Recent recognition of "massive" acetaminophen (APAP) overdoses has led to the question of whether standard dosing of N-acetylcysteine (NAC) is adequate to prevent hepatoxicity in these patients. The ...primary aim of this study was to evaluate the clinical outcome for patients with massive APAP overdose who received standard intravenous NAC dosing of 300 mg/kg over 21 h.
This was a single-center retrospective cohort study conducted by chart review of APAP overdoses reported to a regional poison center from 1 January 2010 to 31 December 2019. Massive APAP overdose was defined by single, acute overdose resulting in an APAP concentration exceeding 300 mcg/mL at 4 h post-ingestion. Standard univariate statistical analysis was conducted to describe the cohort, and a multivariate logistic model was utilized to calculate adjusted odds ratios for risk of hepatoxicity.
1425 cases of APAP overdose were reviewed. 104 cases met the inclusion criteria of massive APAP overdose. Overall, 79 cases (76%) had no acute liver injury or hepatotoxicity, and 25 (24%) developed hepatoxicity. Nine percent (n = 4) of cases receiving NAC within 8 h developed hepatotoxicity. Crude odds for hepatoxicity was 5.5-fold higher for cases who received NAC after 8 h.
Standard NAC dosing received within 8 h prevented hepatoxicity in 91% (n = 40) of cases in our series of massive APAP overdoses. Additional data is needed to determine the clinical outcomes of massive APAP overdose using current intravenous NAC dosing.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
With the need to understand the potential biological impact of the plethora of nanoparticles (NPs) being manufactured for a wide range of potential human applications, due to their inevitable human ...exposure, research activities in the field of NP toxicology has grown exponentially over the last decade. Whilst such increased research efforts have elucidated an increasingly significant knowledge base pertaining to the potential human health hazard posed by NPs, understanding regarding the possibility for NPs to elicit genotoxicity is limited. In vivo models are unable to adequately discriminate between the specific modes of action associated with the onset of genotoxicity. Additionally, in line with the recent European directives, there is an inherent need to move away from invasive animal testing strategies. Thus, in vitro systems are an important tool for expanding our mechanistic insight into NP genotoxicity. Yet uncertainty remains concerning their validity and specificity for this purpose due to the unique challenges presented when correlating NP behaviour in vitro and in vivo This review therefore highlights the current state of the art in advanced in vitro systems and their specific advantages and disadvantages from a NP genotoxicity testing perspective. Key indicators will be given related to how these systems might be used or improved to enhance understanding of NP genotoxicity.
The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong ...to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results. The reasons postulated to explain these discordant data generally point to aspects of Ames test study design. These include vehicle solvent choice, liver S9 species, bacterial strain, compound concentration, and use of pre-incubation versus plate incorporation methods. Many of these concerns have their roots in historical data generated prior to the harmonization of Ames test guidelines. Therefore, we investigated various Ames test assay parameters and used qualitative analysis and quantitative benchmark dose modelling to identify which combinations provided the most sensitive conditions in terms of mutagenic potency. Two alkyl-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were studied. NDMA and NDEA mutagenicity was readily detected in the Ames test and key assay parameters were identified that contributed to assay sensitivity rankings. The pre-incubation method (30-min incubation), appropriate vehicle (water or methanol), and hamster-induced liver S9, alongside Salmonella typhimurium strains TA100 and TA1535 and Escherichia coli strain WP2uvrA(pKM101) provide the most sensitive combination of assay parameters in terms of NDMA and NDEA mutagenic potency in the Ames test. Using these parameters and further quantitative benchmark dose modelling, we show that N-nitrosomethylethylamine (NMEA) is positive in Ames test and therefore should no longer be considered a historically discordant NA. The results presented herein define a sensitive Ames test design that can be deployed for the assessment of NAs to support robust impurity qualifications.
Genetic damage is a key event in tumorigenesis, and chemically induced genotoxic effects are a human health concern. Although genetic toxicity data have historically been interpreted using a ...qualitative screen-and-bin approach, there is increasing interest in quantitative analysis of genetic toxicity dose–response data. We demonstrate an emerging use of the benchmark dose (BMD)-approach for empirically ranking cross-tissue sensitivity. Using a model environmental carcinogen, we quantitatively examined responses for four genetic damage endpoints over an extended dose range, and conducted cross-tissue sensitivity rankings using BMD
100
values and their 90% confidence intervals (CIs). MutaMouse specimens were orally exposed to 11 doses of benzoapyrene. DNA adduct frequency and
lacZ
mutant frequency (MF) were measured in up to 8 tissues, and
Pig
-
a
MF and micronuclei (MN) were assessed in immature (RETs) and mature red blood cells (RBCs). The cross-tissue BMD pattern for
lacZ
MF is similar to that observed for DNA adducts, and is consistent with an oral route-of-exposure and differences in tissue-specific metabolism and proliferation. The
lacZ
MF BMDs were significantly correlated with the tissue-matched adduct BMDs, demonstrating a consistent adduct conversion rate across tissues. The BMD CIs, for both the
Pig
-
a
and the MN endpoints, overlapped for RETs and RBCs, suggesting comparable utility of both cell populations for protracted exposures. Examination of endpoint-specific response maxima illustrates the difficulty of comparing BMD values for a fixed benchmark response across endpoints. Overall, the BMD-approach permitted robust comparisons of responses across tissues/endpoints, which is valuable to our mechanistic understanding of how benzoapyrene induces genetic damage.
Automated microscopy and computational image analysis has transformed cell biology, providing quantitative, spatially resolved information on cells and their constituent molecules from the sub-micron ...to the whole-organ scale. Here we explore the application of spatial statistics to the cellular relationships within tissue microscopy data and discuss how spatial statistics offers cytometry a powerful yet underused mathematical tool set for which the required data are readily captured using standard protocols and microscopy equipment. We also highlight the often-overlooked need to carefully consider the structural heterogeneity of tissues in terms of the applicability of different statistical measures and their accuracy and demonstrate how spatial analyses offer a great deal more than just basic quantification of biological variance. Ultimately, we highlight how statistical modeling can help reveal the hierarchical spatial processes that connect the properties of individual cells to the establishment of biological function.
In this perspective, Summers et al. explore the application of spatial statistics to assess cellular relationships within microscopy images of biological tissue. They highlight the need for careful consideration of the multiscale structural heterogeneity of tissues and the need to be aware of these different scales when choosing a suitable test statistic.
The N-nitrosamine, N-nitrosodimethylamine (NDMA), is an environmental mutagen and rodent carcinogen. Small levels of NDMA have been identified as an impurity in some commonly used drugs, resulting in ...several product recalls. In this study, NDMA was evaluated in an OECD TG-488 compliant Muta™Mouse gene mutation assay (28-day oral dosing across seven daily doses of 0.02-4 mg/kg/day) using an integrated design that assessed mutation at the transgenic lacZ locus in various tissues and at the endogenous Pig-a gene-locus, along with micronucleus frequencies in peripheral blood. Liver pathology was determined together with NDMA exposure in blood and liver. The additivity of mutation induction was assessed by including two acute single-dose treatment groups (i.e. 5 and 10 mg/kg dose on Day 1), which represented the same total dose as two of the repeat dose treatment groups. NDMA did not induce statistically significant increases in mean lacZ mutant frequency (MF) in bone marrow, spleen, bladder, or stomach, nor in peripheral blood (Pig-a mutation or micronucleus induction) when tested up to 4 mg/kg/day. There were dose-dependent increases in mean lacZ MF in the liver, lung, and kidney following 28-day repeat dosing or in the liver and kidney after a single dose (10 mg/kg). No observed genotoxic effect levels (NOGEL) were determined for the positive repeat dose-response relationships. Mutagenicity did not exhibit simple additivity in the liver since there was a reduction in MF following NDMA repeat dosing compared with acute dosing for the same total dose. Benchmark dose modelling was used to estimate point of departure doses for NDMA mutagenicity in Muta™Mouse and rank order target organ tissue sensitivity (liver > kidney or lung). The BMD50 value for liver was 0.32 mg/kg/day following repeat dosing (confidence interval 0.21-0.46 mg/kg/day). In addition, liver toxicity was observed at doses of ≥ 1.1 mg/kg/day NDMA and correlated with systemic and target organ exposure. The integration of these results and their implications for risk assessment are discussed.
Human exposure to persistent, nonbiological nanoparticles and microparticles via the oral route is continuous and large scale (1012–1013 particles per day per adult in Europe). Whether this matters ...or not is unknown but confirmed health risks with airborne particle exposure warns against complacency. Murine models of oral exposure will help to identify risk but, to date, lack validation or relevance to humans. This work addresses that gap. It reports i) on a murine diet, modified with differing concentrations of the common dietary particle, food grade titanium dioxide (fgTiO2), an additive of polydisperse form that contains micro‐ and nano‐particles, ii) that these diets deliver particles to basal cells of intestinal lymphoid follicles, exactly as is reported as a “normal occurrence” in humans, iii) that confocal reflectance microscopy is the method of analytical choice to determine this, and iv) that food intake, weight gain, and Peyer's patch immune cell profiles, up to 18 weeks of feeding, do not differ between fgTiO2‐fed groups or controls. These findings afford a human‐relevant and validated oral dosing protocol for fgTiO2 risk assessment as well as provide a generalized platform for application to oral exposure studies with nano‐ and micro‐particles.
Gastrointestinal exposure to persistent particles is continuous for humans but the risks unknown. Rodents are often used to assess human safety but existing techniques poorly reflect real‐world oral exposures to particles. Here, a generalizable approach is presented, for delivery of dietary particles to intestinal rodent cells in the exact same manner as in humans, and exemplified with food‐additive titanium dioxide.
Recognition of the agents most commonly implicated in causing methemoglobinemia can provide context for making therapeutic decisions and inform the diagnostic process. We evaluated the etiologic ...agents most commonly implicated in clinically significant methemoglobinemia using data from the National Poison Data System (NPDS).
What are the most frequent etiologic agents associated with clinically significant methemoglobinemia.
This was a retrospective cross-sectional chart review using electronic data from the NPDS. The NPDS database was queried to identify cases from July 1, 2007, to June 30, 2017, that were coded as methylene blue treatment recommended and/or performed. Cases were excluded if the substance(s) have never been known to cause methemoglobin or the substances suggested methylene blue was used adjunctively for refractory shock (eg, calcium channel or beta blocker). Multiple substance exposures were reviewed and substances not known to cause methemoglobinemia were excluded.
The primary end point was to summarize the most frequent etiologic agents associated with the administration of methylene blue for clinically significant methemoglobinemia.
There were 2563 substances reported in 1209 cases. After excluding coingestants and cases not associated with methemoglobinemia, there were 1236 substances. The top 4 substance categories were benzocaine, phenazopyridine, dapsone, and nitrates/nitrites.
This study reveals the relative contribution of various drugs and chemicals associated with methylene blue administration. Over two-thirds of all cases were associated with benzocaine, phenazopyridine, dapsone, and nitrates/nitrites.
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