Dose-response Curves Research Articles

Dissociation of Centrally and Peripherally Induced Transcranial Magnetic Stimulation Effects in Nonhuman Primates.

Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation method that is rapidly growing in popularity for studying causal brain-behavior relationships. However, its dose-dependent centrally induced neural mechanisms and peripherally induced sensory costimulation effects remain debated. Understanding how TMS stimulation parameters affect brain responses is vital for the rational design of TMS protocols. Studying these mechanisms in humans is challenging because of the limited spatiotemporal resolution of available noninvasive neuroimaging methods. Here, we leverage invasive recordings of local field potentials in a male and a female nonhuman primate (rhesus macaque) to study TMS mesoscale responses. We demonstrate that early TMS-evoked potentials show a sigmoidal dose-response curve with stimulation intensity. We further show that stimulation responses are spatially specific. We use several control conditions to dissociate centrally induced neural responses from auditory and somatosensory coactivation. These results provide crucial evidence regarding TMS neural effects at the brain circuit level. Our findings are highly relevant for interpreting human TMS studies and biomarker developments for TMS target engagement in clinical applications.SIGNIFICANCE STATEMENT Transcranial magnetic stimulation (TMS) is a widely used noninvasive brain stimulation method to stimulate the human brain. To advance its utility for clinical applications, a clear understanding of its underlying physiological mechanisms is crucial. Here, we perform invasive electrophysiological recordings in the nonhuman primate brain during TMS, achieving a spatiotemporal precision not available in human EEG experiments. We find that evoked potentials are dose dependent and spatially specific, and can be separated from peripheral stimulation effects. This means that TMS-evoked responses can indicate a direct physiological stimulation response. Our work has important implications for the interpretation of human TMS-EEG recordings and biomarker development.

Bifurcation analysis of a tuberculosis progression model for drug target identification

Tuberculosis (TB) is a major cause of morbidity and mortality worldwide. The emergence and rapid spread of drug-resistant M. tuberculosis strains urge us to develop novel treatments. Experimental trials are constrained by laboratory capacity, insufficient funds, low number of laboratory animals and obsolete technology. Systems-level approaches to quantitatively study TB can overcome these limitations. Previously, we proposed a mathematical model describing the key regulatory mechanisms underlying the pathological progression of TB. Here, we systematically explore the effect of parameter variations on disease outcome. We find five bifurcation parameters that steer the clinical outcome of TB: number of bacteria phagocytosed per macrophage, macrophages death, macrophage killing by bacteria, macrophage recruitment, and phagocytosis of bacteria. The corresponding bifurcation diagrams show all-or-nothing dose–response curves with parameter regions mapping onto bacterial clearance, persistent infection, or history-dependent clearance or infection. Importantly, the pathogenic stage strongly affects the sensitivity of the host to these parameter variations. We identify parameter values corresponding to a latent-infection model of TB, where disease progression occurs significantly slower than in progressive TB. Two-dimensional bifurcation analyses uncovered synergistic parameter pairs that could act as efficient compound therapeutic approaches. Through bifurcation analysis, we reveal how modulation of specific regulatory mechanisms could steer the clinical outcome of TB.

Anxiogenic doses of rapamycin prevent URB597-induced anti-stress effects in socially defeated mice

Repeated exposure to psychosocial stress modulates the endocannabinoid system, particularly anandamide (AEA) signaling in brain regions associated with emotional distress. The mTOR protein regulates various neuroplastic processes in the brain disrupted by stress, including adult hippocampal neurogenesis. This kinase has been implicated in multiple effects of cannabinoid drugs and the anti-stress behavioral effects of psychoactive drugs. Therefore, our hypothesis is that enhancing AEA signaling via pharmacological inhibition of the fatty acid amide hydrolase (FAAH) enzyme induces an anti-stress behavioral effect through an mTOR-dependent mechanism. To test this hypothesis, male C57Bl6 mice were exposed to social defeat stress (SDS) for 7 days and received daily treatment with either vehicle or different doses of the FAAH inhibitor, URB597 (0.1; 0.3; 1 mg/Kg), alone or combined with rapamycin. The results suggested that URB597 induced an inverted U-shaped dose–response curve in mice subjected to SDS (with the intermediate dose of 0.3 mg/kg being anxiolytic, and the higher tested dose of 1 mg/Kg being anxiogenic). In a second independent experiment, rapamycin treatment induced an anxiogenic-like response in control mice. However, in the presence of rapamycin, the anxiolytic dose of URB597 treatment failed to reduce stress-induced anxiety behaviors in mice. SDS exposure altered the hippocampal expression of the mTOR scaffold protein Raptor. Furthermore, the anxiogenic dose of URB597 decreased the absolute number of migrating doublecortin (DCX)-positive cells in the dentate gyrus, suggesting an anti-anxiety effect independent of newly generated/immature neurons. Therefore, our results indicate that in mice exposed to repeated psychosocial stress, URB597 fails to counteract the anxiogenic-like response induced by the pharmacological dampening of mTOR signaling.

Novel anthropometric measures are positively associated with erectile dysfunction: a cross-sectional study.

Currently, a growing number of research studies have shown a positive association between obesity and erectile dysfunction, while traditional anthropometric measures, such as BMI, have limited ability to assess the risk of erectile dysfunction. Therefore, this study aimed to investigate the association between the new anthropometric index and erectile dysfunction. A study involving 3594 participants from the National Health and Nutrition Examination Survey was conducted. The study calculated various anthropometric indices such as waist circumference (WC), waist-to-height ratio (WtHR), body mass index (BMI), a body shape index (ABSI), conicity index (CI), and body roundness index (BRI). The relationship between anthropometric indices and erectile dysfunction (ED) was investigated using multivariate logistic regression and restricted cubic splines (RCS). Interaction analysis was conducted on subgroups to confirm the findings. Additionally, the efficacy of various anthropometric indicators in predicting the risk of erectile dysfunction was assessed using the receiver operating characteristic curve (ROC). After adjusting for potential confounding factors, we identified a positive and independent correlation between erectile dysfunction (ED) and all other anthropometric measures except for BMI. Additionally, the risk of ED increased by 49% and 42% for each standard deviation increment in ABSI and CI, respectively. Dose-response curve analysis demonstrated that WC, BMI, WtHR, and CI displayed a non-linear correlation with the risk of ED. The subgroup analysis revealed that individuals classified as White, who had higher levels of WC, ABSI, and CI, were more susceptible to erectile dysfunction compared to people from other races. ROC analysis showed that ABSI was superior in detecting erectile dysfunction (area under the curve: 0.750; 95% CI 0.732-0.768; optimal cutoff value: 0.083) as compared to other indices. The combination of obesity defined by BMI and other anthropometric measures showed that higher ABSI and CI levels were positively associated with the prevalence of erectile dysfunction, independent of BMI (P < .001). In this study, anthropometric indicators including ABSI, BRI, WtHR, CI, and WC were positively associated with erectile dysfunction. To improve the prevention and treatment of this condition, it is recommended that new anthropometric indicators receive greater consideration.

Fluorescent bacteria detection in water using cell imprinted polymer (CIP) coated microparticles in a magnetophoretic microfluidic device

Molecular imprinting has advanced towards synthesizing whole-cell imprints of microorganisms such as bacteria on various sensor surfaces including wire electrodes, quartz crystal microbalances, and microparticles (MPs). We recently introduced cell-imprinted polymers (CIPs) coated on MPs, called CIP-MPs, for bacteria recovery from water. In this paper, we have advanced towards rapid fluorometric Escherichia coli (E. coli) detection by applying fluorescent magnetic CIP-MPs, which were captured by soft ferromagnetic microstructures integrated into a microfluidic channel. The shape of ferromagnetic microstructures was optimized numerically to enhance the magnetophoretic accumulation of CIP-MPs in the microchannel. The device was then fabricated and the flow rate required to enhance bacteria capturing efficiency by CIP-MPs was determined. Decreasing the flow rate reduced the flow-induced drag and increased the interactions between the bacteria and imprinted CIP cavities. Fluorescent imaging of the accumulated CIP-MPs was done before and after bacteria capturing to quantify the changes in the fluorescence intensity as E. coli cells were captured by CIP-MPs in the microchannel. The dose-response curve of the sensor at 0–109 CFU/mL bacterial counts was obtained. Using the 3- and 10-sigma methods on the dose-response curve, the limits of detection (LOD) and quantification (LOQ) of the sensor were determined to be 4 × 102 and 3 × 103 CFU/mL, respectively, within a dynamic range of 102–107 CFU/mL. Lastly, the specificity of the CIP-MPbased sensor towards E. coli was tested and confirmed using Sarcina as a non-specific target bacterium. In summary, our developed sensor offers a promising approach for rapid and low-cost detection of bacteria in water and is suitable for development of portable and durable all-polymeric sensors for point-of-need detection.

Humanized Anti-Carcinoembryonic Antigen Antibodies Brightly Target and Label Gastric Cancer in Orthotopic Mouse Models

IntroductionGastric cancer poses a major therapeutic challenge. Improved visualization of tumor margins at the time of gastrectomy with fluorescent tumor-specific antibodies could improve outcomes. The present report demonstrates the potential of targeting gastric cancer with a humanized anti-carcinoembryonic antigen (CEA) antibody in orthotopic mouse models. MethodsMKN45 cells were injected subcutaneously into nude mice to establish xenograft models. Tumor fragments collected from subcutaneous models were then implanted into the greater curvature of the stomach to establish orthotopic models. For tumor labeling, a humanized anti-CEA antibody (M5A) and IgG as a control, were conjugated with the near-infrared dye IRDye800CW. Time (24-72 h) and dose (50-100 μg) response curves were performed in subcutaneous models. Orthotopic models received 50 μg of M5A-IR800 or 50 μg IgG-IR800 as a control and were imaged after 72 h. Fluorescence imaging was performed on the mice using the LI-COR Pearl Imaging System. ResultsIn subcutaneous models, tumor to background ratios (TBRs) reached 8.85 at 72 h. Median TBRs of orthotopic model primary tumors were 6.25 (interquartile range [IQR] 6.03-7.12) for M5A-IR800 compared to 0.42 (IQR 0.38-0.54) for control. Abdominal wall metastasis median TBRs were 13.52 (IQR 12.79-13.76) for M5A-IR800 and 3.19 (IQR 2.65-3.73) for the control. Immunohistochemistry confirmed CEA expression within tumors. ConclusionsHumanized anti-CEA antibodies conjugated to near-infrared dyes provide specific labeling of gastric cancers in mouse models. Orthotopic models demonstrated bright and specific labeling with TBRs greater than ten times that of control. This tumor-specific fluorescent antibody is a promising potential clinical tool for improving visualization of gastric cancer margins at time of surgical resection.

ROE (Radiotherapy Outcomes Estimator): An open-source tool for optimizing radiotherapy prescriptions

Background and objectivesRadiotherapy prescriptions currently derive from population-wide guidelines established through large clinical trials. We provide an open-source software tool for patient-specific prescription determination using personalized dose-response curves. MethodsWe developed ROE, a plugin to the Computational Environment for Radiotherapy Research to visualize predicted tumor control and normal tissue complication simultaneously, as a function of prescription dose. ROE can be used natively with MATLAB and is additionally made accessible in GNU Octave and Python, eliminating the need for commercial licenses. It provides a curated library of published and validated predictive models and incorporates clinical restrictions on normal tissue outcomes. ROE additionally provides batch-mode tools to evaluate and select among different fractionation schemes and analyze radiotherapy outcomes across patient cohorts. ConclusionROE is an open-source, GPL-copyrighted tool for interactive exploration of the dose-response relationship to aid in radiotherapy planning. We demonstrate its potential clinical relevance in (1) improving patient awareness by quantifying the risks and benefits of a given treatment protocol (2) assessing the potential for dose escalation across patient cohorts and (3) estimating accrual rates of new protocols.

Environmental risk thresholds and prediction models of Cd in Chinese agricultural soils

Soil environmental risk threshold of cadmium (Cd) is an important index in formulating soil protection policy. Environmental risk threshold refers to the maximal allowable critical concentration of hazardous substances in the environment. Although there is less study on how to determine soil Cd environmental risk threshold, it is a crucial indicator in formulating soil conservation policies and a key factor in assessing soil environmental quality. The main research content of the study is deducing the environmental risk threshold, aiming to provide scientific basis for the study of environmental quality standards of agricultural land and provide technical support for the protection of Cd pollution of agricultural land. The hazard concentration of 5 % species (HC5, which protects 95 % of species) was determined here using different toxicological data of Cd from 23 test endpoints, interspecific extrapolation using the species sensitivity distribution (SSD) method, and a prediction model was created on the basis of several soil parameters. According to the findings, Cd effective concentration (EC10) (Cd concentration which blocks 10 % of an endpoint's bioactivity) varied from 0.109 to 221 mg·kg−1, and the hormetic response induced by Cd reached 118 % displaying in the dose-response curve of Lolium perenne L.. Toxicology data was rectified by the aging factor considering biogeochemical processes of the newly added pollutants prior to SSD curves fitting. After that, the prediction model was created with the equation of LogHC5 = 0.147 pH + 0.067 OC -1.616. The field test properly validated the prediction model, demonstrating its ability to forecast Cd toxicity levels for various soil conditions. This study offers a scientifically sound methodology for determining the environmental risk limitation for Cd and identifies critical paths for the preservation of environmental species.

Biological production of epicoccamide-aglycone and its cytotoxicity

Epicoccamide (EPC) is an O-d-mannosylated acyltetramic acid of Epicoccum origin and is a bolaamphiphilic fungal polyketide. EPC displays weak toxicity against Staphylococcus aureus and HeLa cell lines. The EPC biosynthetic gene cluster was previously identified in Epicoccum nigrum and knockout of the glycosyltransferase gene (epcB) abolished EPC production. EPC-aglycone was expected in the epcB knockout but was not found. This study demonstrates that extractive culture using the hydrophobic resin Diaion HP-20 resulted in the production of EPC-aglycone, which was isolated using chromatographic separation techniques, and its structural identity was substantiated by chemical analyses. EPC-aglycone displayed strong antibacterial activity against Staphylococcus aureus, with the minimal inhibitory concentration of 1 μg/mL (64 μg/mL for EPC). EPC-aglycone displayed higher levels of growth inhibition against HeLa cell line (the half inhibitory concentration, 19 μM) and WI-38 (15 μM) cell line than EPC (76 μM and 38 μM vs. HeLa and WI-38, respectively). The dose–response curve fit of growth inhibition indicated that EPC-aglycone adopted a shallow curve (low slope factor), which was different from that of EPC, suggesting that their cellular targets are distinct from each other. This study substantiates that the d-mannose attachment is the final step in EPC biosynthesis, showcasing a glycosylation-mediated modulation of the biological activity of simple acyltetramic acid. This study also highlights the usefulness of extractive cultures in mining cryptic microbial natural products.

REAP-2: An interactive quantitative tool for robust and efficient dose-response curve estimation.

REAP-2 is an interactive dose-response curve estimation tool for Robust and Efficient Assessment of drug Potency. It provides user-friendly dose-response curve estimation for in vitro studies and conducts statistical testing for model comparisons with a redesigned user interface. We also make a major update of the underlying estimation method with penalized beta regression, which demonstrates great reliability and accuracy in dose estimation and uncertainty quantification. In this note, we describe the method and implementation of REAP-2 with a highlight on potency estimation and drug comparison.

Exploring dose–response relationships in Aedes aegypti survival upon bacteria and arbovirus infection

A detailed understanding of how host fitness changes in response to variations in microbe density (an ecological measure of disease tolerance) is an important aim of infection biology. Here, we applied dose–response curves to study Aedes aegypti survival upon exposure to different microbes. We challenged female mosquitoes with Listeria monocytogenes, a model bacterial pathogen, Dengue 4 virus and Zika virus, two medically relevant arboviruses, to understand the distribution of mosquito survival following microbe exposure. By correlating microbe loads and host health, we found that a blood meal promotes disease tolerance in our systemic bacterial infection model and that mosquitoes orally infected with bacteria had an enhanced defensive capacity than insects infected through injection. We also showed that Aedes aegypti displays a higher survival profile following arbovirus infection when compared to bacterial infections. Here, we applied a framework for investigating microbe-induced mosquito mortality and details how the lifespan of Aedes aegypti varies with different inoculum sizes of bacteria and arboviruses.

Baseline micronucleus frequencies and 60Co cytokinesis-block micronucleus assay dose-response curve for biodosimetry in Vietnam.

This study aims to establish baseline micronucleus (MN) frequencies from various populations of residents in Vietnam and develop a 60Co dose-response curve for the cytokinesis-block micronucleus (CBMN) assay. Blood samples were exposed in vitro to a 60Co source at a dose rate of 275mGy per min in a range of 0.1 to 4.0Gy. MN background frequencies were 4.5±3.2, 7.3±4.6, 7.0±3.8 and 13.1±6.7 in 1000 binucleated (BN) cells for 96 healthy donors, 22 male radiation workers and 12 breast cancer patients, respectively. Blood samples from three healthy donors were used to generate the MN dose-response curve: y=C + (0.0496±0.0069)D + (0.0143±0.0026)D2. This curve was verified through an inter-laboratory comparison (RENEB ILC 2021). Our findings highlight the significance of the CBMN assay as an additional essential tool for biodosimetry in Vietnam.

Polybrominated biphenyls (PBBs) and prevalence of autoimmune disorders among members of the Michigan PBB registry

BackgroundPolybrominated biphenyls (PBBs), a class of endocrine disrupting chemicals, were the main chemicals present in one of the largest industrial accidents in the United States. We investigated the association between serum PBB-153 levels and autoimmune disorders among members of the Michigan PBB Registry. MethodsEight hundred and ninety-five members of the registry had both a serum PBB-153 measurement and had completed one or more questionnaires about autoimmune disorders. Autoimmune disorders were examined collectively and within specific organ systems. Sex-stratified unadjusted and adjusted log-binomial models were used to examine the association between tertiles of serum PBB-153 levels and autoimmune disorders. Models were adjusted by lifestage at exposure (in utero, childhood, adulthood), smoking history (never, past, current), and total serum lipid levels (continuous). We utilized cubic spline models to investigate non-linearity between serum PBB-153 levels and the prevalence of autoimmune disorders. ResultsApproximately 12.9% and 20.7% of male and female participants reported having one or more autoimmune disorders, respectively. After adjustment for potential confounders, we observed no association between PBB-153 tertiles and the composite classification of ‘any autoimmune disorder’ in either sex. We observed some evidence for an association between serum PBB-153 levels and rheumatoid arthritis in males and females; however, this was not statistically significant in females. We also observed some evidence for an association between serum PBB-153 levels and neurological- and thyroid-related autoimmune disorders in females, but again this was not statistically significant. Additionally, we identified dose-response curves for serum PBB-153 levels and the prevalence of autoimmune disorders that differed by lifestage of exposure and sex. ConclusionsWe observed some evidence that increasing serum PBB-153 levels were associated with three specified autoimmune disorders. Studies focusing on these three autoimmune disorders and the potential non-linear trend differences by lifestage of exposure warrant further investigation.

Effects of Interfraction Dose Variations of Target and Organs at Risk on Clinical Outcomes in High Dose Rate Brachytherapy for Cervical Cancer.

Meeting dose prescription is critical to control tumors in radiation therapy. Interfraction dose variations (IDVs) from the prescribed dose in high dose rate brachytherapy (HDR) would cause the target dose to deviate from the prescription but their clinical effect has not been widely discussed in the literature. Our previous study found that IDVs followed a left-skewed distribution. The clinical effect of the IDVs in 100 cervical cancer HDR patients will be addressed in this paper. An in-house Monte Carlo (MC) program was used to simulate clinical outcomes by convolving published tumor dose response curves with IDV distributions. The optimal dose and probability of risk-free local control (RFLC) were calculated using the utility model. The IDVs were well-fitted by the left-skewed Beta distribution, which caused a 3.99% decrease in local control probability and a 1.80% increase in treatment failure. Utility with respect to IDV uncertainty increased the RFLC probability by 6.70% and predicted an optimal dose range of 83 Gy-91 Gy EQD2. It was also found that a 10 Gy dose escalation would not affect toxicity. In conclusion, HRCTV IDV uncertainty reduced LC probabilities and increased treatment failure rates. A dose escalation may help mitigate such effects.

OR11-05 High-throughput Screening Identifies TR4 Modulators For Potential Therapeutic Application

Abstract Disclosure: S. Khowal: None. D. Zhang: None. R. Damoiseaux: None. K. Javaherian: None. A.P. Heaney: None. Cushing Disease (CD), due to an adrenocorticotropic hormone (ACTH)-secreting pituitary tumor, leads to excess cortisol and is a life-threatening “orphan disease”. Although surgical removal can be effective, CD frequently recurs. Thereafter, repeat surgery, radiation therapy and/or bilateral adrenalectomy are not always successful and cause significant morbidity. Medical therapy has significantly improved but there is a clear unmet need for efficacious and safe therapies that target the pituitary corticotroph tumor itself to offer biochemical and tumor control. We previously demonstrated that the orphan testicular receptor 4 (TR4) regulates pro-opiomelanocortin gene transcription and ACTH secretion. Herein, we used the Flexi Vector system to identify TR4 modulators by fusing the TR4 LBD (380-615aa) to a 3’ GAL4 DBD to generate a chimeric fusion plasmid, pBIND-TR4-LBD. The pBIND-TR4-LBD construct and an exogenous luciferase reporter construct pGL4.35 (luc2P/9XGAL4UAS), containing 9 copies of a GAL4 responsive upstream activating sequence (UAS), were then transiently transfected into human embryonic kidney (HEK293) cells. Following treatment with TR4 ligands or modulators, our TR4-LBD undergoes a conformational change and recruits additional cofactors and RNA polymerase II to the complex to drive GAL4-directed firefly luciferase expression. In a high throughput screen (HTS) of 27,705 chemicals, we identified several potential “hit” TR4 modulators that induced or inhibited TR4 LBD-directed GAL4UAS-directed luciferase expression by &amp;gt;3 -fold. Compounds from the HTS included ATP-sensitive K+ and calcium channel blockers, steroid hormones and modulators of cell proliferation and inflammation and several agonist and antagonist “hit” compounds induced TR4 &amp;gt;10 fold or inhibited TR4 by 90% respectively with minimal cell toxicity (&amp;lt;10%). In silico analysis of interactions between the TR4 LBD and these potential ligands indicated that the GLU-534 &amp; ARG-565 may be crucial residues involved in TR4 ligand binding. Dose-response curves to calculate EC50 of these potential TR4 hit compounds and mode-of-action characterization are in progress. Our studies have identified several potent TR4 agonistic and antagonistic compounds and lay the framework for the discovery of safe and efficacious lead TR4 ligands that can be further advanced as potential drug therapies for CD and other diseases. Presentation: Friday, June 16, 2023

Relationship between the weight-adjusted-waist index and kidney stone: a population-based study.

At present, a growing number of studies have shown a positive association between obesity and kidney stone, while traditional anthropometric measures, such as body mass index (BMI) and Waist circumference (WC), have limited ability to assess the risk of kidney stone. Therefore, this study aimed to investigate the association between the weight-adjusted-waist index (WWI) and the risk of kidney stone. Data from the National Health and Nutrition Examination Survey (NHANES) between 2009 and 2016 were used. A total of 17,292 participants from NHANES were included in the study. Multivariate logistic regression and restricted cubic splines (RCS) were used to investigate the relationship between WWI and kidney stone. Interaction analysis was performed for subgroups to verify the results. Meanwhile, the receiver operating characteristic curve (ROC) was used to analyze the efficacy of different anthropometric indices in predicting the risk of kidney stone. After adjusting for potential confounding factors, we found a positive and independent association between kidney stone and WWI. After adjusting for all covariates, a one-unit increase in WWI was associated with a 36% increase in the risk of kidney stones. Dose-response curve analysis showed that WWI was non-linear correlated with the prevalence of kidney stone. In ROC analysis, WWI showed better discrimination for kidney stone (area under the curve: 0.612; 95% CI: 0.599-0.626; optimal cutoff value: 11.063) compared with other indices. In this study, increased WWI was strongly associated with the risk of kidney stone.

How to measure the ESR intensity of the Al centre in optically bleached coarse quartz grains for dating purpose?

The ESR intensity of the Al signal has been traditionally extracted from the measurement of the amplitude between the top of the first peak and the bottom of the last peak from g = 2.0185 to g = 1.9928. However, a recent study by Kabacińska and Timar-Gabor (2022) showed the limitations of this method. As a follow-up, we investigated and compared various Al signal intensity extraction methods to evaluate their impact on the De estimation of several coarse-grained quartz samples (100–200 μm) from Early Pleistocene to modern-age deposits.In particular, we tested the potential of using the area of the Al signal near g = 2.0603, as it is theoretically free of any major interfering signals. However, our results show that the extraction methods related to this area do not offer any substantial advantages over the traditional method in the case of coarse-grained samples. Instead, measurement of the ESR intensity is more time consuming, and resulting dose response curves are more scattered. Actually, most Al intensity extraction methods tested in this study return equivalent dose (De) estimates (as well as bleaching coefficient values) within error, suggesting that the interfering signals do not seem to strongly bias the ESR dose evaluation in those coarse-grained quartz samples. This outcome provides additional support in favor of the use of the traditional method. However, the significant inter-sample variability observed in our study nevertheless shows the necessity to extend this investigation to a larger number of samples of various grain sizes, origins and chronologies in order to identify more meaningful patterns on a larger scale.

Broad-Spectrum Antimicrobial Activity of Synthetic Peptides GV185 and GV187.

Optimizing synthetic antimicrobial peptides for safe and enhanced activity against fungal and bacterial pathogens is useful for genetic engineering of plants for resistance to plant pathogens and their associated mycotoxins. Nine synthetic peptides modeled after lytic peptides tachyplesin 1, D4E1 from cecropin A, and protegrin 1 were added to germinated spores of fungal species Aspergillus flavus, Rhizopus stolonifer, Fusarium oxysporum f. sp. vasinfectum, F. verticillioides, F. graminearum, Claviceps purpurea, Verticillium dahliae, and Thielaviopsis basicola and bacterial cultures of Pseudomonas syringae pv. tabaci and Xanthomonas campestris pv. campestris at different doses and inhibitory dose response curves, and were modeled to assess antimicrobial activity. Peptides GV185 and GV187, modified from tachyplesin 1, had superior abilities to inhibit fungal and bacterial growth (50% inhibitory concentrations [IC50] ranging from 0.1 to 8.7 µM). R. stolonifer (IC50 = 8.1 µM), A. flavus (IC50 = 3.1 µM), and F. graminearum (IC50 = 2.2 µM) were less inhibited by GV185 and GV187 than all the remaining fungi (IC50 = 1.4 µM) and bacteria (IC50 = 0.1 µM). Of the remaining peptides, GV193, GV195, and GV196 (IC50 range of 0.9 to 6.6 µM) inhibited fungal growth of A. flavus, F. verticillioides, and F. graminearum less than GV185 and GV187 (IC50 range of 0.8 to 3.9 µM), followed by GV197 (IC50 range of 0.8 to 9.1 µM), whereas GV190 and GV192 inhibited poorly (IC50 range of 28.2 to 36.6 µM and 15.5 to 19.4 µM, respectively) and GV198 stimulated growth. GV185 and GV187 had slightly weaker hydrophobic and cationic residues than other tachyplesin 1 modified peptides but still had unexpectedly high lytic activity. Germinated fungal spores of R. stolonifer and F. graminearum exposed to these two peptides and D4E1 and AGM182 appeared wrinkled, with perforations near potential cytoplasmic leakage, which provided evidence of plasma membrane and cell wall lysis. We conclude that peptides GV185 and GV187 are promising candidates for genetic engineering of crops for resistance to plant-pathogenic bacteria and fungi, including A. flavus and aflatoxin contamination.

Predicting acute paraquat toxicity using physiologically based kinetic modelling incorporating in vitro active renal excretion via the OCT2 transporter

Including active renal excretion in physiologically based kinetic (PBK) models can improve their use in quantitative in vitro- in vivo extrapolation (QIVIVE) as a new approach methodology (NAM) for predicting the acute toxicity of organic cation transporter 2 (OCT2) substrates like paraquat (PQ). To realise this NAM, kinetic parameters Vmax and Km for in vitro OCT2 transport of PQ were obtained from the literature. Appropriate scaling factors were applied to translate the in vitro Vmax to an in vivo Vmax. in vitro cytotoxicity data were defined in the rat RLE-6TN and L2 cell lines and the human A549 cell line. The developed PQ PBK model was used to apply reverse dosimetry for QIVIVE translating the in vitro cytotoxicity concentration-response curves to predicted in vivo toxicity dose-response curves after which the lower and upper bound benchmark dose (BMD) for 50% lethality (BMDL50 and BMDU50) were derived by applying BMD analysis. Comparing the predictions to the in vivo reported LD50 values resulted in a conservative prediction for rat and a comparable prediction for human showing proof of principle on the inclusion of active renal excretion and prediction of PQ acute toxicity for the developed NAM.

Predicting Acute Radio-Induced Toxicity for Head and Neck Cancer Patients: Combining Dosimetry with Biomarker Data, Disclosing a Synergistic Effect

We aimed to establish the added value of combining dosimetry with a binary blood assay for radiosensitivity based on quantification of pATM protein (RADIODTECT©) to predict acute radiotherapy (RT) induced mucositis (MUC) and dysphagia (DYS) in head & neck cancer patients (pts). We enrolled 101 pts prospectively scored for acute toxicity with CTCAE. We considered four endpoints: grade≥2 (G2+) and grade≥3 (G3+) MUC, G2+, and G3+ DYS. We dichotomized the pATM concentration to define radiosensitive (RS) vs. radioresistant (RR) pts using previously described cutoffs for G2+ (57.8 ng/mL) and G3+ toxicity (46 ng/mL). We did RADIODTECT© and toxicity scoring blindly. We considered two already published NTCP models, including (i) the Equivalent Uniform Dose to the oral cavity (n = 0.05, EUD_OC, Odds Ratio [OR] = 1.02) and the mean dose to the parotid glands (Dmean_PG, OR = 1.06) for MUC and (ii) EUD_OC (OR = 1.04), the glottic larynx EUD (n = 0.35, EUD_GL, OR = 1.02) and the volume of pharyngeal constrictor muscles receiving>50Gy (V50Gy_CM, OR = 1.02) for DYS. To account for the association of toxicity with the dose distribution in multiple organs at risk (OARs), we derived a "Weighted Dose Score" (WDS) as a linear combination of the dose factors, using their β-coefficients (= lnOR) as weights. WDS for MUC (WDS_OM) = 0.06*Dmean_PG + 0.02*EUD_OC WDS for DYS (WDS_DYS) = 0.02*V50Gy_CM + 0.02*EUD_GL + 0.04*EUD_OC We used WDS as a comprehensive dose feature to fit a dose response and allowed WDS50 (i.e., the WDS associated with 50% toxicity probability) to be different for RR (WDS50_RR) and RS pts (WDS50_RS). The dose-modifying factor (DMF) is the ratio of WDS50_RS/WDS50_RR. It measures the horizontal shift of the dose-response curve when comparing RS vs. RR pts. We scored G2+ and G3+ MUC in 80 and 41 pts; G2+ and G3+ DYS in 73 and 35 pts. The average concentration of pATM was 57.4ng/mL (sd 22.3ng/mL): 53/101 pts were classified as RS for G2+ toxicity and 35/101 as RS for G3+. On the whole cohort, the RADIODTECT© did not significantly associate with the risk of toxicity. However, we found two different dose-response curves at low WDS. There, the intrinsic biological sensitivity significantly affects the toxicity probability: ORs for RADIODTECT© are 2.6/2.4 for G2+/G3+ DYS, 6.4/2.9 for G2+/G3+ MUC. Furthermore, the difference in the incidence of side effects in RR vs. RS pts decreases as the WDS increases, reaching a region where the doses of OARs play a significant role. When combined with WDS, the RADIODTECT© effectively predicted RS pts, with DMF ranging from 0.77 for G3+ DYS to 0.40 for G2+ MUC. These findings support the hypothesis that dose and biomarkers act synergistically; biologically based radiosensitivity plays a significant role when OARs are exposed at lower doses, while high doses of OARs determine toxicity irrespective of the underlying single pt biological characterization.