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A process analytical technology approach based on near infrared spectroscopy: tablet hardness, content uniformity, and dissolution test measurements of intact tablets.

Near infrared spectroscopy (NIRS) is a nondestructive analytical technique that enables simultaneous measurements of chemical composition (viz. the content in active pharmaceutical ingredient, API) and various physical properties (viz. tablet hardness and dissolution profile) in pharmaceutical tablets. In this work, partial least squares (PLS) calibration models and discriminant partial least squares (DPLS) classification models were constructed by using calibration sets consisting of laboratory samples alone. The laboratory samples were mixtures of the API and excipients that were pressed into tablets. API content, tablet hardness, and dissolution measurements of intact tablets were made by using three different calibration models that are fast--results can be obtained within a few seconds--, simple and robust--they involve minimal analyst intervention--, and clean--they use no toxic reagent and produce no toxic waste. Based on the results, the proposed NIR method is an effective alternative to current reference methods for the intended purpose. The advantages provided by NIR spectroscopy in this context confirm its potential for inclusion in process analytical technologies in the pharmaceutical industry.

Calibration↗

Stationary dynamics approach to analytical approximations for polymer coexistence curves.

Phase separation in polymer blends is an important process. However, the compositions of the coexisting phases can only be predicted by numerical methods. We provide simple analytical expressions which serve as good approximations for the compositions after phase separation of binary homopolymer blends. These approximations are obtained by a stationary dynamics approach: we calculate the compositions of two polymer mixtures such that the stationary diffusion between these distinguishable mixtures vanishes. For the diffusion equations we employ composition-dependent diffusion coefficients, as derived according to the slow- and fast-mode theory from the Flory-Huggins free energy. The analytical results are in good agreement with exact (numerically calculated) binodal compositions. Our coexistence curves are more accurate than some conventional approximations. Another advantage of the stationary dynamics approach is that it is not only applicable to binary polymer blends or polymer solutions, but also to symmetrical multicomponent blends. The same diffusion coefficients may be used to obtain the exact spinodal compositions in multicomponent systems.

Journal Article↗

A Process Analytical Technology approach to near-infrared process control of pharmaceutical powder blending. Part III: Quantitative near-infrared calibration for prediction of blend homogeneity and characterization of powder mixing kinetics.

The Process Analytical Technology (PAT) initiative, undertaken by the Food and Drug Administration (FDA), paves the way for improvement of drug manufacturing through real-time measurements that allow better process understanding. This study is the third and final Part in a series of studies that represent an integrated approach for real-time blend uniformity assessment using near-infrared (NIR) technology. In this study, the development of a quantitative NIR model for prediction of blending end point is presented. Process signature was built into NIR calibration models by using blend samples that were collected from actual blend experiments under different processing conditions. Evaluation of various calibration algorithms including principal component regression (PCR), partial least squares (PLS), and multi-term linear regression (MLR) was performed. It was found that linear regression, using a single wavelength, yielded optimum calibration and prediction results. The blending profiles predicted by the NIR quantitative model correlated well to those determined by the UV reference analytical method. Characterization of intra-shell versus inter-shell powder mixing kinetics and its implication in sensor positioning was also performed and will be discussed.

Calibration↗

The effect of entacapone (OR-611) on brain [18F]-6-L-fluorodopa metabolism: implications for levodopa therapy of Parkinson's disease.

We used PET and [18F]-6-L-fluorodopa ([18F]dopa) to measure the effect of a peripheral COMT inhibitor, entacapone, on the extracerebral metabolism and subsequent striatal uptake of [18F]dopa. Four parkinsonian patients and six age-matched normal controls were each scanned twice, once after carbidopa (150 mg) plus placebo and once after carbidopa (150 mg) plus entacapone (400 mg or 800 mg). Without entacapone premedication, by 90 minutes from injection, only 22% of the [18F] signal in plasma represented unmetabolized [18F]dopa (the balance being 3-O-methyl[18F]dopa). After entacapone medication, this fraction increased to 56% of the [18F] signal (p < 0.0001). We did not find any significant differences between the changes observed in patients versus controls or between those subjects who received 400 mg entacapone versus 800 mg in either this or any of the other reported measures. PET image contrast increased in all cases, reflecting an increase in the specific striatal signal ([striatum-occipital]:occipital ratio increased 38% [p < 0.0001]). Entacapone did not alter the rate of striatal uptake and decarboxylation of [18F]dopa as estimated using a graphic approach with metabolite-corrected plasma as input function to calculate the influx constant, Ki(p) (p = NS). This confirms that such an analytic approach adequately corrects for the effect of extracerebral [18F]dopa methylation. In contrast, the influx constant Ki(o) (calculated using occipital counts as the input function) increased 45% after entacapone (p < 0.0001). This demonstrates the sensitivity of this analytic approach to the presence of peripheral 3-O-methyl[18F]dopa and provides an estimate of the percentage increase in brain free [18F]dopa resulting from entacapone premedication.

Aged↗

An improved approach to the analysis of plasmid DNA breakage by decay of DNA-associated auger emitters.

PURPOSE: To assess DNA breakage by DNA-associated decay of the Auger electron emitter 125I, using an improved analytical approach. MATERIAL AND METHODS: Breakage of pBR322 plasmid DNA following incubation with DNA-binding ligand Hoechst 33258 labelled with 125I was studied by measuring the conversion of native supercoiled to relaxed and linear forms. The analytical approach that was developed considers two distinct sources of breakage: DNA damage at the site of DNA-associated Auger decay (local effect), and DNA damage from the radiation field created by all decay events in the incubation volume (external breakage). In addition, to enable application of Poisson statistics to local breakage events, relaxation events and linearisation events are considered rather than single-stranded and double-stranded breaks. RESULTS: The results indicated that a decay event of DNA-associated 125I induced relaxation and linearisation of the plasmid molecule with probabilities of 0.090 +/- 0.035 and 0.82 +/- 0.04, respectively. Addition of a radical scavenger DMSO increases the probability of relaxation to 0.15 +/- 0.02 and reduces the probability of linearisation to 0.65 +/- 0.05. CONCLUSIONS: Accurate evaluation of the local effect in plasmid breakage requires consideration of external breakage, the contribution of which depends on experimental conditions. The highly efficient production of linearisation events by (125)I-decay restricts the detection of relaxation events by the plasmid assay.

Computer Simulation↗

Analytical cytometric approaches to heterogeneous cell populations in solid tumors: a review.

The problems encountered in studying the heterogeneity of cells in solid tumors is reviewed with emphasis on the role of various analytical cytometric assays for studying both the biology and the dynamics and proliferating, quiescent and dead malignant cells in vitro and in vivo. Due to advances in cytometric technology, many interesting in vitro studies on tumor cells heterogeneity have been and will be conducted over the next several years. For example, the acidic acridine orange staining of HeLa cells in suspension culture does readily discriminate between proliferating and quiescent cells. Some of these assays have been and others will be extended to in vivo studies. However, it is obvious that either the current analytical cytometric techniques must be modified and refined to permit better resolution for the complex situation in vivo or other new analytical cytometric techniques will have to be developed before many interesting studies on tumor cell heterogeneity in vivo can be addressed with reasonable efficiency.

Acridine Orange↗

Introducing a conceptual information retrieval (IR) framework.

This is the third in the series of the articles on an application of the systems analytic approach to evaluation of information retrieval (IR). Previously terminological and evaluation problems associated with IR were identified, and it was proposed that the systems analytic approach can provide solutions to these problems. Here, after the general discussion of a systems approach, different attempts to introduce this approach into IR are presented and critiqued: modelling of IR, identifying boundaries of a system under evaluation, identifying variables under investigation; and creating evaluation frameworks. On the basis of the critique of this work, the authors present their proposal for a solution: first the IR components, their boundaries and relationships are identified, and then the two models of IR are introduced. One of the models addresses components of the IR process and relationships between them, the second one is the process model of IR.

Canada↗

The health and well-being of caregivers of children with cerebral palsy.

OBJECTIVE: Most children enjoy healthy childhoods with little need for specialized health care services. However, some children experience difficulties in early childhood and require access to and utilization of considerable health care resources over time. Although impaired motor function is the hallmark of the cerebral palsy (CP) syndromes, many children with this development disorder also experience sensory, communicative, and intellectual impairments and may have complex limitations in self-care functions. Although caregiving is a normal part of being the parent of a young child, this role takes on an entirely different significance when a child experiences functional limitations and possible long-term dependence. One of the main challenges for parents is to manage their child's chronic health problems effectively and juggle this role with the requirements of everyday living. Consequently, the task of caring for a child with complex disabilities at home might be somewhat daunting for caregivers. The provision of such care may prove detrimental to both the physical health and the psychological well-being of parents of children with chronic disabilities. It is not fully understood why some caregivers cope well and others do not. The approach of estimating the "independent" or "direct" effects of the care recipient's disability on the caregiver's health is of limited value because (1) single-factor changes are rare outside the context of constrained experimental situations; (2) assumptions of additive relationships and perfect measurements rarely hold; and (3) such approaches do not provide a complete perspective, because they fail to examine indirect pathways that occur between predictor variables and health outcomes. A more detailed analytical approach is needed to understand both direct and indirect effects simultaneously. The primary objective of the current study was to examine, within a single theory-based multidimensional model, the determinants of physical and psychological health of adult caregivers of children with CP. METHODS: We developed a stress process model and applied structural equation modeling with data from a large cohort of caregivers of children with CP. This design allowed the examination of the direct and indirect relationships between a child's health, behavior and functional status, caregiver characteristics, social supports, and family functioning and the outcomes of caregivers' physical and psychological health. Families (n = 468) of children with CP were recruited from 19 regional children's rehabilitation centers that provide outpatient disability management and supports in Ontario, Canada. The current study drew on a population available to the investigators from a previous study, the Ontario Motor Growth study, which explored patterns of gross motor development in children with CP. Data on demographic variables and caregivers' physical and psychological health were assessed using standardized, self-completed parent questionnaires as well as a face-to-face home interview. Structural equation modeling was used to test specific hypotheses outlined in our conceptual model. This analytic approach involved a 2-step process. In the first step, observed variables that were hypothesized to measure the underlying constructs were tested using confirmatory factor analysis; this step led to the so-called measurement model. The second step tested hypotheses about relationships among the variables in the structural model. All of the hypothesized paths in the conceptual model were tested and included in the structural model. However, only paths that were significant were shown in the final results. The direct, indirect, and total effects of theoretical constructs on physical and psychological health were calculated using the structural model. RESULTS: The most important predictors of caregivers' well-being were child behavior, caregiving demands, and family function. A higher level of behavior problems was associated with lower levels of both psychological (beta = -.22) and physical health (beta = -.18) of the caregivers, whereas fewer child behavior problems were associated with higher self-perception (beta = -.37) and a greater ability to manage stress (beta = -.18). Less caregiving demands were associated with better physical (beta = .23) and psychological (beta = .12) well-being of caregivers, respectively. Similarly, higher reported family functioning was associated with better psychological health (beta = .33) and physical health (beta = .33). Self-perception and stress management were significant direct predictors of caregivers' psychological health but did not directly influence their physical well-being. Caregivers' higher self-esteem and sense of mastery over the caregiving situation predicted better psychological health (beta = .23). The use of more stress management strategies was also associated with better psychological health of caregivers (beta = .11). Gross income (beta = .08) and social support (beta = .06) had indirect overall effects only on psychological health outcome, whereas self-perception (beta = .22), stress management (beta = .09), gross income (beta = .07), and social support (beta = .06) had indirect total effects only on physical health outcomes. CONCLUSIONS: The psychological and physical health of caregivers, who in this study were primarily mothers, was strongly influenced by child behavior and caregiving demands. Child behavior problems were an important predictor of caregiver psychological well-being, both directly and indirectly, through their effect on self-perception and family function. Caregiving demands contributed directly to both the psychological and the physical health of the caregivers. The practical day-to-day needs of the child created challenges for parents. The influence of social support provided by extended family, friends, and neighbors on health outcomes was secondary to that of the immediate family working closely together. Family function affected health directly and also mediated the effects of self-perception, social support, and stress management. In families of children with CP, strategies for optimizing caregiver physical and psychological health include supports for behavioral management and daily functional activities as well as stress management and self-efficacy techniques. These data support clinical pathways that require biopsychosocial frameworks that are family centered, not simply technical and short-term rehabilitation interventions that are focused primarily on the child. In terms of prevention, providing parents with cognitive and behavioral strategies to manage their child's behaviors may have the potential to change caregiver health outcomes. This model also needs to be examined with caregivers of children with other disabilities.

Adaptation, Psychological↗

A multi-analytical platform approach to the metabonomic analysis of plasma from normal and Zucker (fa/fa) obese rats.

Plasma obtained from 20 week old normal Wistar-derived and Zucker (fa/fa) rats was analysed using a number of different analytical methodologies to obtain global metabolite profiles as part of metabonomic investigations of animal models of diabetes. Samples were analysed without sample pre-treatment using 1H NMR spectroscopy, after acetonitrile solvent protein precipitation by ultra-performance liquid chromatography-MS (UPLC-MS) and after acetonitrile protein precipitation and derivatisation for capillary gas chromatography-MS (GC-MS). Subsequent data analysis using principal components analysis revealed that all three analytical platforms readily detected differences between the plasma metabolite profiles of the two strains of rat. There was only limited overlap between the metabolites detected by the different methodologies and the combination of all three methods of metabolite profiling therefore provided a much more comprehensive profile than would have been provided by their use individually.

Animals↗

Talking the talk: a discourse analysis of mental health nurses talking about their practice.

Mental Health nursing exists as a discipline in the UK within the wider contemporary health care establishment. Throughout its history it has attempted to define itself in ways that differentiate mental health nursing practice from other health care professions and fields of nursing. However, it is not surprising in this climate of contemporary healthcare for individual professional identities to become 'lost' in the melange of interdisciplinary practice. This research presents a discourse analysis of individual mental health nurses' rhetorical constructions of their professional role(s) as they emerge in their talk with each other in focus group discussions. In particular, the focus in this paper is their discursive repertoires related to the historical legacy of mental health nursing and how this sits with what they consider to be a 'custodial and controlling' element of their role. The particular discourse analytic approach adopted in this study illustrates how individuals use language in a particular way to make justifications and explanations of mental health nursing identities. This analytic approach is ensconced within the domain of social psychology and lies at the interface of ethno-methodology and conversation analysis. It is concerned with structural units of discourse, beyond the level of the sentence, that emerge as the nurse participants engage in talking about their practice (Potter and Wetherell, 1987 p.53).

Attitude of Health Personnel↗

[Study concept of traditional Chinese medicine quality standards].

Chinese medicinal materials quality was controlled mainly by modern analytic approach, secondly by traditional identification method, popularizing based on improvement. Chinese medicine prepared slice quality was controlled mainly by traditional identification method, secondly by modern analytic approach, improving based on popularization.

Chromatography↗

Comparative transcriptional profiling of two human embryonic stem cell lines.

Human embryonic stem cells (ESCs) have generated enormous interest due to their ability to self-renew and produce many different cell types. In conjunction with microarray technology, human ESCs provide a powerful tool for employing a systems-based approach to deciphering the molecular mechanisms that control pluripotency and early development. Recent work has focused on defining "stemness" and pluripotency based on different experimental and analytical approaches in both mouse and human ESCs. Using a mixed linear model statistical approach, we report a stringent direct comparison between data sets obtained from two human ESCs (BG01 and H1) in order to obtain a list of genes that are enriched in ESCs. In addition, we used another pluripotent population derived from BG01 ESCs to obtain a list of genes that we consider important to the maintenance of pluripotency. A total of 133 genes overlapped between the three pluripotent populations. A majority of the 133 genes were classified under the key functional categories of cell-cycle regulation, signaling, and regulation of transcription. Key genes expressed were Oct4, Sox2, LeftyA, and Fgf2. Also found to be enriched in all three populations is FLJ10713, a gene encoding a hypothetical protein of unknown function that has been shown in earlier studies to possess a homolog in mouse ESCs and also to cluster tightly with Oct4 in human ESCs. Although there were many genes unique to each pluripotent population, they shared similarities based on functional ontologies that define pluripotency. The significance of our studies underscores the need for direct comparison of stem cell populations that share biological similarities using uniform stringent analytical approaches, in order to better define pluripotency. Our findings have important implications for the maintenance of pluripotency and in developing directed differentiation strategies for various regenerative applications.

Algorithms↗

Experimental approaches and analytical techniques for determining organic compound bound residues in soil and sediment.

Research has shown that many chemicals form persistent and permanently bound residues in soils and sediments that play an important role in soil and sediment detoxification processes, long-term compound partitioning behaviour and compound bioavailability and toxicity in soil and sediment. This article reviews the methodological approaches that have been applied to determine the nature of bound residues in soil and sediment, the application of specific analytical techniques, the type of information they generate, and their relative advantages and disadvantages. It begins by defining bound residues and discussing soil-compound interactions. The application of model compound studies for elucidating specific binding interactions is reviewed along with long-term laboratory and field soil incubation experiments. The use of radiolabelled compounds, isotopically labelled compounds and combinations of both in these experiments are outlined by examples from the literature, along with sequential extraction schemes for releasing bound residues from soil, sediment and humic materials. The importance of spectroscopic methods, and particularly nuclear magnetic resonance techniques for characterising the structure of bound residues in soil and sedimentary humic substances is discussed and illustrated by examples from the literature on the subject. The process of bound residue formation is highly complex and requires further research to establish the mechanisms of bound residue formation and their subsequent environmental and toxicological fate. Much of the uncertainty regarding the elucidation of bound residue formation arises from our poor understanding of the structure of soil and sedimentary organic matter. Significant advances in our understanding of the formation and fate of bound residues will be made when we develop a deeper insight into the complex and heterogeneous structure of soil and sedimentary organic matter.

Journal Article↗

Psychopathological assessment and diagnosis. A study of specificity of single symptoms.

The importance of single symptoms in the diagnostic process has not been adequately studied, mainly because of the complexity of the information involved. The aim of the present study is to investigate the interconnection between psychopathological assessment and diagnostic classification, with the aid of a nonparametric, inductive pattern recognition method. Using the concept of inductive logic and a theory of inductive knowledge acquisition, a model has been developed to describe psychopathological assessment and diagnostic classification. Based on a comprehensive psychopathological assessment in 837 patients with 14 different diagnoses, classification values were calculated for specific symptoms in different diagnostic groups. Furthermore, nonparametric statistical procedures have advantages over discriminant analytic approaches: more information is utilized in differentiating the groups and differentiations can be made between more groups, whereby the rate of correctly classified cases is comparable with discriminant analytic approaches. The pattern recognition method appears to illustrate the multidimensional, medical decision-making in a comprehensible way.

Adult↗

New structural insights into the molecular deciphering of mycobacterial lipoglycan binding to C-type lectins: lipoarabinomannan glycoform characterization and quantification by capillary electrophoresis at the subnanomole level.

Lipoarabinomannans are key molecules of the mycobacterial envelopes involved in many steps of tuberculosis immunopathogenesis. Several of the biological activities of lipoarabinomannans are mediated by their ability to bind human C-type lectins, such as the macrophage mannose receptor, the mannose-binding protein and the surfactant proteins A and D. The lipoarabinomannan mannooligosaccharide caps have been demonstrated to be involved in the binding to the lectin carbohydrate recognition domains. We report an original analytical approach, based on capillary electrophoresis monitored by laser-induced fluorescence, allowing the absolute quantification, in nanomole quantities of lipoarabinomannan, of the number of mannooligosaccharide units per lipoarabinomannan molecule. Moreover, this analytical approach was successful for the glycosidic linkage determination of the mannooligosaccharide motifs and has been applied to the comparative analysis of parietal and cellular lipoarabinomannans of Mycobacterium bovis BCG and Mycobacterium tuberculosis H37Rv, H37Ra and Erdman strains. Significant differences were observed in the amounts of the various mannooligosaccharide units between lipoarabinomannans of different strains and between parietal and cellular lipoarabinomannans of the same strain. Nevertheless, no relationship was found between the number of mannooligosaccharide caps and the virulence of the corresponding strain. The results of the present study should help us to gain more understanding of the molecular basis of lipoarabinomannan discrimination in the process of binding to C-type lectins.

Acetylation↗

Relative transcript quantification by quantitative PCR: roughly right or precisely wrong?

BACKGROUND: When estimating relative transcript abundances by quantitative real-time PCR (Q-PCR) we found that the results can vary dramatically depending on the method chosen for data analysis. RESULTS: Analyses of Q-PCR results from a salmon louse starvation experiment show that, even with apparently good raw data, different analytical approaches 12 may lead to opposing biological conclusions. CONCLUSION: The results emphasise the importance of being cautious when analysing Q-PCR data and indicate that uncritical routine application of an analytical method will eventually result in incorrect conclusions. We do not know the extent of, or have a universal solution to this problem. However, we strongly recommend caution when analysing Q-PCR results e.g. by using two or more analytical approaches to validate conclusions. In our view a common effort should be made to standardise methods for analysis and validation of Q-PCR results.

Animals↗

Meta-analysis of sib pair linkage studies of asthma and the interleukin-9 gene (IL9).

Asthma is a complex disease, with an etiology that includes both genetic and environmental influences that may interact. The moderate heritability of asthma has led researchers to investigate its molecular genetic basis using both exploratory investigations of linkage via genome scans, as well as targeted studies of specific candidate genes. Promising candidate genes include the cytokine genes on chromosome 5q23-31. Both genome scans and association studies of these candidate genes/genomic regions have yielded mixed findings, which raise the possibilities of a true relation that emerges more strongly in certain samples simply due to sampling variability, as well as of genetic heterogeneity. Meta-analytic approaches that combine data across samples and examine how findings may vary as a function of effect modifiers can address both of these possibilities. In this study, we used a meta-analytic approach to examine linkage between the interleukin-9 gene (IL9), one of the cytokine genes located on chromosome 5q31, and asthma diagnoses and serum IgE levels in four samples. We analyzed IBD allele sharing for affected, unaffected, and discordant sib pairs, and as a function of sibling differences in IgE levels. We used a recently developed logistic regression-based method that allows for the inclusion of covariates and/or effect modifiers in the analysis of allele sharing in sib-pairs [Rice et al., Genet Epidemiol 17(Suppl. 1):S691-5, 1999]. Sex of the siblings and transmitting parent were considered both as covariates and effect modifiers in analyses. The results provided little evidence for linkage, or for heterogeneity therein due to sex or transmitting parent, either within or across samples.

Adult↗

Delayed feedback control of the Lorenz system: an analytical treatment at a subcritical Hopf bifurcation.

We develop an analytical approach for the delayed feedback control of the Lorenz system close to a subcritical Hopf bifurcation. The periodic orbits arising at this bifurcation have no torsion and cannot be stabilized by a conventional delayed feedback control technique. We utilize a modification based on an unstable delayed feedback controller. The analytical approach employs the center manifold theory and the near identity transformation. We derive the characteristic equation for the Floquet exponents of the controlled orbit in an analytical form and obtain simple expressions for the threshold of stability as well as for an optimal value of the control gain. The analytical results are supported by numerical analysis of the original system of nonlinear differential-difference equations.

Journal Article↗