Dose-response Correlation Research Articles

The development of fibrosis in a novel model of chronic pancreatitis is mediated by complement factor C5

The development of fibrosis in a novel model of chronic pancreatitis is mediated by complement factor C5

Validation study on urinary biomarkers of exposure for aflatoxin B1, ochratoxin A, fumonisin B1, deoxynivalenol and zearalenone in piglets

The multi-biomarker approach was used to validate urinary biomarkers in piglets administered boluses contaminated with mixtures of deoxynivalenol (DON), aflatoxin B1 (AFB1), fumonisin B1 (FB1), zearalenone (ZEA) and ochratoxin A (OTA) at different concentrations. Boluses contaminated with mycotoxins were prepared by slurrying and freezedrying feed material fortified with culture extracts of selected toxigenic fungi. Piglets were individually placed in metabolic cages to collect urine before gavage and 24 h post dose. Urine samples were hydrolysed with β-glucuronidase and analysed by a multi-biomarker LC-MS/MS method developed and validated to identify and measure biomarkers of FB1, OTA, DON, ZEA and AFB1. Urinary levels of FB1, OTA, DON + de-epoxy-deoxynivalenol, ZEA + alphazearalenol and aflatoxin M1 were selected as biomarkers of FB1, OTA, DON, ZEA and AFB1, respectively. Mean percentages of dietary mycotoxins excreted as biomarkers in 24 h post dose urine were 36.8% for ZEA, 28.5% for DON, 2.6% FB1, 2.6% for OTA and 2.5% for AFB1. A good correlation was observed between the amount of mycotoxins ingested and the amount of relevant biomarkers excreted in 24 h post dose urine. Linear dose-response correlation coefficients ranged between 0.68 and 0.78 for the tested couples of mycotoxin/biomarker. The good sensitivity of the LC-MS/MS method and the good dose-response correlations observed in this study permitted to validate the selected mycotoxin biomarkers in piglets at dietary levels close to the maximum permitted levels reported in Commission Directive 2003/100/EC for AFB1 and the guidance values reported in Commission Recommendation 2006/576/EC for DON, ZEA, OTA and FB1.

Genomic Analysis of Stress Response against Arsenic in Caenorhabditis elegans

Arsenic, a known human carcinogen, is widely distributed around the world and found in particularly high concentrations in certain regions including Southwestern US, Eastern Europe, India, China, Taiwan and Mexico. Chronic arsenic poisoning affects millions of people worldwide and is associated with increased risk of many diseases including arthrosclerosis, diabetes and cancer. In this study, we explored genome level global responses to high and low levels of arsenic exposure in Caenorhabditis elegans using Affymetrix expression microarrays. This experimental design allows us to do microarray analysis of dose-response relationships of global gene expression patterns. High dose (0.03%) exposure caused stronger global gene expression changes in comparison with low dose (0.003%) exposure, suggesting a positive dose-response correlation. Biological processes such as oxidative stress, and iron metabolism, which were previously reported to be involved in arsenic toxicity studies using cultured cells, experimental animals, and humans, were found to be affected in C. elegans. We performed genome-wide gene expression comparisons between our microarray data and publicly available C. elegans microarray datasets of cadmium, and sediment exposure samples of German rivers Rhine and Elbe. Bioinformatics analysis of arsenic-responsive regulatory networks were done using FastMEDUSA program. FastMEDUSA analysis identified cancer-related genes, particularly genes associated with leukemia, such as dnj-11, which encodes a protein orthologous to the mammalian ZRF1/MIDA1/MPP11/DNAJC2 family of ribosome-associated molecular chaperones. We analyzed the protective functions of several of the identified genes using RNAi. Our study indicates that C. elegans could be a substitute model to study the mechanism of metal toxicity using high-throughput expression data and bioinformatics tools such as FastMEDUSA.

Antimutagenic and antirecombinagenic activities of noni fruit juice in somatic cells of Drosophila melanogaster

Noni, a Hawaiian name for the fruit of Morinda citrifolia L., is a traditional medicinal plant from Polynesia widely used for the treatment of many diseases including arthritis, diabetes, asthma, hypertension and cancer. Here, a commercial noni juice (TNJ) was evaluated for its protective activities against the lesions induced by mitomycin C (MMC) and doxorrubicin (DXR) using the Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster. Three-day-old larvae, trans-heterozygous for two genetic markers (mwh and flr3 ), were co-treated with TNJ plus MMC or DXR. We have observed a reduction in genotoxic effects of MMC and DXR caused by the juice. TNJ provoked a marked decrease in all kinds of MMC- and DXR-induced mutant spots, mainly due to its antirecombinagenic activity. The TNJ protective effects were concentration-dependent, indicating a dose-response correlation, that can be attributed to a powerful antioxidant and/or free radical scavenger ability of TNJ.

A Mode-of-Action Approach for the Identification of Genotoxic Carcinogens

Distinguishing between clastogens and aneugens is vital in cancer risk assessment because the default assumption is that clastogens and aneugens have linear and non-linear dose-response curves, respectively. Any observed non-linearity must be supported by mode of action (MOA) analyses where biological mechanisms are linked with dose-response evaluations. For aneugens, the MOA has been well characterised as disruptors of mitotic machinery where chromosome loss via micronuclei (MN) formation is an accepted endpoint used in risk assessment. In this study we performed the cytokinesis-block micronucleus assay and immunofluorescence mitotic machinery visualisation in human lymphoblastoid (AHH-1) and Chinese Hamster fibroblast (V79) cell lines after treatment with the aneugen 17-β-oestradiol (E2). Results were compared to previously published data on bisphenol-A (BPA) and Rotenone data. Two concentration-response approaches (the threshold-[Td] and benchmark-dose [BMD] approaches) were applied to derive a point of departure (POD) for in vitro MN induction. BMDs were also derived from the most sensitive carcinogenic endpoint. Ranking comparisons of the PODs from the in vitro MN and the carcinogenicity studies demonstrated a link between these two endpoints for BPA, E2 and Rotenone. This analysis was extended to include 5 additional aneugens, 5 clastogens and 3 mutagens and further concentration and dose-response correlations were observed between PODs from the in vitro MN and carcinogenicity. This approach is promising and may be further extended to other genotoxic carcinogens, where MOA and quantitative information from the in vitro MN studies could be used in a quantitative manner to further inform cancer risk assessment.

Pancreatic Exocrine Insufficiency (PEI) in chronic pancreatitis (CP) and cystic fibrosis (CF) patients: Combining clinician insights and existing literature to develop a conceptual model to aid in the identification and management of PEI

Pancreatic Exocrine Insufficiency (PEI) in chronic pancreatitis (CP) and cystic fibrosis (CF) patients: Combining clinician insights and existing literature to develop a conceptual model to aid in the identification and management of PEI

Tachysystole in term labor: incidence, risk factors, outcomes, and effect on fetal heart tracings

Recent recommendations called for obstetricians to abandon the terms of "hyperstimulation" and "hypercontractility" in favor of the more rigidly defined term, "tachysystole" (TS). The aim of the current study is to describe incidence of and risk factors for TS, describe fetal heart rate (FHR) changes associated with TS, and investigate maternal and neonatal outcomes associated with TS. For this retrospective cohort study, we reviewed and analyzed the intrapartum FHR and tocometric characteristics of all patients with a singleton, nonanomalous fetus in term labor in a single hospital system over a 28-month period. Univariate association testing was done using χ(2) and t tests, comparing demographics, pregnancy characteristics, outcomes, and TS events. Multivariable association testing between risk factors and TS events were tested using generalized estimating equations, adjusting for multiple pregnancies during the study period for the same woman. There were a total of 50,335 deliveries from 48,529 women during the 28-month period. Of these, there were a total of 7567 TS events in 5363 deliveries among 5332 women. Use of oxytocin or misoprostol, an epidural, hypertension, and induction of labor were associated with an increased risk of TS. We found a doubling of TS events with any oxytocin, a dose-response correlation between oxytocin and TS, FHR changes occurring in a quarter of TS events and, finally, that presence of TS increases the chance of composite neonatal morbidity. TS is associated with specific risk factors and impacts FHR and neonatal morbidity.

Nicotine might have a protective effect in the etiology of multiple sclerosis

Objective: The use of moist snuff is common in Sweden and leads to exposure to high doses of nicotine. Recent studies indicate that exposure to nicotine could modulate immune responses. The aim of this study was to investigate the influence of snuff use on the risk of developing multiple sclerosis (MS), taking smoking habits into consideration. Methods: In two Swedish population-based, case-control studies (7883 cases, 9437 controls), subjects with different snuff use habits were compared regarding MS risk, by calculating odds ratios (ORs) with 95% confidence intervals (CIs). Results: Snuff-takers have a decreased risk of developing MS compared with those who have never used moist snuff (OR 0.83, 95% CI 0.75–0.92), and we found clear evidence of an inverse dose-response correlation between cumulative dose of snuff use and the risk of developing the disease. We further observed that subjects who combined smoking and snuff use had a significantly lower risk for MS than smokers who had never used moist snuff, also after adjustment for amount of smoking. Conclusions: Our results add evidence to the hypothesis that nicotine exerts anti-inflammatory and immune-modulating effects in a way that might decrease the risk of developing MS.

Influence of the Radiation Dose to Salivary Glands on Xerostomia in Patients with Head and Neck Carcinomas

Purpose: Investigation of the influence of radiation dose to salivary glands on xerostomia in patients with head and neck cancers. Methods: From October 2002 to December 2011, 548 patients with head and neck carcinomas were treated in our department using intensity modulated radiotherapy (IMRT). 325 patients were eligible for analysis more than 1 year after irradiation. Xerostomia was evaluated according to the criteria of Radiation Therapy and Oncology Group (RTOG) and xerostomia related questionnaire. For statistical analysis grade 1 and 2 were recorded as mild and grade 3 and 4 as severe xerostomia. The dosimetric values for absolute mean dose, biological equivalent mean dose (EQD2), the relative organ volume not exceeding 20 Gy, 25 Gy and 30 Gy (V20, V25, V30) for all 4 major salivary glands or for both parotid glands only were used for analysis. V20 revealed the best discrimination between both patient groups (with vs. without xerostomia), compared to parameters V25 and V30. Therefore the volume of the salivary glands receiving less than 20 Gy (V 20Gy) was analyzed additionally. Mann-Whitney-U-test, Kruskal-Wallis-test and logistic regression were used in statistical analysis. Results: A TD 50 can be determined for the occurrence of xerostomia more than one year after radiotherapy for both parotid glands of 19.3 Gy for the mean dose absolute, 11.2 Gy for the mean dose EQD2, 38.2% for V20, 26.8% for V25, 18.7% for V30, 34.9 ml for V 20Gy. For all major salivary glands theses values were 25.7 Gy for the mean dose absolute, 15.6 Gy for the mean dose EQD2, 51.3% for V20, 41.1% for V25, 33.9% for V30 and 34.8 ml for V 20Gy. Conclusions: The identification of a tolerance dose for the salivary glands for treatment planning appears to be difficult, as the dose-response correlation only shows a flat slope. Additionally, a large interindividual variability seems to exist. We could not found any threshold dose for development of xerostomia.

The pharmacokinetics and pharmacodynamics of vancomycin in clinical practice: evidence and uncertainties

Vancomycin has been used extensively since the late 1950s. Despite the introduction of several new valuable anti-Gram-positive antibiotics during recent years and the waning susceptibility of staphylococci to vancomycin, it remains the gold standard for the treatment of bacteraemia caused by methicillin-resistant staphylococci. Vancomycin has clear dose-response and dose-toxicity correlations. It is widely accepted that these correlations are best predicted by the AUC/MIC model, with target levels of >400 being the clinical cut-off. The experimental base of this model is less robust than frequently believed, and several important issues in vancomycin resistance, such as biofilm resistance and the inoculum effect, are not included. Based on this model, current dosing guidelines propose intermittent dosing of vancomycin with target trough levels of 15-20 mg/L. Dose adaptations according to renal function have been proposed but are not yet validated. Clinical data also support the use of continuous infusion with target plateau levels of 20-25 mg/L, with similar efficacy at the cost of lower nephrotoxicity. Despite decades of intense clinical use and numerous studies and publications, the optimal dosing strategy for vancomycin reconciling the high needs of the dose-response relationship with the serious drawbacks of the dose-toxicity relationship remains to be established.

Radiation dose response correlation between thermoluminescence and optically stimulated luminescence in quartz

The fast, linearly modulated optically stimulated luminescence (LM-OSL) component in quartz is the main dosimetric signal used for the dating applications of this material. Since the blue light stimulation (470nm, 40mWcm −2) time needed to obtain the fast LM-OSL component is less than 50s the electron trapping levels responsible for it are still highly populated. In this way an active radiation history is created which could play an important role in the dosimetric characteristics of the fast OSL signal. In the present work the dose response behavior of the fast OSL signal is investigated in quartz samples with an annealed radiation history and quartz samples possessing an artificial radiation history. A computerized curve de-convolution analysis of the LM-OSL curves for 50s stimulation time showed that it consists of three individual OSL components. The faster component C1 with peak maximum time around 5s has a linear dose response in virgin samples, which turns to a slight superlinearity as a function of the artificial radiation history. On the other hand the component C2 with peak maximum time at 12s is slightly superlinear which turns into strong superlinearity as a function of artificial radiation history. Finally, component C3 with peak maximum time at about 45s is strongly superlinear for both virgin samples and as a function of artificial radiation history. The implications to practical application are discussed.

Improved tumour response prediction with equivalent uniform dose in pre-clinical study using direct intratumoural infusion of liposome-encapsulated 186Re radionuclides

Crucial to all cancer therapy modalities is a strong correlation between treatment and effect. Predictability of therapy success/failure allows for the optimization of treatment protocol and aids in the decision of whether additional treatment is necessary to prevent tumour progression. This work evaluated the relationship between cancer treatment and effect for intratumoural infusions of liposome-encapsulated 186Re to head and neck squamous cell carcinoma xenografts of nude rats. Absorbed dose calculations using a dose-point kernel convolution technique showed significant intratumoural dose heterogeneity due to the short range of the beta-particle emissions. The use of three separate tumour infusion locations improved dose homogeneity compared to a single infusion location as a result of a more uniform radioactivity distribution. An improved dose–response correlation was obtained when using effective uniform dose (EUD) calculations based on a generic set of radiobiological parameters (R2 = 0.84) than when using average tumour absorbed dose (R2 = 0.22). Varying radiobiological parameter values over ranges commonly used for all types of tumours showed little effect on EUD calculations, which suggests that individualized parameter use is of little significance as long as the intratumoural dose heterogeneity is taken into consideration in the dose–response relationship. The improved predictability achieved when using EUD calculations for this cancer therapy modality may be useful for treatment planning and evaluation.

Antiulcerogenic activity of peptide concentrates obtained from hydrolysis of whey proteins by proteases from Cynara cardunculus

Peptide concentrates generated by hydrolysis of whey with aqueous extracts of flowers of Cynara cardunculus were studied for possible protection of the stomach mucosa against ulcerative lesions caused by oral administration of absolute ethanol. Both the whole peptide fraction obtained via hydrolysis of whey protein concentrate (peptide concentrate, PepC) and its fraction below 3 kDa (PepCF) were able to reduce gastric injuries to significant levels ( p < 0.05). Single-dose experiments, using 100 mg kg −1 body weight (bw) of either PepCF or PepC, led to 68.5% and 37.4% protection, respectively – which compare well with 93.4% protection by 200 mg kg −1 bw carbenoxolone (a positive control). No dose-response correlation could be demonstrated. Gastric cytoprotection by PepCF appears to depend on sulphydryl-containing moieties, whereas PepC likely protects the gastric mucosa via the prostaglandin cycle and production of nitric oxide.

Testing the cytotoxicity and genotoxicity of the antimalarial drug mefloquine

Numerous drugs show significant behavioral, developmental, teratogenic and mutagenic effects. This study investigates the cytotoxic and genotoxic effects of two doses (20 and 40mg/kg body weight) of the antimalarial drug mefloquine (MQ), in male mice. The parameters included the assessment of: mitotic index, cell cycle kinetics, and frequency of chromosomal aberrations in bone marrow cells, translocation frequency in spermatocytes and head and tail abnormalities in sperm. A high dose of mefloquine resulted in a decreased mitotic index, suggesting a dose–response correlation. A notable recovery in mitotic activity was observed during the first and third week post treatment, which approached the mitotic index of control. Chromosomal abnormalities including gaps, breaks, and fragments also increased with the higher dose of mefloquine. Spermatids and secondary spermatocytes were moderately sensitive to the drug; whereas primary spermatocytes were more sensitive, and spermatogonia were highly sensitive to both doses of MQ. ConclusionMefloquine (MQ) at the doses used can be considered as a drug with a potential mutagenic effect. The results obtained from the spermatocyte diakinesis-metaphase 1 test and sperm abnormalities suggest that MQ may contribute to high incidence of birth defects and congenital abnormalities.

Malathion and fenvalerate induce micronuclei in mouse bone marrow cells

Health effects of pesticides are a major public health concern. In this study, the genotoxic effects of two commonly-used pesticides, malathion, and fenvalerate, were investigated in mice in vivo. Induction of micronuclei in bone marrow cells was used as the test parameter following exposure to 2.5, 5 or 10 mg/kg malathion by intraperitoneal (i.p.) or per oral (p.o.) exposure. Exposure by both routes was found to cause a significant increase in micronucleated polychromatic erythrocytes (PCEs) in a dose-dependent manner (r = 0.9769; P < 0.05). The highest dose (10 mg/kg) induced significant (P < 0.05) cytotoxicity. In contrast, fenvalerate caused an increase in micronucleated PCEs only at higher doses (10 and 20 mg/kg) via i.p. injection, and was not associated with cytotoxicity. A significant dose-response correlation was not observed in the dose ranges tested for fenvalerate (r = 0.8704; P > 0.05). The results suggest that technical grade malathion is a genotoxic agent. In contrast, technical grade fenvalerate appears to be a potent genotoxic agent, but this observation should be confirmed with further investigation(s).

Evaluating Local Control and Dose-Response Correlation after High-dose-Rate Interstitial Gynecologic Brachytherapy

Evaluating Local Control and Dose-Response Correlation after High-dose-Rate Interstitial Gynecologic Brachytherapy

131I-Tositumomab Radioimmunotherapy: Initial Tumor Dose–Response Results Using 3-Dimensional Dosimetry Including Radiobiologic Modeling

For optimal treatment planning in radionuclide therapy, robust tumor dose-response correlations must be established. Here, fully 3-dimensional (3D) dosimetry was performed coupling SPECT/CT at multiple time points with Monte Carlo-based voxel-by-voxel dosimetry to examine such correlations. Twenty patients undergoing (131)I-tositumomab for the treatment of refractory B-cell lymphoma volunteered for the study. Sixty tumors were imaged. Activity quantification and dosimetry were performed using previously developed 3D algorithms for SPECT reconstruction and absorbed dose estimation. Tumors were outlined on CT at multiple time points to obtain absorbed dose distributions in the presence of tumor deformation and regression. Equivalent uniform dose (EUD) was calculated to assess the biologic effects of the nonuniform absorbed dose, including the cold antibody effect. Response for correlation analysis was determined on the basis of the percentage reduction in the product of the largest perpendicular tumor diameters on CT at 2 mo. Overall response classification (as complete response, partial response, stable disease, or progressive disease) used for prediction analysis was based on criteria that included findings on PET. Of the evaluated tumor-absorbed dose summary measures (mean absorbed dose, EUD, and other measures from dose-volume histogram analysis), a statistically significant correlation with response was seen only with EUD (r = 0.36 and P = 0.006 at the individual tumor level; r = 0.46 and P = 0.048 at the patient level). The median value of mean absorbed dose for stable disease, partial response, and complete response patients was 196, 346, and 342 cGy, respectively, whereas the median value of EUD for each of these categories was 170, 363, and 406 cGy, respectively. At a threshold of 200 cGy, both mean absorbed dose and EUD had a positive predictive value for responders (partial response + complete response) of 0.875 (14/16) and a negative predictive value of 1.0 (3/3). Improved dose-response correlations were demonstrated when EUD incorporating the cold antibody effect was used instead of the conventionally used mean tumor-absorbed dose. This work demonstrates the importance of 3D calculation and radiobiologic modeling when estimating absorbed dose for correlation with outcome.

Optimizing thrombelastography (TEG) assay conditions to monitor rFVIIa (NovoSeven®) therapy in haemophilia a patients

IntroductionThere is no established laboratory method that can predict the most optimal dose of bypassing agents for treatment of haemophilia A. The objectives of the study was to develop an assay that can a) differentiate between the haemostatic capacity in blood from healthy individuals and severe and moderate haemophilia patients; b) show a dose-response correlation to rFVIIa addition; and c) show dose response differences of rFVIIa addition to plasma samples from non-inhibitor patients of different severity. Materials and MethodsCitrated whole blood from 25 haemophilia A patients was used in four thrombelastography (TEG) assays initiated with: 1) kaolin, 2) Tissue Factor (TF, Innovin 1:42,500), 3) TF 1:42,500+1.2nM tPA (tissue plasminogen activator) or 4) TF 1:200,000. rFVIIa was added to give a final concentration in the range of 0.02-4.8µg/ml. ResultsThe TEG assays showed large differences in clot formation demonstrated by prolonged clotting time (R-time), decreased maximum thrombus generation (MTG) between severe and moderate haemophilia A patients and between haemophilia patients and healthy males. The maximal amplitudes (MA) of the clot and resistance against fibrinolysis were only compromised when TF with tPA was added. ConclusionIn vitro addition of rFVIIa improved all TEG profiles significantly in a dose-dependent manner; but only the TEG assay containing kaolin could differentiate between the rFVIIa doses, showing that blood from severe patients need higher doses of rFVIIa to normalize the clot formation profile compared to blood from moderate patients. Kaolin seems to be the most useful TEG assay for monitoring rFVIIa treatment.

Transcriptional Analysis of an E2F Gene Signature as a Biomarker of Activity of the Cyclin-Dependent Kinase Inhibitor PHA-793887 in Tumor and Skin Biopsies from a Phase I Clinical Study

A transcriptional signature of the pan-cyclin-dependent kinase (Cdk) inhibitor PHA-793887 was evaluated as a potential pharmacodynamic and/or response biomarker in tumor and skin biopsies from patients treated in a phase I clinical study. We first analyzed the expression of a number of known E2F-dependent genes that were predicted to be modulated after Cdk2 and Cdk4 inhibition in xenograft tumor and skin samples of mice treated with the compound. This panel of 58 selected genes was then analyzed in biopsies from seven patients treated with PHA-793887 in a phase I dose escalation clinical trial in solid tumors. Quantitative real-time PCR or microarray analyses were done in paired skin and tumor biopsies obtained at baseline and at cycle 1. Analysis by quantitative real-time PCR of the signature in skin biopsies of patients treated at three different doses showed significant transcriptional downregulation with a dose-response correlation. These data show that PHA-793887 modulates genes involved in cell cycle regulation and proliferation in a clinical setting. The observed changes are consistent with its mechanism of action and correlate with target modulation in skin and with clinical benefit in tumors.

Association of sex hormones and C‐reactive protein levels in men

The age-associated decline in sex hormone levels in men is paralleled by an increase in cardiovascular disease and associated risk factors including low grade chronic inflammation. The objective of this analysis was to investigate the association between sex hormone levels and C-reactive protein (CRP) in a population-based sample of men. Population-based, cross-sectional observational survey. A multistage stratified design was used to recruit a random sample of 2301 racially and ethnically diverse men age 30-79 years. Blood samples were obtained on 1899 men. Analyses were conducted on 1559 men with complete data on CRP and sex hormone levels. High-sensitivity CRP levels. The association between CRP and sex hormone levels was assessed using multiple linear regression models. An inverse association was observed, in both bivariate and multivariate analyses, between CRP and total testosterone, free testosterone and SHBG levels. These associations remained statistically significant after adjusting for age, body mass index, comorbid conditions and lifestyle factors. A positive trend between oestradiol (total and free) and CRP levels was not statistically significant. A robust, inverse dose-response correlation between testosterone and SHBG levels with CRP levels provides further evidence of a potential role of androgens in inflammatory processes.