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PubMed2026

Critical insights on the application of the theory of planned behaviour to food handlers' food safety practices.

Foodborne diseases remain a significant public health concern, often linked to unsafe food-handling practices. The Theory of Planned Behaviour (TPB) is widely used to predict and explain food safety behaviours, yet its application in this field has not been systematically and in-depth evaluated. This review evaluated how the TPB has been applied to study food handlers' behaviour, focusing on methodological approaches, use of the TACT (Target, Action, Context, and Time) framework, validity, elicitation studies, and reliability. Seventeen studies were included following a systematic search of four databases (Scopus, Web of Science, Wiley Online Library, and Taylor & Francis Online). Data were extracted on behaviour definition, aim of study, main findings, use of indirect and direct TPB measures, use of elicitation studies, internal consistency, content validation, analytical methods used, and any extensions to the original TPB framework. Key elements related to adherence to core TPB principles and measurement practices were extracted using a Checklist. Most studies used direct measures of TPB constructs, and only a few reported procedures for content validation. Considerable variability was found in the reporting of key measurement and psychometric practices. Five studies fully applied the TACT framework, while nine incorporated additional factors such as knowledge and moral norms. Elicitation studies were conducted in five cases where indirect measures were employed. Analytical approaches were mainly based on multiple linear regression, with limited use of more advanced techniques such as structural equation modeling. Twelve studies reported internal consistency results. Overall, the review highlights opportunities to strengthen methodological practices in future TPB research on food safety. Greater attention to conducting and reporting content validation, full application of the TACT framework, reporting of internal consistency, and consistent inclusion of elicitation studies when using indirect measures may enhance transparency, reinforcing the credibility and trustworthiness of research findings. A major methodological limitation of this review was that screening and data extraction were conducted by a single reviewer and no formal quality or risk-of-bias assessment of the included studies was performed. Despite these limitations, the findings provide practical guidance for the development and validation of TPB-based questionnaires and may support more robust food safety research, interventions, and policy initiatives aimed at improving food handlers' practices.

Humans↗

PubMed2005

Synaptic shot noise and conductance fluctuations affect the membrane voltage with equal significance.

The subthreshold membrane voltage of a neuron in active cortical tissue is a fluctuating quantity with a distribution that reflects the firing statistics of the presynaptic population. It was recently found that conductance-based synaptic drive can lead to distributions with a significant skew. Here it is demonstrated that the underlying shot noise caused by Poissonian spike arrival also skews the membrane distribution, but in the opposite sense. Using a perturbative method, we analyze the effects of shot noise on the distribution of synaptic conductances and calculate the consequent voltage distribution. To first order in the perturbation theory, the voltage distribution is a gaussian modulated by a prefactor that captures the skew. The gaussian component is identical to distributions derived using current-based models with an effective membrane time constant. The well-known effective-time-constant approximation can therefore be identified as the leading-order solution to the full conductance-based model. The higher-order modulatory prefactor containing the skew comprises terms due to both shot noise and conductance fluctuations. The diffusion approximation misses these shot-noise effects implying that analytical approaches such as the Fokker-Planck equation or simulation with filtered white noise cannot be used to improve on the gaussian approximation. It is further demonstrated that quantities used for fitting theory to experiment, such as the voltage mean and variance, are robust against these non-Gaussian effects. The effective-time-constant approximation is therefore relevant to experiment and provides a simple analytic base on which other pertinent biological details may be added.

Action Potentials↗

PubMed1998

Retrieval dynamics in oscillator neural networks.

We present an analytical approach that allows us to treat the long-time behavior of the recalling process in an oscillator neural network. It is well known that in coupled oscillatory neuronal systems, under suitable conditions, the original dynamics can be reduced to a simpler phase dynamics. In this description, the phases of the oscillators can be regarded as the timings of the neuronal spikes. To attempt an analytical treatment of the recalling dynamics of such a system, we study a simplified model in which we discretize time and assume a synchronous updating rule. The theoretical results show that the retrieval dynamics is described by recursion equations for some macroscopic parameters, such as an overlap with the retrieval pattern. We then treat the noise components in the local field, which arise from the learning of the unretrieved patterns, as gaussian variables. However, we take account of the temporal correlation between these noise components at different times. In particular, we find that this correlation is essential for correctly predicting the behavior of the retrieval process in the case of autoassociative memory. From the derived equations, the maximal storage capacity and the basin of attraction are calculated and graphically displayed. We also consider the more general case that the network retrieves an ordered sequence of phase patterns. In both cases, the basin of attraction remains sufficiently wide to recall the memorized pattern from a noisy one, even near saturation. The validity of these theoretical results is supported by numerical simulations. We believe that this model serves as a convenient starting point for the theoretical study of retrieval dynamics in general oscillatory systems.

Artifacts↗

PubMed2004

Pharmacogenetics of lipid diseases.

The genetic basis for most of the rare lipid monogenic disorders have been elucidated, but the challenge remains in determining the combination of genes that contribute to the genetic variability in lipid levels in the general population; this has been estimated to be in the range of 40-60 per cent of the total variability. Therefore, the effect of common polymorphisms on lipid phenotypes will be greatly modulated by gene-gene and gene-environment interactions. This approach can also be used to characterise the individuality of the response to lipid-lowering therapies, whether using drugs (pharmacogenetics) or dietary interventions (nutrigenetics). In this regard, multiple studies have already described significant interactions between candidate genes for lipid and drug metabolism that modulate therapeutic response-although the outcomes of these studies have been controversial and call for more rigorous experimental design and analytical approaches. Once solid evidence about the predictive value of genetic panels is obtained, risk and therapeutic algorithms can begin to be generated that should provide an accurate measure of genetic predisposition, as well as targeted behavioural modifications or drugs of choice and personalized dosages of these drugs.

Animals↗

PubMed2006

Hypothesis testing approaches to the exon prediction problem.

MOTIVATION: Many gene identification methods assign scores to gene elements prior to their assembly into predicted genes. The scoring system is often based on log-likelihood ratios. These methods usually perform well but it is difficult to interpret how significant a score is. RESULTS: We have developed several tests of significance for the scores: (1) a sum-of-scores test (SST), (2) an intersection-union test (IUT), based on a multiple hypothesis testing interpretation of an exon's score and (3) a meta-analytical approach (MA), which combines several P-values, corresponding to the exon's parts, to yield a global P-value. We performed simulation studies, which show that the MA has better sensitivity and specificity than other methods and is easier to interpret by non-expert users. This is an improvement over other methods and is especially relevant for users who would like to predict incomplete gene sequences.

Algorithms↗

PubMed2005

Pediatric adherence: perspectives of mothers of children with HIV.

This study approached pediatric adherence practices from the perspective of mothers of children with HIV in the USA. The study aimed to articulate what is involved in the daily life experience of giving or supervising a child's HIV medication (i.e., adherence practices) in order to clarify, in more dynamic terms than is often found in adherence research, what promotes or impedes adherence. A team-based qualitative analytic approach was used to analyze the narrative responses of 71 maternal caregivers of children with HIV to interview questions regarding the activities and stresses of caring for a child with HIV. Four themes of dealing with medication on a daily basis that impacted mothers' adherence practices emerged from the analysis: (1) Mothers' attitudes and feelings related to adherence practices. (2) The impact of the medications on adherence practices. (3) Interactions of mothers and children related to adherence practices. (4) Developmental issues and responsibility for medication adherence. These themes, taken together, demonstrate the contextual and longitudinal factors that impact adherence and illustrate the complexity of influences on adherence practices. We found that adherence practices were impacted in a positive way by mothers' commitment to adherence, and in a negative way by feelings of stigma and guilt, by the effects of bereavement on children and by children adopting their mothers' attitudes about medications. The interactive process of giving medication was shaped by children's behavior, mothers' developmental expectations for children, and, for mothers with HIV, their adherence for themselves. We found that pediatric adherence often came at a cost to the caregiving mother's well-being.

Adolescent↗

PubMed2004

Quantitative characterization of edge enhancement in phase contrast x-ray imaging.

The aim of this study was to model the edge enhancement effect in in-line holography phase contrast imaging. A simple analytical approach was used to quantify refraction and interference contrasts in terms of beam energy and imaging geometry. The model was applied to predict the peak intensity and frequency of the edge enhancement for images of cylindrical fibers. The calculations were compared with measurements, and the relationship between the spatial resolution of the detector and the amplitude of the phase contrast signal was investigated. Calculations using the analytical model were in good agreement with experimental results for nylon, aluminum and copper wires of 50 to 240 microm diameter, and with numerical simulations based on Fresnel-Kirchhoff theory. A relationship between the defocusing distance and the pixel size of the image detector was established. This analytical model is a useful tool for optimizing imaging parameters in phase contrast in-line holography, including defocusing distance, detector resolution and beam energy.

Biophysical Phenomena↗

PubMedDate not supplied

Selected analytical methods used at the Centers for Disease Control and Prevention for measuring environmental pollutants in serum.

Blood serum is one of the more viable matrices used in assessing exposure to persistent environmental contaminants or their metabolites, especially those that are lipophilic. Analytic methods currently in use for this matrix usually involve liquid/liquid extraction followed by adsorption chromatography as a cleanup step, and low- or high-resolution gas chromatography with either electron-capture or mass spectrometric detection. The traditional analytic methods are labor intensive, have low sample throughput, and use excessive amounts of solvents and reagents. Two analytic approaches that address the requirements of modern laboratories more effectively are: 1) solid-phase extraction (SPE), used to analyze serum for several classes of compounds of environmental concern (e.g., polychlorinated biphenyls [PCBs], persistent pesticides, dioxins, furans, and coplanar polychlorinated biphenyls [CPCBs]), and 2) fast chromatography with a two-dimensional gas chromatographic system, which can be used in the determinative step for these types of analytes.

Benzofurans↗

PubMed1990

A simplified approach to alpha dosimetry for small spheres labelled on the surface.

The radiation doses to spheres of radii 5-200 microns, labelled on the surface with alpha emitters were studied in order to simulate conditions of radioimmunotherapy for small tumours. The absorbed fraction of emitted energy and the mean absorbed dose per alpha particle in smaller concentric spherical targets were calculated for different source sizes. Calculations were first performed for monoenergetic emissions. We then considered the dosimetry of two common alpha emitters described in the literature (211At and 212Bi). The results agree well with different analytical approaches reported in the literature, but differ from those obtained using a Monte Carlo code. The computing features have been deliberately kept to a low level to allow for simple introduction into hospital work. Comparison of the mean absorbed dose per particle between alpha and beta emitters seems to favour the use of alpha emitters. However, their high toxicity introduces a practical radiation protection problem and our mathematical dosimetric approach is valid only for homogeneous distributions of radionuclides when, in the case of alpha emitters, the total dose delivered would be much too high to be of practical use.

Alpha Particles↗

PubMed2005

The use of chemical derivatization to enhance liquid chromatography/tandem mass spectrometric determination of 1-hydroxypyrene, a biomarker for polycyclic aromatic hydrocarbons in human urine.

This article presents an analytical approach that used chemical derivatization to enhance mass spectrometric (MS) response in electrospray ionization (ESI) mode of 1-hydroxypyrene (1-OHP), a commonly used biomarker to monitor human exposure to polycyclic aromatic hydrocarbons (PAHs). The enhancement successfully enabled the desired detection of 50 pg/mL in human urine. The introduction of an MS-friendly dansyl group to 1-OHP enhanced both ionization efficiency in the ESI source and collision-activated dissociation (CAD) in the collision cell. The response increase was estimated to be at least 200-fold, and enabled the reduction of sample size to only 100 microL. The selective MS detection also facilitated a fast (run time 3 min) liquid chromatography (LC) method which successfully resolved the analyte and interferences. The sample processing procedure included enzymatic hydrolysis of glucuronide and sulfate conjugates, liquid-liquid extraction, derivatization with dansyl chloride and a final liquid-liquid extraction to generate clean extracts for LC/MS/MS analysis. This approach has been validated as sensitive, linear (50-1000 pg/mL), accurate and precise for the quantitation of 1-OHP in human urine. This is the first report of using chemical derivatization to enhance MS/MS detection with fast chromatography in the determination of 1-OHP in human urine.

Biomarkers↗

PubMed2003

Prospects for inferring pairwise relationships with single nucleotide polymorphisms.

An extraordinarily large number of single nucleotide polymorphisms (SNPs) are now available in humans as well as in other model organisms. Technological advancements may soon make it feasible to assay hundreds of SNPs in virtually any organism of interest. One potential application of SNPs is the determination of pairwise genetic relationships in populations without known pedigrees. Although microsatellites are currently the marker of choice for this purpose, the number of independently segregating microsatellite markers that can be feasibly assayed is limited. Thus, it can be difficult to distinguish reliably some classes of relationship (e.g. full-sibs from half-sibs) with microsatellite data alone. We assess, via Monte Carlo computer simulation, the potential for using a large panel of independently segregating SNPs to infer genetic relationships, following the analytical approach of Blouin et al. (1996). We have explored a 'best case scenario' in which 100 independently segregating SNPs are available. For discrimination among single-generation relationships or for the identification of parent-offspring pairs, it appears that such a panel of moderately polymorphic SNPs (minor allele frequency of 0.20) will provide discrimination power equivalent to only 16-20 independently segregating microsatellites. Although newly available analytical methods that can account for tight genetic linkage between markers will, in theory, allow improved estimation of relationships using thousands of SNPs in highly dense genomic scans, in practice such studies will only be feasible in a handful of model organisms. Given the comparable amount of effort required for the development of both types of markers, it seems that microsatellites will remain the marker of choice for relationship estimation in nonmodel organisms, at least for the foreseeable future.

Computer Simulation↗

PubMed2000

Radiation physics and genetic targeting: new directions for radiotherapy. The Douglas Lea Lecture 1999.

Radiation as a cancer treatment modality is of high physical precision but limited biological specificity. Targeted radiotherapy, the delivery of radiation to cancer cells by radioisotopes conjugated to tumour-seeking targeting agents, is a biologically attractive option but is currently effective for just a few tumour types (neuroblastoma, lymphoma) for which efficacious targeting agents are available. Radiobiological modelling and radiation microdosimetry have provided useful guidelines in choosing treatment strategies for targeted radiotherapy. These considerations generally favour the incorporation of targeted radiotherapy as one component of a multimodal treatment regimen. Very recently, gene therapy techniques have been developed which should enhance the clinical efficacy of both external beam radiation and targeted radiotherapy. Typically, non-harmful viruses are modified to incorporate therapeutic genes which cause altered cellular radiosensitivity or which facilitate the cellular uptake of targeting agents. To achieve specificity, therapeutic genes would be co-transfected with tissue-specific promoter genes causing the therapeutic genes to be expressed in cells of particular types. In laboratory models, our research group are exploring the transfection-mediated uptake of the targeting agents MIBG and sodium iodide. These approaches do not require transfection of every cell in order to cure a tumour-cells which have escaped transfection may be sterilized by radiation cross-fire from transfected neighbours. A new task for radiation microdosimetry is to quantify the cross-fire effect and to compute the efficacies of gene transfection which will be required for tumour cure. In the spirit of Douglas Lea, the analytic approach of physics can be used to illuminate and enhance developments in genetics, to the benefit of medicine.

3-Iodobenzylguanidine↗

PubMed2026

Causal relationship between asthma and hernia risk: A Mendelian randomization study.

Epidemiological associations between asthma and various hernia subtypes have been reported, but the causality and direction remain unclear. This study employs a two‑sample Mendelian randomization (MR) approach to systematically assess the causal associations between asthma and 6 hernia subtypes. Using publicly available summary data of genome-wide association studies, asthma was selected as the exposure, and diaphragmatic hernia, umbilical hernia, femoral hernia, hiatus hernia, inguinal hernia, and ventral hernia were selected as outcomes. Instrumental variables were strictly screened (F-statistic > 10). The inverse‑variance weighted method was used as the primary analytical approach, supplemented with MR Egger and weighted median methods. Sensitivity analyses included heterogeneity tests, horizontal pleiotropy tests, Steiger directionality tests, leave‑one‑out analyses, and Radial MR. Reverse MR was performed for validation. Forward MR analyses revealed a significant positive causal effect of asthma on diaphragmatic hernia (odds ratio [OR] = 1.19, 95% confidence interval [CI]: 1.08-1.31, P < .001) and a suggestive association with umbilical hernia (OR = 1.19, 95% CI: 1.05-1.34, P = .007). The umbilical hernia association was significant only by the inverse‑variance weighted method; weighted median (P = .102) and MR-Egger (P = .210) estimates were not statistically significant, and the estimate attenuated after outlier removal (confirmatory OR = 1.13, 95% CI: 1.01-1.26, P = .028). Sensitivity analyses showed no significant heterogeneity or pleiotropy. Reverse MR did not identify significant causal effects of hernias on asthma, although power limitations for certain hernia subtypes should be considered. No significant associations were observed between asthma and the other hernia subtypes, although the null findings for femoral and ventral hernias should be interpreted with caution due to limited statistical power. This study provides genetic evidence supporting asthma as a causal risk factor for diaphragmatic hernia, with a suggestive association for umbilical hernia. The diaphragmatic hernia finding was robust across multiple sensitivity analyses, whereas the umbilical hernia association was less consistent and requires further confirmation. These findings contribute to a deeper understanding of the mechanistic links between asthma and specific hernia subtypes.

Mendelian Randomization Analysis↗

PubMed1998

Analytical techniques used to study the degradation of proteins and peptides: chemical instability.

Instability of peptides and proteins can be divided into two forms: chemical and physical instability. Chemical instability is due to modification/alteration of amino acid residues. There are several types of degradation reactions responsible for this instability. Most frequently described reactions are oxidation, reduction, deamidation, hydrolysis, arginine conversion, beta-elimination and racemisation. However, any study of the degradation of a chemical substance lacks reliability when the analytical methodology, that is used is not properly validated. Especially in the investigation, where degradation processes lead to their parent compounds, validation of the analysis is pivotal for the correct interpretation of the results. It is therefore appropriate and useful to assemble an overview of degradation processes in relation to the analytical methods to monitor them. An overview like this can help investigators to make the right choices in their analytical approach of stability problems. The degradation reactions involved in peptide/protein degradation as well as the methods to monitor them are summarized and discussed.

Arginine↗

PubMed2003

Summary of Group 8: Development and extension of linkage methods.

The diverse contributions to Group 8 focus on the development and extension of linkage methods, and share themes that are organized around approaches to analysis. The themes discussed include issues of the accuracy of estimates of marker identity-by-descent (IBD) information, the influence of such IBD information on linkage detection, and methods for dealing with genetic heterogeneity and multiple testing. In addition, challenges were identified and solutions were offered for coping with some of the common problems of complex trait analysis, including trait model selection and computational compromises. Analytic approaches based on Bayesian and Monte Carlo methods were prominent, and provided optimistic results.

Bayes Theorem↗

PubMed1997

Modeling dynamic contraction of muscle using the cross-bridge theory.

During normal, voluntary movements, skeletal muscles typically contract in a highly dynamic manner; the length of the muscle and the speed of contraction change continuously. In this study, we present an approach to predict the accurate behavior of muscles for such dynamic contractions using Huxley's cross-bridge model. A numerical procedure is proposed to solye, without any assumptions, the partial differential equation that governs the attachment distribution function in Huxley's cross-bridge model. The predicted attachment distribution functions, and the corresponding force responses for shortening and stretching, were compared with those obtained using Zahalak's analytical solution and those obtained using the so-called "distribution moment model" in transient and steady-state contractions. Compared to the distribution moment model, the solutions obtained using our model are exact rather than approximate. The solutions obtained using the analytical approach and the present approach were virtually identical; however, in terms of CPU times, the present approach was 250-300 times faster than Zahalak's. From the results of this study, we concluded that the proposed solution is an exact and efficient way for solving the partial differential equation governing the cross-bridge model.

Mathematics↗

PubMed2005

Metabolic investigation in psychiatric disorders.

A multiplicity of theories have been proposed over the years that aim to conceptualize the pathophysiology of neuropsychiatric disorders, including impaired neurotransmission, viral infections, genetic mutation, energy metabolism deficiency, excitotoxicity, oxidative stress, and others. It is likely that complex disorders such as schizophrenia, bipolar disorder, and major depression are associated with multiple etiologies and pathogenetic mechanisms. In light of the interwoven biochemistry of human organs, identifying a network of multiple interacting biochemical pathways that account for the constellation of clinical and biological features would advance our understanding of these disorders. One such approach is to evaluate simultaneously the multiple metabolites in order to uncover the dynamic relations in the relevant biochemical systems. These metabolites are a group of low-molecular-weight, redox-active compounds, such as antioxidants, amino acids, catecholamines vitamins, lipids, and nucleotides, which reflect the metabolic processes, including anabolism and catabolism as well as other related cellular processes (e.g., signal transduction, regulation, detoxification, etc.). Such an analytic approach has the potential to yield valuable insights into the likely complex pathophysiological mechanisms that affect multiple metabolic pathways and thereby offer multiple windows of therapeutic opportunities.

Animals↗

PubMed2004

Identification of "insoluble" red dyewoods by high performance liquid chromatography-photodiode array detection (HPLC-PDA) fingerprinting.

The paper describes a high performance liquid chromatography-UV/Vis spectrometry detection analytical approach to the identification of some redwood species of historical importance in textile dyeing. The group of extracted dyestuffs considered as "insoluble" because of their non-aqueous or alkaline extraction conditions is present in the wood of the Pterocarpus family and Baphia nitida species. First, the crude extracts of tinctorial and related species and their chromatographic fingerprints were studied. This part of work shows that some species not yet mentioned in the literature have potential dyeing properties. Subsequent experiments performed on the redwood cargo of a 200-year-old archaeological shipwreck allowed identification of the water-logged wood species. Furthermore, the different methods of dyestuff extraction used for dyeing according to traditional recipes and their impact on analytical results were studied. They show that standard recovery obtained by acid hydrolysis of dyestuff from dyed yarns is inadequate. Hence, alternative solvent-based procedures were proposed. The identification of species in textile threads then becomes possible. The applied approach was validated by analysis of dyed reference yarns with some indications of crude material extraction mode. The employed method of analysis seems to be useful for "insoluble" wood species identification in cultural heritage artifacts as well as for phytochemical purposes, despite the fact that very few detected color compounds were chemically identified.

Chromatography, High Pressure Liquid↗