Low Dose Levels Research Articles

The behavior of natural biomass materials as drug carriers in releasing loaded Gentamicin sulphate

Pharmaceutical and clinicians researchers are looking for novel drug carriers to maintain the drug level in the body in low and effective dose. Thus, the present research concerned with studying the behavior of some natural biomass materials, namely microcrystalline cellulose, MCC, nanocrystalline cellulose, NCC, nanomethylcellulose, MC, and carboxymethyl cellulose, CMC, as a drug carrier materials for the Gentamicin sulphate, GM, by following up their rate of releasing the loaded drug with the time. Knowing of the initial rate of the releasing to each one and the sustaining rate along the period of the treatment, helps in choosing the best carrier for the drug that matches the patients requirements either whom are in need for a rapid dose (high level) of the drug followed by slow (low level) dose or those in need to start with the low level of the drug followed by high level of the drug. We chose MCC, NCC, MC and CMC, as natural, nontoxic biodegradable and renewable biomass materials, beside their low cost, to carry out this study. The results of the drug release, which measured by UV spectra, showed that the MCC, NCC, MC and CMC loaded with 0.025 g of the GM drug released 27.2%, 42.1%, 29.7%, 28.5% of the drug, respectively, along 10 days. All of them achieved the slow of the drug release but their behavior were different, where MCC, NCC and CMC started with low release then increased, and inversely, MC gave high rate of drug release and then decreased. The cause of this behavior was concerned to the adsorbing of the drug particles on the surface of the biomass materials or absorbing of the drug particles into the pores of the biomass materials. This was indicated by the study of their morphological image using the SEM, as well as indicating the presence of the functional group using the FT-IR study. The XRD, EDX and Agar Diffusion Assay, i.e. antimicrobial activity, against Staphylococcus aureus, Escherichia Coli, Pseudomonas aeruginosa and Bacillus subtilis were carried out to make help in choosing of the best carrier convenient to the case of the illness requirement.

Rapid Tritium Analysis Method in Seafood for Dose Evaluation

We have developed a tritium screening method focused on seafood. Time saving and simplicity of tritium analysis were achieved by performing analysis as total tritium that simultaneously obtains the recovered water of TFWT and OBT. We carried out the experiment using HTO and L-leucine [4, 5 – 3H], and confirmed that total tritium was sufficiently recovered. The developed method has a low detection limit, and it gives us a tool to judge smoothly the annual radiation dose caused by consumption of seafood is below the guidelines authorized by international organizations, the safety level for public. The detectable radiation dose by tritium is 9.2 × 10–6 mSv/y for average consumption of seafood in Japan. This method can evaluate 2–3 orders lower dose level authorized by international organizations for public.

Beam angle comparison for distal esophageal carcinoma patients treated with intensity-modulated proton therapy.

PurposeTo compare the dosimetric performances of intensity‐modulated proton therapy (IMPT) plans generated with two different beam angle configurations (the Right–Left oblique posterior beams and the Superior–Inferior oblique posterior beams) for the treatment of distal esophageal carcinoma in the presence of uncertainties and interplay effect.Methods and MaterialsTwenty patients’ IMPT plans were retrospectively selected, with 10 patients treated with the R‐L oblique posterior beams (Group R‐L) and the other 10 patients treated with the S‐I oblique posterior beams (Group S‐I). Patients in both groups were matched by their clinical target volumes (CTVs—high and low dose levels) and respiratory motion amplitudes. Dose‐volume‐histogram (DVH) indices were used to assess plan quality. DVH bandwidth was calculated to evaluate plan robustness. Interplay effect was quantified using four‐dimensional (4D) dynamic dose calculation with random respiratory starting phase of each fraction. Normal tissue complication probability (NTCP) for heart, liver, and lung was calculated, respectively, to estimate the clinical outcomes. Wilcoxon signed‐rank test was used for statistical comparison between the two groups.ResultsCompared with plans in Group R‐L, plans in Group S‐I resulted in significantly lower liver Dmean and lung V30Gy[RBE] with slightly higher but clinically acceptable spinal cord Dmax. Similar plan robustness was observed between the two groups. When interplay effect was considered, plans in Group S‐I performed statistically better for heart Dmean and V30Gy[RBE], lung Dmean and V5Gy[RBE], and liver Dmean, with slightly increased but clinically acceptable spinal cord Dmax. NTCP for liver was significantly better in Group S‐I.ConclusionsIMPT plans in Group S‐I have better sparing of liver, heart, and lungs at the slight cost of spinal cord maximum dose protection, and are more interplay‐effect resilient compared to IMPT plans in Group R‐L. Our study supports the routine use of the S‐I oblique posterior beams for the treatments of distal esophageal carcinoma.

Coamorphisation of acetyl salicylic acid and curcumin for enhancing dissolution, anti-inflammatory effect and minimizing gastro toxicity

ObjectiveThe study was aimed to develop coamorphous mixture of acetyl salicylic acid (ASA) and curcumin (CU) for enhancing dissolution, anti-inflammatory effect and minimizing gastro toxicity. SignificanceDeveloped coamorphous of ASA and CU enhanced solubility and anti-inflammatory efficacy while minimizing the gastro toxicity at low dose level. MethodsThe coamorphous were developed by solvent evaporation method at various weight ratios of drugs: PVP K 30 and optimized. The mixtures were characterized for saturation solubility, amorphism (PXRD, DSC, FTIR), SEM, in vitro dissolution. The anti-inflammatory and gastro protective activities were performed to assess the bioavailability and gastro toxicity of the ASA and CU coamorphous mixture respectively. ResultsSolubility study revealed ~5.5 and ~3076 fold rise in solubility of ASA and CU than their pure form. Solid state characterization of the coamorphous mixture suggested complete amorphisation of the ASA and CU at 1:3 weight ratio. FTIR study confirmed the hydrogen bond formation suggested the enhancement of solubility and leads to bioavailability. DSC, PXRD and SEM confirmed the amorphism. Adequate release of ASA and CU suitable for ensuring oral bioavailability and efficacy and also be expected to be a suitable formulation for oral administration of mixture. Significant inhibition (5 fold) of paw edema and protective index (>75) of SD revealed enhancement of anti-inflammatory activity and reduction of gastro toxicity. ConclusionCoamorphous mixture of ASA and CU at low dose level is a promising approach for combination therapy in inflammation.

Low-dose aspirin and COX inhibition in human skeletal muscle.

Skeletal muscle health has been shown to benefit from regular consumption of cyclooxygenase (COX)-inhibiting drugs. Aspirin, especially at low doses, is one of the most commonly consumed COX inhibitors, yet investigations of low-dose aspirin effects on skeletal muscle are nonexistent. The goal of this study was to examine the efficacy of low-dose aspirin on skeletal muscle COX production of the inflammatory regulator prostaglandin (PG)E2 at rest and after exercise. Skeletal muscle biopsies (vastus lateralis) were taken from eight individuals [4 men, 4 women; 25 ± 1 yr; 81.4 ± 3.4 kg; maximal oxygen consumption (V̇o2max): 3.33 ± 0.21 L/min] before and 3.5 h after 40 min of cycling at 70% of V̇o2max for the measurement of ex vivo PGE2 production. Muscle strips were incubated in Krebs-Henseleit buffer (control) or supplemented with one of two aspirin concentrations that reflected blood levels after a low (10 µM; typical oral dose: 75-325 mg) or standard (100 µM; typical oral dose: 975-1,000 mg) dose. Low (-22 ± 5%)- and standard (-28 ± 5%)-dose aspirin concentrations both reduced skeletal muscle PGE2 production, independent of exercise (P < 0.05). There was no difference in PGE2 suppression between the two doses (P > 0.05). In summary, low-dose aspirin levels are sufficient to inhibit the COX enzyme in skeletal muscle and significantly reduce production of PGE2, a known regulator of skeletal muscle health. Aerobic exercise does not appear to alter the inhibitory efficacy of aspirin. These findings may have implications for the tens of millions of individuals who chronically consume low-dose aspirin.NEW & NOTEWORTHY This study demonstrated that even low-dose aspirin concentrations can significantly reduce the prostaglandin (PG)E2/cyclooxygenase (COX) pathway activity in human skeletal muscle and this effect is not altered during the recovery period following aerobic exercise. These findings are noteworthy since aspirin is one of the most commonly consumed drugs in the world and nonaspirin COX-inhibiting drugs have been shown to regulate skeletal muscle health in sedentary and exercise-training individuals.

Observer Performance for Detection of Pulmonary Nodules at Chest CT over a Large Range of Radiation Dose Levels.

Background There is a wide variation in radiation dose levels that can be used with chest CT in order to detect indeterminate pulmonary nodules. Purpose To compare the performance of lower-radiation-dose chest CT with that of routine dose in the detection of indeterminate pulmonary nodules 5 mm or greater. Materials and Methods In this retrospective study, CT projection data from 83 routine-dose chest CT examinations performed in 83 patients (120 kV, 70 quality reference mAs [QRM]) were collected between November 2013 and April 2014. Reference indeterminate pulmonary nodules were identified by two nonreader thoracic radiologists. By using validated noise insertion, five lower-dose data sets were reconstructed with filtered back projection (FBP) or iterative reconstruction (IR; 30 QRM with FBP, 10 QRM with IR, 5 QRM with FBP, 5 QRM with IR, and 2.5 QRM with IR). Three thoracic radiologists circled pulmonary nodules, rating confidence that the nodule was a 5-mm-or-greater indeterminate pulmonary nodule, and graded image quality. Analysis was performed on a per-nodule basis by using jackknife alternative free-response receiver operating characteristic figure of merit (FOM) and noninferiority limit of -0.10. Results There were 66 indeterminate pulmonary nodules (mean size, 8.6 mm ± 3.4 [standard deviation]; 21 part-solid nodules) in 42 patients (mean age, 51 years ± 17; 21 men and 21 women). Compared with the FOM for routine-dose CT (size-specific dose estimate, 6.5 mGy ± 1.8; FOM, 0.86 [95% confidence interval: 0.80, 0.91]), FOM was noninferior for all lower-dose configurations except for 2.5 QRM with IR. The sensitivity for subsolid nodules at 70 QRM was 60% (range, 48%-72%) and was significantly worse at a dose of 5 QRM and lower, whether or not IR was used (P < .05). Diagnostic image quality decreased with decreasing dose (P < .001) and was better with IR at 5 QRM (P < .05). Conclusion CT images reconstructed at dose levels down to 10 quality reference mAs (size-specific dose estimate, 0.9 mGy) had noninferior performance compared with routine dose in depicting pulmonary nodules. Iterative reconstruction improved subjective image quality but not performance at low dose levels. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by White and Kazerooni in this issue.

Human Muscle Mass Measurement through passive Flexible UWB-Myogram Antenna sensor to diagnose Sarcopenia

Sarcopenia disease is due to low muscle mass in humans. Sarcopenia leads to osteoporosis, metabolic syndrome and difficulty in performing day-to-day activities. At present, Dual-energy X-ray Absorptiometry (DXA) measures muscle mass with few limitations. They are variations in measurements according to region under investigation, irregularities in hydration status, and low precision in tall and obese persons. These limitations are due to low dosage level of X-ray radiations in certain muscle regions of human body such as heart, head, lower and upper extremities. This paper presents a non-invasive passive flexible Ultra Wide Band (UWB) Myogram antenna sensor for the prediction of Sarcopenia through human muscle mass measurement. This antenna is adhesively fixed on ventral surface of forearm and biceps for the measurement of skeletal and lean mass respectively. The proposed antenna sensor performs electromagnetic energy absorption from muscle tissues under radiating near-field condition. The muscle tissue signal from antenna is applied to blind source filtering-Non-negative Matrix Factorization (NMF), then subjected to Multi-Synchro Squeezing Transform (MSST), and finally correlated using linear regression machine learning algorithm to diagnose Sarcopenia. Furthermore, the proposed methodology is developed as a product through the MATLAB Mobile App compatible with Android devices. The proposed method of diagnosing Sarcopenia achieves an accuracy of 85% in fifty samples.

An Updated Review of Toxicity Effect of the Rare Earth Elements (REEs) on Aquatic Organisms.

Simple SummaryRare earth elements (REEs) have become important metals in modern-day technology. The process of discarding obsolete equipment containing REEs, use of REEs containing phosphate fertilizers, mining, and dispersion from indigenous rocks may increase the likelihood of REEs contamination in water bodies. Thus, the contamination may contribute to their release into surrounding ecosystems. This review paper aims to understand the bioavailability, accumulation, interaction, and toxicity criteria of REEs with aquatic organisms. The currently available literature is confined to reports of a few REEs. There exists substantial knowledge gaps persistence on the health effects. The REEs related to health effects also point to favorable and adverse effects after exposure. The studies have also demonstrated that REEs follow a hormetic concentration- related trend, making it stimulatory or protective at low dose levels and adverse at high dose concentrations. Based on limited information on REEs’ effects, we highlight the need for more detailed studies on REEs’ effects individually/collectively. The studies should also include detailed outcomes related to growth inhibition, embryotoxicity, cytogenetic effects, and organ-specific toxicity. We believe that aquatic biota is an efficient platform to study the effects of REEs and might yield beneficial human health information.Rare earth elements (REEs) or “technology metals” were coined by the U.S. Department of Energy, a group of seventeen elements found in the Earth’s crust. These chemical elements are vital and irreplaceable to the world of technology owing to their unique physical, chemical, and light-emitting properties, all of which are beneficial in modern healthcare, telecommunication, and defense. Rare earth elements are relatively abundant in Earth’s crust, with critical qualities to the device performance. The reuse and recycling of rare earth elements through different technologies can minimize impacts on the environment; however, there is insufficient data about their biological, bioaccumulation, and health effects. The increasing usage of rare earth elements has raised concern about environmental toxicity, which may further cause harmful effects on human health. The study aims to review the toxicity analysis of these rare earth elements concerning aquatic biota, considering it to be the sensitive indicator of the environment. Based on the limited reports of REE effects, the review highlights the need for more detailed studies on the hormetic effects of REEs. Aquatic biota is a cheap, robust, and efficient platform to study REEs’ toxicity, mobility of REEs, and biomagnification in water bodies. REEs’ diverse effects on aquatic life forms have been observed due to the lack of safety limits and extensive use in the various sectors. In accordance with the available data, we have put in efforts to compile all the relevant research results in this paper related to the topic “toxicity effect of REEs on aquatic life”.

Cone Beam CT Imaging of the Paranasal Region with a Multipurpose X-ray System—Image Quality and Radiation Exposure

Besides X-ray and fluoroscopy, a previously introduced X-ray scanner offers a 3D cone beam option (Multitom Rax, Siemens Healthcare). The aim of this study was to evaluate various scan parameters and post-processing steps to optimize image quality and radiation exposure for imaging of the parasinus region. Four human cadaver heads were examined with different tube voltages (90–121 kV), dose levels (DLs) (278–2180 nGy) and pre-filtration methods (none, Cu 0.2 mm, Cu 0.3 mm and Sn 0.4 mm). All images were reconstructed in 2 mm slice thickness with and without a metal artifact reduction algorithm in three different kernels. In total, 80 different scan protocols and 480 datasets were evaluated. Image quality was rated on a 5-point Likert scale. Radiation exposure (mean computed tomography volume index (CTDIvol) and effective dose) was calculated for each scan. The most dose-effective combination for the diagnosis of sinusitis was 121 kV/DL of 278/0.3 mm copper (CTDIvol 1.70 mGy, effective dose 77 µSv). Scan protocols with 121 kV/DL1090/0.3 mm copper were rated sufficient for preoperative sinus surgery planning (CTDIvol 4.66 mGy, effective dose 212 µSv). Therefore, sinusitis and preoperative sinus surgery planning can be performed in diagnostic image quality at low radiation dose levels with a multipurpose X-ray system.

Abstract CT156: Characterization of PEN-866, a Heat Shock Protein 90 (HSP90) binding conjugate of SN-38, in patient plasma and tumors from the first in human study

Abstract Background: Heat Shock Protein 90 (HSP90) is a molecular chaperone that aids in folding and trafficking of proteins and is upregulated in cells under stress. HSP90 is overexpressed in cancer cells and exists in the activated configuration within the tumor microenvironment. PEN-866 is a novel small molecule drug conjugate containing a HSP90 targeting moiety that accumulates in tumors and releases its payload SN-38 through a cleavable linker within the tumor cells. The first in human phase 1/2a PEN-866 study was designed to assess safety, pharmacokinetics (PK), and exploratory biomarkers of PEN-866 related to its mechanism of action. Here we describe the evaluation of PEN-866 and the payload SN-38 in plasma and tumors. Methods: Patients with advanced solid malignancies were enrolled in dose escalation cohorts and received PEN-866 IV on days 1, 8, and 15 in 28-days cycles, over a dose range of 16-228 mg/m2. Plasma samples were collected up to 8 days after the first dose and up to 24 hours after the third dose. Non-compartmental analysis was performed to obtain PK parameters. Optional tumor biopsies were collected from two patients and analyzed for PEN-866 and SN-38 concentrations. Results: PEN-866 plasma concentration profile was biphasic with a rapid concentration decline after end of infusion resulting in an average half-life (t½) of approximately 10 hours across all dose cohorts. PEN-866 maximum plasma concentrations (Cmax) ranged from 0.69 to 54 µg/mL and area under the concentration curve (AUC) from 0.80 to 88 h·µg/mL. The Cmax and AUC increased higher than dose proportionally at the lower dose levels which resulted in higher clearance (CL) and volume of distribution (Vd) variability. Free SN-38 AUC's were generally low demonstrating linker stability in circulation and low systemic exposure. PEN-866 and SN-38 levels in patient tumors confirmed accumulation and retention of the conjugate up to 6 days after PEN-866 dose and the targeted release of SN-38. Conclusion: PEN-866 has an extended plasma half-life in patients with advanced solid malignancies and showed good stability in circulation with limited plasma exposure of the payload SN-38. Analysis of tumor biopsies up to 6 days after dosing demonstrated significant accumulation and extended exposures of PEN-866 and SN-38 within the tumor tissue that exceed plasma exposures. Citation Format: Anish Thomas, Kristina Kriksciukaite, Gerald Falchook, Johanna Bendel, Susanna Ulahannan, Christophe Redon, Laura Mei, Kerry Whalen, Jeffrey Bloss, Mark T. Bilodeau. Characterization of PEN-866, a Heat Shock Protein 90 (HSP90) binding conjugate of SN-38, in patient plasma and tumors from the first in human study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT156.

Pre-clinical studies of EC2629, a highly potent folate- receptor-targeted DNA crosslinking agent

Folate receptor (FR)-targeted small molecule drug conjugates (SMDCs) have shown promising results in early stage clinical trials with microtubule destabilizing agents, such as vintafolide and EC1456. In our effort to develop FR-targeted SMDCs with varying mechanisms of action, we synthesized EC2629, a folate conjugate of a DNA crosslinking agent based on a novel DNA-alkylating moiety. This agent was found to be extremely potent with an in vitro IC50 ~ 100× lower than folate SMDCs constructed with various microtubule inhibitors. EC2629 treatment of nude mice bearing FR-positive KB human xenografts led to cures in 100% of the test animals with very low dose levels (300 nmol/kg) following a convenient once a week schedule. The observed activity was not accompanied by any noticeable weight loss (up to 20 weeks post end of dosing). Complete responses were also observed against FR-positive paclitaxel (KB-PR) and cisplatin (KB-CR) resistant models. When evaluated against FR-positive patient derived xenograft (PDX) models of ovarian (ST070), endometrial (ST040) and triple negative breast cancers (ST502, ST738), EC2629 showed significantly greater anti-tumor activity compared to their corresponding standard of care treatments. Taken together, these studies thus demonstrated that EC2629, with its distinct DNA reacting mechanism, may be useful in treating FR-positive tumors, including those that are classified as drug resistant.

Association of prenatal alcohol exposure with preadolescent alcohol sipping in the ABCD study®

BackgroundEarly alcohol use initiation is one of the strongest predictors of alcohol use disorders. Identifying modifiable risk factors for problematic alcohol use can guide prevention initiatives. Globally, approximately 10% of women consume alcohol during pregnancy, however the impact of prenatal alcohol exposure (PAE) on offspring alcohol use patterns has been understudied. The aim of this study was to examine associations between PAE and preadolescent alcohol use behaviors. MethodsCross-sectional data were utilized from 10,119 children aged 9.0–10.9 years (M = 9.9, SD = 0.6) enrolled in the Adolescent Brain Cognitive Development Study®, based in the United States. Linear mixed models tested associations between PAE and endorsement of non-religious alcohol sipping in offspring, when adjusting for confounding factors. ResultsIn total, 2675 (26.4 %) youth were prenatally exposed to alcohol. Among PAE youth, total standard drinks consumed during pregnancy ranged from 0.4–90.0 drinks (M = 26.8, SD = 24.5). Compared to unexposed youth, those with any alcohol exposure during early pregnancy (∼0−7 weeks) were 1.7 times (95 % CI 1.4–2.0, p < .0001) more likely to endorse sipping alcohol by ages 9–10, while youth with low-level doses of alcohol throughout the entire pregnancy were 2.9 times (95 % CI 1.9–4.6, p < .0001) more likely to endorse sipping, when adjusting for confounding factors. A dose-dependent association between total standard drinks consumed during pregnancy and youth sipping endorsement was observed (β = 0.2, 95 % CI 0.1–0.2, p < .0001). ConclusionsThis study shows that any alcohol use during pregnancy may play an important role in very early alcohol use experimentation among offspring by ages 9–10.

Comparative Dosimetric Analysis and Normal Tissue Complication Probability Modelling of Four-Dimensional Computed Tomography Planning Scans Within the UK NeoSCOPE Trial

AimsNeoSCOPE is a trial of two different neoadjuvant chemoradiotherapy regimens for resectable oesophageal cancer and was the first multicentre trial in the UK to incorporate four-dimensional computed tomography (4D-CT) into radiotherapy planning. Despite 4D-CT being increasingly accepted as a standard of care for lower third and junctional oesophageal tumours, there is limited evidence of its benefit over standard three-dimensional computed tomography (3D-CT). MaterialsUsing NeoSCOPE 4D-CT cases, we undertook a dosimetric comparison study of 3D-CT versus 4D-CT plans comparing target volume coverage and dose to organs at risk. We used established normal tissue complication probability models to evaluate the potential toxicity reduction of using 4D-CT plans in oesophageal cancer. Results4D-CT resulted in a smaller median absolute PTV volume and lower dose levels for all reported constraints with comparable target volume coverage. NTCP modelling suggests a significant relative risk reduction of cardiac and pulmonary toxicity endpoints with 4D-CT. ConclusionOur work shows that incorporating 4D-CT into treatment planning may significantly reduce the toxicity burden from this treatment.

Occurrence and transformation of gabapentin in urban water quality engineering: Rapid formation of nitrile from amine during drinking water chlorination

The occurrence and fate of the popular pharmaceutical gabapentin (GBP) in the urban water cycle were investigated with a focus on its transformation during water chlorination. GBP was detected in all samples with average concentrations of 1285 ng/L (n = 24) for wastewater effluent, 304 ng/L for river water (n = 22), and 180 ng/L for drinking water treatment plant (DWTP) influent (n = 4). The monitoring sites were located in the Nakdong River watershed, Korea. GBP was rapidly (within 20 min) transformed into 1-cyanocyclohexylacetic acid (GBP-nitrile) under typical chlorination conditions (1.4 mgCl2/L). When there was a molar excess of chlorine to GBP, the primary amine of GBP was double-chlorinated to form N-Cl2 GBP with a second-order rate constant of >103 M−1 s−1. Decomposition of N-Cl2 GBP had a first-order rate constant of (0.5–1.0) × 10−2 s−1 and produced GBP-nitrile with a yield of 87%–100%. We propose that N-Cl2 GBP is transformed into N-Cl GBP imine and then to GBP-nitrile via two consecutive dehydrochlorinations with the former as the rate-limiting step. N-Cl2 GBP had a much higher decomposition rate than N-Cl2 produced from other simple aliphatic amines, which could be related to the structural features of GBP such as its carboxyl group and quaternary β-carbon. The wastewater effluent samples did not contain GBP-nitrile even in the chlorinated effluent because of the relatively low chlorine dose or high ammonia level. In a full-scale DWTP employing a pre-chlorination unit, GBP present in the influent river water was fully transformed into GBP-nitrile. The formed GBP-nitrile was degraded in subsequent ozonation (•OH oxidation) and biological activated carbon filtration (biodegradation) processes. The toxicity of GBP-nitrile is thought to be low but further studies are warranted to assess the toxicological relevance of nitrile formation during water chlorination.

Pig-a gene mutation assay study design: critical assessment of 3- versus 28-day repeat-dose treatment schedules.

The in vivo Pig-a assay is being used in safety studies to evaluate the potential of chemicals to induce somatic cell gene mutations. Ongoing work is aimed at developing an Organisation for Economic Cooperation and Development (OECD) test guideline to support routine use for regulatory purposes (OECD project number 4.93). Among the details that will need to be articulated in an eventual guideline are recommended treatment and harvest schedules. With this in mind, experiments reported herein were performed with Wistar Han rats exposed to aristolochic acid I (AA), 1,3-propane sultone, chlorambucil, thiotepa or melphalan using each of two commonly used treatment schedules: 3 or 28 consecutive days. In the case of the 3-day studies, blood was collected for Pig-a analysis on days 15 or 16 and 29 or 30. For the 28-day studies blood was collected on day 29 or 30. The effect of treatment on mutant reticulocytes and mutant erythrocytes was evaluated with parametric pair-wise tests. While each of the five mutagens increased mutant phenotype cell frequencies irrespective of study design, statistical significance was consistently achieved at lower dose levels when the 28-day format was used (e.g. 2.75 vs 20 mg/kg/bw for AA). To more thoroughly investigate the dose-response relationships, benchmark dose (BMD) analyses were performed with PROAST software. These results corroborate the pair-wise testing results in that lower BMD values were obtained with the 28-day design. Finally, mutagenic potency, as measured by BMD analyses, most consistently correlated with the mutagens' tumorigenic dose 50 values when the lengthier treatment schedule was used. Collectively, these results suggest that both 3- and 28-day treatment schedules have merit in hazard identification-type studies. That being said, for the purpose of regulatory safety assessments, there are clear advantages to study designs that utilise protracted exposures.

Abstract IA18: The exposome and cancer

Abstract The exposome is a term used to characterize exposure to all exogenous environmental agents, socioeconomic conditions, lifestyle, and diet along with markers of endogenous processes across the lifetime of an organism or community of interest. It integrates exposures with molecular or apical responses over time. Measures of the exposome enable data-driven discovery or hypothesis-free research, identifying associations between exposures and biologic endpoints of importance. Two strategies for linking the exposome to health outcomes have been described, and both can be useful. A “top-down” approach adopts untargeted analytic including omic methods to measure features of exogenous and endogenous exposures in biologic specimens. This approach allows contrasts of profiles between diseased and healthy populations. Omic profiles can be used to generate hypotheses to identify particularly relevant exposures, develop biomarkers for high-throughput screens, and determine sources of exposure. A “bottom-up” approach starts with a set of exposures from multiple sources to determine pathways or networks by which those exposures lead to disease. This is laborious and if confined to external sources of exposure, it misses chemical features of the internal environment associated with, for example, metabolism, gender, inflammation, obesity, stress, and discrimination. Most kinds of cancer are multifactorial in origin, and a causal pie model is often used to depict this complexity. Various combinations of component causes accumulate over a lifetime before becoming sufficient to initiate tumor formation and growth. Key events, alone and in combination, initiate adverse outcome pathways. Early biologic changes at low dose levels, exposures during critical windows of vulnerability during various life stages, interactions between exposures and components of mixtures, and gene-environment and internal-external interactions must be considered. In addition to technological challenges, this presentation will briefly raise four issues that must be considered when applying the concept of the exposome to the origins and prevention of cancer: 1) Biologic assumptions: Which signatures, biomarkers, key events, or adverse outcome pathways are important in the pathogenesis of cancer and what determines their variability among individuals or communities? 2) What biologic changes associated with measures of the exposome are adaptive or adverse? When do adaptive responses become adverse? 3) Multilevel variables—individual, family, community, and societal—influence disease risk. Which chemical and nonchemical stressors should be included in exposome assessment? 4) For purposes of prevention, what are the various sources of relevant exposures and their relative ranking in aggregated exposure pathways associated with adverse outcome pathways related to cancer? Citation Format: Ted Schettler. The exposome and cancer [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr IA18.

Anticytokine Activity Enhances Osteogenesis of Bioactive Implants.

In dental clinical practice, systemic steroids are often applied at the end of implant surgeries to reduce postsurgical inflammation (tissue swelling, etc.) and to reduce patient discomfort. However, the use of systemic steroids is associated with generalized catabolic effects and with a temporarily reduced immunological competence. We hypothesize that by applying locally anticytokine antibodies (antitumor necrosis factor alpha and anti-interleukin-1 beta) together with a bioactive osteogenic implant at the time of the surgical intervention for the placement of a construct, we will be able to achieve the same beneficial effects as those using systemic steroids but are able to avoid the generalized antianabolic effects and the reduced immunocompetence effects, associated with the systemic use of steroids. In an adult rat model, a collagen sponge, soaked with the osteogenic agent bone morphogenetic protein-2, was used as an example for a bioactive implant material and was surgically placed subcutaneously. In the acute inflammatory phase after implantation (2 days after surgery) we investigated the local inflammatory tissue response, and 18 days postsurgically the efficiency of local osteogenesis (to assess possible antianabolic effects). We found that the negative control groups, treated postsurgically with systemic steroids, showed a significant suppression of both the inflammatory response and the osteogenetic activity, that is, they were associated with significant general antianabolic effects, even when steroids were used only at a low dose level. The local anticytokine treatment, however, was able to significantly enhance new bone formation activity, that is, the anabolic activity, over positive control values with BMP-2 only. However, the anticytokine treatment was unable to reduce the local inflammatory and swelling responses.

Efficacy of Sunflower Oil in Modulating Rumen Functions and Reducing Enteric Methane Production in Buffalo (Bubalus bubalis)

Enteric methane emission from ruminant livestock reduces the efficiency of feed energy utilization and contributes to global warming. An experiment was conducted to investigate the effects of sunflower (SFL) oil supplementation on methanogenesis, volatile fatty acids composition and feed fermentation pattern by in vitro gas production (IVGP) test. SFL oil was examined at three concentrations (0, 0.4 and 0.8 ml/ 30 ml buffered rumen fluid). In vitro incubation was carried out with sorghum hay (200 ± 5 mg) as substrate in 100 ml calibrated glass syringes following standard IVGP protocol. Addition of SFL oil resulted in increase (p &lt; 0.05) in total gas production and decrease (p &lt; 0.05) in methane concentration in head space gas, irrespective of level of inclusion. Linear decrease (p &lt; 0.001) in feed degradability was evident with increasing doses of oil. Acetate production decreased (p &lt; 0.05) without affecting propionate, however, butyrate production increased (p &lt; 0.05) with addition of oil, irrespective of doses. The ratio of acetate to propionate was reduced (p &lt; 0.01) with addition of oils. It is concluded that sunflower oil supplementation exerted inhibitory effects on methane production; however, dry matter degradability was also reduced. Further studies need to be carried out with lower dose levels for their practical application in animal feeding practices.

The impact of oral exposure to low-dose tris(2-butoxyethyl) phosphate in allergic asthmatic mice.

Tris(2-butoxyethyl) phosphate (TBEP) is a major organophosphorus flame retardant and has been widely increasing as a substitute for brominated flame retardants. TBEP may have adverse effects on human health; however, its impact on immune and allergic responses remains largely uncharacterized. In this study, the effects of low-dose TBEP comparable with the level of actual human exposure to that of human tolerable daily intake on allergic asthmatic mice were explored. Five-week-old C3H/HeJSlc male mice consumed a diet containing approximately 0.02, 0.2 or 2 μg/kg/day TBEP and were intratracheally administrated ovalbumin (OVA) (1 μg/mouse every 2 weeks from 5 to 11 weeks of age). Exposure to 2 μg/kg/day TBEP with OVA tended to enhance allergic pulmonary inflammation and significantly elevated mRNA levels of interleukin-5, eotaxin-1 and estrogen receptor alpha (ERα) compared with OVA alone. In mediastinal lymph nodes (MLNs), TBEP (0.2 or 2 μg/kg/day) with OVA significantly increased in total cell number and promoted conventional dendritic cell activation than OVA alone; MLN cell proliferation by OVA restimulation was also enhanced in these groups. In the bone marrow (BM), TBEP (0.02 or 0.2 μg/kg/day) with OVA resulted in a net decrease in total cell number and fraction of CCR2+ Gr-1+ cells; the fraction of Gr-1+ cells increased. In conclusion, oral exposure to low-dose TBEP levels equivalent to tolerable daily intake may exacerbate allergic pulmonary inflammation by promoting a skewed T-helper 2 cell response, upregulation of ERα and dysregulation of both MLN and BM microenvironments.

The effects of complex metal oxide mixtures on three soil invertebrates with contrasting biological traits

For regulatory purposes, the concentration addition model is the default first tier for assessing joint-action toxicity of metal mixtures. Although many researchers have evaluated binary and ternary mixtures, fewer have investigated joint-action toxicity in more complex mixtures, where deviations from additivity are more likely due to the greater number of potential interactions. In this study, we tested fixed ratios of five metals (lead, copper, nickel, zinc, cobalt) as metal oxide mixtures on three soil invertebrate species (Enchytraeus crypticus, Folsomia candida, Oppia nitens) at different dose effect levels (EC10-EC90) in an acid sandy forest and a loamy soil. Total metal concentrations for mixture ratios in soil did not explain or correlate with species responses. For F. candida, toxicity was linked to metal solubility, while for O. nitens and E. crypticus, toxicity did not correlate with total or extractable metals. In O. nitens and E. crypticus, however, soil ingestion could be an important route of exposure. Analysing the joint effect of metal mixtures, F. candida response was globally additive, while E. crypticus and O. nitens both presented synergistic effects at low-dose effect levels. Estimations at the EC50 level underestimated the deviations from additivity which were larger at higher and especially lower effect levels. Testing across different effect concentrations (EC10-EC90) was an important tool allowing the identification of these larger deviations from additivity outside the EC50 threshold. Considering most protection thresholds are set below the EC50 level, and it was in this low effect range where the highest synergisms were observed, risk assessment schemes should test additivity at the target protection level using representative test organisms.