Biomedical subjects

R Q Yu

Publications and source records attributed to R Q Yu.

At least 37 records · Page 2Linked to original sources

PubMed1994

Artificial neural networks applied to classification of mutagenic activity of nitro-substituted polycyclic aromatic hydrocarbons.

Three-layer artificial neural networks (ANN) with back-propagation of error have been applied to classification of nitro-substituted polycyclic aromatic hydrocarbons (NPAH) based on the regularity that the structure difference of NPAH compounds leads to different mutagenic activity towards Salmonella typhimurium. The network's architecture and parameters were optimized to give maximum correct classification rate of 93.8% for two different classes of NPAHs: weakly active and strongly active ones. The results compared favourably with those obtained by nonlinear mapping pattern recognition method. Considering that the most important factor for NPAH's mutagenicity might be the electron effect of the substituted nitro-groups, an electrotopological state index of nitrogen atom was introduced additionally as one of network's inputs, and the correct classification rate was consequently raised to 97.5%. The network's prediction ability for untrained samples was also satisfactory.

Mutagens↗

PubMed1993

Preliminary fluorimetric screening of fourteen palladium complexes as potential antitumor agents.

Making use of the fact that the combination of a drug substance with DNA may inhibit the duplication, synthesis and proliferation of DNA and the consistency of the in vivo and in vitro interactions, the authors worked out a preliminary screening method for testing complex agents as potential antitumor drugs using ethidium bromide as a fluorescence probe. In this report, the method was applied for in vitro testing fourteen synthesized palladium(II)/phenanthroline/amino acid/chloride complexes as potential non-platinum antitumor agents. The fluorimetric screening method was compared with methylene blue tube test and trypan blue dye exclusion assay. All three methods gave agreeable results. Among the complexes tested, [Pd(phen)(lys)]Cl, [Pd(phen)(arg)]Cl and [Pd(phen)(pro)]Cl showed antineoplastic ratios for animal tumor S-180 56%, 50% and 48%, respectively, in accordance with the order of their binding constants with DNA, 7.96 x 10(6), 4.52 x 10(6) and 1.0 x 10(6), respectively. The test results show that fluorimetric method is simple, cheap and rapid, suitable for preliminary screening of antitumor complexes.

Animals↗

PubMed1993

Preliminary screening of non-platinum complexes of Schiff bases as antitumour agents using fluorimetry.

Based on the consistency of the in vivo and in vitro interactions of drugs with DNA, a fluorimetric method has been developed as a new in vitro method for preliminary screening of antitumour agents. This method was tested using Schiff bases synthesized from salicylaldehyde with 1-alanine, 1-asparagine and 1-histidine, and complexes of these Schiff bases with Cu(II), Zn(II), Ni(II) and Sn(IV) as potential antitumour agents. The study of the interaction of the complexes with DNA by a fluorescence probe ethidium bromide (EthBr)-DNA system indicated the parallelism between the binding constants and antineoplastic ratios. The relationship between structure and antitumour activity was investigated.

Animals↗

PubMed1991

[Studies on surfactants used for thin layer chromatographic separation of flavones].

The micellar thin layer chromatographic behaviours of rutin, quercetin and morin were studied. The methods of separation and identification were established: Polyamide thin coating was used as the stationary phase and 4% Zeph--acetylacetone--H2O (5:1.5:1.5) used as the mobile phase. The method was applied to the separation and identification of quercetin and rutin in samples of Sophorae flos and satisfactory result was obtained.

Chromatography, Thin Layer↗

PubMed1991

[Spectrophotometric determination of multicomponent vitamins by flexible tolerance simplex method].

Based on the brief discussion of error propagation in multivariate calibration and analysis, the flexible tolerance simplex method (FTSM) was applied to analyze vitamin B1, B2, B6 and niacinamide simultaneously. The results obtained were comparatively satisfactory both in precision and in accuracy. The average recoveries of vitamin B1, B2, B6 and niacinamide were 99.8 +/- 0.9% (CV), 100. 1 +/- 0.8% (CV), 100.2 +/- 2.1% (CV) and 100.1 +/- 0.7% (CV) respectively. All these show that FTSM, with calibration matrix K calculated from K = ASCST (CSCST)-1, is one of the most efficient procedures for improving accuracy, especially when there are interactions between variables and the problem is ill-conditioned.

Mathematics↗

PubMed1990

[IR spectra resolution of pure components for unknown mixtures].

The spectral resolution into individual components from a set of unknown mixture IR spectra was investigated. The method based on iterative target transformation of factor analysis is developed and used to treat several three-component and two-component mixture systems of amino-acids. The results show that the method proposed in this paper is applicable.

Amino Acids↗

PubMed1990

Primary amine drug selective electrodes with special crown ethers as neutral carriers.

Ionophores selectively sensitive to primary amines have been synthesized which display low potentiometric selectivity coefficients for K+, Na+ and NH4+ ions, secondary and tertiary amines as well as quaternary ammonium ions. These ionophores include macrocyclic polyethers with dinaphthyl subunits and azocrown ether with nitrogen donor atoms. The feasibility of these ionophores for preparing primary amine drug selective electrodes was investigated in detail. Practically usable PVC membrane electrodes sensitive to primary amine drugs, such as mexiletine, dopamine, metaraminol and tryptamine, and aliphatic primary amines have been prepared with these ionophores as neutral carriers. Direct potentiometric methods for assaying these drugs have been proposed by using the prepared electrodes. The proposed primary amine drug selective electrodes are remarkably superior to those based on ion-associates. Compared with the electrodes based on common ethers, the interference by K+, Na+ and NH4+ ions is substantially reduced. A digital simulation of the electrochemical process concerning the membrane transport was performed and some interesting conclusions have been drawn.

Dopamine↗

PubMed1990

[Studies on sensor for L-ascorbic acid using biotissue slice].

Bioselective membrane electrode for L-ascorbic acid has been made with tissue slices. It is made from porcine liver tissue slice covering an oxygen electrode. The influence of buffer mediator, pH, temperature, antiseptics, slice thickness, etc. on the response characteristics of the electrode was examined. In the presence of copper ions, a linear relationship between dynamic response of the electrode and the logarithm of concentration of L-ascorbic acid was observed for the range of 21.14 micrograms/ml to 352.3 micrograms/ml, with a correlation coefficient of 0.9996 and the Michaelis constant of 0.8 mmol/L. The electrode has been used to determine L-ascorbic acid in drugs, the analytical results were satisfactory.

Animals↗

PubMed1990

[Kalman filtering-titrimetry: potentiometric titration of benzalkonium bromide].

The application of Kalman filtering and smoothing to titrimetry has been investigated. The method is suitable for titration systems in both thermodynamic equilibrium and non-equilibrium (dynamic). Particularly, Kalman filtering and smoothing can give correct results in cases when other traditional methods failed. The effect of model noise, titration rate and sampling time was also examined on the accuracy of the filtering titrimetry. The proposed method has been applied to potentiometric titration and rapid determination of benzalkonium bromide.

Benzalkonium Compounds↗

PubMed1989

[Simultaneous qualitative and quantitative analysis of mixtures by multivariate spectrophotometry].

By the use of stepwise regression method in conjunction with the theory of figures of merit for the multicomponent spectrophotometry, mixtures with known scope of possibly present species can be simultaneously analyzed qualitatively and quantitatively. There is no need for the analysis to acquire the spectral data matrix from a series of mixture samples with varied concentration as for the case of target transformation factor analysis. Analytical results can be obtained from the spectral data vector of just one assayed sample. The method has been testified by analyzing synthetic mixtures and pharmaceutical preparations with satisfactory results.

Amino Acids↗

PubMed1989

[Synchronous fluorescent determination of phenol and resorcinol using linear regression of multiwavelength data].

A method for simultaneous determination of phenol and resorcinol in mixtures using fluorimetry is developed by combining synchronous fluorescence technique with linear regression of multiwavelength data. The effect of solution pH and other mental variables was examined and the optimal condition for determination of phenol and resorcinol was established. The proposed method was applied to fluorescent assay of resorcinol based on preparation with recoveries of 97.18 ( +/- 2.42)% and 98.15 (+/- 2.70)% for phenol and resorcinol, respectively.

Phenols↗

PubMed1988