, little is known about the physiological actions of this medicine, particularly at the cellular and molecular levels. Therefore, the aim of the present study was to explore possible cellular mechanisms of the CP on the cardiovascular system. 2. Cultured human vascular endothelial cells (EC) and vascular smooth muscle cells (VSMC) were exposed to the CP at various concentrations for periods ranging from hours to days. Cellular DNA synthesis was determined by a [(3)H]-thymidine incorporation assay, proliferation and death were assessed by investigations of cell numbers and apoptosis, whereas the expression of extracellular adhesion molecules was analysed by flow-cytometry and Western blotting. 3. The CP extract at concentrations of less than 200 microg/mL was not associated with cell damage. At doses beyond the therapeutic range (10-20 microg/mL), the CP appeared to exert a mild inhibitory effect on DNA synthesis and proliferation of EC in serum-enriched cultures. The CP significantly attenuated tumour necrosis factor-alpha-induced expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in a dose-dependent manner, with 50 and 100 microg/mL CP producing decreases in the expression of ICAM-1 of 26-32% and 32-44%, respectively, and of VCAM-1 of approximately 23% and 27-42%, respectively. The CP did not affect apoptosis in EC under conditions of serum-deprivation. 4. In VSMC, the CP significantly inhibited platelet-derived growth factor BB-induced DNA synthesis and cell proliferation in a dose-dependent manner. The CP did not affect VSMC expression of adhesion molecules. 5. We conclude that the CP inhibits expression of ICAM-1 and VCAM-1 in EC and proliferation of VSMC in a manner that has potentially beneficial therapeutic effects.

Apoptosis↗
PubMed2005

Effects of Compound Dan-shen Root Dropping Pill on hemorheology in high-fat diet induced hyperlipidemia in dogs.

The purpose of this study was to examine the effects of Compound Dan-shen Root Dropping Pill (CDRDP) (Tasly Group, Tianjing, China) on hemorheology and biorheology of dogs suffering from hyperlipidemia induced by high-fat diet. Eighteen dogs were randomly divided into two groups: the high-fat diet group (H group); the control group (C group), fed with a standard laboratory diet. Six month later, six dogs in the H group were chosen as the drug-taking group (D group), to which CDRDP was administered, fed with the same diet as H group. In the 4th month, blood was taken from the veins of the dogs, and blood triglyceride (TG), total cholesterol (TC), RBC hemorheological indexes as well as malondialdehyde (MDA), glutathione transferase (GSH-ST) and superoxide dismutase (SOD) activities in plasma and erythrocytes were measured. Compared with H group, TC, TG, plasma MDA levels, the whole blood viscosity, RBC osmotic fragility and the value of CHOL (cholesterol)/PL (phospholipid) of the membrane of D group decreased, however, erythrocyte GSH-ST, histopathological changes in liver, deformation index (DI), orientation index (DI)or, small deformation index (DI)d, electrophoresis ratio and microfluidity of the membrane lipid bilayer of RBCs, increased distinctly. CDRDP can improve micro-hemorheological characteristics, therefore has a significant therapy application of hyperlipidemia.

Animals↗
PubMed2004

Electrostatic layer-by-layer assembled carbon nanotube multilayer film and its electrocatalytic activity for O2 reduction.

Multilayer films of shortened multiwalled carbon nanotubes (MWNTs) are homogeneously and stably assembled on glassy carbon electrodes with the layer-by-layer (LBL) method, based on electrostatic interaction of positively charged poly(diallyldimethylammonium chloride) and negatively charged and shortened MWNTs. The film assembly and electrochemical property as well as the electrocatalytic activity toward O2 reduction of the MWNT multilayer film are studied. Scanning electron microscopy, the quartz crystal microbalance technique, ultraviolet-visible-near-infrared spectroscopy, and cyclic voltammetry are used for characterization of film assembly. Experimental results revealed that film growth is uniform, almost with the same coverage of the MWNTs in each layer, and that the assembled MWNTs are mainly in the form of small bundles or single tubes on the electrodes. Electrochemical studies indicate that the LBL assembled MWNT films possess a remarkable electrocatalytic activity toward O2 reduction in alkaline media. This property, combined with the well-dispersed, porous and conductive features of the MWNT film illustrated with the LBL method, suggests the potential application of the MWNT film for constructing an efficient alkaline air electrode for energy conversions.

Journal Article↗
PubMed2004

Gel permeation chromatography of fullerene-centered macromolecules.

Gel permeation chromatography (GPC) behavior of fullerene-centered macromolecules is investigated. Because of the globular shape of the macromolecules, their GPC results are different from those of linear polystyrene standards. These macromolecules may serve as alternative molecular weight standards for polymers or dendrimers of similar globular structures. The results also show that the GPC analysis is capable of discerning relatively minor structural differences in the fullerene-centered macromolecules.

Journal Article↗
PubMed2003

Aligned nanotubes.

Since the discovery of carbon nanotubes by lijima in 1991, various carbon nanotubes with either a single- or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size-dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat-panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.

Journal Article↗