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At least 19 recordsLinked to original sources
PubMed2006

[Application of the combined use of uniform experimental design and orthogonal experimental design in biomedicial engineering].

A new optimized experimental designing method in biomedical engineering study is provided in this paper. The characteristic of the uniform design and orthogonal design was compared. Then, a new experimental design was proposed, which was the combined use of the two experimental designs. Discussed the theoretical basis, using method and its advantages. Furthermore, we proved the validity through our experiment. This method has the specificity of uniform design, fewer times of experiment and suit for experiment with multi-factors and multi-levels. This makes full use of the advantages of orhtogonal design which is widely used and can be analyzed by simple intuitionist analysis, avoids the disadvantages of uniform design in which data can only be processed by computer software. It can be widely used in the research and development of biomedicine engineering.

Biomedical Engineering↗
PubMed2005

Study of formulation variables influencing the drug release rate from matrix tablets by experimental design.

Experimental design was utilized to simultaneously investigate the effect of varying the type of diluent (insoluble Calcium phosphate or water-soluble arabic gum) and the diluent/matrix ratio on the drug release behaviour from both lipophilic (glyceryl behenate, Compritol) or hydrophilic (hydroxypropylmethylcellulose) matrix tablets. Ketoprofen, theophylline and sodium sulphadiazine were selected as model drugs on the basis of their respectively very low, medium and high water-solubility, in order to evaluate the influence of this parameter as well. The selected response variables were the dissolution efficiency (i.e. the area under the dissolution curve) after one and six hours and the time necessary to dissolve 10% drug. Tablets obtained by direct compression of drug-diluent-matrix ternary mixtures prepared according to the experimental plan provided for by an asymmetric screening matrix, were tested for drug release properties using a USP paddle apparatus. Graphic analysis of the effects allowed identification, for each examined drug, of the formulation factors active on the selected responses and determination of the proper level of the variables to be selected for the response improvement. The different results obtained with the three examined drugs pointed out the role of the drug solubility in determining the influence of formulation parameters on drug release rate from matrix tablets.

Calcium Phosphates↗
PubMed2006

Optimization and modeling of laccase production by Trametes versicolor in a bioreactor using statistical experimental design.

Experimental design and response surface methodologies were applied to optimize laccase production by Trametes versicolor in a bioreactor. The effects of three factors, initial glucose concentration (0 and 9 g/L), agitation (100 and 180 rpm), and pH (3.0 and 5.0), were evaluated to identify the significant effects and its interactions in the laccase production. The pH of the medium was found to be the most important factor, followed by initial glucose concentration and the interaction of both factors. Agitation did not seem to play an important role in laccase production, nor did the interaction agitation x medium pH and agitation x initial glucose concentration. Response surface analysis showed that an initial glucose concentration of 11 g/L and pH controlled at 5.2 were the optimal conditions for laccase production by T. versicolor. Under these conditions, the predicted value for laccase activity was >10,000 U/L, which is in good agreement with the laccase activity obtained experimentally (11,403 U/L). In addition, a mathematical model for the bioprocess was developed. It is shown that it provides a good description of the experimental profile observed, and that it is capable of predicting biomass growth based on secondary process variables.

Algorithms↗
PubMed1998

Optimization of an antibiotic residue screening test, based on inhibition of Bacillus subtilis BGA, with experimental design.

Experimental design was applied to an agar-diffusion inhibition test for the screening of residues of veterinary antimicrobial drugs in slaughter animals. The effects and interactions of four independent parameters were studied: the dextrose content of the culture medium, the trimethoprim concentration in the culture medium, the thickness of the agar-layer and the preincubation time. The effects on the inhibition zones of sulphadimidine, oxytetracycline, streptomycin and tylosin, substances of four different antibiotic groups were measured. An optimized multi-residue test was established with the parameter values that yielded the best sensitivity for the four substances.

Animals↗
PubMed2000

Development of spray-dried acetaminophen microparticles using experimental designs.

Experimental factorial designs were built to investigate the effects of five parameters on production yields and moisture contents of spray-dried products. These factors concerned both the solution feed (drug concentration, colloidal silica concentration and polymer/drug ratio) and the spray dryer (inlet temperature and feed rate). Three formulations containing cellulose derivatives and acetaminophen were tested. The aim of the study was to optimize the operating conditions to maximize production yields while minimizing moisture contents. First screening experiments consisting of fractional factorial designs revealed the most significant factors to be inlet temperature, feed rate and their interaction for both formulations containing sodium carboxymethylcellulose and feed rate and colloidal silica concentration for the formulation containing microcrystalline cellulose. Then, the optimal operating conditions were estimated by response surface methodology. Central rotational composite designs showed quadratic models were adequate. New assays were carried out using these last conditions to evaluate both the repeatability and reproducibility of the spray-drying technique. Yields above 80% and moisture content of approximately 1% were reached. The characterization of microparticles revealed the poor flowability of the spray-dried products due to significant cohesiveness and very small size (less than 55 microm).

Acetaminophen↗
PubMed2005

Music and video iconicity: theory and experimental design.

Experimental studies on the relationship between quasi-musical patterns and visual movement have largely focused on either referential, associative aspects or syntactical, accent-oriented alignments. Both of these are very important, however, between the referential and areferential lays a domain where visual pattern perceptually connects to musical pattern; this is iconicity. The temporal syntax of accent structures in iconicity is hypothesized to be important. Beyond that, a multidimensional visual space connects to musical patterning through mapping of visual time/space to musical time/magnitudes. Experimental visual and musical correlates are presented and comparisons to previous research provided.

Attention↗
PubMed2001

Use of a statistically designed experimental approach to optimize the propylketal derivatization of barbiturates.

The derivatization of barbiturates with dimethylformamide dipropylacetal and dimethylformamide diisopropylacetal is studied with respect to the optimization of reaction recovery and reliability. A second-order orthogonal experimental design is utilized in order to obtain regression equations for the reaction recovery dependence on the derivatization solution composition, incubation temperature, and time for amobarbital, butalbital, pentobarbital, phenobarbital, and secobarbital. Regression equations for the effect of incubation temperature and time on the derivative recovery and the optimum conditions for derivatization recoveries are obtained. Differences in the phenomena of the derivative formation are evaluated between the two derivatizing reagents and the barbiturates. Based on the analysis of the obtained equations, it is concluded that the dipropylketal derivative of barbiturates is superior in comparison with diisopropylketal when considering the milder conditions of the reaction, absence of sudden changes in the recovery with a variation in the derivatization parameters, and reliability for the simultaneous testing of the barbiturates. A method for the routine testing of the barbiturates by gas chromatography-mass spectrometry in urine specimens is included.

Barbiturates↗
PubMed2002

Didanosine extended-release matrix tablets: optimization of formulation variables using statistical experimental design.

Statistical experimental design was applied to evaluate the influence of some process and formulation variables and possible interactions among such variables, on didanosine release from directly-compressed matrix tablets based on blends of two insoluble polymers, Eudragit RS-PM and Ethocel 100, with the final goal of drug release behavior optimization. The considered responses were the percent of drug released at three determined times, the dissolution efficiency at 6 h and the time to dissolve 10% of drug. Four independent variables were considered: tablet compression force, ratio between the polymers and their particle size, and drug content. The preliminary screening step, carried out by means of a 12-run asymmetric screening matrix according to a D-optimal design strategy, allowed evaluation of the effects of different levels of each variable. The drug content and the polymers ratio had the most important effect on drug release, which, moreover, was favored by greater polymers particle size; on the contrary the compression force did not have a significant effect. The Doehlert design was then applied for a response-surface study, in order to study in depth the effects of the most important variables. The desirability function was used to simultaneously optimize the five considered responses, each having a different target. This procedure allowed selection, in the studied experimental domain, of the best formulation conditions to optimize drug release rate. The experimental values obtained from the optimized formulation highly agreed with the predicted values. The results demonstrated the reliability of the model in the preparation of extended-release matrix tablets with predictable drug release profiles.

Anti-HIV Agents↗
PubMed1998

Optimization of the processing of matrix pellets based on the combination of waxes and starch using experimental design.

An experimental design was used in order to optimize the one-step production process of matrix pellets based on the combination of waxes and starch. The parameters tested were the impeller speed (x1) and the mixing time (x2). Ibuprofen and theophylline were used as model drugs at a concentration of 60 and 70% (w/w), respectively. The 0.8-1.25 mm yield fraction of the matrix pellets was evaluated as the response factor Y. A quadratic equation was fitted to the experimental data and used to predict the response factor Y of the theophylline and the ibuprofen. The contour plots of both formulations revealed a flat and therefore rugged region from the upper left to the lower right of the domain investigated. The energy input into the system during the production process controlled the pellet growth, the impeller speed having a greater impact on the energy input compared to the mixing time.

Delayed-Action Preparations↗
PubMed2006

A call for clinically driven experimental design in assessing neuroprotection in experimental Parkinsonism.

Parkinson's disease is a progressive neurodegenerative disorder. At present, only symptomatic treatments are of proven efficacy, whereas strategies that slow or stop the neurodegenerative process are currently not available. The selection of interesting drug candidates or surgical strategies should be based on the soundest clinically driven preclinical validation. My goal here is not to discuss the relative merits of the available models, but to simply raise the issue of the experimental design that has led to the demonstration of efficacy of given compounds in these models. As some compounds previously shown to be active in classic experimental designs fail when tested in clinically relevant experimental designs, I emphasize the need for progressive screening methods and for the use of different animal species before entering into the clinic.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

DESIGN: computerized optimization of experimental design for estimating Kd and Bmax in ligand binding experiments. I. Homologous and heterologous binding to one or two classes of sites.

We have developed a versatile computer program for optimization of ligand binding experiments (e.g., radioreceptor assay system for hormones, drugs, etc.). This optimization algorithm is based on an overall measure of precision of the parameter estimates (D-optimality). The program DESIGN uses an exact mathematical model of the equilibrium ligand binding system with up to two ligands binding to any number of classes of binding sites. The program produces a minimal list of the optimal ligand concentrations for use in the binding experiment. This potentially reduces the time and cost necessary to perform a binding experiment. The program allows comparison of any proposed experimental design with the D-optimal design or with assay protocols in current use. The level of nonspecific binding is regarded as an unknown parameter of the system, along with the affinity constant (Kd) and binding capacity (Bmax). Selected parameters can be fixed at constant values and thereby excluded from the optimization algorithm. Emphasis may be placed on improving the precision of a single parameter or on improving the precision of all the parameters simultaneously. We present optimal designs for several of the more commonly used assay protocols (saturation binding with a single labeled ligand, competition or displacement curve, one or two classes of binding sites), and evaluate the robustness of these designs to changes in parameter values of the underlying models. We also derive the theoretical D-optimal design for the saturation binding experiment with a homogeneous receptor class.

Binding Sites↗
PubMed1986

Flexibility of single-subject experimental designs. Part II: Design selection and arrangement of experimental phases.

The purpose of this paper is to present a taxonomy of single-subject experimental designs and discuss relevant examples that underscore the versatility and flexibility of this approach to clinical research. The proposed taxonomy serves as a heuristic model that may facilitate an understanding of single-subject experimental designs. Four general evaluation strategies employed in applied research--treatment-no treatment comparison, component assessment, treatment-treatment comparison, and successive level analysis--are discussed within this schema. Each of these evaluation strategies is related to commonly posed clinical research questions, and published examples of design options that address these questions are presented. Throughout the discussion basic considerations relating to appropriate design selection are reviewed.

Classification↗
PubMed1991

Stimulus intensity and experimental design effects on motor response processing.

Experimental design effects and range effects may have influenced previous studies on motor response processing (Grice & Hunter, 1964; Grice, Nullmeyer, & Schnizlein, 1979; Poulton, 1973). This investigation was conducted concurrently with two experiments. First, Erlebacher's (1977) more powerful analysis of variance (ANOVA) model, which allows for the testing of the independent variable (stimulus intensity effect), the experimental design effect (between-subjects [BS] vs. within-subjects [WS]), and the important interaction between independent variable and experimental design was utilized to clarify if the nature of the experimental design (BS, WS) biases motor response processing. Second, Erlebacher's (1977) ANOVA model was used to determine if motor response processing was affected by stimulus intensity and experimental design when different ranges of auditory stimuli were compared. Results indicate motor response processing was inversely affected by increasing stimulus intensity. Experimental design effects and range effects did not appear to bias motor response processing. We conclude stimulus intensity effects on motor response processing appear to be the result of true neuromotor functioning and not artifacts of experimental design or of range effects.

Acoustic Stimulation↗
PubMed1978

The application of experimental design in bioengineering.

The use of factorial designs in experimentation and the careful planning of the three basic phases of experimental projects, will maximize the reliable information from the experiment and minimize the cost and effort to the experimentor. The application of the principles of good experimental design are illustrated in a case study of experimentation which investigates a new mode of peritoneal dialysis.

Biomedical Engineering↗