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TOMOCOMD-CARDD, a novel approach for computer-aided 'rational' drug design: I. Theoretical and experimental assessment of a promising method for computational screening and in silico design of new anthelmintic compounds.

In this work, the TOMOCOMD-CARDD approach has been applied to estimate the anthelmintic activity. Total and local (both atom and atom-type) quadratic indices and linear discriminant analysis were used to obtain a quantitative model that discriminates between anthelmintic and non-anthelmintic drug-like compounds. The obtained model correctly classified 90.37% of compounds in the training set. External validation processes to assess the robustness and predictive power of the obtained model were carried out. The QSAR model correctly classified 88.18% of compounds in this external prediction set. A second model was performed to outline some conclusions about the possible modes of action of anthelmintic drugs. This model permits the correct classification of 94.52% of compounds in the training set, and 80.00% of good global classification in the external prediction set. After that, the developed model was used in virtual in silico screening and several compounds from the Merck Index, Negwer's handbook and Goodman and Gilman were identified by models as anthelmintic. Finally, the experimental assay of one organic chemical (G-1) by an in vivo test coincides fairly well (100%) with model predictions. These results suggest that the proposed method will be a good tool for studying the biological properties of drug candidates during the early state of the drug-development process.

Animals↗

Chronolab: an interactive software package for chronobiologic time series analysis written for the Macintosh computer.

Methods based on periodic regression have been designed for the detection of periodic components in short, noisy, and nonequidistant time series (as they are usually present in medicine and biology). The procedure consists of fitting a set of (cosine) curves to the data, with the analyst choosing the domain of trial periods to be analyzed and the distance between consecutive trial periods. We here describe an interactive program for least-squares rhythmometry written in C language for the Macintosh computer. For any given number of time series to be analyzed at once, the program is able to perform two different kinds of analyses: (a) linear in time, for the sequential fit of trial periods; and (b) linear in frequency, for the sequential fit of harmonic components from an initial fundamental period. For each series and for each trial period fitted to the data, the program gives the following information: fitted period; percent rhythm; p value from testing the assumption of zero amplitude; rhythm-adjusted mean or mesor, amplitude, and acrophase, each with corresponding standard errors and 95% confidence intervals when the component is statistically significant; and (when required by the analyst) p values from tests of sinusoidality, normality of residuals, and homogeneity of variance. Additionally, the program provides a summary report for each time series analyzed, including descriptive statistics such as the number of data analyzed for that series, minimum, maximum, arithmetic mean, standard deviation, standard error, 90% range, and 50% range. The analyst is also able to transform the data before doing any rhythmometric analysis. Transformations already integrated in the program include square root, logarithm, inverse, data as percentage of mean, data as percentage of mesor, and elimination of values outside +/- 3 SD from the mean. When several periods are suspected to be statistically significant, a multiple-component analysis can be also used by the concomitant least-squares fit of several harmonics. The program allows the simultaneous analysis of several periods in several variables from several individuals, with limitations depending solely on internal memory availability and speed requirements from the user. When series from different subjects or different variables in the same subject are available for analysis, a parameter test also included in the program can be used for comparison of rhythm characteristics at any given period. All information required in a single analysis is given by the analyst in the form of self-explanatory commands grouped in different "menus."(ABSTRACT TRUNCATED AT 400 WORDS)

Biometry↗

Efficient solid state NMR powder simulations using SMP and MPP parallel computation.

Methods for parallel simulation of solid state NMR powder spectra are presented for both shared and distributed memory parallel supercomputers. For shared memory architectures the performance of simulation programs implementing the OpenMP application programming interface is evaluated. It is demonstrated that the design of correct and efficient shared memory parallel programs is difficult as the performance depends on data locality and cache memory effects. The distributed memory parallel programming model is examined for simulation programs using the MPI message passing interface. The results reveal that both shared and distributed memory parallel computation are very efficient with an almost perfect application speedup and may be applied to the most advanced powder simulations.

Journal Article↗

A computer-based method of selecting clones for a full-length cDNA project: simultaneous collection of negligibly redundant and variant cDNAs.

We describe a computer-based method that selects representative clones for full-length sequencing in a full-length cDNA project. Our method classifies end sequences using two kinds of criteria, grouping, and clustering. Grouping places together variant cDNAs, family genes, and cDNAs with sequencing errors. Clustering separates those cDNA clones into distinct clusters. The full-length sequences of the clones selected by grouping are determined preferentially, and then the sequences selected by clustering are determined. Grouping reduced the number of rice cDNA clones for full-length sequencing to 21% and mouse cDNA clones to 25%. Rice full-length sequences selected by grouping showed a 1.07-fold redundancy. Mouse full-length sequences showed a 1.04-fold redundancy, which can be reduced by approximately 30% from the selection using our previous method. To estimate the coverage of unique genes, we used FANTOM (Functional Annotation of RIKEN Mouse cDNA Clones) clusters (). Grouping covered almost all unique genes (93% of FANTOM clusters), and clustering covered all genes. Therefore, our method is useful for the selection of appropriate representative clones for full-length sequencing, thereby greatly reducing the cost, labor, and time necessary for this process.

Animals↗

A fast method for computing high-significance disease association in large population-based studies.

Because of rapid progress in genotyping techniques, many large-scale, genomewide disease-association studies are now under way. Typically, the disorders examined are multifactorial, and, therefore, researchers seeking association must consider interactions among loci and between loci and other factors. One of the challenges of large disease-association studies is obtaining accurate estimates of the significance of discovered associations. The linkage disequilibrium between SNPs makes the tests highly dependent, and dependency worsens when interactions are tested. The standard way of assigning significance (P value) is by a permutation test. Unfortunately, in large studies, it is prohibitively slow to compute low P values by this method. We present here a faster algorithm for accurately calculating low P values in case-control association studies. Unlike with several previous methods, we do not assume a specific distribution of the traits, given the genotypes. Our method is based on importance sampling and on accounting for the decay in linkage disequilibrium along the chromosome. The algorithm is dramatically faster than the standard permutation test. On data sets mimicking medium-to-large association studies, it speeds up computation by a factor of 5,000-100,000, sometimes reducing running times from years to minutes. Thus, our method significantly increases the problem-size range for which accurate, meaningful association results are attainable.

Algorithms↗

Computer-simulation methods in human linkage analysis.

In human linkage analysis, many statistical problems without analytical solution could be solved by ad hoc Monte Carlo procedures were efficient computer-simulation methods available for members of family pedigrees. In this paper, a general method is described for randomly generating genotypes at one or more marker loci, given observed phenotypes at loci linked among themselves and with the markers. The method is based on a well-known expansion of the multivariate probability of genotypes, given phenotypes, into a product of conditional univariate probabilities that may be viewed as corresponding to conditionally independent univariate random variables. This representation allows a recursive evaluation of the univariate probabilities that can be implemented in a surprisingly simple manner by carrying out successive "risk calculations" with respect to marker genotypes, given observed phenotypes and marker genotypes already generated. Potential applications to various unresolved problems are discussed. The method is applied to 28 published families analyzed for genetic linkage between hereditary motor and sensory neuropathy I and the Duffy (FY) blood group locus and confirms heterogeneity of hereditary motor and sensory neuropathy I. An implementation of the simulation methods developed in the LINKAGE program package will be available later in 1989.

Chromosomes, Human↗

[Studies on Cnidium fruits by stereological method and computer image analysis].

The fruits, pollen grains, vascular bundles, stomata and endosperm cells of 4 Cnidium species were studied and determined by stereological method and computer image analysis technique. Statistical data were presented. In the volume of fruit and the area of vascular bundle, Cnidium dahuricum is the biggest, then C. salinum, C. japonicum and C. monnieri successively. In the volume of pollen grain,C. salinum is the biggest, followed by C. dahuricum, C. japonicum and C. monnieri in succession. In the volume of endosperm cell, C. dahuricum is also the biggest, and then C. japonicum, C. salinum and C. monnieri in order.

Fruit↗

Assessing transcription factor motif drift from noisy decoy sequences.

Genome scale identification of transcription factor binding sites (TFBS) is fundamental to understanding the complexities of mRNA expression at both the cell and organismal levels. While high-throughput experimental methods provide associations between transcription factors and the genes they regulate under a specified experimental condition, computational methods are still required to pinpoint the exact location of binding. Moreover, since the binding site is an intrinsic property of the promoter region, computational methods are in principle more general than condition dependent experimental methods. Computational identification of TFBSs is complicated in at least two different ways. First, transcription factors bind a heterogeneous distribution of sites and therefore have a distribution of affinities. Second, the set of sequences for which a common site is to be determined do not all have a site for the TF of interest. In this paper, we evaluate the robustness of TFBS identification with respect to both effects. We show addition of upstream regions that do not have the TFBS destroy the specificity of the predicted binding site. We also propose a method to calculate the distance between position weight matrices that can be used to measure "drift'' from the canonical binding site. The results presented here could be useful in developing future transcription factor binding site identification algorithms.

Algorithms↗

Computer-based methods for the mouse full-length cDNA encyclopedia: real-time sequence clustering for construction of a nonredundant cDNA library.

We developed computer-based methods for constructing a nonredundant mouse full-length cDNA library. Our cDNA library construction process comprises assessment of library quality, sequencing the 3' ends of inserts and clustering, and completing a re-array to generate a nonredundant library from a redundant one. After the cDNA libraries are generated, we sequence the 5' ends of the inserts to check the quality of the library; then we determine the sequencing priority of each library. Selected libraries undergo large-scale sequencing of the 3' ends of the inserts and clustering of the tag sequences. After clustering, the nonredundant library is constructed from the original libraries, which have redundant clones. All libraries, plates, clones, sequences, and clusters are uniquely identified, and all information is saved in the database according to this identifier. At press time, our system has been in place for the past two years; we have clustered 939,725 3' end sequences into 127,385 groups from 227 cDNA libraries/sublibraries (see http://genome.gse.riken.go.jp/).

5' Untranslated Regions↗

A method of computing the intersurface distance between opposing teeth.

Conventional methods of clinically evaluating tooth occlusion, employing articulating papers and bite impression materials, do not permit a quantitative analysis the occlusion. To overcome this, the shapes of opposing teeth are digitized in three-dimensions and intersurface distances are evaluated in detail. Computational geometry deals with this as a closest-point problem, i.e. the closest points from each surface point must be found by scanning the opposing surface. This process is, in most cases, quite time consuming. In order to expedite the computations required, we present here an algorithm for this determination, whereby the scan area is successively reduced without complicating the scanning procedure, thus accelerating the search. The efficiency of this algorithm was experimentally proved by comparing its computation time with that of the algorithm previously used.

Algorithms↗

Comparison of a computer based method and the classical manual method for radiographic joint space width assessment in hip osteoarthritis.

OBJECTIVE: To compare the intraobserver reliability and the sensitivity to change of 2 techniques evaluating the cartilage breakdown in hip osteoarthritis (OA). METHODS DESIGN: 3 year longitudinal study. PARTICIPANTS: patients with painful hip OA. OUTCOME: coxofemoral joint space width (JSW) at baseline and at 3 year followup was measured on anteroposterior weight-bearing radiographs by 2 methods: a manual method to obtain JSW at the narrowest point (minimal JSW) using a 0.1 mm graduated magnifying glass and a computer based method to obtain minimal and average JSW. STATISTICAL ANALYSIS: Two assessments, at one month interval, of each pair of films; evaluation of the intraobserver reliability using the intraclass coefficient of correlation, and the Bland and Altman approach, obtaining the smallest detectable difference (SDD). For each technique, percentage of progressors was evaluated, i.e., the percentage of patients with change greater than the SDD. Evaluation of sensitivity to change was performed using the standardized response mean (SRM), with 95% CI calculated using the jackknife method. RESULTS: Twenty-five pairs of films were evaluated. There were no statistically significant differences between the 3 analyses in the calculated intraclass coefficients of correlation, percentage of progressors, or SRM. CONCLUSION: These results suggest that both techniques are reliable and sensitive enough to detect changes in a relevant percentage of patients with hip OA after a 3 year followup.

Aged↗

Special computer graphical method for detection of myocardial infarction.

The application of computer graphics for detection of myocardial infarction is reviewed and a special method is described. It is based on construction of two isointegral maps (Q wave map and ST segment map) realized in contour representation and using the Selvester distribution of the left ventricle.

Computer Graphics↗

Computer-aided dosage form design. II. Methods for defining a zero-order sustained-release delivery system of maximum formulating flexibility.

Classical methods employing pharmacokinetic data to calculate zero-order release rates for sustained release products require that a constant-rate drug delivery system must have a duration which is exactly equal to the desired dosage interval. This traditional approach fails to establish the minimum acceptable duration and also fails to provide any flexibility in the formulation goal. While it does calculate one pair of duration and dose values, there are infinite pairs of values capable of maintaining the desired plasma concentrations using the selected dosing interval. In the current method, computer simulations are used to establish the boundary conditions within which any pair of duration and dose values will maintain the desired levels when administered on the chosen dosing interval. By comparing the boundary conditions for every subject in a group, a single set of conditions which would work for the entire group can be selected. These final limits represent the broadest specifications for zero-order drug delivery system design for that particular drug combined with the plasma concentration goals and the desired dosing interval. The method is illustrated using theophylline pharmacokinetics.

Adult↗

On the direct Fourier method for computer tomography.

The paper considers the direct Fourier methods (DFM's) for reconstructing an image from its given X-ray projections. The main purpose here is to use concepts from numerical analysis to estimate the errors in the methods. We also suggest an alternative to the interpolations involved in the DFM's and estimate the number of terms involved. Realizing that one of the main reasons for the degradation of the quality of the reconstruction is the Gibbs phenomenon, we suggest a way to overcome this difficulty and give numerical evidence of its efficacy.

Algorithms↗

Press-to-zirconia: a case study utilizing cad/cam technology and the wax injection method.

Computer technology is increasingly becoming an effective tool in restorative dentistry. Whether chairside or laboratory-fabricated, computer-aided design/ computer-aided manufacturing (CAD/CAM) engineering has become widely accepted in the fabrication of dental restorations. Zirconia has been successfully used in medical therapy and is now considered a viable alternative to metal as a substrate in single- and multiple-unit fixed restorations. Proper tooth preparation and handling of this material is essential for a successful outcome. This presentation will discuss how CAD/CAM systems can utilize zirconia frameworks to provide treatment of a maxillary anterior restoration.

Computer-Aided Design↗

Standardized testing of patient management skills. A computer-based method.

Clinical cases can be simulated by using computers with programs designed to provide all of the information required to make a diagnosis and initiate a treatment plan. The cases are uncued, simulate time, and require sound clinical judgment for management. All transactions between the physician and case are recorded so that each action can be evaluated from the standpoint of timeliness, sequence, appropriateness, risk, and cost. Results from field studies indicate that the performance by residents in the management of clinical case simulations measures more than knowledge.

Clinical Competence↗