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In cell biology, pharmacology and toxicology dose-response and concentration-response curves are frequently fitted to data with statistical methods. Such fits are used to derive quantitative measures (e.g. EC 20 values) describing the relationship between the concentration of a compound or the strength of an intervention applied to cells and its effect on viability or function of these cells. Often, a reference, called negative control (or solvent control), is used to normalize the data. The negative control data sometimes deviate from the values measured for low (ineffective) test compound concentrations. In such cases, normalization of the data with respect to control values leads to biased estimates of the parameters of the concentration-response curve. Low quality estimates of effective concentrations can be the consequence. In a literature study, we found that this problem occurs in a large percentage of toxicological publications. We propose different strategies to tackle the problem, including complete omission of the controls. Data from a controlled simulation study indicate the best-suited problem solution for different data structure scenarios. This was further exemplified by a real concentration-response study. We provide the following recommendations how to handle deviating controls: (1) The log-logistic 4pLL model is a good default option. (2) When there are at least two concentrations in the no-effect range, low variances of the replicate measurements, and deviating controls, control values should be omitted before fitting the model. (3) When data are missing in the no-effect range, the Brain-Cousens model sometimes leads to better results than the default model. [ABSTRACT FROM AUTHOR]

Few researches have been investigated on the effects of ambient air pollutants from coal combustion on acute exacerbation of chronic obstructive pulmonary disease (AECOPD) hospitalizations. The whole time series was split into heating season and non-heating season. We used a quasi-Poisson generalized linear regression model combined with distributed lag non-linear models (DLNMs) to estimate the relative cumulative risk and calculate the air pollutant hospitalization burden of AECOPD for lag 0–7 days in heating season and non-heating season. There were higher PM2.5, PM10, NO2, SO2, and CO concentrations in heating seasons than non-heating season in Shijiazhuang; however, O3 was higher in non-heating season than heating season. The AECOPD-associated relative cumulative risks for PM2.5, PM10, NO2, and SO2 for lag 0–7 days were significantly positively associated with hospitalization in heating and non-heating season; we found that the cumulative relative risk of NO2 was the greatest in every 1 unit of air pollutants during the heating season and the cumulative relative risk of SO2 was the greatest during the non-heating season. The results showed that 17.8%, 12.9%, 1.7%, 16.7%, and 10.5% of AECOPD hospitalizations could be attributable to PM2.5, PM10, SO2, NO2, and CO exposure in heating season, respectively. However, the results showed that 19.5%, 22.4%, 15%, 8.3%, and 10.4% of AECOPD hospitalizations could be attributable to PM2.5, PM10, SO2, NO2, and O3 exposure in non-heating season, respectively. The attributable burden of AECOPD hospitalization in heating season and non-heating season are different. PM2.5, PM10, NO2, and CO are the main factors of heating season, while PM10, PM2.5, SO2, and O3 are the main factors of non-heating season. In conclusions, the centralized heating can change the influence of attributable risk. When government departments formulate interventions to reduce the risk of acute hospitalization of chronic obstructive pulmonary disease (COPD), the influence of heating on disease burden should be considered. [ABSTRACT FROM AUTHOR]

Vascular disorders are a major problem as their pathophysiology has not been fully understood, therefore animal models are implemented to extrapolate the results obtained on animals to humans. The isolated tissue bath technique is a classical pharmacological tool for evaluating concentration-response relationship and to measure the isometric contraction of isolated large conduit (thoracic aorta) arteries. The aim of this study was to investigate the stability of thoracic rings from 10-week-old male Wistar rats during 2, 4, 6 and 8 h of incubation. The vascular response to potassium chloride (KCl), noradrenaline (NA) and acetylcholine (ACh) was analyzed in tissue baths. In addition, histological morphology of the aortic rings after the incubation period was studied. No difference was observed in the contraction to NA (mg of tension, 8 h: 1711 ± 53.85 vs. control: 1567 ± 48.55, P>0.0928) and vasodilation to ACh (% relaxation, 8 h: 64.7 ± 4.05 vs. control: 71.21 ± 3.613, P>0.05) of the thoracic rings among the investigated groups of rats. The integrity of the tunica media and adventitia structure remained unaffected during the first 6 h of incubation. Within 8-hour incubation, slight degeneration of the tunica media smooth muscle structure took place. The results indicate that incubation carried up to 6 h constitutes a reliable experimental model, as to the NA and ACh application. However, longer experiments should be performed with caution due to the appearance of some initial structural changes of the tunica media smooth muscle cells of a rat aorta starting from the eighth hour of incubation. Thus, it is reasonable to carry out similar experiments with an extended range of experimental reagents, and in different pathological conditions to verify the results obtained in this experiment. [ABSTRACT FROM AUTHOR]

The present study discovered four novel hyaluronan-degrading enzyme (hyaluronidase) inhibitors including chikusetsusaponins and catechins through the activity-guided separation of Panax japonicus and Prunus salicina , respectively. Although the discovery resulted in identification of usual frequent hitters, subsequent mechanistic characterizations under our DMSO-perturbed assay conditions and related protocols revealed that chikusetusaponin IV would serve as an aggregating and non-specific binding inhibitor, while (−)-epicatechin would interact specifically with enzyme at the catalytic site or more likely at a kind of catechin-binding site with a relatively week inhibitory activity. The latter description might provide a possible explanation for the well-known fact that a series of catechin have been described as frequent hitters in biological assays with a moderate activity. Thus, the present study demonstrated a practical and robust methodology to characterize initial screening hits mechanistically molecule-by-molecule in the early stage of natural product-based drug discovery. [ABSTRACT FROM AUTHOR]

The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) is the major pest of the Brassicaceae family. In the Agreste region of Pernambuco (Brazil), a Brassica producing center, P. xylostella is under continuous selection pressure by insecticides leading to increased frequency of resistance genes in this species. The objective of the present study was to monitor the resistance of P. xylostella populations to spinosad, chlorfenapyr, and chlorantraniliprole as well as the susceptibility to spinetoram in the Agreste region of Pernambuco (Brazil). Concentration-response bioassays were performed with spinosad, chlorfenapyr and spinetoram to estimate the LC values. Furthermore, a concentration corresponding to label dose for registered products (chlorantraniliprole, spinosad, and chlorfenapyr) and diagnostic concentration for chlorantraniliprole and spinosad were used. The LC to spinosad varied from 0.017 (Recife) to 3.64 (Bezerros II) mg a. i./L (RR varying up to ~200-fold), while for spinetoram, they varied from 0.0013 (Alegre) to 0.198 (Bezerros II) mg a. i./L (RR varying up to ~150-fold). The LC for chlorfenapyr ranged from 0.43 (Recife) to 42.23 (Bezerros II) mg a. i./L (RR varying up to ~100-fold). Plutella xylostella populations developed resistance to chlorfenapyr and spinosad. Apparently, there was no alteration of the resistance levels to chlorantraniliprole in the field. Cross-resistance between spinosad and spinetoram (RR ~ 150-fold) as well as between the spinosyns and chlorfenapyr was observed. The field populations were susceptible to concentration corresponding to label doses of spinosad (mortality > 80 %) and chlorfenapyr (mortality > 80 %), but a considerable loss of susceptibility to both insecticides was observed. Immediate attention to correct rotation of products is necessary to delay development of resistance in this pest. [ABSTRACT FROM AUTHOR]

Hyaluronan-degrading enzyme (hyaluronidase) is involved in tumor growth and inflammation, and as such, hyaluronidase inhibitors have received recent attention as potential therapeutics. The previous studies have successfully discovered a wide range of inhibitors, but unfortunately most of them are dissimilar to original ligand hyaluronan and the mode of action is poorly understood. The present study mechanistically characterized these structurally unrelated inhibitors by interpreting the behavior of concentration–response curves under several in vitro assay conditions. Detergent-addition conditions definitely identified aggregation-based inhibitors. Subsequently, DMSO-perturbed conditions, though preliminary, highlighted the inhibitors that might bind to enzyme non-specifically. Here, an intriguing implication of the latter description is that DMSO-perturbed conditions would generate non-productive but not-denatured enzyme that is an assembly of effective species to capture non-specific binding molecules, and thereby would attenuate their inhibitory activities. [ABSTRACT FROM AUTHOR]

Background/aim: This study investigates whether 1-(2-trifluoromethylphenyl)-imidazole (TRIM), originally proposed as a nitric oxide synthase inhibitor and also suggested to be an inhibitor of store-operated calcium entry in mouse anococcygeal muscle, inhibits receptor-independent and -dependent responses in rat thoracic aorta. Materials and methods: Cyclopiazonic acid- and serotonin-induced vascular responses were investigated in aortic segments isolated from male Sprague Dawley rats using isolated tissue experiments. Changes in intracellular calcium levels were also monitored via front surface fluorescence measurements in fura-2-loaded embryonic rat vascular smooth muscle cell line A7r5. Results: TRIM inhibited serotonin-mediated vascular contractions without affecting cyclopiazonic acid-induced responses. In addition, TRIM caused a nonlinear rightward shift in the serotonin concentration-response curve, possibly via serotonin receptor modulation. Conclusion: TRIM may have an impact on investigation of tissue-specific receptor-independent and -dependent vascular responses. It may also be used as a lead compound in the development of selective serotonin receptor modulators. [ABSTRACT FROM AUTHOR]

This study investigated the presence of sweetness synergism in milk and instant coffee systems. It consists of three parts: 1) modeling concentration–sweetness intensity curves of sweeteners (stevia, sucralose, xylose, tagatose and erythritol); 2) measuring the sweetness potencies of sweeteners compared to sucrose at wide concentration range; and 3) investigating the presence of sweetness synergisms in binary sweetener mixtures. The panelists evaluated sweetness and other sensory characteristics of sweeteners using descriptive analysis. Based on the modeled curve derived from step 1, the concentration of each sweetener with sweetness intensity equal to 2.5% or 2.8% sucrose was calculated for milk and coffee systems, respectively. For the sweetness synergism study, one type of intense sweetener was mixed with one type of bulk sweetener, each eliciting 2.5% or 2.8% equi-sweetness to sucrose, and compared with 5% sucrose added to a milk system or 5.6% sucrose added to a coffee system. The sweetness potencies of bulk sweeteners generally increased whereas the sweetness potencies of intense sweeteners decreased as the concentration increased. The binary sweetener mixtures mostly showed additivity in milk and suppression in coffee system rather than synergism when the concentration dependent nature of sweetness potency for each sweetener was taken into account. [ABSTRACT FROM AUTHOR]

A main goal of the U.S. Tox21 program is to profile a 10K-compound library for activity against a panel of stress-related and nuclear receptor signaling pathway assays using a quantitative high-throughput screening (qHTS) approach. However, assay artifacts, including nonreproducible signals and assay interference (e.g., autofluorescence), complicate compound activity interpretation. To address these issues, we have developed a data analysis pipeline that includes an updated signal noise–filtering/curation protocol and an assay interference flagging system. To better characterize various types of signals, we adopted a weighted version of the area under the curve (wAUC) to quantify the amount of activity across the tested concentration range in combination with the assay-dependent point-of-departure (POD) concentration. Based on the 32 Tox21 qHTS assays analyzed, we demonstrate that signal profiling using wAUC affords the best reproducibility (Pearson’s r = 0.91) in comparison with the POD (0.82) only or the AC50 (i.e., half-maximal activity concentration, 0.81). Among the activity artifacts characterized, cytotoxicity is the major confounding factor; on average, about 8% of Tox21 compounds are affected, whereas autofluorescence affects less than 0.5%. To facilitate data evaluation, we implemented two graphical user interface applications, allowing users to rapidly evaluate the in vitro activity of Tox21 compounds. [ABSTRACT FROM AUTHOR]

The present study was done to explore the cholinergic systems operating in the wall of the isolated rat bladder. In a first set of experiments, bladder strips in vitro were subjected to cumulative concentration-response curve (CRC) to non-selective muscarine agonist carbachol or the partially M2 > M3 selective agonist arecaidine to establish optimal concentration to be used thereafter. In a second set of experiments, the effects of drugs (solifenacin, isoproterenol and mirabegron) were tested on urinary bladder contraction induced by the non-selective muscarinergic agonist carbachol. For both agonists, the contractile responses are qualitatively similar: an initial transient rise in tension followed by complex bursts of high-frequency small 'micro'-contractions superposed on a tonic contraction, with immediate transient 'rebound' contraction after the agonist is washed from the preparation. This rebound contraction is greater with carbachol than arecaidine. Components of the responses to cholinergic stimulation, notably the micro-contractions, were found to be differently stimulated and inhibited by the M3 > M2 selective antagonist solifenacin and by the β-adrenoceptor agonists isoprenaline and mirabegron. A physiological role for the muscarinic dependent phasic contractions and the micro-anatomical elements that might be involved are not known but may be related to non-voiding activity observed during filling cystometry in conscious animals related to afferent discharge and possibly sensation. Furthermore, suggestions for the potential impact of these findings and design of further studies in relation to bladder physiology, pharmacology and pathology are discussed. [ABSTRACT FROM AUTHOR]

Chemical and physical analyses are commonly used as screening methods for the environmental water. However, these methods can only look for the targeted substance but may miss unexpected toxicants. Furthermore, the synergistic effects of mixture cannot be detected. In order to set up the assay criteria for determining various biological activities at a cellular level that could potentially lead to toxicity of environmental water samples, a novel test based on cellular response by using Real-Time Cellular Analyzer (RTCA) is proposed in this study. First, the water sample is diluted to a series of strengths (80%, 60%, 40%, 30%, 20% and 10%) to get the multi-concentration cellular response profile. Then, the area under the cellular response profile (AUCRP) is calculated. Comparing to the normal cell growth of negative control, a new biological activity index named Percentage of Effect (PoE) has been presented which reflects the cumulative inhibitory activity of cell growth over the log-phase. Finally, a synthetical index PoE 50 is proposed to evaluate the intensity of biological activities in water samples. The biological experiment demonstrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The threshold model based on monotonic concentration-response curves (CRCs) is unsuitable to assess the risk of chemicals with non-monotonic CRCs. The non-monotonic CRCs of mixtures may relate to the characteristics of some individual component. To reveal the cause of the mixtures resulting in the non-monotonic CRCs, we used the microplate toxicity analysis to determine the toxicity effects of six 1-alkyl-3-methyl-imidazolium ([amim]X) salts and their mixtures on Vibrio qinghaiensis sp.-Q67 (Q67). It was shown that the CRCs of six [amim]X salts are monotonic S-shaped while those of the senary mixtures designed by the uniform design ray (UD-ray) are all non-monotonic. The mixtures were further split into two ternary mixtures, one containing 1-ethyl-3-methyl-imidazolium ([emim]X) salts (noted as UTE) and the other one containing 1-butyl-3-methyl-imidazolium ([bmim]X) salts (noted as UTB). It was found that the CRCs of UTE mixtures are all non-monotonically J-shaped, while only one (UTB-R3) among UTB mixtures has a little stimulating effect and the CRCs of the other three mixtures (UTB-R1, UTB-R2 and UTB-R4) are monotonic. The CRCs of the binary mixtures designed by the direct equipartition ray design (EquRay) procedure were further examined. The CRCs of the mixtures containing [emim]Cl are non-monotonic J-shaped while those of the mixtures without [emim]Cl are still monotonic. Thus, it can conclude that it is [emim]Cl that causes the non-monotonic CRCs in [amim]X mixtures, even though the CRC of individual [emim]Cl is monotonic. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop an optimal sensory evaluation protocol to model the concentration-response (C-R) curve of various sweeteners in skimmed milk system. C-R curve was modeled for xylose, tagatose, erythritol, sucralose, and stevia. Five concentrations of each sweetener corresponding to the sweetness of 1%, 2%, 3.5%, 5%, and 7% sucrose were calculated by the sweetness potency value obtained from a previous study. Three types of sensory evaluation method were compared for their accuracy in modeling the C-R curve. Traditional method measured the sweetness intensities of 5 concentration levels of a specific sweetener in one test set (eg. xylose 1.6%, 3.2%, 5.6%, 7.9%, 11.1%). Hetero sample-equi concentration method measured the sweetness of 6 types of sweeteners having similar sweetness intensity level in one test set (eg. set 1: sucrose 1%, xylose 1.6%, tagatose 1.2%, erythritol 1.7%, sucralose 0.002%, stevia 0.04%; set 2: sucrose 2%, xylose 3.2%, tagatose 2.4%, erythritol 3.3%, sucralose 0.004%, stevia 0.08%, etc.). Sucrose-sweetener combined method measured the sweetness of 5 levels of specific sweetener as well as the 5 levels of sucrose in one test set. All samples were evaluated by 10 trained panelists. Reference standards for sweetness intensities were provided in all methods. To identify the most accurate sensory evaluation protocol, the concentrations of each sweetener corresponding to the sweetness levels of 1.5% and 4.5% sucrose were interpolated from the C-R curve modeled for each sweetener measured by the 3 methods. The actual sweetness intensities of the interpolated concentrations of each sweetener were validated with the sweetness intensities of 1.5% and 4.5% sucrose levels. The result showed that the sucrose-sweetener combined method was the most accurate protocol. Traditional method tended to overestimate the sweetness potency value of sweeteners in low concentration range whereas hetero sample-equi concentration method tended to underestimate the value. Another significant finding was that the sweetness potency value of each sweetener changed as the concentration changed. [ABSTRACT FROM AUTHOR]

The acute ecotoxicity of a set of mixture samples (washing powders, wastes, fuel extracts etc.) was assessed using four acute ecotoxicity assays with aquatic organisms (Daphnia magna, Poecilia reticulata, Artemia salina and Desmodesmus subspicatus). The experimental concentration-response curves were fitted by seven two-parameter sigmoid equations using non-linear regression. The regression performance of the equations was compared in three categories (overall fit, mid-range fit, and low-effect fit) using non-parametric statistics. The best overall fit was achieved by Weibüll, Bolztman (i.e. logistic), modified Gompertz and log- Weibüll equations. The best low-effect fit was achieved by a modified Gompertz curve. Those equations transforming concentrations to log c fitted significantly worse than those not transforming them. The obtained EC50 values calculated by all of the equations were comparable to those calculated by the probit model. The results show that regardless of the knowledge of the susceptibility distribution or the mechanisms of toxic action simple two-parameter equations fit the data from acute ecotoxicity assays well and might be used for their evaluation. Key words: Acute eco [ABSTRACT FROM AUTHOR]

Abstract: Toxicity data on chemicals, supposed to have a narcotic or polar narcotic toxicological mode of action, have been produced on the luminescent bacterium Vibrio fischeri using the Microtox® test procedure. Advanced statistical methods have been used to calculate statistically sound values for ecotoxicological endpoints. Simple quantitative structure activity relationship (QSAR) equations were developed for narcotics and polar narcotics. These equations were compared with those proposed by the European Technical Guidance Document on Risk Assessment for other aquatic organisms (algae, Daphnia, and fish). Similarities and differences are discussed. The need for including the bacterial component in the ecotoxicological risk assessment for aquatic ecosystems is highlighted. [Copyright &y& Elsevier]

Background and purpose:Heterologous expression of α1, β2 and γ2S(γ1) subunits produces a mixed population of GABAA receptors containing α1β2 or α1β2γ2S(γ1) subunits. GABA sensitivity (lower in receptors containing γ1 or γ2S subunits) and the potentiation of GABA-activated chloride currents (IGABA) by benzodiazepines (BZDs) are dependent on γ2S(γ1) incorporation. A variable γ subunit incorporation may affect the estimation of IGABA potentiation by BZDs. We propose an approach for estimation of BZD efficiency that accounts for mixed population of α1β2 and α1β2γ2S(γ1) receptors.Experimental approach:We investigated the relation between GABA sensitivity (EC50) and BZD modulation by analysing triazolam-, clotiazepam- and midazolam-induced potentiation of IGABA in Xenopus oocytes under two-microelectrode voltage clamp.Key results:Plotting EC50 versus BZD-induced shifts of GABA concentration-response curves (ΔEC50(BZD)) of oocytes injected with different amounts of α1, β2 and γ2S(γ1) cRNA (1:1:1–1:1:10) revealed a linear regression between γ2S(γ1)-mediated reduction of GABA sensitivity (EC50) and ΔEC50(BZD). The slope factors of the regression were always higher for oocytes expressing α1β2γ1 subunit receptors (1.8±0.1 (triazolam), 1.6±0.1 (clotiazepam), 2.3±0.2 (midazolam)) than for oocytes expressing α1β2γ2S receptors (1.4±0.1 (triazolam), 1.4±0.1 (clotiazepam), 1.3±0.1 (midazolam)). Mutant GABAA receptors (α1β2-R207Cγ2S) with lower GABA sensitivity showed higher drug efficiencies (slope factors=1.1±0.1 (triazolam), 1.1±0.1 (clotiazepam), 1.2±0.1 (midazolam)).Conclusions and implications:Regression analysis enabled the estimation of BZD efficiency when variable mixtures of α1β2 and α1β2γ2S(γ1) receptors are expressed and provided new insights into the γ2S(γ1) dependency of BZD action.British Journal of Pharmacology (2008) 155, 424–433; doi:10.1038/bjp.2008.271; published online 7 July 2008 [ABSTRACT FROM AUTHOR]

An efficient and versatile Compound Management operation is essential for the success of all downstream processes in high-throughput screening (HTS) and small molecule lead development. Staff, equipment, and processes need to be not only reliable, but remain flexible and prepared to incorporate paradigm changes. In the present report, we describe a system and associated processes that enable handling of compounds for both screening and follow-up purposes at the NIH Chemical Genomics Center (NCGC), a recently established HTS and probe development center within the Molecular Libraries Initiative of the NIH Roadmap. Our screening process, termed quantitative HTS (qHTS), involves assaying the complete compound library, currently containing >200,000 members, at a series of dilutions to construct a full concentration–response profile. As such, Compound Management at the NCGC has been uniquely tasked to prepare, store, register, and track a vertically developed plate dilution series (i.e., inter-plate titrations) in the 384-well format. These are compressed into a series of 1536-well plates and are registered to track all subsequent plate storage. Here, we present details on the selection of equipment to enable automated, reliable, and parallel compound manipulation in 384- and 1536-well formats, protocols for preparation of inter-plate dilution series for qHTS, as well as qHTS-specific processes and issues. [Copyright &y& Elsevier]

Abstract: Hormesis and essentiality are likely real and common effects at the level of the individual. However, the widespread incorporation of stimulatory effects into applications of ecotoxicology requires the acceptance of assumptions, value judgements and possibly lowering of water/sediment quality standards. There is also currently little data appropriate for considering hormetic effects in the ecotoxicological context. Except perhaps in the case of fitting concentration–response curves, it is not clear that incorporation of hormetic and essentiality type responses into ecotoxicology is necessary. Furthermore, its incorporation presents considerable intellectual and practical changes for ecotoxicology and could have unanticipated consequences. [Copyright &y& Elsevier]

Background and purpose:This paper is intended to assist pharmacologists in making the most of statistical analysis and in avoiding common errors that can lead to false conclusions.Approach:A scenario is presented where a pathway inhibitor increased blood pressure responses to an agonist by about one third. The fictional experimenter concludes that the inhibitor enhanced the responses to the agonist, but has not applied any statistical analysis. Questions are asked of the reader, and a discussion of the author's answers is presented.Results:The agonist responses have unequal standard errors, as often seen in data like these concentration-response curves with responses expressed as change from baseline. The uneven variability (heteroscedasticity) violates an assumption of conventional parametric statistical analyses, but can be corrected by data transformation. Expressing the data as absolute blood pressure and then transforming it to log blood pressure eliminated the heteroscedasticity, but made evident an effect of the inhibitor on baseline blood pressure.Conclusions and implications:Statistical analysis is a sensible precaution against mistakes, but cannot protect against all erroneous conclusions. In this scenario, the inhibitor reduced the blood pressure and increased responses to the agonist. However, it is likely that the latter effect was a consequence of the former and thus no conclusion can be safely drawn about any direct interaction between the agonist and the pathway inhibitor from this experiment. Where results are awkward to interpret because of confounding factors such as an altered baseline, statistical analysis may not be very useful in supporting a safe conclusion.British Journal of Pharmacology (2007) 152, 295–298; doi:10.1038/sj.bjp.0707370; published online 9 July 2007 [ABSTRACT FROM AUTHOR]

Formyl peptides released from Gram-negative bacteria ligate a group of specific mammalian receptors, expressed mainly on granulocytes, monocytes, and macrophages. Receptor ligation activates different transduction cascades, eventually leading to the release of reactive oxygen species and other bactericidal chemical species, and the activation of the actin cytoskeleton with extension of lamellipodia and migration toward the sites of maximal formyl peptide concentration. In vitro, under conditions of nongradient formyl peptide concentrations, lamellipodia form all around the cell contour (chemokinesis). In granulocytes challenged under these conditions with N-formyl-methionyl-leucyl-phenylalanine, (i) the power spectrum of the contour of activated cells shows a peak at a specific periodicity, indicating that the lamellipodial extension is not completely random but stochastically conforms to a deterministic scheme, and (ii) the morphological response (percent of cells exhibiting chemokinesis) tends to reach a maximum at certain drug concentrations, then declining at higher concentrations. Accordingly, the logarithm of the drug concentration-polarizing effect curve is bell-shaped. Herein we illustrate theoretical models for the simulation of these two components of the chemokinetic responses. We show that the main traits of the general morphology and arrangement of lamellipodia may be simulated by an algorithm that starting from a situation of random distribution of active receptors on the cell membrane, encompasses in the successive calculation cycles both a local autocatalytic enhancement of the actin polymerization and a relative inhibition of the actin polymerization at some distance from the more active polymerization foci. In addition, a drug log concentration-polarizing effect bell-shaped curve may be simulated by assuming that the N-formyl-methionyl-leucyl-phenylalanine, while binding with high affinity to the specific receptor, is also able to bind to another lower affinity receptor that may effect depolarizing actions or, more generally, metabolic blocking effects. Under these conditions, at low drug concentrations the polarizing effect brought about by the ligation of the specific receptor is largely predominant. However, as the drug concentration increases and the specific receptors approach saturation, the inhibitory effects become more and more powerful and the net polarizing effect is reduced. [ABSTRACT FROM AUTHOR]

Abstract: Increasing salinity has the potential to affect freshwater organisms. Yet sub-lethal effects of salinity on macroinvertebrates are poorly understood. Growth and development of Ischnura heterosticta (Odonata: Coenagrionidae) was experimentally shown to be faster in 5–20mS/cm than 0.1–1mS/cm, while in 35mS/cm all individuals died. In 30mS/cm about half died and growth was similar to the 0.1mS/cm treatment. The salinity–growth relationship cannot be explained indirectly, that is salinity affecting the survival of their prey. Tissue content and concentration of Ca, Mg, Na and K in emerged adults showed no evidence of deficiencies at low salinity. Heart beat rate was similar across treatments, except at 35mS/cm, where it was slower. Respiration and feeding were similar at 0.1, 10 and 30mS/cm. While there are similarities in I. heterosticta and other species'' salinity response, there are differences and studies on more species are urgently needed. [Copyright &y& Elsevier]

Abstract: The growth and reproduction of the freshwater snail Physa acuta (Gastropoda: Physidae) were measured at various salinity levels (growth: distilled water, 50, 100, 500, 1000 and 5000μS/cm; reproduction: deionized water, 100, 500, 1000 and 3000μS/cm) established using the artificial sea salt, Ocean Nature. This was done to examine the assumption that there is no direct effect of salinity on freshwater animals until a threshold, beyond which sub-lethal effects, such as reduction in growth and reproduction, will occur. Growth of P. acuta was maximal in terms of live and dry mass at salinity levels 500–1000μS/cm. The number of eggs produced per snail per day was maximal between 100 and 1000μS/cm. Results show that rather than a threshold response to salinity, small rises in salinity (from low levels) can produce increased growth and reproduction until a maximum is reached. Beyond this salinity, further increases result in a decrease in growth and reproduction. Studies on the growth of freshwater invertebrates and fish have generally shown a similar lack of a threshold response. The implications for assessing the effects of salinisation on freshwater organisms need to be further considered. [Copyright &y& Elsevier]

Bioanalytical equivalents (BEQs) of mixtures and environmental samples are widely used to reflect the potential threat of pollutants in the environment and can be obtained by bioassays or using chemical analysis combined with relative potencies (REPs). In this study, the relationships between bioassay-detected BEQs (Bio-BEQs) and chemically analyzed BEQs (Chem-BEQs) were studied. BEQs and REPs are correlated with effect level and the concentration-response curves of the reference standard and sample. Thus, effect level (e.g., EC 10 , EC 25 and EC 50) should be addressed for the BEQ values obtained from bioassays or chemical analyses. The previous prerequisites for REPs application (i.e., curves that are parallel and have the same maximum response) are redundant, and the use of REPs for the calculation of BEQs or in risk assessment should instead be based on the same effect level. For a complex mixture with many components, all active components can be regarded as dilutions of a standard compound for inducing a specific effect. Relative toxicity estimates based on EC 50 ignore the contribution of weak-active components with maximum response below EC 50 of the reference standard, especially in complex mixtures or environmental samples. REPs based on an effect level EC 10 that can be clearly discriminated from background response are recommended for BEQ calculation. As an example, the aryl hydrocarbon receptor (AhR)-mediated activity of US EPA priority polycyclic aromatic hydrocarbons (PAHs) in RTL-W1 cells was used to assess the reliability of REPs for mixture toxicity prediction based on the effect level EC 10. Unlabelled Image • Effect level should be addressed for bioanalytical equivalents. • Components can be viewed as dilutions of a compound for inducing a specific effect. • Toxicity estimates at a high effect level ignore weak-active components. • Relative potencies at EC 10 can be used to calculate bioanalytical equivalents. [ABSTRACT FROM AUTHOR]

A proteolysis-targeting chimera (PROTAC) is a new technology that marks proteins for degradation in a highly specific manner. During screening, PROTAC compounds are tested in concentration-response (CR) assays to determine their potency, and parameters such as the half-maximal degradation concentration (DC 50 ) are estimated from the fitted CR curves. These parameters are used to rank compounds, with lower DC 50 values indicating greater potency. However, PROTAC data often exhibit biphasic and polyphasic relationships, making standard sigmoidal CR models inappropriate. A common solution includes manual omitting of points (the so-called masking step), allowing standard models to be used on the reduced data sets. Due to its manual and subjective nature, masking becomes a costly and nonreproducible procedure. We therefore used a Bayesian changepoint Gaussian processes model that can flexibly fit both nonsigmoidal and sigmoidal CR curves without user input. Parameters such as the DC 50 , maximum effect D max , and point of departure (PoD) are estimated from the fitted curves. We then rank compounds based on one or more parameters and propagate the parameter uncertainty into the rankings, enabling us to confidently state if one compound is better than another. Hence, we used a flexible and automated procedure for PROTAC screening experiments. By minimizing subjective decisions, our approach reduces time and cost and ensures reproducibility of the compound-ranking procedure. The code and data are provided on GitHub (https://github.com/elizavetasemenova/gp_concentration_response).

Exposure to air pollutants is a significant trigger of asthma in China. However, there is little evidence of which pollutants are associated most with asthma at the national level, and little research on pollutants' critical values based on concentration-response (C-R) curves. Further, the potential influential variables of air pollutants have not been identified clearly. In this study, logistic regression analyses were used to evaluate the associations between air pollutants and asthma based on 14176 samples across 12 provinces in China in 2015. We also fit a generalized additive model to evaluate the nonlinear C-R curves to identify the critical values. Our results showed that PM 10-2.5 (odds ratios, 95% confidence intervals: 0.95, 0.90–1.00) and NO X (odds ratios, 95% confidence intervals: 0.98, 0.96–1.00) were associated significantly with asthma's prevalence (p < 0.05) in China, in which the correlation between NO X pollution and asthma's prevalence was relatively more significant. The risk of asthma increased significantly when the average annual PM 10-2.5 and NO X concentrations exceeded approximately 40 μg/m3 and 67 μg/m3, respectively. The results of structural equation modelling confirmed that economic scale was the most important driving force for PM 10-2.5 and NO X pollution. Economic scale primarily had a direct influence on increased PM 10-2.5 concentrations, while it primarily had an indirect influence on increased NO X concentrations. Our findings contribute to the limited evidence on PM 10-2.5 and NO X pollution's effects on asthma's prevalence in China. • PM 10-2.5 and NO X were associated significantly with prevalence of asthma in China. • The critical value of PM 10-2.5 concentrations for asthma was 40 μg/m3 in China. • The critical value of NO X concentrations for asthma was 67 μg/m3 in China. • Economic scale had the strongest impact on PM 10-2.5 and NO X pollution. [ABSTRACT FROM AUTHOR]

• Sweetness potencies of sweeteners at sucrose equivalent 1%–16% were measured. • Sweetness potencies of intense sweeteners, but not bulk sweeteners, changed markedly. • Sweetness potency measured over a narrow range was more accurate than wider range. The main objective of the present study was to determine the effect of the concentration range of sweetener on the accuracy of sweetness potency, defined as the ratio of target sweetener and sucrose concentrations at equivalent sweetness intensity level (Wee, Tan, & Forde, 2018), measurement. Attempts were made to measure the sweetness potencies of two bulk sweeteners (powder allulose and liquefied allulose) and three intense sweeteners (sucralose, rebaudioside A, rebaudioside D) using a sucrose-sweetener combined (SSC) method. Three sets of sample combination were evaluated in three independent descriptive analysis testing sessions. One set of sweetener samples had a sucrose-equivalent concentration (SEC) range of 2–15%, wide range condition. The other two sample sets had narrower SEC ranges, of 1–9% for the narrow-range, low-concentration condition, and 8–16% for the narrow-range, high-concentration condition. All samples were evaluated by 10 trained panelists. Reference standards for sweetness intensities were provided during the testing sessions. Overall, the predicted sweetness potency measured over the wide concentration range was less accurate than that measured over the narrower range. Additionally, the results showed that the sweetness potencies were little affected by the concentration for bulk sweeteners, while the sweetness potencies changed dramatically for intense sweeteners. The SSC method was previously proposed for reducing the contextual bias caused by a range-frequency effect during sweetness intensity measurement. However, the present study has revealed that this method is not completely free from psychological biases and that the accuracy of measuring sweetness potency can be affected by the concentration range over which the panelist is evaluating. Thus, the concentration range of sample sets that are evaluated together should be determined carefully to ensure accurate measurement of sweetness. [ABSTRACT FROM AUTHOR]

Ethnopharmacological Relevance: Coptidis Rhizoma has been used to treat diabetes mellitus for more than 1400 years in China. Berberine, one of the main alkaloids of Coptidis Rhizoma, is a principal antidiabetic component of Coptidis Rhizoma. To investigate the effects of berberine on impaired neurogenic contractility of detrusor muscle from urinary bladder of rats with early stage diabetes., Materials and Methods: The detrusor muscle strips were isolated from urinary bladders of streptozotocin-induced diabetic rats, 5% sucrose-induced diuretic rats or normal rats, and were placed in organ bath. The contractions induced by electrical field stimulation (EFS), carbachol, KCl, adenosine triphosphate, and the effects of berberine on those contractions were measured., Results: The EFS- or KCl-induced contraction of detrusor muscle was significantly decreased in diabetic rats as compared with diuretic or normal rats. Atropine and suramin inhibited EFS-induced contraction. In diabetic rats, the atropine sensitive components were decreased in EFS-induced contraction of detrusor muscle, and the adenosine triphosphate-induced contraction was significantly increased. The carbachol-induced contrations were not different among groups. Berberine significantly potentiated EFS-induced contractions of detrusor muscle both from normal and diabetic rats, but the potentiated effect of BBR was more sensitive to atropine in diabetic rats. Berberine also potentiated adenosine triphosphate-induced contraction of detrusor muscle, but did not change carbachol- or KCl-induced contraction., Conclusion: The neurogenic contraction of urinary bladder detrusor muscle is decreased while purinergic contraction of bladder detrusor muscle is increased in rats with early stage diabetes. Berberine increases the neurogenic contractile response to EFS possibly via both presynaptic increasing neurotransmitters release and postsynaptic potentiation of purinergic transmitter-regulated response in rat urinary bladder detrusor; and in diabetic rats, berberine increases neurogenic contractile response mainly via the presynaptic increasing acetylcholine release., (© 2013 Published by Elsevier Ireland Ltd.)

The last two decades have provided a large weight of preclinical data implicating the neurokinin-1 receptor (NK1) and its cognate ligand substance P (SP) in a broad range of both central and peripheral disease conditions. However, to date, only the NK1 receptor antagonist aprepitant has been approved as a therapeutic and this is to prevent chemotherapy-induced nausea & vomiting (CINV). The belief remained that the full therapeutic potential of NK1 receptor antagonists had yet to be realized; therefore clinical evidence that NK1 receptor antagonists may be effective in major depression disorder, resulted in a significant further investment in discovering novel CNS penetrant druggable NK1 receptor antagonists to address this condition. At GlaxoSmithKline after the discovery of casopitant, that went on to demonstrate efficacy as a novel antidepressant in the clinic, additional novel analogues of this NK1 receptor antagonist were designed to further enhance its drug developability characteristics. Herein, we therefore describe the discovery process and the vivo pharmacological and pharmacokinetic profile of the new NK1 receptor antagonist 3a (also called orvepitant), selected as clinical candidate and further progressed into clinical studies for major depressive disorder. Moreover, molecular modeling studies enabled us to improve the pharmacophore model of the NK1 receptor antagonists with the identification of a region able to accommodate a variety of heterocycle moieties., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Ethopharmacology Relevance: Lippia alba (Mill.) N. E. Brown (Verbenaceae) is an aromatic species used in Central and South America as eupeptic for indigestion. In Argentina, it is used by the "criollos" from the Chaco province. There are several chemotypes which differ in the chemical composition of the essential oils. Nowadays, it is experimentally cultivated in some countries of the region, including Argentina., Aim of the Study: To compare the chemical composition and pharmacology of the essential oils from two chemotypes: "citral" (CEO) and "linalool" (LEO), in isolated rat duodenum and ileum., Methods: Contractile concentration-response curves (CRC) of acetylcholine (ACh) and calcium in 40mM K(+)-medium (Ca(2+)-CRC) were done in isolated intestine portions, in the absence and presence of CEO or LEO at different concentrations., Results: Likewise verapamil, CEO and LEO induced a non-competitive inhibition of the ACh-CRC, with IC50 of 7.0±0.3mg CEO/mL and 37.2±4.2mg LEO/mL. l-NAME, a NO-synthase blocker, increased the IC50 of CEO to 26.1±8.7mg CEO/mL. Likewise verapamil, CEO and LEO non-competitively inhibited the Ca(2+)-CRC, with IC50 of 6.3±1.7mg CEO/mL, 7.0±2.5mg LEO/mL and 0.24±0.04mg verapamil/mL (pIC50: 6.28). CEO was proved to possess limonene, neral, geranial and (-)-carvone as the major components, while LEO was rich in linalool., Conclusions: Results suggest that CEO has five times more potency than LEO to inhibit muscarinic contractions. The essential oils of both chemotypes interfered with the Ca(2+)-influx, but with an IC50 about 28 times higher than that of verapamil. Moreover, CEO partially stimulated the NO production. These results show the medicinal usefulness of both Lippia alba chemotypes, thus validating its traditional use, potency and mechanism of action., (© 2013 Published by Elsevier Ireland Ltd.)