Biomedical subjects

Hong-Yu Zhang

Publications and source records attributed to Hong-Yu Zhang.

52 records · Page 3Linked to original sources

PubMed2004

[Identification and analysis of F2 stable population derived from the cross of triploid x diploid in rice].

Polyploid strain 149-B, that was generated naturally from a rice twin-seedling population SAR-2, has been determined as triploid (2n = 36). It was then used as the female parent crossing with a normal diploid variety SH R363. From its F2 generation we obtained a genetic-stable population. To prove the uniformity of such a population, SSR markers were used to survey the F2 individual plants. The results showed that F2 individuals carried only one parental molecular marker at each polymorphic locus, and their genotypes were identical with F1 progeny. Based on the above experiments, we consider that this F2 population is definitely an early-generation stable population. Meanwhile, we discussed the possible mechanism of the special phenomenon as well.

Crosses, Genetic↗

PubMed2004

[Clinical analysis of rituximab combined with chemotherapy in treating aggressive B-cell non-Hodgkin's lymphoma].

BACKGROUND & OBJECTIVE: The efficacy of standard treatment, including cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP regimen), for patients with aggressive B-cell non-Hodgkin's lymphoma (B-NHL) is still unsatisfactory. Rituximab, a chimeric monoclonal antibody against B-cell antigen CD20, has therapeutic activity in B-NHL. This study was to determine efficacy and safety of the combination of rituximab and chemotherapy in treating Chinese patients with aggressive B-NHL, and to analyze influence factors on the response. METHODS: Records of 75 patients with aggressive B-NHL,received infusions of 375 mg/m(2) of rituximab combined with or without chemotherapy in our center,have been retrospectively analyzed. Influence of age, clinical stage, serum level of lactate dehydrogenase (LDH), international prognostic index (IPI) score, and bulk disease on response were evaluated. RESULTS: Response rate of rituximab alone group was 83.3% (5/6)with complete response (CR) rate of 66.7% (4/6). In 43 naive patients, the combination of rituximab and chemotherapy achieved an overall response rate (ORR) of 90.7% with CR rate of 67.4%; while in 26 recurrent or relapsed patients, the combination therapy achieved an ORR of 79.2% with CR rate of 29.2% (7/26), and partial response (PR) rate of 50.0% (13/26), 6 patients had a progressive disease (20.8%). Efficacy of immunochemotherapy was poor on patients with advanced disease(P=0.046), increased serum level of LDH (P=0.024), recurrence or relapse (P=0.009), and bulk disease (P=0.013). All patients can tolerate the treatment. No treatment-related death occurred. CONCLUSION: The addition of rituximab to the chemotherapy regimen increases the response rate and CR rate in Chinese patients with aggressive B-NHL, without a clinically significant increase in toxicity. Patients with advanced disease, higher serum level of LDH, recurrence or relapse, and bulk disease had a poor response.

Adult↗

PubMed2004

[Comparative activity of antihistamines on area under dose-response curve from histamine-induced wheal and flare responses in human skin].

OBJECTIVE: To compare the activity of antihistamines by the index of area under dose-response curve (AUDRC) obtained from histamine-induced wheal and flare reactions. METHODS: Mizolastine 10 mg, loratadine 10 mg, and placebo were given to 90 healthy volunteers and 60 allergic patients in a double-blind and randomized manner. Histamine titration tests (histamine concentrations 54.3, 20.0, 7.3, and 2.7 mmol/L) were performed for each one before dosing and 2, 4, and 24 hours after dosing. The reactivity was evaluated by histamine-induced wheal and flare areas. The AUDRC values of the wheal and flare areas as a function of the natural logarithm transformed histamine concentration were calculated for each subject, and compared. RESULTS: There was no significant difference of the wheal and flare areas between health volunteers and allergic patients. The AUDRC(27-54.3 mmol/l.) for wheal and flare of mizolastine was 115.7, 23.4, 7.7, 49.8 and 902.1, 40.9, 2.6, 46.9 ln (mmol/L) x mm2 at each time (before dosing and 2, 4, 24 hours after dosing) respectively. Compared with loratadine [116.2, 80.2, 49.7, 71.9 and 957.6, 495.3, 153.5, 205.9 ln (mmol/L) x mm2], mizolastine decreased AUDRC(2.7 - 54.3 mmol/L significantly (P < 0.01). CONCLUSION: Histamine-induced wheal and flare inhibition test is a reliable pharmacodynamic model for antihistamines, and AUDRC may be an useful index to predict antihistamines pharmacodynamic activity.

Adolescent↗

PubMed2003

Perylenequinones act as broad-spectrum fungicides by generating reactive oxygen species both in the dark and in the light.

Natural perylenequinonoid pigments (PQPs) have long been known as excellent photosensitizers. Here it is reported that PQPs, when dispersed into a micellar system, are unexpectedly very effective in inhibiting the growth of various fungi in the dark and that light can enhance the activity further. In both cases, reactive oxygen species (ROS) play a crucial role. The unique ROS-based antifungal mechanism and the excellent physicochemical properties of PQPs promise the advent of a new generation of wide-spectrum agrofungicides.

Agrochemicals↗

PubMed2003

A theoretical investigation on DPPH radical-scavenging mechanism of edaravone.

The mechanism of edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one) to scavenge DPPH radical is clarified by density functional theory (DFT) calculations. It is revealed that H-atom-abstraction rather than electron-transfer reaction is involved in the radical-scavenging process of edaravone, and H-atom at position 4 is readily to be abstracted. The C-H bond dissociation enthalpy (BDE) of edaravone is higher than the O-H BDE of alpha-tocopherol, accounting for the activity difference between the two antioxidants. As substituents have little influence on the C-H BDE, 2-pyrazolin-5-one is recognized as the active center for edaravone.

Antipyrine↗

PubMed2003

Structure-antioxidant activity relationship of ferulic acid derivatives: effect of carbon side chain characteristic groups.

Differences in the antioxidant activity of some biosynthetically related ferulic acid derivatives induced by the presence of characteristic groups (-COOH, -CHO, -CH(2)OH, -CH(3), and -COOC(2)H(5)) at the end of their carbon side chain were investigated using both experimental and computational methods. The relative order of the scavenging activity toward the DPPH radical derived from kinetic studies was isoeugenol approximately coniferyl alcohol >> ferulic acid approximately coniferyl aldehyde approximately ethyl ferulate. In bulk oil autoxidation (45 degrees C) the same order of activity was obtained. In the o/w emulsion autoxidation, lipophilicity of the phenols was the determining factor because the least polar compounds bearing -CH(3) and -COOC(2)H(5) were the most effective ones. The order of activity based on the O-H bond dissociation enthalpy (BDE) and ionization potential (IP) values, calculated by the density functional theory (DFT) method, was in accordance with the experimental radical scavenging order and with the electron-donating/withdrawing properties of the characteristic groups. Other molecular descriptors could not complement the experimental findings.

Antioxidants↗

PubMed2003

Why B-ring is the active center for genistein to scavenge peroxyl radical: a DFT study.

The structure-activity relationship for genistein to scavenge peroxyl radical was clarified by density functional theory (DFT) calculations using the B3LYP/6-31G(d,p) method. It was revealed that the conjugation of an electron-withdrawing 1,4-pyrone group with A-ring of genistein was not beneficial to enhance the radical-scavenging activities. Thus, hydroxyl in B-ring became the active center of genistein to scavenge peroxyl radical.

Free Radical Scavengers↗

PubMed2003

Substituent effects on O--H bond dissociation enthalpies and ionization potentials of catechols: a DFT study and its implications in the rational design of phenolic antioxidants and elucidation of structure-activity relationships for flavonoid antioxidants.

Density functional theory (DFT) on B3LYP/6-31G(d,p) level was employed to investigate the substituent effects on O--H bond dissociation enthalpies (BDEs) and ionization potentials (IPs) of catechols. It was revealed that the ortho hydroxyl of catechol was effective for the reduction of the O--H BDE; however, the group had little influence on the IP. The para substituent effects upon O--H BDEs and IPs for catechols were roughly the same as those for monophenols, and this gave the catechol moiety more potential than monophenol to be used as a lead compound in rational design of phenolic antioxidants. In addition, the 1,4-pyrone effects on O--H BDEs of catecholic rings A or B of flavonoids were also investigated. Although 1,4-pyrone extended the conjugation system of flavonoids, it was not beneficial to reduce the O--H BDE as a result of its electron-withdrawing property. Thus, 1,4-pyrone was unlikely to be favorable to enhance the H-abstraction activity of flavonoids.

Antioxidants↗

PubMed2003

Application of Molecular Adsorbents Recirculating System to remove NO and cytokines in severe liver failure patients with multiple organ dysfunction syndrome.

BACKGROUND: Molecular Adsorbents Recirculating System (MARS) is a new promising artificial liver support therapy, the aim of this study was to assess the effectiveness of MARS to remove nitrous oxide (NO) and cytokines in severe liver failure patients with multiple organ dysfunction syndrome (MODS). METHODS: Sixty single MARS treatments were performed with length of 6-24 h on 24 severe liver failure patients (18 males/6 females) with MODS. RESULTS: The MARS therapy was associated with a significant removal of NO and certain cytokines such as TNF-alpha, IL-6, IL-8, and INF-gamma, together with marked reduction of other non-water-soluble albumin bound toxins and water-soluble toxins, these were associated with a improvement of the patients' clinical conditions including hepatic encephalopathy, deranged hemodynamic situation and as well as renal and respiratory function, thus resulted into marked decrease of Sequential Organ Failure Assessment (SOFA) score and improved outcome: nine patients were able to be discharged from the hospital or bridged to successful liver transplantation, the overall survival of 24 patients was 37.5%. CONCLUSION: We can confirm the positive therapeutic impact and safety to use MARS on liver failure patients with MODS associated with elevated levels of NO and cytokines.

Adolescent↗

PubMed2002

Theoretical elucidation on the antioxidant mechanism of curcumin: a DFT study.

[reaction: see text] Bond dissociation enthalpies (BDEs) for the curcumin-related compounds have been calculated using density functional theory (DFT) methods. It was found that the antioxidant mechanism of curcumin was a H-atom abstraction from the phenolic group, not from the central CH2 group in the heptadienone link. Curcumin, methylcurcumin, and half-curcumin had similar O-H BDEs, indicating that the two phenolic groups in curcumin were independent of each other.

Antioxidants↗

PubMed2002

Electronic effects on O-H proton dissociation energies of phenolic cation radicals: a DFT study.

The electronic effects on O-H proton dissociation energies (PDEs) of para- and meta-substituted phenolic cation radicals have been investigated by density functional theory (DFT) using B3LYP function on a 6-31G(d, p) basis set. The calculation results indicate that electron-donating groups raise the O-H PDE and electron-withdrawing groups reduce the parameter, which are opposite to the electronic effects on O-H bond dissociation energies (BDEs). In addition, the electronic effects on O-H PDE are much stronger than those on O-H BDE. The differences result from the distinct electronic effects on stabilities of phenolic cation radicals and parent phenols. The finding also implies the proton-transfer process is unlikely a rate-controlling step for phenolic antioxidants to scavenge free radicals. Moreover, like O-H BDE, O-H PDE correlate better with the resonance parameter R+ than with field/inductive parameter F. Therefore, O-H PDEs of para-substituted phenolic cation radicals are mainly governed by the resonance effect.

Journal Article↗

PubMed2002

Theoretical elucidation on structure-antioxidant activity relationships for indolinonic hydroxylamines.

Indolinonic hydroxylamines (IH), representing a new type of antioxidants, are comparative to alpha-tocopherol to protect lipids from oxidation. To elucidate the structure-activity relationship for IH, B3LYP/6-31G(d, p) method was employed to calculate the O-H bond dissociation enthalpy (BDE), a theoretical parameter to characterize the free radical scavenging activity. By constructing several model molecules, it was revealed that hydroxylamine was the key structural factor for this type of antioxidants, and substituents had little effect on the O-H BDE. If the =NR of IH was substituted by =O, its activity got lower.

Antioxidants↗

PubMed2000

Theoretical Elucidation on Activity Differences of Ten Flavonoid Antioxidants.

Theoretical methods including structure-activity relationships (SAR) and quantum chemical calculations were used to elucidate the free radical scavenging activity differences of 10 flavonoid antioxidants. SAR could give a qualitative explanation on the antioxidant activity differences. And a further elucidation was performed by a theoretical parameter, the difference of heat of formation between antioxidant and its free radical (deltaHOF), calculated by Austin Model 1 (AM1) method. Besides, deltaHOF showed a linear correlationship with the logarithm of the relative antioxidant efficiency (lgRAE, r = 0.7523), indicating that the theoretical methods were effective to elucidate the differences of antioxidant activity. On the other hand, the ineffectiveness of another theoretical parameter, the highest occupied molecular orbit (HOMO) energy level, was verified further.

Journal Article↗

PubMed1998

Quantum Chemistry Calculation Study on Photosensitization of Perylenequinonoid Derivatives.

AM1 method has been employed to calculate perylenequinonoid photosensitizers (PQDs). Parameters such as heat of formation (HF), HOMO, LUMO levels and spin density destribution of free radicals are obtained. In combination with experimental results, several photophysical and photochemical characteristics of PQDs are elucidated, which lay a foundation for investigating photosensitive mechanisms of PQDs further.

Journal Article↗

PubMedDate not supplied

A theoretical elucidation on the solvent-dependent photosensitive behaviors of C60.

In this paper, the solvent-dependent photosensitive behaviors of fullerene (C(60)) were investigated in polar and nonpolar solvents by time-dependent density functional theory (TD-DFT) calculation. Based on the calculated physicochemical parameters on triplet state, it is revealed that excited-state C(60) only generates (1)O(2) via energy transfer in benzene, but can give birth to O(2)(.-) and (1)O(2) in water via energy transfer and electron transfer, respectively. Considering the fact that electron transfer is more favorable compared with energy transfer in polar biological systems, especially with the presence of electron donors, the O(2)(.-)-generating process will get predominant in physiological systems. These results account well for the experimental observations that O(2)(.-) and (.)OH are primarily responsible for the photoinduced DNA cleavage by C(60) under physiological conditions, whereas (1)O(2) plays a critical role in nonpolar solvents.

DNA Damage↗

PubMedDate not supplied

Exposure of human lung cancer cells to 8-chloro-adenosine induces G2/M arrest and mitotic catastrophe.

8-Chloro-adenosine (8-Cl-Ado) is a potent chemotherapeutic agent whose cytotoxicity in a variety of tumor cell lines has been widely investigated. However, the molecular mechanisms are uncertain. In this study, we found that exposure of human lung cancer cell lines A549 (p53-wt) and H1299 (p53-depleted) to 8-Cl-Ado induced cell arrest in the G2/M phase, which was accompanied by accumulation of binucleated and polymorphonucleated cells resulting from aberrant mitosis and failed cytokinesis. Western blotting showed the loss of phosphorylated forms of Cdc2 and Cdc25C that allowed progression into mitosis. Furthermore, the increase in Ser10-phosphorylated histone H3-positive cells revealed by fluorescence-activated cell sorting suggested that the agent-targeted cells were able to exit the G2 phase and enter the M phase. Immunocytochemistry showed that microtubule and microfilament arrays were changed in exposed cells, indicating that the dynamic instability of microtubules and microfilaments was lost, which may correlate with mitotic dividing failure. Aberrant mitosis resulted in mitotic catastrophe followed by varying degrees of apoptosis, depending on the cell lines. Thus, 8-Cl-Ado appears to exert its cytotoxicity toward cells in culture by inducing mitotic catastrophe.

Adenosine↗