Biomedical subjects
Publications and source records attributed to Yong Zhao.
Two new biflavonoids, 3"-hydroxyamentoflavone-7-O-methyl ether (1) and 3"-hydroxyamentoflavone (2), were isolated from the fruits of Aristolochia contorta Bge. Their structures were elucidated by HR-ESI-MS, 1D-, and 2D-NMR spectroscopy.
This research examined the effects of instructional set on Internet use by low-income adults during a 16-month longitudinal study. Participants (n = 117) received instructions that focused on either the Internet's communication tools or its information tools. Internet use was continuously and automatically recorded. Survey measures of computer and Internet experiences, affect and attitudes were obtained to examine their mediational role in the relationship between instructional set and Internet use. Results indicated that instructions focused on the Internet's information tools led to greater Internet use than instructions focused on its communication tools or only basic instructions about how to use the Internet. Implications for reducing the digital divide are discussed.
Glycine betaine (GB) and proline contents of leaf and root were simultaneously determined by HPLC-ESI-MS at seedling stage in the three wheat (Triticum aestivum L.) varieties (salt tolerance from high to low), SW12, Ningchun No.4 and Chinese Spring (C.S) under 5 different salt stress levels. The GB contents among SW12, Ningchun No.4 and C.S were found outstanding difference by ANOVA (P<0.01) and consistent with salt tolerance in wheat. Proline contents were not different among 3 wheat varieties in leaf, but difference was found in the root between the Ningchun No.4 and C.S (P<0.05). The result suggested GB, as one of the materials for osmotic adjustment in plant, had the closest relationship with salt tolerance and could be used as an index of salt tolerance in wheat.
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OBJECTIVE: To discuss the protective effects of pueraria compound on the cerebral ischemic injury. METHOD: Using the middle cerebral artery occlusion model (MCAO) in rats and cerebral ischemia-reperfusion models in gerbils and mice, we investigated the influence of pueraria compound on the brain water content and the infarct size, the cerebral apoplexy exponent, the contents of lactic acid (LA) and lipid peroxide (LPO), the activities of lactic dehydrogenase (LDH), glutathione peroxidase (GPx) and Na+ -K+ -ATPase. RESULT: Pueraria compound obviously reduced the brain water content and the infrarct size in MCAO, improved motor abilities in the cerebral ischemia-reinfusion model of gerbils, decreased the contents of LA and LPO and increased the activities of LDH, GPx and Na+ -K+ -ATPase in cerebral ischemia-reinfusion model of mice. CONCLUSION: Pueraria compound has the function of antioxidation and protective effect on ischemic brain tissue.
OBJECTIVE: To observe the acute and chronic renal toxicity induced by Radix Aristolochiae Fangchi Extract (RAFE) in different doses in rats. METHOD: The conventional method of acute toxicity was used. RAFE at the dose of 25.0 mg x kg(-1) x d(-1), 120.0 mg x kg(-1) x d(-1) and 200.0 mg x kg(-1) x d(-1) and aristolochic acid (AA, 10.0 mg x kg(-1) x d(-1)) were interruptedly administrated to rats for 13 week by gastric tube, and the sample of blood, urine and kidney were collected at 4 week, 8 week and 13 week respectively. The indexes of renal function were measured and the morphology of kidney was observed. RESULT: LD50 of RAFE was 36.8 g x kg(-1) (the crude drug) and the 95% confidence limit was 38.8 - 28.9 g x kg(-1). The changes of renal functions were azotemia, massive proteinuria and the increase of urinary NAGase (beta-N-acetylglucosaminidase) in the earlier period of administration with RAFE in rats. Pathological changes of renal tissue were as follows: acute renal tubular necrosis mainly in the boundary of cortex and medulla was observed in the earlier period, and with the elongation of administration, the pathological process of renal interstitial fibrosis observed in the middle and high groups of RAFE and AA group. CONCLUSION: RAFE at middle and high doses administrated by interrupted gavage above 13 week can cause the injury of renal tubular functions in rats. NAGase can be used as one of observation targets in the earlier period of renal injury.
OBJECTIVE: To investigate the effect of Qingkailing and Methylprednisolone (MP) injection alone or combined on the acute lung injury (ALI) induced by oleic acid in rabbits. METHOD: The rabbits were randomly divided into 11 groups: oleic acid group; control group; treatment groups including low, middle and high dosage groups of Qingkailing and MP alone and combined, respectively. ALI model was established by i.v. oleic acid (0.05 mL x kg(-1)) in these groups, and then i.v. above drugs respectively, while in control group, the same volume of normal saline was given. The respiratory amplitude and rate were observed, and blood samples were taken from cervical artery for blood-gas analysis before and at 30, 60, 120 min after oleic acid or normal saline administration. At the end of experiment, the concentration of LDH, CAT and MDA in the lung tissue were measured and pathologic changes of lung tissue were observed microscopically. RESULT: Compared with oleic acid group, the respiratory amplitude markedly enhanced (P < 0.05) and respiratory rate lowered (P < 0.05) in the low, middle and high dose groups of Qingkailing and MP injection. On the 30 min of treatment, PaO2 increased significantly (P < 0.05) in the low and middle dose groups of combined Qingkailing and MP injection; PaCO2 decreased markedly (P < 0.05) on the 120 min of treatment in each treatment group. The level of LDH significantly increased (P < 0.05), CAT and MDA decreased (P < 0.05) in the middle and high groups of Qingkailing and MP injection. The low and middle dose groups of combined Qingkailing and MP injection can alleviate the pathological changes induced by oleic acid. CONCLUSION: The curative effect of the low dose group of combined Qingkailing and MP for the ALI induced by oleic acid was better than Qingkailing and MP alone, while the big dose groups of Qingkailing and MP alone better than the combination at the same dosage.
OBJECTIVE: To investigate the effect of Qingikailing and Shengmai injection alone or combined on the acute lung injury (AL) induced by oleic acid in rabbits. METHOD: The rabbits were randomly divided into 11 groups: oleic acid group; control group; treatment groups including low, middle and high dosage groups of Qingkailing and Shengmai injection alone and combined, respectively. ALI model was established by iv oleic acid (0.05 mL x kg(-1)) in these groups, and then iv above drugs respectively,while in control group, the same volume of normal saline was given. The respiratory amplitude and rate were observed, and blood samples were taken from cervical artery for blood-gas analysis before and at 30, 60, 120 min after oleic acid or normal saline administration. At the end of experiment, the concentration of LDH, CAT and MDA in the lung tissue were measured and pathologic changes of lung tissue were observed microscopically. RESULT: Compared with oleic acid group, the respiratory amplitude markedly enhanced (P < 0.05) in the low and high dose groups of Qingkailing and Shengmai injection. PaO2 increased significantly (P < 0.05) in the low dose group of combined Qingkailing and Shengmai injection, PaCO2 decreased markedly (P < 0.05) in the low dose groups of Qingkailing and Shengmai injection alone and combined. The level of MDA significantly decreased (P < 0.05) in the each group of Qingkailing and Shengmai injection alone, the level of MDA significantly decreased (P < 0.05) and CAT increased (P < 0.05) in the low dose group of combined Qingkailing with Shengmai injection. The low dose group of combined Qingkailing and Shengmai injection can alleviate the pathological changes induced by oleic acid. CONCLUSION: The curative effect of the low dose group of combined Qingkailing with Shengmai injection for the ALI induced by oleic acid was better than Qingkailing and Shengmai injection alone at the same dosage.
From the fruits of Aristolochia contorta Bge, beside the known aristolochic acids IVa and VII, aristolactam-N-beta-D-glucopyanoside, aristoloctam Ia N-beta-D-glucopyanoside, pinitol and daucosterol, a new biflavonoid was isolated. Its structure was determined as (+/-)-2"R,3"R-dihydro-3"-hydroxyamentoflavone (1) by means of spectral methods including 1D-, 2D-NMR and HR-ESIMS and the known compounds were identified on the basis of comparing their NMR data with those of the corresponding compounds in the literature.
OBJECTIVE: Following the former report, we continue to observe the chronic renal tubular-interstitial injury induced by Radix Aristolochiae Fangchi Extract(RAFE) in rats in order to understand whether RAFE in different doses causes the renal tubular-interstitial injury or not. METHOD: RAFE at the dose of 25.0 mg x kg(-1) x d(-1), 120.0 mg kg(-1) x d(-1) and 200.0 mg x kg(-1) x d(-1) and aristolochic acid (AA, 10.0 mg x kg(-1) d(-1)) was interruptedly administrated by gastric tube for 22 w and 4 w durg withdrawal. Blood, urine and kidney were taken out respectively in 17 w, 22 w and 26 w to measure the indexes of renal function. The morphology of kidney was observed, and Masson staining of kidney were made respectively to compare RAFE groups with AA group. RESULT: Pathological changes of renal tissue forms were as follows: All RAFE groups and AA group could develop the pathological process of renal tubular injury-chronic renal interstitial fibrosis. The pathologic changes of RAFE were similar with AA. CONCLUSION: RAFE at all doses administrated interruptedly by gastric tube above 13 w caused chronic renal tubulo-interstitium fibrosis. The renal injury in functions and tissue forms in rats were similar with AA closely. The results showed that AA was the main toxic composition of RAFE.
B and T lymphocyte attenuator (BTLA), identified as an immune inhibitory receptor recently, plays widespread roles on T and B cells. Emerging evidence has generated plentiful information on the mechanisms which BTLA mediates negative regulation in immune responses and involves in a variety of physiological and pathological processes. The exploration of the biological mechanisms and regulation of BTLA will open possibilities on novel therapeutic strategies in immune-related diseases.
Members of the voltage-gated-like ion channel superfamily have a conserved pore structure. Transmembrane helices that line the pore (M2 or S6) are thought to gate it at the cytoplasmic end by bending at a hinge glycine residue. Proline residues favor bending of alpha-helices, and substitution of proline for this glycine (G219) dramatically stabilizes the open state of a bacterial Na(+) channel NaChBac. Here we have probed S6 pore-lining residues of NaChBac by proline mutagenesis. Five of 15 proline-substitution mutants yielded depolarization-activated Na(+) channels, but only G219P channels have strongly negatively shifted voltage dependence of activation, demonstrating specificity for bending at G219 for depolarization-activated gating. Remarkably, three proline-substitution mutations on the same face of S6 as G219 yielded channels that activated upon hyperpolarization and inactivated very slowly. Studies of L226P showed that hyperpolarization to -147 mV gives half-maximal activation, 123 mV more negative than WT. Analysis of combination mutations and studies of block by the local anesthetic etidocaine favored the conclusion that hyperpolarization-activated gating results from opening of the cytoplasmic gate formed by S6 helices. Substitution of multiple amino acids for L226 indicated that hyperpolarization-activated gating was correlated with a high propensity for bending, whereas depolarization-activated gating was favored by a low propensity for bending. Our results further define the dominant role of bending of S6 in determining not only the voltage dependence but also the polarity of voltage-dependent gating. Native hyperpolarization-activated gating of hyperpolarization- and cyclic nucleotide-gated (HCN) channels in animals and KAT channels in plants may involve bending at analogous S6 amino acid residues.
Nucleic acid molecules may fold into secondary structures, and the formation of such structures is involved in many biological processes and technical applications. The folding and unfolding rate constants define the kinetics of conformation interconversion and the stability of these structures and is important in realizing their functions. We developed a method to determine these kinetic parameters using an optical biosensor based on surface plasmon resonance. The folding and unfolding of a nucleic acid is coupled with a hybridization reaction by immobilization of the target nucleic acid on a sensor chip surface and injection of a complementary probe nucleic acid over the sensor chip surface. By monitoring the time course of duplex formation, both the folding and unfolding rate constants for the target nucleic acid and the association and dissociation rate constants for the target-probe duplex can all be derived from the same measurement. We applied this method to determine the folding and unfolding rate constants of the G-quadruplex of human telomere sequence (TTAGGG)(4) and its association and dissociation rate constants with the complementary strand (CCCTAA)(4). The results show that both the folding and unfolding occur on the time scale of minutes at physiological concentration of K(+). We speculate that this property might be important for telomere elongation. A complete set of the kinetic parameters for both of the structures allows us to study the competition between the formation of the quadruplex and the duplex. Calculations indicate that the formation of both the quadruplex and the duplex is strand concentration-dependent, and the quadruplex can be efficiently formed at low strand concentration. This property may provide the basis for the formation of the quadruplex in vivo in the presence of a complementary strand.
The role of putrescine, spermidine and spermine in phorbol 12-myristate-13-acetate (PMA)-induced macrophage differentiation was examined in human HL-60 and U-937 myeloid leukemia cells. Unlike other polyamines, spermine affected this differentiation by acting as a negative regulator. This negative regulation was established by showing that the PMA-induced macrophage phenotype, but not PMA-associated replication arrest, was abrogated (a) by replenishing the PMA-evoked decrease in cellular spermine levels with this polyamine from an exogenous source and (b) by blocking PMA-induced expression of the polyamine catabolic enzyme N(1)-spermidine/spermine acetyltransferase (SSAT) with antisense oligonucleotides in the presence of low substrate level. The PMA-evoked reduction in cellular spermine appears to result from an increase in the activity of SSAT and a decrease in the activity of ornithine decarboxylase, the polyamine biosynthetic enzyme. To a degree, these changes are due to corresponding changes in the expression of the genes that code for these enzymes. When cell differentiation is initiated, SSAT expression is increased after PMA-evoked activation of protein kinase C-beta. The present studies raise the possibility that agents able to reduce spermine levels in patients' myeloid leukemia cells may enhance the activity of differentiation therapy drugs for this type of leukemia.
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Voltage-gated sodium channels are members of a large family with similar pore structures. The mechanism of opening and closing is unknown, but structural studies suggest gating via bending of the inner pore helix at a glycine hinge. Here we provide functional evidence for this gating model for the bacterial sodium channel NaChBac. Mutation of glycine 219 to proline, which would strongly favor bending of the alpha helix, greatly enhances activation by shifting its voltage dependence -51 mV and slowing deactivation by 2000-fold. The mutation also slows voltage-dependent inactivation by 1200-fold. The effects are specific because substitutions of proline at neighboring positions and substitutions of other amino acids at position 219 have much smaller functional effects. Our results fit a model in which concerted bending at glycine 219 in the S6 segments of NaChBac serves as a gating hinge. This gating motion may be conserved in most members of this large ion channel protein family.
Abdominal aortic aneurysm (AAA) is one of a number of diseases associated with a prominent inflammatory cell infiltrate and local destruction of structural matrix macromolecules. This inflammatory infiltrate is predominately composed of T lymphocytes and macrophages. Delineating specific contribution of these inflammatory cells and their cytokines in AAA formation is the key to understanding AAA and other chronic inflammatory disease processes. Our previous studies have demonstrated that macrophages are the major source of matrix metalloproteinase-9, which is required for aneurysmal degeneration in the murine AAA model. However, the role of CD4(+) T cells, the most abundant infiltrates in aneurysmal aortic tissue, is uncertain. In the present study, we found that in the absence of CD4(+) T cells, mice are resistant to aneurysm induction. Previous studies have shown that IFN-gamma levels are increased in AAA. IFN-gamma is a main product of T cells. Intraperitoneal IFN-gamma was able to partially reconstitute aneurysms in CD4(-/-) mice. Furthermore, mice with a targeted deletion of IFN-gamma have attenuation of MMP expression and inhibition of aneurysm development. Aneurysms in IFN-gamma(-/-) mice can be reconstituted by reinfusion of competent splenocytes from the corresponding wild-type mice. This study demonstrates the pivotal role that T cells and the T cell cytokine, IFN-gamma, play in orchestrating matrix remodeling in AAA. This study has important implications for other degenerative diseases associated with matrix destruction.
BACKGROUND: The etiologic agent of severe acute respiratory syndrome (SARS) has been confirmed to be a novel coronavirus (CoV), namely SARS-CoV. Developing safe and effective SARS-CoV vaccines is essential for us to prevent the possible reemergence of its epidemic. Previous experiences indicate that inactivated vaccine is conventional and more hopeful to be successfully developed. Immunogenicity evaluation of an experimental inactivated SARS-CoV vaccine in rabbits was conducted and reported in this paper. METHODS: The large-scale cultured SARS-CoV F69 strain was inactivated with 0.4% formaldehyde and purified, then used as the immunogen combined with Freund's adjuvant. Eight adult New Zealand rabbits were immunized four times with this experimental inactivated vaccine. Twelve sets of rabbit serum were sampled from the third day to the seventy-fourth day after the first vaccination. The titers of specific anti-SARS-CoV IgG antibody were determined by indirect enzyme-linked immunosorbent assay, and the neutralizing antibody titers were detected with micro-cytopathic effect neutralization test. RESULTS: Rapid and potent humoral immune responses were induced by the inactivated SARS-CoV vaccine in all the eight test rabbits. Titers of both specific IgG antibody and neutralizing antibody peaked at about six weeks after first vaccination, with the maximum value of 1:81 920 and 1:20 480, respectively. After that, serum antibody levels remained at a plateau or had a slight decrease, though two boosters were given in the succedent 4 to 5 weeks. Cross neutralization response existed between SARS-CoV F69 strain and Z2-Y3 strain. CONCLUSIONS: The inactivated SARS-CoV vaccine made from F69 strain owns strong immunogenicity, and the cross neutralization response between the two different SARS-CoV strains gives a hint of the similar neutralizing epitopes, which provide stable bases for the development of inactivated SARS-CoV vaccines.