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Related Parameters (relate + parameter)
Selected AbstractsFLUORESCENCE-BASED MAXIMAL QUANTUM YIELD FOR PSII AS A DIAGNOSTIC OF NUTRIENT STRESSJOURNAL OF PHYCOLOGY, Issue 4 2001Jean-Paul Parkhill In biological oceanography, it has been widely accepted that the maximum quantum yield of photosynthesis is influenced by nutrient stress. A closely related parameter, the maximum quantum yield for stable charge separation of PSII, (,PSII)m, can be estimated by measuring the increase in fluorescence yield from dark-adapted minimal fluorescence (Fo) to maximal fluorescence (Fm) associated with the closing of photosynthetic reaction centers with saturating light or with a photosynthetic inhibitor such as 3,-(3,4-dichlorophenyl)-1,,1,-dimethyl urea (DCMU). The ratio Fv/Fm (= (Fm, Fo)/Fm) is thus used as a diagnostic of nutrient stress. Published results indicate that Fv/Fm is depressed for nutrient-stressed phytoplankton, both during nutrient starvation (unbalanced growth) and acclimated nutrient limitation (steady-state or balanced growth). In contrast to published results, fluorescence measurements from our laboratory indicate that Fv/Fm is high and insensitive to nutrient limitation for cultures in steady state under a wide range of relative growth rates and irradiance levels. This discrepancy between results could be attributed to differences in measurement systems or to differences in growth conditions. To resolve the uncertainty about Fv/Fm as a diagnostic of nutrient stress, we grew the neritic diatom Thalassiosira pseudonana (Hustedt) Hasle et Heimdal under nutrient-replete and nutrient-stressed conditions, using replicate semicontinuous, batch, and continuous cultures. Fv/Fm was determined using a conventional fluorometer and DCMU and with a pulse amplitude modulated (PAM) fluorometer. Reduction of excitation irradiance in the conventional fluorometer eliminated overestimation of Fo in the DCMU methodology for cultures grown at lower light levels, and for a large range of growth conditions there was a strong correlation between the measurements of Fv/Fm with DCMU and PAM (r2 = 0.77, n = 460). Consistent with the literature, nutrient-replete cultures showed consistently high Fv/Fm (,0.65), independent of growth irradiance. Under nutrient-starved (batch culture and perturbed steady state) conditions, Fv/Fm was significantly correlated to time without the limiting nutrient and to nutrient-limited growth rate before starvation. In contrast to published results, our continuous culture experiments showed that Fv/Fm was not a good measure of nutrient limitation under balanced growth conditions and remained constant (,0.65) and independent of nutrient-limited growth rate under different irradiance levels. Because variable fluorescence can only be used as a diagnostic for nutrient-starved unbalanced growth conditions, a robust measure of nutrient stressed oceanic waters is still required. [source] FS04.5 Iodopropynylbutyl carbamate (IPBC) 0.2% is suggested for patch testing of patients with eczema possibly related to preservativesCONTACT DERMATITIS, Issue 3 2004Jochen Brasch Iodopropynylbutyl carbamate (IPBC)is a preservative that has been increasingly used for skin care products and cosmetics within the last years and the first cases of contact sensitization have meanwhile been reported. Therefore, a surveillance for IPBC contact allergy is now necessary. Our study was aimed to find out a suitable test concentration of IPBC for this purpose. The data 8106 patients tested by 23 centres of the German Contact Dermatitis Research Group (DKG) and the Information Network of Departments of Dermatology (IVDK)in the time from May 2001 to July 2003 with IPBC in concentrations of 0.1%, 0.2%, 0.3%, and 0.5% were retrospectively evaluated. Criteria considered to determine the optimal test concentration of IPBC were the reaction index, the positivity ratio, the rate of crescendo reactions, and the relation of IPBC-reactions with MOAHLFA-indices, with irritant reactions to sodium lauryl sulfate, and with positive reactions to the most common standard contact allergens and 4 other preservatives. For statistical evaluations the exact McNemar test was applied and odds ratios were calculated according to the profile likelihood method, as derived from logistic regression analyses. The rate of positive reactions to IPBC increased from 0.5% with IPBC 0.1% to 1.7% with IPBC 0.5%, but there was a problem with sensitivity or specificity with both of these 2 concentrations. Therefore, we focused on IPBC 0.2%(0.8% positive reactions) and IPBC 0.3%(1.3% positive reactions) for further detailed analyses. An evaluation of the related parameters revealed that with IPBC 0.2% as compared to IPBC 0.3% a higher percentage of crescendo reactions, a higher reaction index, a lower number of doubtful reactions, a plausible association of positive reactions with reactions to other preservatives, nd no association with a pronounced skin irritability was found. In conclusion, we recommend to start with IPBC 0.2% for patch testing of all persons with contact dermatitis that may be related to preservatives. [source] Dual injection capillary electrophoresis: Foundations and applicationsELECTROPHORESIS, Issue 23-24 2004Feliciano Priego-Capote Abstract The state of the art of capillary electrophoresis (CE) approaches based on dual injection is here reported. Dual injection strategies have been proposed with three main objectives: (i) to provide information about reaction kinetics and/or related parameters, (ii) to perform in-capillary derivatization for improving separation and/or determination, (iii) to develop electrophoretic methods for the simultaneous analysis of anionic and cationic compounds. For the first two purposes, dual injection, which involves sample and reagent, can be realized either from the same end of the capillary (electrophoretically mediated microanalysis, EMMA) or from the two ends of the capillary (electroinjection analysis, EIA). The third objective, with dual injection of sample from the two ends of the capillary, takes advantage of moving cationic and anionic compounds with opposite directions. The foundations of each alternative, conditions necessary for working with them, restrictions, applications as well as perspectives are reviewed in order to establish the advantages, shortcomings, and convenience or no of their use in comparison to conventional CE. [source] Testing Option Pricing Models with Stochastic Volatility, Random Jumps and Stochastic Interest RatesINTERNATIONAL REVIEW OF FINANCE, Issue 3-4 2002George J. Jiang In this paper, we propose a parsimonious GMM estimation and testing procedure for continuous-time option pricing models with stochastic volatility, random jump and stochastic interest rate. Statistical tests are performed on both the underlying asset return model and the risk-neutral option pricing model. Firstly, the underlying asset return models are estimated using GMM with valid statistical tests for model specification. Secondly, the preference related parameters in the risk-neutral distribution are estimated from observed option prices. Our findings confirm that the implied risk premiums for stochastic volatility, random jump and interest rate are overall positive and varying over time. However, the estimated risk-neutral processes are not unique, suggesting a segmented option market. In particular, the deep ITM call (or deep OTM put) options are clearly priced with higher risk premiums than the deep OTM call (or deep ITM put) options. Finally, while stochastic volatility tends to better price long-term options, random jump tends to price the short-term options better, and option pricing based on multiple risk-neutral distributions significantly outperforms that based on a single risk-neutral distribution. [source] Metabolic effects of p -coumaric acid in the perfused rat liverJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 1 2006Leonardo C.N. Lima The p -coumaric acid, a phenolic acid, occurs in several plant species and, consequently, in many foods and beverages of vegetable origin. Its antioxidant activity is well documented, but there is also a single report about an inhibitory action on the monocarboxylate carrier, which operates in the plasma and mitochondrial membranes. The latter observation suggests that p -coumaric acid could be able to inhibit gluconeogenesis and related parameters. The present investigation was planned to test this hypothesis in the isolated and hemoglobin-free perfused rat liver. Transformation of lactate and alanine into glucose (gluconeogenesis) in the liver was inhibited by p -coumaric acid (IC50 values of 92.5 and 75.6 ,M, respectively). Transformation of fructose into glucose was inhibited to a considerably lower degree (maximally 28%). The oxygen uptake increase accompanying gluconeogenesis from lactate was also inhibited. Pyruvate carboxylation in isolated intact mitochondria was inhibited (IC50 = 160.1 ,M); no such effect was observed in freeze,thawing disrupted mitochondria. Glucose 6-phosphatase and fructose 1,6-bisphosphatase were not inhibited. In isolated intact mitochondria, p -coumaric acid inhibited respiration dependent on pyruvate oxidation but was ineffective on respiration driven by succinate and ,-hydroxybutyrate. It can be concluded that inhibition of pyruvate transport into the mitochondria is the most prominent primary effect of p -coumaric acid and also the main cause for gluconeogenesis inhibition. The existence of additional actions of p -coumaric acid, such as enzyme inhibitions and interference with regulatory mechanisms, cannot be excluded. © 2006 Wiley Periodicals, Inc. J Biochem Mol Toxicol 20:18,26, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20114 [source] Factors related to the resting tongue position among partially and completely edentulous subjectsJOURNAL OF ORAL REHABILITATION, Issue 6 2005E. KOTSIOMITI summary, The prevalence of abnormal (retracted) position of the tongue at rest was examined in subjects with varying number of natural lower teeth. The aim of the study was to explore the relationship between tongue retraction and state of dentition and to identify potentially related parameters. The resting tongue positions were recorded in subjects partially edentulous in the lower jaw (n = 164) and compared with those met in dentate (n = 57) and completely edentulous participants (n = 84). Potentially related parameters, such as age, sex, duration of edentulism, palate vault and signs of temporomandibular disorders were also recorded. Tongue retraction was observed in a small percentage (12·3%) of the dentate, almost half (45·7%) of the partially edentulous and in the majority (67·8%) of the completely edentulous participants. The number of natural lower teeth correlated with the resting tongue position in the partially edentulous group. The tongue position at rest was also found weakly related to signs of temporomandibular disorders in the dentate group and to the sex and duration of edentulism in the partially edentulous group. It was concluded that the abnormal positioning of the resting tongue is increasingly observed with decreasing number of natural teeth, possibly in accordance with the morphological and functional alterations that result from teeth loss. The presence of a retracted tongue affects the complete denture construction; however, its effect on denture function remains questionable. [source] An evaluation of mathematical models for predicting skin permeabilityJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2008Guoping Lian Abstract A number of mathematical models have been proposed for predicting skin permeability, mostly empirical and very few are deterministic. Early empirical models use simple lipophilicity parameters. The recent trend is to use more complicated molecular structure descriptors. There has been much debate on which models best predict skin permeability. This article evaluates various mathematical models using a comprehensive experimental dataset of skin permeability for 124 chemical compounds compiled from various sources. Of the seven models compared, the deterministic model of Mitragotri gives the best prediction. The simple quantitative structure permeability relationships (QSPR) model of Potts and Guy gives the second best prediction. The two models have many features in common. Both assume the lipid matrix as the pathway of transdermal permeation. Both use octanol,water partition coefficient and molecular size. Even the mathematical formulae are similar. All other empirical QSPR models that use more complicated molecular structure descriptors fail to provide satisfactory prediction. The molecular structure descriptors in the more complicated QSPR models are empirically related to skin permeation. The mechanism on how these descriptors affect transdermal permeation is not clear. Mathematically it is an ill-defined approach to use many colinearly related parameters rather than fewer independent parameters in multi-linear regression. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:584,598, 2008 [source] von Willebrand factor activation, granzyme-B and thrombocytopenia in meningococcal diseaseJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 5 2010M. J. HOLLESTELLE Summary.,Background:,During invasive meningococcal disease, severe thrombocytopenia is strongly associated with a poor outcome. Objectives:,In order to elucidate the pathophysiological mechanism behind the development of thrombocytopenia, we studied the role of von Willebrand factor (VWF) in meningococcal disease. Patients/methods:,Thirty-two children with severe meningococcal disease admitted to our university hospital were included in this study. VWF and related parameters were measured and results were correlated with the development of shock and thrombocytopenia. Results:,At admission, all patients had increased levels of (active) VWF and VWF propeptide. The highest VWF propeptide levels were observed in patients with shock, indicating acute endothelial activation. Although VWF propeptide levels in patients with shock, with or without thrombocytopenia, were similar, increased active VWF was significantly lower in patients with thrombocytopenia as compared with patients without thrombocytopenia. ADAMTS13 was moderately decreased. However, the VWF multimeric pattern was minimally increased. We assume that these findings are explained by VWF consumption and perhaps by granzyme B (GrB). In vitro experiments showed that GrB is able to cleave VWF multimers in plasma, whereas GrB was high in patients with shock, who developed thrombocytopenia. Conclusions:,Our results demonstrate that consumption of VWF, derived from endothelial cells, could be a key feature of meningococcal disease and primary to the development of thrombocytopenia during shock. [source] ADAMTS-13, von Willebrand factor and related parameters in severe sepsis and septic shockJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 11 2007J. A. KREMER HOVINGA Summary. Background:,Insufficient control of von Willebrand factor (VWF) multimer size as a result of severely deficient ADAMTS-13 activity results in thrombotic thrombocytopenic purpura associated with microvascluar thrombosis and platelet consumption, features not seldom seen in severe sepsis and septic shock. Methods:,ADAMTS-13 activity and VWF parameters of 40 patients with severe sepsis or septic shock were compared with those of 40 healthy controls of the same age and gender and correlated with clinical findings and sepsis outcome. Results:,ADAMTS-13 activity was significantly lower in patients than in healthy controls [median 60% (range 27,160%) vs. 110% (range 63,200%); P < 0.001]. VWF parameters behaved reciprocally and both VWF ristocetin cofactor activity (RCo) and VWF antigen (VWF:Ag) were significantly (P < 0.001) higher in patients compared with controls. Neither ADAMTS-13 activity nor VWF parameters correlated with disease severity, organ dysfunction or outcome. However, a contribution of acute endothelial dysfunction to renal impairment in sepsis is suggested by the significantly higher VWF propeptide and soluble thrombomodulin levels in patients with increased creatinine values as well as by their strong positive correlations (creatinine and VWF propeptide rs = 0.484, P < 0.001; creatinine and soluble thrombomodulin rs = 0.596, P < 0.001). Conclusions:,VWF parameters are reciprocally correlated with ADAMTS-13 activity in severe sepsis and septic shock but have no prognostic value regarding outcome. [source] Stop test or pressure-flow study?NEUROUROLOGY AND URODYNAMICS, Issue 3 2004Measuring detrusor contractility in older females Abstract Aims Impaired detrusor contractility is common in older adults. One aspect, detrusor contraction strength during voiding, can be measured by the isovolumetric detrusor pressure attained if flow is interrupted mechanically (a stop test). Because interruption is awkward in practice, however, simple indices or nomograms based on measurements made during uninterrupted voiding are an appealing alternative. We investigated whether such methods, originally developed for males, might be applicable in female subjects, and attempted to identify a single best method. Methods We compared stop-test isovolumetric pressures with estimates based on pressure-flow studies in a group of elderly women suffering from urge incontinence. Measurements were made pre- and post-treatment with placebo or oxybutynin, allowing investigation of test,retest reliability and responsiveness to small changes of contractility. Results Existing methods of estimating detrusor contraction strength from pressure-flow studies, including the Schäfer contractility nomogram and the projected isovolumetric pressure PIP, greatly overestimate the isovolumetric pressure in these female patients. A simple modification provides a more reliable estimate, PIP1, equal to pdet.Qmax,+,Qmax (with pressure in cmH2O and Qmax in ml/sec). Typically PIP1 ranges from 30 to 75 cmH2O in this population of elderly urge-incontinent women. PIP1, however, is less responsive to a small change in contraction strength than the isovolumetric pressure measured by mechanical interruption. Conclusions The parameter PIP1 is simple to calculate from a standard pressure-flow study and may be useful for clinical assessment of detrusor contraction strength in older females. For research, however, a mechanical stop test still remains the most reliable and responsive method. The Schäfer contractility nomogram and related parameters such as DECO and BCI are not suitable for use in older women. Neurourol. Urodynam. 23:184,189, 2004. © 2004 Wiley-Liss, Inc. [source] A unified approach to the analysis of Horton-Strahler parameters of binary tree structuresRANDOM STRUCTURES AND ALGORITHMS, Issue 3-4 2002Markus E. Nebel Abstract The Horton-Strahler number naturally arose from problems in various fields, e.g., geology, molecular biology and computer science. Consequently, detailed investigations of related parameters for different classes of binary tree structures are of interest. This paper shows one possibility of how to perform a mathematical analysis for parameters related to the Horton-Strahler number in a unified way such that only a single analysis is needed to obtain results for many different classes of trees. The method is explained by the examples of the expected Horton-Strahler number and the related rth moments, the average number of critical nodes, and the expected distance between critical nodes. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 252,277, 2002 [source] ORIGINAL ARTICLE: The Polycystic Ovary Syndrome Does Not Predict Further Miscarriage in Japanese Couples Experiencing Recurrent MiscarriagesAMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 1 2009Mayumi Sugiura-Ogasawara Problem, It has been a matter of controversy whether the polycystic ovary syndrome (PCOS) is actually a causal factor of miscarriages because of the absence of internationally established criteria. We, therefore, in this study investigated whether PCOS and a polycystic ovary (PCO) morphology have predictive value for subsequent miscarriages using new International and Japanese criteria. Method of study, A total of 195 patients with a history of two consecutive first trimester miscarriages and without abnormal chromosomes in either partner, antiphospholipid antibodies or uterine anomalies, were examined. The prospective pregnancy outcome was compared between patients with and without PCOS, PCO morphology, elevated luteinizing hormone (LH), hyperandrogenism and obesity. Results, Of a total of 195 patients, 56 (28.7%) miscarried subsequently. Three (1.5%) and 12 (6.2%) were diagnosed as suffering from PCOS by Japanese and International criteria respectively. There was no relation between a diagnosis of PCOS, PCO morphology, elevated LH, free testosterone or obesity and the subsequent miscarriage rate. Conclusion, A routine test for diagnosis of PCOS is not necessary in patients experiencing recurrent miscarriages because none of the related parameters examined in this study predicted subsequent miscarriage. [source] A Conceptual Analysis of Price Setting in Australian Local GovernmentAUSTRALIAN ACCOUNTING REVIEW, Issue 2 2010Garry D. Carnegie A complex set of issues underlies the pricing of the diverse range of goods and services from which Australian local governments derive a significant portion of their revenues. Although local governments have a not-for-profit orientation, they are expected to be financially viable and embrace a broad notion of accountability. They are also expected to influence the behaviour of constituents in accordance with policy decisions, but be equitable in doing so. These and related parameters are discussed and illustrated in order to reveal and elucidate the nature of pricing decisions in local government, and to differentiate the local government context from other price-setting environments. [source] Human head exposure to a 37 Hz electromagnetic field: Effects on blood pressure, somatosensory perception, and related parametersBIOELECTROMAGNETICS, Issue 3 2004Sergio Ghione Abstract Previous studies have shown that exposure to an electromagnetic field (EMF) of 37 Hz at a flux density of 80 ,T peak enhances nociceptive sensitivity in mice. Here we examined the effects on pain sensitivity and some indexes of cardiovascular regulation mechanisms in humans by measuring electrical cutaneous thresholds, arterial blood pressure, heart rate and its variability, and stress hormones. Pain and tolerance thresholds remained unchanged after sham exposure but significantly decreased after electromagnetic exposure. Systolic blood pressure was significantly higher during electromagnetic exposure and heart rate significantly decreased, both during sham and electromagnetic exposure, while the high frequency (150,400 mHz) component of heart rate variability, which is an index of parasympathetic activity, increased as expected during sham exposure but remained unchanged during electromagnetic exposure. Cortisol significantly decreased during sham exposure only. These results show that exposure to an EMF of 37 Hz also alters pain sensitivity in humans and suggest that these effects may be associated with abnormalities in cardiovascular regulation. Bioelectromagnetics 25:167,175, 2004. © 2004 Wiley-Liss, Inc. [source] Alkyl Naphthalenes and Phenanthrenes: Molecular Markers for Tracing Filling Pathways of Light Oil and Condensate ReservoirsACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 5 2010LI Meijun Abstract: Condensates and light oils are generally characterized by high maturity, low concentration of sterane and terpane biomarkers and low content of non-hydrocarbon fraction. As a result, some commonly-used sterane, terpane and carbazole migration parameters in conventional oil reservoirs may have a certain limitation in condensate and light oil reservoirs for their poor signal-noise ratios in the gas chromatography-mass spectrometry (GC-MS). Naphthalene, phenanthrene and their methylated substituents, however, are present in significant concentrations in condensates and light oils. Taking the Fushan depression (in the Beibuwan Basin, Northern South China Sea) as an example, this paper attempts for the first time to use polycyclic aromatic hydrocarbon (PAH)-related parameters to trace migration directions and filling pathways for condensate and light oil reservoirs. The result shows that TMNr (i.e. 1,3,7-TMN/ (1,3,7-TMN + 1,2,5-TMN), TMN: trimethylnaphthalene)), MPI-1 (i.e. 1.5×(2-MP + 3-MP)/(P + 1-MP + 9-MP), P: phenanthrene MP: methylphenanthrene), MN/DMN (,methylnaphthalene/,dimethylnaphthalene, %) and MN/TMN (,methylnaphthalene/,trimethylnaphthalene, %) can be used to trace the filling pathways of condensate and light oil reservoirs. These parameters, together with geological consideration and other bulk oil properties (e.g. the gas to oil ratio and density), suggest that the condensates and light oils in the Huachang oil and gas field are mainly sourced from the Bailian sag that is located to the northeast of the Huachang uplift in the Fushan depression. [source] Lipid-Bilayer Permeation of Drug-Like CompoundsCHEMISTRY & BIODIVERSITY, Issue 11 2009Stefanie Abstract Lipid-bilayer permeation is determinant for the disposition of xenobiotics in the body. It controls the pharmacokinetic behavior of drugs and is, in many cases, a prerequisite for intracellular targeting. Permeation of in vivo barriers is in general predicted from lipophilicity and related parameters. This article goes beyond the empirical correlations, and elucidates the processes and their interplay determining bilayer permeation. A flip-flop model for bilayer permeation, which considers the partitioning rate constants beside the translocation rate constants, is compared with the diffusion model based on Fick's first law. According to the flip-flop model, the ratios of aqueous volumes to barrier area can determine whether partitioning or translocation is rate-limiting. The flip-flop model allows permeation of anions and cations, and expands our understanding of pH-dependent permeation kinetics. Some experimental evidences for ion-controlled permeation at pH,7 are also included in this work. [source] | |||||||||||||||||||