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Biomedical subjects

Ru-Qin Yu

Publications and source records attributed to Ru-Qin Yu.

At least 55 records · Page 3Linked to original sources

Quantitative structure-activity relationships (QSAR): studies of inhibitors of tyrosine kinase.

A quantitative structure-activity relationship (QSAR) study of the 1-phenylbenzimidazoles as inhibitors of the platelet-derived growth factor receptor (PDGFR) was performed. Some new electronic parameters Q(o), Q(m) and Q(p) are suggested for characterizing the effect of substituents. Many other descriptors are also used which are selected by evolution algorithm (EA) using modified Cp as objective function proposed by the present authors. The descriptor Q(m) is shown to be an important variable to express effect of substituents. The variable selection shows that spatial descriptors are most important variables revealing important properties of the inhibitors. Electron-releasing substitutes at 5-position and the absence of bulky groups at 4,7-positions of the parent structure can enhance inhibitor activity. Principal component analysis is performed to classify this series of compounds.

Benzimidazoles↗

An amperometric immunosensor based on an electrochemically pretreated carbon-paraffin electrode for complement III (C3) assay.

An electrochemical immunosensor based on the adsorption of anti-complement III antibody onto an electrochemical pretreated carbon-paraffin electrode has been proposed for the detection of complement III (C(3)). The competitive immunoassay format was adopted with horseradish peroxide-C(3) (HRP-C(3)) as a tracer, 3,3'5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide as the enzyme substrates. In order to measure the amount of HRP-C(3) binding onto the electrode surface, the product of the enzyme catalytic reaction was detected at 100 mV (vs. Ag/AgCl reference electrode). The system was optimized to realize a reliable determination of C(3) in the range of 0.06-10 microg/ml. It exhibits some advantages, such as simplicity of fabrication, rapidity of measurement, and satisfactory sensitivity and reproducibility.

Antibodies↗

Geometrical bounding of data space and nonlinear classification of chemical data using MPGA algorithm.

This paper develops a multi-parturition genetic algorithm (MPGA) to be used in geometrical bounding of the overlapped clusters in a data set for the classification of chemical data. Two new operators have been introduced to modify the conventional genetic algorithm, namely, multi-parturition and decimation and orientated creation to improve the linear classification results and diminish the computational time. To circumvent the difficulty commonly encountered in the treatment of linearly inseparable chemical data sets, the optimized linear classifier is further modified to provide a complementary nonlinear classifier. For this reason the space regions of the overlapped clusters have been bounded by erection of half-hyperellipsoids over the linearly misclassified patterns. The proposed MPGA was applied to classify a number of chemical and other data sets with a dimension from 4 to 14. Experimental results have indicated that the proposed MPGA could classify seriously overlapped data sets with an acceptable error rate.

Journal Article↗

An improved trilinear decomposition algorithm based on a Lagrange operator.

An improved trilinear decomposition algorithm based on a Lagrange operator (LO) is developed in this paper, which introduces a Lagrange operator and penalty terms in the loss function to improve the performance of the algorithm. Compared to the traditional parallel factor (PARAFAC) algorithm, the algorithm not only may converge much faster, but also overcome the sensibility to estimate the number of components. A set of simulated and measured excitation/emission fluorescence data were treated by both the proposed and traditional PARAFAC algorithm to compare their efficiencies. The analytical results obtained with real chemical system containing aspirin and its metabolic products show that the trilinear decomposition methodology is a promising tool to obtain spectral and composition information from mixtures without chemical separation.

Journal Article↗

Carbazole as fluorescence carrier for preparation of doxycycline sensor.

Carbazole is a promising pharmaceutical species. A novel optical sensor for determining doxycycline based on the fluorescence quenching of N-allylcarbazole immobilized on an quartz glass plate surface by covalent bonding has been described. The sensor shows satisfactory virtues in reversibility, repeatability, selectivity and sufficient lifetime resulting from its excellent optode membrane. Its response time is less than 60 s. The determination range and detection limit of the sensor are 6.0 x 10(-7)-2.0 x 10(-3) M and 2.0 x 10(-7) M, respectively. The lifetime of each sensor is at least three to four months. The sensor can be used for direct determination of doxycycline in pharmaceutical preparations and urine samples.

Animals↗

Quartz-crystal microbalance immunosensor for Schistsoma-japonicum-infected rabbit serum.

A quartz-crystal microbalance immunosensor (QCM) has been developed for the direct determination of Schistosoma-japonicum-infected rabbit serum. A self-assembled monolayer with carboxyl groups was first coated on a gold electrode of a quartz-crystal resonator by the spontaneous adsorption of 3-mercaptopropionic acid. Schistosoma-japonicum molecular antigen of 32 kD molecular weight was then covalently attached to the crystal surface. The QCM immunosensor was used to detect infected rabbit serum (IRS49-2000); a maximum titer of 1:800 was achieved.

3-Mercaptopropionic Acid↗

An algorithm for three-way data analysis that alternatively minimizes coupled vector (COV) resolution error and PARAFAC error.

A novel algorithm, alternatively minimizing coupled vector (COV) resolution error and PARAFAC error algorithm, is proposed in this paper. This algorithm can overcome the problem of slow convergence and is insensitive to the estimation of component number, such problems are unavoidable while using the traditional parallel factors analysis (PARAFAC) algorithm. In other words, this algorithm is capable of improving the computing speed and providing accurate resolutions provided that the number of factors used in the computation is no less than that of the actual underlying ones. The characteristic performances were demonstrated with a novel fluorescence data array.

Journal Article↗

Variable selection by an evolution algorithm using modified Cp based on MLR and PLS modeling: QSAR studies of carcinogenicity of aromatic amines.

The variable selection in QSAR studies by MLR and PLS modeling has been performed using the evolution algorithm (EA). The Cp statistic has been modified and used as the objective function in the EA search for different combinations of molecular descriptors. For MLR modeling a few information-rich descriptors are selected for model formulation. In PLS modeling, the proposed procedure selects a relatively large number of information-containing descriptors, and a PLS model is formulated based on a few latent variables, which are linear combinations of the selected descriptors. The proposed procedures were used for the prediction of carcinogenicity of aromatic amines.

Algorithms↗

An optical fiber chemical sensor for mercury ions based on a porphyrin dimer.

The synthesis of a novel fluoroionophore, 5-p-[[4-(10',15',20'-triphenyl-5'-porphinato) phenyloxyl]-1-butyloxyl]phenyl-10,15,20-triphenylporphine (DTPP), and its application for preparation of a Hg(II)-sensitive optical fiber chemical sensor are described. The response of the sensor is based on the fluorescence quenching of DTPP by coordination with Hg(II). The porphyrin dimer-based sensor shows a linear response toward Hg(II) in the concentration range 5.2 x 10(-7)-3.1 x 10(-4) mol x L(-1), with a working pH range from 2.4 to 8.0. The sensor shows excellent selectivity for Hg(II) over transition metal cations including Cd(II), Co(II), Cu(II), Ni(II), Pb(II), Zn(II), and Fe(III). As a sensing agent, the porphyrin dimer shows obviously better fluorescence response characteristics toward Hg(II) compared to porphyrin monomer or metalloporphyrin. The effect of the composition of the sensor membrane was studied, and the experimental conditions were optimized. The sensor has been used for determination of Hg(II) in water samples.

Algorithms↗

A new redundant variable pruning approach--minor latent variable perturbation-PLS used for QSAR studies on anti-HIV drugs.

A new approach for eliminating the redundant variables in the multivariable data matrix encountered in QSAR studies, minor latent variable perturbation (MLVP)-PLS method has been proposed. In the latent variable (LV) space, the minor latent variables (LVs) with small covariances are mainly formulated by linear combinations of the redundant variables including information-deficient and highly correlative ones, while the major LVs with large covariances are mainly contributed by the informative variables. Deleting a minor LV, which is equivalent to a perturbation for LV space, could make the redundant variables not well be represented in LV subspace, leading to strong variation of their PLS regression coefficients. The informative variables could still be normally represented in LV subspace with the PLS regression coefficients remaining relatively stable. MLVP-PLS utilizes this fact to discriminate the informative and redundant variables. It gradually identifies and eliminates the redundant variables according to the relative variation of PLS regression coefficients after perturbations are given. The elimination process is terminated according to some proposed criteria. Applying the method to the quantitative structure-activity relationship (QSAR) studies on TIBO derivatives as potential anti-HIV drugs has demonstrated the feasibility and robustness of the proposed approach. A deeper insight into the effect of different structural parameters on the bio-activity of TIBO derivatives has been reached.

Anti-HIV Agents↗

N-allyl-4-(N-2'-hydroxyethyl)amino-1,8-naphthalimide as a fluorophore for optical chemosensing of nitrofurantoin.

N-Allyl-4-(N-2'-hydroxyethyl)amino-1,8-naphthalimide (AHEAN), a naphthalimide derivative, was synthesized as a new fluorophore for optical chemical sensor preparation. To prevent leakage of the fluorophore, AHEAN was photo-copolymerized with 2-hydroxypropyl methacrylate on a glass surface treated with a silanizing agent. An optical chemical sensor based on AHEAN can be utilized for nitrofurantoin assay based on fluorescence quenching. The sensor shows sufficient repeatability, selectivity and a fast response of less than 30 s. Nitrofurantoin can be determined in the range between 1.00 x 10(-6) and 1.00 x 10(-3) mol l(-1) with a detection limit of 4.8 x 10(-7) mol l(-1). Most commonly co-existing drug substances and ions do not interfere with the nitrofurantoin assay. The sensor was applied to the analysis of pharmaceutical and urine samples.

Allyl Compounds↗

Inner chromatogram projection (ICP) for resolution of GC-MS data with embedded chromatographic peaks.

The chromatographic peak located inside another peak in the time direction is called an embedded or inner peak in contradistinction with the embedding peak, which is called an outer peak. The chemical components corresponding to inner and outer peaks are called inner and outer components, respectively. This special case of co-eluting chromatograms was investigated using chemometric approaches taking GC-MS as an example. A novel method, named inner chromatogram projection (ICP), for resolution of GC-MS data with embedded chromatographic peaks is derived. Orthogonal projection resolution is first utilized to obtain the chromatographic profile of the inner component. Projection of the two-way data matrix columnwise-normalized along the time direction to the normalized profile of the inner component found is subsequently performed to find the selective m/z points, if they exist, which represent the chromatogram of the outer component by itself. With the profiles obtained, the mass spectra can easily be found by means of a least-squares procedure. The results for both simulated data and real samples demonstrate that the proposed method is capable of achieving satisfactory resolution performance not affected by the shapes of chromatograms and the relative positions of the components involved.

Journal Article↗

An amperometric immunosensor based on a conducting immunocomposite electrode for the determination of Schistosoma japonicum antigen.

A renewable amperometric immunosensor based on a graphite-paraffin-Schistosoma japonicum antibody (SjAb) biocomposite electrode has been prepared for the detection of Schistosoma japonicum antigen (SjAg). Competitive ELISA was employed involving HRP-SjAg as a tracer and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The product of an enzyme catalytic reaction was detected at +0.1 V (vs. Ag/AgCl reference electrode) for measuring the amount of HRP-labeled SjAg binding to the electrode surface. The assay conditions were optimized, including the amount of SjAb loading in the electrode and HRP-SjAg in the incubation solution, the pH of the measuring solution and the incubation time. The measuring range was 0.5-30 microg/ml under the optimum conditions. Rabbit serum samples of different infection degree were measured, which demonstrated that the immunosensor meets the demands of clinical analysis. It exhibits some advantages, such as simplicity of fabrication, rapidity of measurement, and satisfactory sensitivity and reproducibility.

Animals↗

Spectrofluorometric resolution of closely overlapping drug mixtures using chemometrics methods.

A modified parallel factors analysis (PARAFAC) algorithm with a penalty diagonalization error (PDE), newly proposed by the present authors, was utilized to simultaneously resolve drug mixtures of propranolol (PRO), dipyridamole (DIP) and amiloride (AMI) without any loss of sensitivity. The analyses were performed in aqueous solution. The experimental results demonstrated that the profiles of the spectra and the concentrations could be accurately resolved using the PDE algorithm with a high sensitivity and stable repeatability. That is to say, the closely overlapping problem of the spectra could be easily solved. Furthermore, simultaneous determinations of three kinds of tablets, which contain PRO, AMI and DIP, respectively, were successfully performed with satisfactory results.

Algorithms↗

Interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine) with DNA.

The fluorescence spectral characteristics and interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine) [Et2Sn(salen)] with DNA are described. The polarity of the solvent has a strong effect on the fluorescence characteristics of Et2Sn(salen). Et2Sn(salen) bound to DNA showed a marked decrease in the fluorescence intensity with a bathochromic shift of the excitation and emission peaks. A hypochromism in the UV absorption spectra was also observed. KI quenching and competitive binding to DNA between Et2Sn(salen) and ethidium bromide (EB) were studied in connection with other experimental observations to show that the interactive model between Et2Sn(salen) and DNA is an intercalative one. The pH and salt effect on the fluorescence properties was also investigated. The intrinsic binding constant was estimated to be 1.071 x 10(5) mol L(-1) in base pairs and the binding site number is 1.98, respectively. A linear relationship between F/F0 and the concentration of calf thymus DNA covers 5.1 x 10(-6) - 2.41 x 10(-4) mol L(-1), which can be utilized for determining traces of calf thymus DNA with a detection limit of 1.1 x 10(-7) mol L(-1) in base pairs.

Animals↗

A novel piezoelectric biosensor for the detection of phytohormone beta-indole acetic acid.

A novel piezoelectric immunosensor has been developed for the determination of beta-indole acetic acid (IAA) in dilute solutions. The detection is based on competitive immunoreaction between a hapten (IAA) and an antigen (IAA-BSA, hapten-protein conjugation) bound to an anti-IAA antibody, immobilized on a quartz crystal microbalance (QCM). The frequency change (y) of the sensor caused by antigen is linearly related to the logarithm of the concentration of IAA (x) in the range of 0.5 ng/ml - 5 microg/ml with a regression equation of the form y = -23x + 151 (r = 0.9937).

Animals↗

Glycosylated metalloporphyrins as neutral carriers for PVC membrane electrodes.

In this paper, the synthesis of a novel ionophore, chloro[5,10,15,20-tetrakis[2-(2,3,4,6-tetraacetyl-beta-D-glucopyranosyl)-1-O-phenyl]porphinato]manganese (MnT(o-glu)PPCl), and its application as a neutral carrier for a PVC membrane electrode are described. The MnT(o-glu)PPCl-based PVC membrane electrode shows a potentiometric responses to SCN- over a concentration range of 3.4 x 10(-7) - 1.0 x 10(-1) mol L(-1) with a Nernstian slope and a response time of 20 s. The electrode exhibits an anti-Hofmeister selectivity toward SCN- with respect to common coexisting anions. As active materials, MnT(o-glu)PPCl shows better selectivity toward SCN- than chloro(tetraphenylporphinato)manganese (MnTPPCl). The effect of the electrode membrane compositions has been studied and the experimental conditions were optimized. The electrode was applied to the determination of SCN- in body fluids with satisfactory results.

Biosensing Techniques↗

Bacteria-modified amperometric immunosensor for a Brucella melitensis antibody assay.

A novel amperometric immunosensor setup is described which uses horseradish peroxidase (HRP) as a label in conjunction with a current-based Brucella sensor. The Bacteria modified immunosensor was constructed by using a biocomposite formed by dispersing graphite powder into a mixture of Brucella melitensis and silicate polymer gel. The enzyme-labeled antibody can readily diffuse toward the encapsulated antigen (Brucella melitensis), which retains its binding properties, and the association reaction is easily detected at the surface exposed to the solution. The use of an oaminophenol (o-AP) substrate and amperometric detection at -150 mV (vs. SCE) results in a relatively low detection limit of 3.5 ng/ml and a linear detection range of 3.5 ng/ml to 200 ng/ml. Based on an optimized parameter, the prepared sensor was used to detect the Brucella melitensis antibody in serum samples by using a competitive binding assay. The results demonstrate the feasibility of employing the proposed immunosensor for the detection for Brucella melitensis antibody in a clinical analysis.

Animals↗