Differentiating Ischemic Hepatitis from Acetaminophen Overdose in Acute Liver Failure: Role of Acetaminophen Adducts-Ischemic Hepatitis vs Acetaminophen Overdose.

BACKGROUND AND AIMS: Acetaminophen (APAP) hepatotoxicity and ischemic hepatic injury (IH) demonstrate remarkably similar biochemical patterns. Deciding between these two etiologies in the setting of acute liver failure (ALF) can be challenging. We reviewed all cases in the Acute Liver Failure Study Group (ALFSG) registry where these diagnoses were considered, to determine reasons for, and frequency of, difficulties making these diagnoses. We hypothesized that the newly developed APAP-CYS adduct assay could help in discerning the correct diagnosis. METHODS: Among 3364 patients with ALF or acute liver injury (ALI: INR ≥ 2.0 but without encephalopathy) between 1998 and 2019, 1952 (58%) received a final diagnosis of either APAP (1681) or IH (271). We utilized a review committee of senior hepatologists as well as the APAP-CYS assay (where sera were available), measuring the presence of toxic by-products of APAP injury to optimize adjudication. RESULTS: With these methods, a total of 575 adduct positive APAP cases included 488 recognized APAP, as well as an additional 87 patients previously diagnosed as other etiologies. Nine cases initially attributed to IH were deemed combination APAP-IH injuries. Conversely, 215 of the 280 IH subjects tested for adducts disclosed 173 confirmed as IH with adduct testing below the toxicity threshold, while 9 cases were revised from APAP to the IH-APAP combination phenotype, where both hypotension and APAP likely played a role. CONCLUSIONS: Discerning APAP from IH can be difficult-in rare cases, combined injury is observed (18/1952). APAP-CYS testing resulted in revising the diagnosis in 14.6% of cases.

Racial Disparity in Adherence to Endocrine Therapy among Women with Early-Stage Hormone Receptor Positive Breast Cancer: An Analysis of Arkansas All-Payers Claims Database.

INTRODUCTION/BACKGROUND: To assess racial/ethnic disparities in endocrine therapy (ET) adherence among women with breast cancer. MATERIALS AND METHODS: A retrospective cohort study of Arkansas All-Payer Claims Database (APCD) linked to Arkansas Cancer Registry (ACR). Women with stages 0-3 HR+ breast cancer diagnosed in 2013-2017 were followed from cancer diagnosis for a year to determine ET initiation. Among women who initiated ETs within 1 year of diagnosis, we assessed first-year compliance (proportion of days covered ≥ 0.8) and followed them for 5 years, censoring at death, end of data availability (December 21, 2019), or disenrollment from insurance coverage, whichever occurred first, to determine time to discontinuation. Regression analysis was conducted to determine racial/ethnic disparities in ET use adjusting for patients demographic, clinical, tumor characteristics and county-level socioeconomic factors. RESULTS: Among women with continuous insurance coverage, 81% initiated ET within 1 year of diagnosis; 80% were compliant in the first year of ET use and 27.4% discontinued ET by year 5 among those who initiated ET in the first year. There were no racial/ethnic differences in ET initiation or first-year compliance adjusting for covariates. NHB women were significantly less likely to discontinue ET within 5 years after ET initiation compared to NHW women after (HR, 95% CI, 0.76, 0.58-0.98; P = .035). CONCLUSION: After adjusting for patients' and tumor characteristics, there were no racial/ethnic differences in ET initiation within 1 year of diagnosis and ET compliance within first year of ET use. However, NHB women were less likely to discontinue ET within 5 years of initiation.

Association of Acetaminophen (Paracetamol) Use With Severity and Outcomes in Patients With Viral Hepatitis-Associated Acute Liver Failure.

INTRODUCTION: Acute viral hepatitis (AVH) comprises 11% of acute liver failure (ALF) in North America while acetaminophen (APAP) toxicity represents 46%. The use of APAP to treat prodromal hepatitis symptoms is common. It is unknown if concurrent APAP use impacts liver injury in AVH-induced ALF. METHODS: In this prospective, multicenter cohort study, 356 patients meeting criteria for AVH including hepatitis A, B, Epstein-Barr virus, and herpes simplex virus, all leading to ALF (hepatic encephalopathy after acute illness, international normalized ratio ≥1.5), or acute liver injury (acute liver injury, international normalized ratio >2.0, no hepatic encephalopathy) were reviewed for evidence of APAP use: APAP ingestion history or measurement of serum APAP level or APAP-CYS adducts, a specific biomarker released into blood with APAP injury. Patients were grouped by APAP exposure level, from high (measurable APAP levels or toxic APAP-CYS), medium (therapeutic APAP-CYS), low (history of APAP ingestion only and/or barely detectable APAP-CYS), or no exposure recorded. RESULTS: Two hundred five of 356 patients (57.5%) with AVH-ALF had evidence of APAP use: 87 out of 356 (24%) demonstrated high or medium exposures. The aminotransferase and bilirubin levels of high/medium group resembled a mixed APAP-viral injury. Mortality was the highest (51.6%, 21.4%, 28.8%, and 30.5%), and transplant-free survival was the lowest (22.6%, 44.6%, 41.5%, and 40.4%) in the high exposure group compared with medium, low, and no exposure groups. However, the specific comparisons of mortality and transplant-free survival between the high exposure and no exposure groups were not statistically different even after adjusting for baseline patient characteristics differences. DISCUSSION: APAP use in AVH-ALF is common and may negatively impact outcomes compared with little or no APAP exposure. Prospective studies of the safest and effective dose of APAP to use in patients with AVH are needed.

Physiologically-based pharmacokinetic modeling of pantoprazole to evaluate the role of CYP2C19 genetic variation and obesity in the pediatric population.

Pantoprazole is a proton pump inhibitor indicated for the treatment of gastroesophageal reflux disease, a condition that disproportionately affects children with obesity. Appropriately dosing pantoprazole in children with obesity requires understanding the body size metric that best guides dosing, but pharmacokinetic (PK) trials using traditional techniques are limited by the need for larger sample sizes and frequent blood sampling. Physiologically-based PK (PBPK) models are an attractive alternative that can account for physiologic-, genetic-, and drug-specific changes without the need for extensive clinical trial data. In this study, we explored the effect of obesity on pantoprazole PK and evaluated label-suggested dosing in this population. An adult PBPK model for pantoprazole was developed using data from the literature and accounting for genetic variation in CYP2C19. The adult PBPK model was scaled to children without obesity using age-associated changes in anatomical and physiological parameters. Lastly, the pediatric PBPK model was expanded to children with obesity. Three pantoprazole dosing strategies were evaluated: 1 mg/kg total body weight, 1.2 mg/kg lean body weight, and US Food and Drug Administration-recommended weight-tiered dosing. Simulated concentration-time profiles from our model were compared with data from a prospective cohort study (PAN01; NCT02186652). Weight-tiered dosing resulted in the most (>90%) children with pantoprazole exposures in the reference range, regardless of obesity status or CYP2C19 phenotype, confirming results from previously published population PK models. PBPK models may allow for the efficient study of physiologic and developmental effects of obesity on PK in special populations where clinical trial data may be limited.

Pharmacokinetics and safety of a single dose of telavancin in pediatric subjects 2-17 years of age.

Antimicrobial resistance increases infection morbidity in both adults and children, necessitating the development of new therapeutic options. Telavancin, an antibiotic approved in the United States for certain bacterial infections in adults, has not been examined in pediatric patients. The objectives of this study were to evaluate the short-term safety and pharmacokinetics (PK) of a single intravenous infusion of telavancin in pediatric patients. Single-dose safety and PK of 10 mg/kg telavancin was investigated in pediatric subjects >12 months to ≤17 years of age with known or suspected bacterial infection. Plasma was collected up to 24-h post-infusion and analyzed for concentrations of telavancin and its metabolite for noncompartmental PK analysis. Safety was monitored by physical exams, vital signs, laboratory values, and adverse events following telavancin administration. Twenty-two subjects were enrolled: 14 subjects in Cohort 1 (12-17 years), 7 subjects in Cohort 2 (6-11 years), and 1 subject in Cohort 3 (2-5 years). A single dose of telavancin was well-tolerated in all pediatric age cohorts without clinically significant effects. All age groups exhibited increased clearance of telavancin and reduced exposure to telavancin compared to adults, with mean peak plasma concentrations of 58.3 µg/mL (Cohort 1), 60.1 µg/mL (Cohort 2), and 53.1 µg/mL (Cohort 3). A 10 mg/kg dose of telavancin was well tolerated in pediatric subjects. Telavancin exposure was lower in pediatric subjects compared to adult subjects. Further studies are needed to determine the dose required in phase 3 clinical trials in pediatrics.

Hands-Free Analytical Urine Testing Technology Validated for Drug-Facilitated Crime Investigations.

Forensic laboratories need quick and simple technology to improve turnaround times, while delivering reliable results. The goal of this study is first to create a simplified workflow to meet new Academy Standards Board requirements for urine testing in drug-facilitated crime investigations and, second, to create "ready-to-go", "hands-free" testing technology to further streamline analytical procedures. A first of its kind, the ToxBox forensic test kit is used to validate a single analytical procedure for opioids, benzodiazepines, cannabinoids, antidepressants, and several other drug classes. Method performance indicators follow accreditation requirements and include accuracy, precision, measurement uncertainty, calibration models, reportable range, sensitivity, specificity, carryover, interference, ion suppression/enhancement, and analyte stability. "Hands-free" testing platforms require the use of new suspended-state technology to stabilize NIST-traceable standards premanufactured at precise concentrations in the presence of sample preparation reagents. By suspending all reaction components in the solid state, with air gaps between the phases, reference standards and process controls are built in a "ready-to-go" format and stabilized for long-term storage in the presence of a sample matrix, ß-d-glucuronidase, and enzymatic buffers. "Hands-free" test kits are removed from storage, incubated at either ambient temperature or 60 °C, and assayed using validated methods. This is the first example of how complex forensic testing workflows can be streamlined with new "hands-free" testing strategies to meet analytical challenges associated with quantitative and confirmatory analyses.

Hepatic pyruvate and alanine metabolism are critical and complementary for maintenance of antioxidant capacity and resistance to oxidative insult.

OBJECTIVE: Mitochondrial pyruvate is a critical intermediary metabolite in gluconeogenesis, lipogenesis, and NADH production. As a result, the mitochondrial pyruvate carrier (MPC) complex has emerged as a promising therapeutic target in metabolic diseases. Clinical trials are currently underway. However, recent in vitro data indicate that MPC inhibition diverts glutamine/glutamate away from glutathione synthesis and toward glutaminolysis to compensate for loss of pyruvate oxidation, possibly sensitizing cells to oxidative insult. Here, we explored this in vivo using the clinically relevant acetaminophen (APAP) overdose model of acute liver injury, which is driven by oxidative stress. METHODS: We used pharmacological and genetic approaches to inhibit MPC2 and alanine aminotransferase 2 (ALT2), individually and concomitantly, in mice and cell culture models and determined the effects on APAP hepatotoxicity. RESULTS: We found that MPC inhibition sensitizes the liver to APAP-induced injury in vivo only with concomitant loss of alanine aminotransferase 2 (ALT2). Pharmacological and genetic manipulation of neither MPC2 nor ALT2 alone affected APAP toxicity, but liver-specific double knockout (DKO) significantly worsened APAP-induced liver damage. Further investigation indicated that DKO impaired glutathione synthesis and increased urea cycle flux, consistent with increased glutaminolysis, and these results were reproducible in vitro. Finally, induction of ALT2 and post-treatment with dichloroacetate both reduced APAP-induced liver injury, suggesting new therapeutic avenues. CONCLUSIONS: Increased susceptibility to APAP toxicity requires loss of both the MPC and ALT2 in vivo, indicating that MPC inhibition alone is insufficient to disrupt redox balance. Furthermore, the results from ALT2 induction and dichloroacetate in the APAP model suggest new metabolic approaches to the treatment of liver damage.

A longitudinal study of SARS-CoV-2 antibody seroprevalence and mitigation behaviors among college students at an Arkansas University.

Objective: Assess university students' SARS-CoV-2 antibody seroprevalence and mitigation behaviors over time. Participants: Randomly selected college students (N = 344) in a predominantly rural Southern state. Methods: Participants provided blood samples and completed self-administered questionnaires at three timepoints over the academic year. Adjusted odds ratios and 95% confidence intervals were estimated from logistic regression analyses. Results: SARS-CoV-2 antibody seroprevalence was 18.2% in September 2020, 13.1% in December, and 45.5% in March 2021 (21% for those with no vaccination history). SARS-CoV-2 antibody seroprevalence was associated with large social gatherings, staying local during the summer break, symptoms of fatigue or rhinitis, Greek affiliation, attending Greek events, employment, and using social media as the primary COVID-19 information source. In March 2021, seroprevalence was associated with receiving at least one dose of a COVID-19 vaccination. Conclusion: SARS-CoV-2 seroprevalence was higher in this population of college students than previous studies. Results can assist leaders in making informed decisions as new variants threaten college campuses.

Rural Research Network to engage rural and minority community members in translational research.

Background: To address the high prevalence of health disparities and lack of research opportunities among rural and minority communities, the University of Arkansas for Medical Sciences (UAMS) developed the Rural Research Network in January 2020. Aim: The aim of this report is to describe our process and progress in developing a rural research network. The Rural Research Network provides a platform to expand research participation opportunities to rural Arkansans, many of whom are older adults, low-income individuals, and underrepresented minority populations. Methods: The Rural Research Network leverages existing UAMS Regional Programs family medicine residency clinics within an academic medical center. Results: Since the inception of the Rural Research Network, research infrastructure and processes have been built within the regional sites. Twelve diverse studies have been implemented with recruitment and data collection from 9248 participants, and 32 manuscripts have been published with residents and faculty from the regional sites. Most studies were able to recruit Black/African American participants at or above a representative sample. Conclusions: As the Rural Research Network matures, the types of research will expand in parallel with the health priorities of Arkansas. Relevance to Patients: The Rural Research Network demonstrates how Cancer Institutes and sites funded by a Clinical and Translational Science Award can collaborate to expand research capacity and increase opportunities for research among rural and minority communities.

Solithromycin in Children and Adolescents With Community-acquired Bacterial Pneumonia.

BACKGROUND: Solithromycin is a new macrolide-ketolide antibiotic with potential effectiveness in pediatric community-acquired bacterial pneumonia (CABP). Our objective was to evaluate its safety and effectiveness in children with CABP. METHODS: This phase 2/3, randomized, open-label, active-control, multicenter study randomly assigned solithromycin (capsules, suspension or intravenous) or an appropriate comparator antibiotic in a 3:1 ratio (planned n = 400) to children 2 months to 17 years of age with CABP. Primary safety endpoints included treatment-emergent adverse events (AEs) and AE-related drug discontinuations. Secondary effectiveness endpoints included clinical improvement following treatment without additional antimicrobial therapy. RESULTS: Unrelated to safety, the sponsor stopped the trial prior to completion. Before discontinuation, 97 participants were randomly assigned to solithromycin (n = 73) or comparator (n = 24). There were 24 participants (34%, 95% CI, 23%-47%) with a treatment-emergent AE in the solithromycin group and 7 (29%, 95% CI, 13%-51%) in the comparator group. Infusion site pain and elevated liver enzymes were the most common related AEs with solithromycin. Study drug was discontinued due to AEs in 3 subjects (4.3%) in the solithromycin group and 1 (4.2%) in the comparator group. Forty participants (65%, 95% CI, 51%-76%) in the solithromycin group achieved clinical improvement on the last day of treatment versus 17 (81%, 95% CI, 58%-95%) in the comparator group. The proportion achieving clinical cure was 60% (95% CI, 47%-72%) and 68% (95% CI, 43%-87%) for the solithromycin and comparator groups, respectively. CONCLUSIONS: Intravenous and oral solithromycin were generally well-tolerated and associated with clinical improvement in the majority of participants treated for CABP.

The Spice of Death: Sudden Cardiac Arrest After Novel Psychoactive Substance Exposure.

ABSTRACT: Novel psychoactive substances (NPSs), commonly referred to as "K2" or "spice," are a relatively new toxicology challenge for pediatricians. Adolescents often incorrectly believe that these drugs are safe and can be used without major adverse effects. Although recent legislation attempts to ensure that these drugs are not commercially available, many are able to be purchased online as "not fit for human consumption" or under various misnomers such "incense." In addition, there is a wide chemical variation among these substances, making regulation challenging. Standard urine drug screens test for tetrahydrocannabinol, which may not cross-react with synthetic substances, making NPS poisonings difficult to diagnose. We report a case of fatal cardiac arrest in a 16-year-old adolescent boy temporally associated with use of the NPS, 5F-ADB. The case illustrates the dangerous consequences that these unregulated substances pose to users, as well as the need for the consideration of comprehensive toxicological testing in patients with a history of substance use and sudden cardiac arrest, despite a negative drug screen.

Short-Term Safety of Repeated Acetaminophen Use in Patients With Compensated Cirrhosis.

Current guidelines recommend restricting acetaminophen (APAP) use in patients with cirrhosis, but evidence to support that recommendation is lacking. Prior studies focused on pharmacokinetics (PK) of APAP in cirrhosis but did not rigorously examine clinical outcomes, sensitive biomarkers of liver damage, or serum APAP-protein adducts, which are a specific marker of toxic bioactivation. Hence, the goal of this pilot study was to test the effects of regularly scheduled APAP dosing in a well-defined compensated cirrhosis group compared to control subjects without cirrhosis, using the abovementioned outcomes. After a 2-week washout, 12 subjects with and 12 subjects without cirrhosis received 650 mg APAP twice per day (1.3 g/day) for 4 days, followed by 650 mg on the morning of day 5. Patients were assessed in-person at study initiation (day 1) and on days 3 and 5. APAP-protein adducts and both conventional (alanine aminotransferase) and sensitive (glutamate dehydrogenase [GLDH], full-length keratin 18 [K18], and total high-mobility group box 1 protein) biomarkers of liver injury were measured in serum on the mornings of days 1, 3, and 5, with detailed PK analysis of APAP, metabolites, and APAP-protein adducts throughout day 5. No subject experienced adverse clinical outcomes. GLDH and K18 were significantly different at baseline but did not change in either group during APAP administration. In contrast, clearance of APAP-protein adducts was dramatically delayed in the cirrhosis group. Minor differences for other APAP metabolites were also detected. Conclusion: Short-term administration of low-dose APAP (650 mg twice per day, <1 week) is likely safe in patients with compensated cirrhosis. These data provide a foundation for future studies to test higher doses, longer treatment, and subjects who are decompensated, especially in light of the remarkably delayed adduct clearance in subjects with cirrhosis.

Arkansans' Preferred COVID-19 Testing Locations.

INTRODUCTION: A contributing factor to racial and ethnic disparities during the COVID-19 pandemic may be the accessibility and acceptability of COVID-19 testing. Previous studies found that access to testing has not been equitable across several sociodemographic indicators. This study documents the preferred testing locations and examines differences across sociodemographic factors with a specific focus on race and ethnicity. METHODS: This study includes a primary analysis of cross-sectional data using a self-administered digital survey distributed to Arkansas residents using ARresearch, a volunteer research participant registry. The survey had 1288 responses, and 1221 met eligibility criteria for inclusion in the survey. Participants provided sociodemographic information and were asked to select up to 3 preferred testing locations from 12 options. Chi-square tests assessed differences in testing site preference across relevant sociodemographic groups. RESULTS: Participants preferred drive-through clinics as their top location for COVID-19 testing, with 55% reporting this was their preferred method of testing. This pattern was consistent across all comparison groups (ie, age, sex, race/ethnicity, education, insurance status). Significant differences in testing location preference were observed across age, race and ethnicity, and education, with the most differences observed across race and ethnicity. CONCLUSION: This study reveals that race and ethnicity are important to consider when deciding where to offer COVID-19 testing. The preferences for testing locations among the most vulnerable demographics will be used to develop targeted responses aimed at eliminating disparities in COVID-19 in Arkansas.

Perceived Barriers to COVID-19 Testing.

(1) Background: Prior studies have documented that access to testing has not been equitable across all communities in the US, with less testing availability and lower testing rates documented in rural counties and lower income communities. However, there is limited understanding of the perceived barriers to coronavirus disease 2019 (COVID-19) testing. The purpose of this study was to document the perceived barriers to COVID-19 testing. (2) Methods: Arkansas residents were recruited using a volunteer research participant registry. Participants were asked an open-ended question regarding their perceived barriers to testing. A qualitative descriptive analytical approach was used. (3) Results: Overall, 1221 people responded to the open-ended question. The primary barriers to testing described by participants were confusion and uncertainty regarding testing guidelines and where to go for testing, lack of accessible testing locations, perceptions that the nasal swab method was too painful, and long wait times for testing results. (4) Conclusions: This study documents participant reported barriers to COVID-19 testing. Through the use of a qualitative descriptive method, participants were able to discuss their concerns in their own words. This work provides important insights that can help public health leaders and healthcare providers with understanding and mitigating barriers to COVID-19 testing.

Dissemination Protocol for Community-Based Participatory Research Partnerships with Marshallese Pacific Islanders in Arkansas.

BACKGROUND: The Pacific Islander population in the United States (U.S.) has rapidly increased since 2000, especially in southern states like Arkansas where the largest population of Marshallese in the continental U.S. reside. The Marshallese community faces significant health disparities with high prevalence of diabetes, obesity, obesity-related cancers, and other chronic conditions. OBJECTIVES: Researchers have utilized a community-based participatory research (CBPR) approach that fully engages Marshallese stakeholders in research to address the community's health disparities. Sharing research findings with participants and stakeholders is a core principle of CBPR. METHODS: This manuscript describes the methods that the academic-community research partnership used to develop a dissemination protocol for sharing results from multiple pilot studies and randomized control trials. Examples and details of specific activities that resulted from putting the dissemination plan in action are presented. CONCLUSIONS: Implementation of CBPR principles ensures that researchers fully engage stakeholders in all aspects of research, including the dissemination of study results. This manuscript describes the dissemination protocol for an academic- community research partnership with the Marshallese community and provides a practical example for how to implement successful community-engaged dissemination.

Exogenous phosphatidic acid reduces acetaminophen-induced liver injury in mice by activating hepatic interleukin-6 signaling through inter-organ crosstalk.

We previously demonstrated that endogenous phosphatidic acid (PA) promotes liver regeneration after acetaminophen (APAP) hepatotoxicity. Here, we hypothesized that exogenous PA is also beneficial. To test that, we treated mice with a toxic APAP dose at 0 h, followed by PA or vehicle (Veh) post-treatment. We then collected blood and liver at 6, 24, and 52 h. Post-treatment with PA 2 h after APAP protected against liver injury at 6 h, and the combination of PA and N-acetyl-l-cysteine (NAC) reduced injury more than NAC alone. Interestingly, PA did not affect canonical mechanisms of APAP toxicity. Instead, transcriptomics revealed that PA activated interleukin-6 (IL-6) signaling in the liver. Consistent with that, serum IL-6 and hepatic signal transducer and activator of transcription 3 (Stat3) phosphorylation increased in PA-treated mice. Furthermore, PA failed to protect against APAP in IL-6-deficient animals. Interestingly, IL-6 expression increased 18-fold in adipose tissue after PA, indicating that adipose is a source of PA-induced circulating IL-6. Surprisingly, however, exogenous PA did not alter regeneration, despite the importance of endogenous PA in liver repair, possibly due to its short half-life. These data demonstrate that exogenous PA is also beneficial in APAP toxicity and reinforce the protective effects of IL-6 in this model.

Two SARS-CoV-2 Genome Sequences of Isolates from Rural U.S. Patients Harboring the D614G Mutation, Obtained Using Nanopore Sequencing.

Two coding-complete sequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were obtained from samples from two patients in Arkansas, in the southeastern corner of the United States. The viral genome was obtained using the ARTIC Network protocol and Oxford Nanopore Technologies sequencing.

Pre-treatment twice with liposomal clodronate protects against acetaminophen hepatotoxicity through a pre-conditioning effect.

BACKGROUND AND AIM: Acetaminophen (APAP) overdose is a major cause of acute liver injury, but the role of macrophages in propagation of the hepatotoxicity is controversial. Early research revealed that macrophage inhibitors protect against APAP injury. However, later work demonstrated that macrophage ablation by acute pre-treatment with liposomal clodronate (LC) exacerbates the toxicity. To our surprise, during other studies, we observed that pre-treatment twice with LC seemed to protect against APAP hepatotoxicity, in contrast to acute pre-treatment. The aim of this study was to confirm that observation and to explore the mechanisms. METHODS: We treated mice with empty liposomes (LE) or LC twice per week for 1 week before APAP overdose and collected blood and liver tissue at 0, 2, and 6 h post-APAP. We then measured liver injury (serum ALT activity, histology), APAP bioactivation (total glutathione, APAP-protein adducts), oxidative stress (oxidized glutathione [GSSG]), glutamate cysteine-ligase subunit c (Gclc) mRNA, and nuclear factor erythroid 2-related factor (Nrf2) immunofluorescence. We also confirmed ablation of macrophages by F4/80 immunohistochemistry. RESULTS: Pre-treatment twice with LC dramatically reduced F4/80 staining, protected against liver injury, and reduced oxidative stress at 6 h post-APAP, without affecting APAP bioactivation. Importantly, Gclc mRNA was higher in the LC group at 0 h and total glutathione was higher at 2 h, indicating accelerated glutathione re-synthesis after APAP overdose due to greater basal glutamate-cysteine ligase. Oxidative stress was lower in the LC groups at both time points. Finally, total Nrf2 immunofluorescence was higher in the LC group. CONCLUSIONS: We conclude that multiple pre-treatments with LC protect against APAP by accelerating glutathione re-synthesis through glutamate-cysteine ligase. Investigators using two or possibly more LC pre-treatments to deplete macrophages, including peritoneal macrophages, should be aware of this possible confounder.