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Quantitative Aspects (quantitative + aspect)
Selected AbstractsQuantitative aspects of contact allergy to chromium and exposure to chrome-tanned leatherCONTACT DERMATITIS, Issue 3 2002Malene Barré Hansen The potential of trivalent and hexavalent chromium to induce and elicit allergic contact dermatitis and the degree of chromium exposure from leather products are reviewed. Chromium dermatitis is often due to exposure in the occupational environment, with cement being one of the most common chromium sources. However, consumer products such as chromium(III)-tanned leather products are also an important source of chromium exposure. Apart from Cr(III), which is used for tanning, leather often also contains trace amounts of Cr(VI), which is formed by oxidation of Cr(III) during the tanning process. In a recent study of the Cr(VI) content of leather products bought on the Danish market, 35% of such articles had a Cr(VI) content above the detection limit of 3 p.p.m., ranging from 3.6 p.p.m. to 14.7 p.p.m. Leachable Cr(III) was detected at levels of 430,980 p.p.m. An examination of available dose,response studies showed that exposure to occluded patch test concentrations of 7,45 p.p.m. Cr(VI) elicits a reaction in 10% of the chromium-sensitive patients. When reviewing repeated open exposure studies, it is seen that either exposure to 5 p.p.m. Cr(VI) in the presence of 1% sodium lauryl sulfate (SLS) or exposure to 10 p.p.m. Cr(VI) alone both elicit eczema in chromium-sensitive patients. The eliciting capacity of Cr(III) has not been systematically investigated but, compared to Cr(VI), much higher concentrations are needed to elicit eczema. [source] Quantitative aspects of the regulation of ovarian development in selected anautogenous Diptera: integration of endocrinology and nutritionENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2001L. Barton Browne Abstract Aspects of the influence of nutrition on the degree of ovarian development in selected anautogenous Diptera are reviewed. The Diptera considered are several mosquito species, with emphasis on Aedes aegypti, the house fly, Musca domestica, the Australian bush fly, M. vetustissima and the blowflies, Lucilia cuprina and Phormia regina. All the selected species display discrete ovarian cycles in which all oocytes destined to reach maturity in a particular ovarian cycle develop synchronously. In these species, the proportion of females maturing oocytes and, where such data exist, the number of oocytes they mature are positively correlated with the amount of any particular nitrogen-containing material ingested or given by enema or by infusion. In addition, the degree of ovarian development may be affected by the chemical composition of nitrogen-containing food. Possible physiological bases for the observed relationships are discussed. Available evidence suggests that whether or not a female matures any oocytes is hormonally regulated and that the number of oocytes matured is probably regulated by the availability of nutrients. Some approaches that might further elucidate the physiological regulatory mechanisms involved in ovarian development are outlined. [source] In vivo corneal confocal microscopy in keratoconusOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 3 2005Joanna G. Hollingsworth Abstract Purpose:, To evaluate the corneas of keratoconic subjects using in vivo confocal microscopy. Methods:, Slit scanning confocal microscopy was used to evaluate the central cornea of one eye of each of 29 keratoconic subjects (mean age 31 ± 10 years; range 16,49 years). Quantitative aspects of corneal morphology were compared against data from control subjects. Results:, Compared with normal control corneas, epithelial wing cell nuclei were larger (p < 0.0001) and epithelial basal cell diameter was larger (p < 0.05) in the keratoconic cornea. Many of the keratoconic corneas investigated showed increased levels of stromal haze and reflectivity, which appeared to be related to the presence of apical scarring on slit lamp examination. A grading scale was devised to quantify the levels of haze. This scale was shown to provide a measure of the level of scarring present. The anterior keratocyte density (AKD) and posterior keratocyte density were 19% lower (p < 0.0001) and 10% lower (p = 0.004) than in controls, respectively. The reduction in AKD was significantly associated with three factors: a history of atopy, eye rubbing and the presence of corneal staining. The mean endothelial cell density in keratoconus was 6% greater than that of normal controls (p = 0.05). The level of endothelial polymegethism was shown not to be different between keratoconic subjects and matched controls (paired t -test: t = 1.82, p = 0.08). Conclusions:, Confocal microscopy demonstrates significant quantitative alterations of corneal morphology in keratoconus. [source] The ProteoMiner and the FortyNiners: Searching for gold nuggets in the proteomic arenaMASS SPECTROMETRY REVIEWS, Issue 6 2008Pier Giorgio Righetti Abstract The present review covers modern aspects of combinatorial peptide ligand libraries (CPLL), as used to analyze the "low-abundance proteome" in association with mass spectrometry. First, the capturing properties of baits of different lengths (from single amino acid to hexa-peptides) are described to show that a plateau is rapidly reached above a tetra-peptide in length, thus confirming the validity of having adopted hexapeptides for the considered application. The mechanism of interaction with proteins from very complex proteomes and the ability to decrease the dynamic concentration range is demonstrated with the help of mass spectrometry analysis. Examples are given on how treatment with CPLLs dramatically improves the detectability of peptides in mass spectrometry analysis, permitting detection of a very large number of proteins as compared with control, untreated samples. The use of complementary libraries is discussed with the aim to discover additional low-abundance species that escaped the first library. A discussion on the possibility to discover extremely rare gene products, and the quantitative aspect of the technology when associated with mass spectrometry is also provided. Some insights on the applications for hidden, low-abundance biomarkers are also presented. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 596,608, 2008 [source] Guidelines for improving the reproducibility of quantitative multiparameter immunofluorescence measurements by laser scanning cytometry on fixed cell suspensions from human solid tumorsCYTOMETRY, Issue 1 2006Stanley Shackney Abstract Background: Laser scanning Cytometry (LSC) is a versatile technology that makes it possible to perform multiple measurements on individual cells and correlate them cell by cell with other cellular features. It would be highly desirable to be able to perform reproducible, quantitative, correlated cell-based immunofluorescence studies on individual cells from human solid tumors. However, such studies can be challenging because of the presence of large numbers of cell aggregates and other confounding factors. Techniques have been developed to deal with cell aggregates in data sets collected by LSC. Experience has also been gained in addressing other key technical and methodological issues that can affect the reproducibility of such cell-based immunofluorescence measurements. Methods and results: We describe practical aspects of cell sample collection, cell fixation and staining, protocols for performing multiparameter immunofluorescence measurements by LSC, use of controls and reference samples, and approaches to data analysis that we have found useful in improving the accuracy and reproducibility of LSC data obtained in human tumor samples. We provide examples of the potential advantages of LSC in examining quantitative aspects of cell-based analysis. Improvements in the quality of cell-based multiparameter immunofluorescence measurements make it possible to extract useful information from relatively small numbers of cells. This, in turn, permits the performance of multiple multicolor panels on each tumor sample. With links among the different panels that are provided by overlapping measurements, it is possible to develop increasingly more extensive profiles of intracellular expression of multiple proteins in clinical samples of human solid tumors. Examples of such linked panels of measurements are provided. Conclusions: Advances in methodology can improve cell-based multiparameter immunofluorescence measurements on cell suspensions from human solid tumors by LSC for use in prognostic and predictive clinical applications. © 2005 Wiley-Liss, Inc. [source] Clustering and switching in semantic fluency: predictors of the development of Alzheimer's diseaseINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 10 2008Ana B. Fagundo Abstract Objective The aims of the study are twofold: (1) to compare semantic fluency, clustering and switching performance among subjects with memory complaints, patients with Alzheimer Disease (AD), and healthy controls; and (2) to examine the clinical utility of the clustering/switching scoring system in the prediction of incident AD in subjects with memory complaints. Methods A semantic fluency task was used to compare thirty eight subjects with memory complaints, forty two AD patients and twenty five healthy controls on the total number of words generated, clustering and switching performance. Subjects with memory complaints were followed-up for a maximum period of two years and re-evaluated. They remained in the memory complaints group (twenty eight subjects) or were defined as probable AD (ten subjects). Results AD patients generated fewer correct words (p,<,0.001) and showed a reduction in clustering (p,=,0.008) and switching (p,<,0.001). Subjects with memory complaints showed a significant reduction in correct words (p,<,0.001) and clustering performance (p,=,0.008) compare to controls. In the first evaluation, the subgroup of patients who converted to AD at follow up produced less correct words (p,<,0.01) and smaller clusters (p,=,0.007) than the subgroup who did not become demented. There were no differences in switching between these two subgroups. AD development was better predicted by cluster size than by the total number of words generated or by switching. Conclusions Subjects with memory complaints and AD patients have an alteration in both qualitative and quantitative aspects of semantic fluency. A clustering analysis could enhance the reliability of early AD diagnosis. Copyright © 2008 John Wiley & Sons, Ltd. [source] Schmorl's nodes: clinical significance and implications for the bioarchaeological recordINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1 2008K. J. Faccia Abstract Back pain is one of the major contributors to disability and loss of productivity in modern populations. However, osteological correlates of back pain are often absent or, as yet, unidentified. As bioarchaeologists depend on osteological evidence to interpret quality of life in the past, back pain, with its profound effects on modern populations, is largely overlooked in archaeological samples. This study addresses this shortcoming in bioarchaeological analysis by exploring the relationship between a defined vertebral osteological lesion, the Schmorl's node, and its effect on quality of life in a clinical population. Using patient insight, healthcare practitioner diagnoses and MR imaging analyses, this study investigates: (1) Schmorl's nodes and sociodemographic factors; (2) the number, location and quantitative aspects (e.g. length, depth, area) of Schmorl's nodes, and how these influence the reporting of pain; (3) the dynamic effects of Schmorl's nodes, in combination with other variables, in the reporting of pain; and (4) the perception and impact of pain that patients attribute to Schmorl's nodes with regard to quality-of-life issues. The results of this study indicate that Schmorl's nodes located in the central portion of the vertebral body are significantly associated with patient reporting of pain, and that the presence of osteophytes, in the affected vertebral region, may increase the likelihood that an individual will report pain. This finding provides bioarchaeologists with an osteological correlate to begin interpreting the presence and impact of pain in archaeological populations, with implications for scoring Schmorl's nodes. Copyright © 2007 John Wiley & Sons, Ltd. [source] Forms of Governance in European Union Social Policy: Continuity and/or Change?INTERNATIONAL SOCIAL SECURITY REVIEW, Issue 2 2006Gerda Falkner This article addresses the question of the evolution of regulatory and distributive social policy at European Union (EU) level, with special emphasis on its quantitative aspects. Data collected in meticulous detail on the EU's powers in the area of social policy and their practical implementation from the early days of European integration through to the end of 2002 are presented in a range of figures and tables. It becomes apparent that, quantitatively speaking, the body of EU social law in existence to date is impressive. Contrary to expectation, non-binding forms of action have not replaced those which are binding, or at least not yet. Soft law and the "open method of coordination", the subject of so much recent debate, are rather a complement to classic legislation, entailing a minimum of harmonization. In terms of political science and legal theory this means that while the neo-voluntarism and legalization hypotheses highlight important aspects of EU social policy, neither of them represents the whole story. [source] Issues in pension system designINTERNATIONAL SOCIAL SECURITY REVIEW, Issue 1 2002Maria Augusztinovics External conditions for pension system design and demographic and labour market trends are briefly considered and the latter found decisive. Basic concepts, e.g. social assistance and insurance, redistribution and actuarial fairness, are then introduced. Then it is argued that the "public PAYG versus private funded" dichotomy has attracted an unduly large share of attention in recent pension reform debates, as such institutional changes do not really address the basic problems, while quantitative aspects, the relationship between contribution and replacement rates, have been improperly neglected or shielded by the paradigmatic controversy. The next, crucial point is that traditional, employment-based, earnings-related forms of pension insurance are endangered by new trends on the labour market; hence, new solutions will have to be sought to ensure pension coverage for the entire population. A brief plea for more, relevant and comparative information on pension issues follows. The paper concludes with a concise summary and by contemplating what could and should be expected from the Second World Assembly on Ageing. [source] Modulation of sexual signalling by immune challenged male mealworm beetles (Tenebrio molitor, L.): evidence for terminal investment and dishonestyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2006B. SADD Abstract Organisms partition resources into life-history traits in order to maximise fitness over their expected lifespan. For the males of many species fitness is determined by qualitative and quantitative aspects of costly sexual signals: The notion that epigamic traits are costly forms the cornerstone of those theories that propose parasites drive sexual selection. Consequently studies examining this notion assume sexual signalling is honest (i.e. driven by cost) when they seek to identify correlations or causal links between male immune function and attractiveness. We demonstrate that immune challenged males of the mealworm beetle, Tenebrio molitor, increased their investment in epigamic pheromone signals: these males became significantly more attractive to females whilst increasing the activity of a key immune effector system. In other words males increase terminal reproductive effort (invest in attractiveness) in response to a survival threat (immune insult). Consequently the signal preferred by the female is dishonest when considering the male's condition. [source] Comparative LC-MS: A landscape of peaks and valleysPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 4 2008Antoine H. P. America Dr. Abstract Quantitative proteomics approaches using stable isotopes are well-known and used in many labs nowadays. More recently, high resolution quantitative approaches are reported that rely on LC-MS quantitation of peptide concentrations by comparing peak intensities between multiple runs obtained by continuous detection in MS mode. Characteristic of these comparative LC-MS procedures is that they do not rely on the use of stable isotopes; therefore the procedure is often referred to as label-free LC-MS. In order to compare at comprehensive scale peak intensity data in multiple LC-MS datasets, dedicated software is required for detection, matching and alignment of peaks. The high accuracy in quantitative determination of peptide abundancies provides an impressive level of detail. This approach also requires an experimental set-up where quantitative aspects of protein extraction and reproducible separation conditions need to be well controlled. In this paper we will provide insight in the critical parameters that affect the quality of the results and list an overview of the most recent software packages that are available for this procedure. [source] Cytologic, hormonal, and ultrasonographic correlates of the menstrual cycle of the New World monkey Cebus apellaAMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2005R.E. Ortiz Abstract Few reports on the reproductive physiology of Cebus apella have been published. In this study we characterized menstrual cycle events by means of vaginal cytology, ultrasonography (US), and hormonal measurements in serum during three consecutive cycles in 10 females, and assessed the probability that ovulation would occur in the same ovary in consecutive cycles in 18 females. The lengths and phases of the cycles were determined according to vaginal cytology. Taking the first day of endometrial bleeding as the first day of the cycle, the mean cycle length ± SEM was 19.5±0.4 days, with follicular and luteal phases lasting 8.2±0.2 and 11.3±0.4 days, respectively. The follicular phase included menstruation and the periovulatory period, which was characterized by the presence of a large number of superficial eosinophilic cells in the vaginal smear. The myometrium, endometrium, and ovaries were clearly distinguished on US examination. During each menstrual cycle a single follicle was recruited at random from either ovary. The follicle grew from 3 mm to a maximum diameter of 8,9 mm over the course of 8 days, in association with increasing estradiol (E2) serum levels (from 489±41 to 1600±92 pmol/L). At ovulation, the mean diameter of the dominant follicle usually decreased by >20%, 1 day after the maximum E2 level was reached. Ovulation was associated with an abrupt fall in E2, a decreased number of eosinophilic cells, the presence of leukocytes and intermediate cells in the vaginal smear, and a progressive increase in progesterone (P) levels that reached a maximum of 892±65 nmol/L on days 3,6 of the luteal phase. The menstrual cycle of Cebus apella differs in several temporal and quantitative aspects from that in humans and Old World primates, but it exhibits the same correlations between ovarian endocrine and morphologic parameters. Am. J. Primatol. 66:233,244, 2005. © 2005 Wiley-Liss, Inc. [source] Quantitative steps in symbiogenesis and the evolution of homeostasisBIOLOGICAL REVIEWS, Issue 3 2003S. A. L. M. KOOIJMAN ABSTRACT The merging of two independent populations of heterotrophs and autotrophs into a single population of mixotrophs has occurred frequently in evolutionary history. It is an example of a wide class of related phenomena, known as symbiogenesis. The physiological basis is almost always (reciprocal) syntrophy, where each species uses the products of the other species. Symbiogenesis can repeat itself after specialization on particular assimilatory substrates. We discuss quantitative aspects and delineate eight steps from two free-living interacting populations to a single fully integrated endosymbiotic one. The whole process of gradual interlocking of the two populations could be mimicked by incremental changes of particular parameter values. The role of products gradually changes from an ecological to a physiological one. We found conditions where the free-living, epibiotic and endobiotic populations of symbionts can co-exist, as well as conditions where the endobiotic symbionts outcompete other symbionts. Our population dynamical analyses give new insights into the evolution of cellular homeostasis. We show how structural biomass with a constant chemical composition can evolve in a chemically varying environment if the parameters for the formation of products satisfy simple constraints. No additional regulation mechanisms are required for homeostasis within the context of the dynamic energy budget (DEB) theory for the uptake and use of substrates by organisms. The DEB model appears to be closed under endosymbiosis. This means that when each free-living partner follows DEB rules for substrate uptake and use, and they become engaged in an endosymbiotic relationship, a gradual transition to a single fully integrated system is possible that again follows DEB rules for substrate uptake and use. [source] Marginal Mark Regression Analysis of Recurrent Marked Point Process DataBIOMETRICS, Issue 2 2009Benjamin French Summary Longitudinal studies typically collect information on the timing of key clinical events and on specific characteristics that describe those events. Random variables that measure qualitative or quantitative aspects associated with the occurrence of an event are known as marks. Recurrent marked point process data consist of possibly recurrent events, with the mark (and possibly exposure) measured if and only if an event occurs. Analysis choices depend on which aspect of the data is of primary scientific interest. First, factors that influence the occurrence or timing of the event may be characterized using recurrent event analysis methods. Second, if there is more than one event per subject, then the association between exposure and the mark may be quantified using repeated measures regression methods. We detail assumptions required of any time-dependent exposure process and the event time process to ensure that linear or generalized linear mixed models and generalized estimating equations provide valid estimates. We provide theoretical and empirical evidence that if these conditions are not satisfied, then an independence estimating equation should be used for consistent estimation of association. We conclude with the recommendation that analysts carefully explore both the exposure and event time processes prior to implementing a repeated measures analysis of recurrent marked point process data. [source] | ||||||||||||||||