Biomedical subjects

Zhen-Dong Wang

Publications and source records attributed to Zhen-Dong Wang.

6 recordsLinked to original sources

PubMed2006

Computer-based QSARs for predicting mixture toxicity of benzene and its derivatives.

During the past decades, the Quantitative structure-activity relationships (QSARs) have been proven to be reliable tools when little or no empirical data are available in medicinal chemistry, biochemistry, toxicology, and environmental sciences. However, only few studies that quantitatively predict mixtures toxicity have been reported. In this study, the QASR models for the binary mixtures toxicity of 12 benzene and its derivatives, including eight non-polar-narcotic compounds and four polar narcotic compounds were developed, without reference to exact toxicity mechanisms of single compounds. All parameters for the QSAR studies were defined on the basis of quantum mechanical calculations and these parameters were selected by the stepwise procedure. The results of this study provided a simple means of predicting the binary mixtures toxicity from the chemical structure.

Benzene↗

PubMed2004

Modification of the Wiener index 4.

A novel topological index W(F) is defined by the matrices X, W, and L as W(F) = XWL. Where L is a column vector expressing the characteristic of vertices in the molecule; X is a row vector expressing the bonding characteristics between adjacent atoms; W is a reciprocal distance matrix. The topological index W(F), based on the distance-related matrix of a molecular graph, is used to code the structural environment of each atom type in a molecular graph. The good QSPR/QSAR models have been obtained for the properties such as standard formation enthalpy of inorganic compounds and methyl halides, retention indices of gas chromatography of multiple bond-containing hydrocarbons, aqueous solubility, and octanol/water partition of benzene halides. These models indicate that the idea of using multiple matrices to define the modified Wiener index is valid and successful.

Journal Article↗

PubMed2004

[An experimental study on dissolving and detaching vitreoretinal interface with enzymes].

OBJECTIVE: To investigate the safety dosage of intravitreal injection of Plasmin, Hyaluronidase and their combination and to evaluate their efficacy in the formation of posterior vitreous detachment (PVD) through animal experiments. METHODS: Eight rabbits each were randomly assigned to one of six groups and one eye of each rabbit were experimental eye, the other is control eye. The position of drug injection was in posterior 1/3 of vitreous before papillary. The drug-injection groups were assigned as following: the first group-Hyaluronidase 20 IU (0.1 ml BSS), the second group-Hyaluronidase 30 IU (0.1 ml BSS), the third group-Plasmin 1 IU (0.1 ml BSS), the forth group-Plasmin 2 IU (0.1 ml BSS), the fifth group-Plasmin 3 IU (0.1 ml BSS), the sixth group- Hyaluronidase 20 IU (0.05 ml BSS) combined with Plasmin 1 IU (0.05 ml BSS); the control eyes were injected with BSS (0.1 ml) at the same position. The experimental rabbits were followed for 2 weeks, and in this period all eyes were examined with slit-lamp biomicroscopy, +90 D preset lens, indirect ophthalmoscope, electroretinography, B-scan, and optical coherence tomography. After two weeks, the animals were killed and the eyes enucleated. Scan electron and light microscopy were performed. RESULTS: Hyaluronidase concentration of 20 IU, Plasmin concentration of 1 IU and their combination didn't produce inflammatory response and retinal toxicity in the experimental eyes. 30 IU Hyaluronidase and 2 IU Plasmin both caused mild inflammatory response in the vitreous without retinal histological changes, while the latter caused a reversible decrease in the ERG b-wave. 3 IU of Plasmin caused severe inflammatory response with retinal histological and electroretinographic changes. In safety dosage neither Hyaluronidase nor Plasmin alone were successful in producing completely posterior vitreous detachment (PVD), but the latter can produce partial PVD. The combination of Plasmin (1 IU) and Hyaluronidase (20 IU) was effective on producing completely PVD without retinal toxicity. CONCLUSION: 20 IU of Hyaluronidase and 1 IU of Plasmin are safe to retina and others structures in the eyes without any toxicity. Posterior vitreous injection of Hyaluronidase (20 IU) combined with Plasmin (1 IU) can produce complete posterior vitreous detachment.

Animals↗

PubMed2003

Novel topological index F based on incidence matrix.

Based on incidence matrix W, the novel topological index F is defined by the matrices L, W, X as F = LWX. The properties, the chemical environments, and the interaction of the vertexes in a molecule are taken into account in this definition. Several good QSPR models in the hetero-atom-containing organic compounds and inorganic compounds are obtained. Moreover, based on the definition of F and the values C(i) of the vertexes or the values (m)F(ij) of the chemical bonds, we have obtained serial indices, (m)F(v), (m)F(b), and F(w). They are successfully applied to QSPR models and good correlation results have been obtained as well.

Journal Article↗

PubMedDate not supplied

Modification of Wiener Index and its application.

A novel topological index based on the Wiener Index is proposed as W* = 1/2 sigma (n)(i,j=1) S(*)(ij), the element S(*)(ij) of the distance matrix is defined either as S(*)(ij) = alpha x square root of I(i)I(j)/R(ij) (atoms i and j are adjacent) or as S(*)(ij) = = alpha x (j-i+1)square root of I(i) x x x x x I(j)/R(ij) (atoms i and j are not adjacent), where I(i) and I(j) represent the electronegativity of vertices i or j, respectively, R(ij)() is the sum of the bond length between the vertices i and j in a molecular graph, and alpha = (Z(i)/Z(j))(0.5), where Z(i) and Z(j) are the atomic numbers of the positive valence atom i and the negative valence atom j, respectively. The properties and the interaction of the vertices in a molecule are taken into account in this definition. That is why the application of the index W to heteroatom-containing and multiple bond organic systems and inorganic systems is possible. Correlation coefficients above 0.97 are achieved in the prediction of the retention index of gas chromatography of the hydrocarbons, the standard formation enthalpy of methyl halides, halogen-silicon, and inorganic compounds containing transition metals.

Journal Article↗

PubMedDate not supplied

Modification of the Wiener Index. 2.

A novel topological index based on the Wiener Index is proposed as W = 1/2, summation(n/ij)=S*(ij) the element S*(ij) of the distance matrix is defined either as S*(ij)= square root (E(i)E(j)/R(ij) (atoms i and j are adjacent) or as S*(ij)=(j-i+1)square root (E(i)...xE /R(ij) (atoms i and j are not adjacent), where E(i) and E(j) represent the total energy of the valence electrons of vertexes i and j, respectively, R(ij) is the sum of the distance between the vertexes i and j in a molecular graph. The distance and the energy of the vertexes in a molecule are taken into account in this definition. Hence the application of the index W to multiple bond and heteroatom-containing organic systems and inorganic systems is possible. Good correlation coefficients are achieved not only in the standard formation enthalpy of methyl halides, halogen-silicon, but also in the retention index of gas chromatography of the hydrocarbons.

Journal Article↗