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PubMed2004

Metabonomics and its role in drug development and disease diagnosis.

This article describes the new approach known as metabonomics, a combination of data-rich analytical chemistry and chemometrics for profiling metabolism in complex systems. Two main analytical approaches have been used, namely nuclear magnetic resonance spectroscopy and mass spectrometry, however, most literature on mammalian systems pertains to nuclear magnetic resonance spectroscopy. The technologies are reviewed in relation to other -omics, and how these methods can be applied to drug safety assessment, characterization of genetically modified animal models of disease, diagnosis of human disease and drug therapy monitoring is demonstrated.

Animals↗
PubMed2004

Confidence levels for the comparison of microarray experiments.

A common experimental strategy utilizing microarrays is to develop a signature of genes responding to some treatment in a model system, and then ask whether the same genes respond in an analogous way in a more natural and uncontrolled environment. In statistical terms, the question posed is whether genes score similarly on some statistical test in two independent data sets. Approaches to this problem ignoring gene/gene correlations common to all microarray data sets are known to give overstated statistical confidence levels. Permutation approaches have been proposed to give more accurate confidence levels, but can not be applied when sample sizes are small. Here we argue that the product moment correlation between test statistics in the two experiments is an ideal measure for summarizing concordance between the experiments, as confidence levels accounting for intergene correlations depend only on a single number - the average squared correlation between gene pairs in the data set. The resulting null standard deviation is shown to vary by less than a factor of two over six distinct experimental data sets, suggesting that a universal constant may be used for this quantity. We show how a hidden assumption of the permutation approach may lead to incorrect p-values, while the analytic approach presented here is shown to be resistant to this assumption.

Journal Article↗
PubMed1993

A study on client selection criteria and services for home health care--C.V.A., head and spinal cord injury in patients.

This study was done to clarify the types of health care that should be offered. It focus on developing client selection criteria based on the needs of inpatients with cerebral vascular diseases, head injuries and spinal cord injuries. Two research methods were adopted. One was a methodological approach for developing client selection criteria and the other was analytical approach to clarify the types of services to be offered. From the research findings, the following summarized conclusions have been drawn. 1. The problem and item criteria used to select patients requiring home health care, namely, a prototype evaluation tool, consisted of 12 items in four areas; physiological status, functional status, psychological status and environmental status. After assessing each item at three levels, the categorization was done according to the classification criteria. The item internal consistency of the completed tool was .8358, .8390, the interrater reliability was in the range of 84 percent-98 percent and the classification consistency was 92 percent. As external criteria, the relationship of the prototype tool to the Health Status Scale, the Barthel Index of Functional Status Assessing Devices and the number of health problems of the patient was examined and all were found to be statistically significant, verifying the validity of the tool. 2. Using the tool to classify the inpatients according to the established client selection criteria, 84.2 percent were classified as patients requiring home health care, 8.8 percent were assessed as suitable for outpatient care and 7.0 percent were assessed as patients needing to be hospitalized. 3. Clients assessed as requiring home health care had 72 different kinds of health problems, which could be classified into four categories; 54 types of physiological status problems, 8, psychological, 6, functional and 4, environmental status problems. For each problem, the percentage of patients who suffered from the disorders ranged from 2.1 percent-66 percent. More than half of the subjects had problems related to urination, paralysis, contracture or locomotion. For the physiological category, many of the health problems were due to disorders of muscles and bone, whereas skin and breathing disorders were relatively low. The mean number of health problems in this category as 11.1. 4. Reviewing the literature, it was found that home health care consisted of 10 activity areas, namely, sanitation, nutrition, breathing, skin, body temperature maintenance, medication, assessment and observation, education and counselling.(ABSTRACT TRUNCATED AT 400 WORDS)

Cerebrovascular Disorders↗
PubMed2000

Comparison of packed-column supercritical fluid chromatography--tandem mass spectrometry with liquid chromatography--tandem mass spectrometry for bioanalytical determination of (R)- and (S)-ketoprofen in human plasma following automated 96-well solid-phase extraction.

The popularity of packed-column supercritical fluid, subcritical fluid, and enhanced fluidity liquid chromatographies (pcSFC) for enantiomeric separations has increased steadily over the past few years. The addition of a significant amount (typically 20-95%) of a viscosity lowering agent, such as carbon dioxide, to the mobile phase provides a number of advantages for chiral separations. For example, higher mobile-phase flow rates can often be attained without a concomitant loss in chromatographic efficiency since diffusion coefficients, and optimum velocities, are typically higher in pcSFC. Ultratrace enantioselective quantitation of drugs in biomatrixes is an ideal application for these chromatographic attributes. To demonstrate the utility of this approach, a pcSFC tandem mass spectrometry (pcSFC-MS/MS) method was compared to a LC-MS/MS method for quantitation of the (R)- and (S)-enantiomers of ketoprofen (kt), a potent nonsteroidal, anti-inflammatory drug, in human plasma. After preparation using automated solid-phase extraction in the 96-well format, kt enantiomers were separated on a Chirex 3005 analytical column using isocratic conditions. Validation data and study sample data from patients dosed with either orally or topically administered ketoprofen were generated using both pcSFC and LC as the chromatographic methods to compare and contrast these analytical approaches. Generally, most analytical attributes, including specificity, linearity, sensitivity, accuracy, precision, and ruggedness, for both of these methods were comparable with the exception that the pcSFC separation provided a roughly 3-fold reduction in analysis time. A 2.3-min pcSFC separation and a 6.5-min LC separation provided equivalent, near-baseline-resolved peaks, demonstrating a significant time savings for analysis of large batch pharmacokinetic samples using pcSFC.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2004

Comprehensive decision analytical modelling in economic evaluation: a Bayesian approach.

Decision analytical models are widely used in economic evaluation of health care interventions with the objective of generating valuable information to assist health policy decision-makers to allocate scarce health care resources efficiently. The whole decision modelling process can be summarised in four stages: (i) a systematic review of the relevant data (including meta-analyses), (ii) estimation of all inputs into the model (including effectiveness, transition probabilities and costs), (iii) sensitivity analysis for data and model specifications, and (iv) evaluation of the model. The aim of this paper is to demonstrate how the individual components of decision modelling, outlined above, may be addressed simultaneously in one coherent Bayesian model (sometimes known as a comprehensive decision analytical model) and evaluated using Markov Chain Monte Carlo simulation implemented in the specialist software WinBUGS. To illustrate the method described, it is applied to two illustrative examples: (1) The prophylactic use of neurominidase inhibitors for the prevention of influenza. (2) The use of taxanes for the second-line treatment of advanced breast cancer. The advantages of integrating the four stages outlined into one comprehensive decision analytical model, compared to the conventional 'two-stage' approach, are discussed.

Adolescent↗
PubMed1989

Studies on anabolic steroids. I. Integrated methodological approach to the gas chromatographic-mass spectrometric analysis of anabolic steroid metabolites in urine.

The analytical and methodological imperatives for large-scale and routine gas chromatographic-mass spectrometric screening of anabolic steroid urinary metabolites are described. Several aspects of their isolation, enzymatic hydrolysis, derivatization and metabolism in humans are discussed. Gas chromatographic-mass spectrometric data illustrating artifacts arising from enzymatic hydrolysis of 3 beta-ol-5-en steroids, and describing new metabolites of boldenone, methanedienone and stanozolol, as well as the conversion of norethisterone into 19-nortestosterone metabolites through de-ethylation at C-17, are presented. The analytical approach developed for gas chromatographic-mass spectrometric screening of anabolic steroids is based on the sequential selection-ion monitoring of specific and discrete ion groups characteristic to the steroids of interest under high-resolution chromatographic conditions. The major analytical and methodological requirements necessary to provide irrefutable evidence, in the case where the presence of a synthetic anabolic steroid or a testosterone to epitestosterone ratio higher than 6:1 is suspected in a given urine specimen, are also discussed.

Anabolic Agents↗
PubMedDate not supplied

[Gastrin tissue levels in patients with peptic ulcer: a different methodological approach].

The function of G cells has been mainly evaluated by serum gastrin. A different analytical approach considers the direct determination of gastrin levels (ng/g of wet tissue) in perendoscopic biopsies, but, up to now, the results are contradictory. In the present study we evaluated, by means of a RIA method, the concentration of gastrin (ng/g of protein nitrogen) in homogenized gastroduodenal biopsies in 127 patients with peptic ulcer and in 12 dyspeptic patients. The results demonstrated: 1) a significant gradient of gastrin concentrations among the different anatomical sites, according to the distribution of the G cells; 2) a correlation with serum gastrin levels; 3) a good equivalence of gastrin content in adjacent biopsy specimens. This preliminary report indicates that it is possible directly quantitate tissue levels of gastrin by means of an accurate and simple method.

Adult↗
PubMed2002

Metapopulation models for extinction threshold in spatially correlated landscapes.

Simple analytical models assuming homogeneous space have been used to examine the effects of habitat loss and fragmentation on metapopulation size. The models predict an extinction threshold, a critical amount of suitable habitat below which the metapopulation goes deterministically extinct. The consequences of non-random loss of habitat for species with localized dispersal have been studied mainly numerically. In this paper, we present two analytical approaches to the study of habitat loss and its metapopulation dynamic consequences incorporating spatial correlation in both metapopulation dynamics as well as in the pattern of habitat destruction. One approach is based on a measure called metapopulation capacity, given by the dominant eigenvalue of a "landscape" matrix, which encapsulates the effects of landscape structure on population extinctions and colonizations. The other approach is based on pair approximation. These models allow us to examine analytically the effects of spatial structure in habitat loss on the equilibrium metapopulation size and the threshold condition for persistence. In contrast to the pair approximation based approaches, the metapopulation capacity based approach allows us to consider species with long as well as short dispersal range and landscapes with spatial correlation at different scales. The two methods make dissimilar assumptions, but the broad conclusions concerning the consequences of spatial correlation in the landscape structure are the same. Our results show that increasing correlation in the spatial arrangement of the remaining habitat increases patch occupancy, that this increase is more evident for species with short-range than long-range dispersal, and that to be most beneficial for metapopulation size, the range of spatial correlation in landscape structure should be at least a few times greater than the dispersal range of the species.

Algorithms↗
PubMed1996

Sensitive methods to study human apolipoprotein B metabolism using stable isotope-labeled amino acids.

The objective of the study was to develop a sensitive method using stable isotope-labeled tracers that would permit the determination of apolipoprotein B (apoB) metabolism in very low-density lipoprotein subfractions (VLDL1, Sf 60-400; VLDL2, Sf 20-60), intermediate-density lipoprotein (IDL, Sf 12-20), and low-density lipoprotein (LDL, Sf 0-12). Six normolipidemic subjects were given trideuterated leucine, and its clearance from plasma and appearance in the four apoB-containing lipoprotein fractions were followed by use of a highly sensitive gas chromatography-mass spectrometry technique in which the m + 3-to-m + 2 ion ratio was selectively monitored. This analytic approach permitted the precise measurement of low enrichments in IDL and LDL and extension of the turnover out to 250-300 h. A compartmental model was developed to derive rate constants from the plasma and apoB enrichment curves. The model was uniquely identifiable once parameter dependencies had been introduced to reduce the number of unknowns. Values were obtained for apoB input into all lipoprotein density intervals, together with rates of interconversion and catabolism; these agreed well with results from radioiodinated tracer experiments. An alternative model structure was also explored in which input occurred only into VLDL1. Altering the protocol of tracer administration (bolus vs. primed constant infusion) and dose (over a 10-fold range) had no influence on the results obtained. The analytic and modeling approach described will permit stable isotopes to be used to elucidate key features of apoB metabolism in normal and pathological states.

Adult↗
PubMed2005

[The application of structural equation model approach in epidemiological research].

OBJECTIVE: To discuss application of structural equation model (SEM) approach in epidemiological research. METHODS: A brief overview on major components of SEM, statistical assumptions underlying the use of SEM, and current software available to users and how SEM can be used were discussed through a practical epidemiological research project. RESULTS: Advantages of SEM comparing with conventional epidemiological approach were shown. SEM, having the nature of comprehensive thinking and analytic approach, not only exploring the association between factors and diseases but also among factors. It also served a confirmatory, rather than exploratory approach on data modeling, as well as having the capability of correcting estimates by separating measurement error from the equations, to provide modeling the latent variables. CONCLUSION: SEM approach could be used in epidemiological research as having some advantages comparing with conventional epidemiological approaches.

Epidemiologic Methods↗
PubMedDate not supplied

The measurement and integration of behavioral variables: aggregation and complexity as important issues.

The measurement of motor activity in animals is central to the description of animal behavior in general. A wide variety of measurement procedures have been used in the past and various researchers have suggested that multiple measures or "behavioral profiles" be used to describe the effects of various types of experimental manipulations. However, many of the measures used have been found to be unreliable. The principle of aggregation, which states that the sum of a set of multiple measurements is a more stable and representative estimator than any single measurement, allows for construction of variables which are more reliable and have greater generalizability. Examples are provided which show that the application of aggregation can substantially increase correlations within variables over time as well as between variables. Application of factor analytic procedures to multivariate motor activity data is suggested to be a useful method of reducing many variables into fewer, more complex variables, which have greater phenomenon realism. Examples of the application of such factor analytic approaches are provided, both for the traditional two-way factor analytic methods as well as a more recent procedure (PARAFAC model) developed for analysis of three-way longitudinal data sets. It is suggested that multivariate analytic procedures are appropriate for data reduction and description in the area of behavioral neuroscience.

Animals↗
PubMed2001

A hierarchical regression approach to meta-analysis of diagnostic test accuracy evaluations.

An important quality of meta-analytic models for research synthesis is their ability to account for both within- and between-study variability. Currently available meta-analytic approaches for studies of diagnostic test accuracy work primarily within a fixed-effects framework. In this paper we describe a hierarchical regression model for meta-analysis of studies reporting estimates of test sensitivity and specificity. The model allows more between- and within-study variability than fixed-effect approaches, by allowing both test stringency and test accuracy to vary across studies. It is also possible to examine the effects of study specific covariates. Estimates are computed using Markov Chain Monte Carlo simulation with publicly available software (BUGS). This estimation method allows flexibility in the choice of summary statistics. We demonstrate the advantages of this modelling approach using a recently published meta-analysis comparing three tests used to detect nodal metastasis of cervical cancer.

Computer Simulation↗
PubMed1985

Two MMPI approaches for identifying alcoholics: evaluation and implications for further research.

Though contrasting MMPI approaches yield opposing conclusions regarding personalities of alcoholics, the relative efficacy of the approaches has not been evaluated. In this study of 309 domiciliary patients, the alcoholism scale and cluster analytic approaches were compared with respect to the identification of alcoholics and excessive-drinking subjects. The MacAndrew Alcoholism Scale significantly identified alcoholics; however, there was no identification with the profiles of the clinical scales generated by the cluster analytic technique. The conclusions suggest the greater efficacy of the alcoholism scale approach and suggest that the clustering strategy might be more fruitfully applied to alcoholism scales.

Alcohol Drinking↗
PubMed2003

Approach for identifying glaucomatous optic nerve progression by scanning laser tomography.

PURPOSE: To describe and test an analytical approach for identifying glaucomatous optic nerve change by scanning laser tomography. METHODS: The approach (1). analyzed 30 degrees sectors of rim area by (2). a novel and reproducible experimental reference plane, (3). estimated and accounted for measurement variability in each sector, and (4). required that any change exceeding variability in a single (positive) test should be confirmed as repeatable by a criterion requiring two of three consecutive tests to be positive. The sensitivity and false-positive rate of a single positive test and the two-of-three criterion were assessed in image series of one eye each of 20 ocular hypertension patients who converted to glaucoma (referred to as converters) who had unambiguous disease progression, and in one eye each of 20 normal control subjects. RESULTS: Eighteen of 20 (90% sensitivity) converters and 7 of 20 (35% false-positive responses) control subjects had single positive test results, but with confirmation by the two-of-three criterion, the false-positive rate improved to 5% (1/20) whereas sensitivity was relatively preserved at 85% (17/20). CONCLUSIONS: Estimates of rim area variability in each sector of each nerve allowed change consistent with disease progression to be distinguished from measurement variability. Confirming that change is repeatable by the criterion used in the study resulted in considerably fewer false-positive responses than did testing without confirmation, but with sensitivity not significantly compromised in the former. By this approach, eyes with progressive glaucoma could be distinguished from unchanging normal control eyes.

Diagnostic Techniques, Ophthalmological↗
PubMed2004

Identification and determination of phase II nabumetone metabolites by high-performance liquid chromatography with photodiode array and mass spectrometric detection.

Chromatographic analyses play an important role in the identification and determination of phase I and phase II drug metabolites. While the chemical standards of phase I metabolites are usually available from commercial sources or by various synthetic, degradation or isolation methods, the phase II drug metabolites have usually more complicated structures, their standards are in general inaccessible and their identification and determination require a comprehensive analytical approach involving the use of xenobiochemical methods and the employment of hyphenated analytical techniques. In this work, various high-performance liquid chromatography (HPLC) methods were employed in the evaluation of xenobiochemical experiments leading to the identification and determination of phase II nabumetone metabolites. Optimal conditions for the quantitative enzymatic deconjugation of phase II metabolites were found for the samples of minipig bile, small intestine contents and urine. Comparative HPLC analyses of the samples of above-mentioned biomatrices and of the same biomatrices after their enzymatic treatment using beta-glucuronidase and arylsulfatase afforded the qualitative and quantitative information about phase II nabumetone metabolites. Hereby, three principal phase II nabumetone metabolites (ether glucuronides) were discovered in minipig's body fluids and their structures were confirmed using liquid chromatography (LC)-electrospray ionization mass spectrometric (MS) analyses.

Animals↗
PubMed2006

Sample size planning for the standardized mean difference: accuracy in parameter estimation via narrow confidence intervals.

Methods for planning sample size (SS) for the standardized mean difference so that a narrow confidence interval (CI) can be obtained via the accuracy in parameter estimation (AIPE) approach are developed. One method plans SS so that the expected width of the CI is sufficiently narrow. A modification adjusts the SS so that the obtained CI is no wider than desired with some specified degree of certainty (e.g., 99% certain the 95% CI will be no wider than omega). The rationale of the AIPE approach to SS planning is given, as is a discussion of the analytic approach to CI formation for the population standardized mean difference. Tables with values of necessary SS are provided. The freely available Methods for the Behavioral, Educational, and Social Sciences (K. Kelley, 2006a) R (R Development Core Team, 2006) software package easily implements the methods discussed.

Confidence Intervals↗
PubMed2001

A marginal likelihood approach for estimating penetrance from kin-cohort designs.

The kin-cohort design is a promising alternative to traditional cohort or case-control designs for estimating penetrance of an identified rare autosomal mutation. In this design, a suitably selected sample of participants provides genotype and detailed family history information on the disease of interest. To estimate penetrance of the mutation, we consider a marginal likelihood approach that is computationally simple to implement, more flexible than the original analytic approach proposed by Wacholder et al. (1998, American Journal of Epidemiology 148, 623-629), and more robust than the likelihood approach considered by Gail et al. (1999, Genetic Epidemiology 16, 15-39) to presence of residual familial correlation. We study the trade-off between robustness and efficiency using simulation experiments. The method is illustrated by analysis of the data from the Washington Ashkenazi Study.

Algorithms↗
PubMed2000

[Planning of epidemiologic studies using the example of parasitic diseases].

Epidemiology is concerned with the study of diseases and risk factors for diseases in populations. Livestock related studies require that the term disease is extended to cover all conditions that directly or indirectly may affect the economic, social and ecological value of livestock or constitute a public health risk. The objectives of epidemiologic studies range from the quantification of traits, e.g., prevalence of a disease in a population (descriptive approach), to the analysis of correlation between diseases and putative risk factors (analytic approach). The type of epidemiologic study must be selected accordingly. In this paper we present the most important types of epidemiologic studies using example data. Our aim is to give an orientation for the planning of epidemiologic studies.

Animals↗