A Performance Evaluation of Liver and Skeletal Muscle-Specific miRNAs in Rat Plasma to Detect Drug-Induced Injury

Blood biomarkers for sarcopenia: A systematic review and meta-analysis of diagnostic test accuracy studies

Biomarkers are emerging as a potential tool for screening or diagnosing sarcopenia. We aimed to summarize the current evidence on the diagnostic test accuracy of biomarkers for sarcopenia. We comprehensively searched Ovid MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials up to January 2023 and only included diagnostic test accuracy studies. We identified 32 studies with 23,840 participants (women, 58.26%) that assessed a total of 30 biomarkers. The serum creatinine to cystatin C ratio (Cr/CysC) demonstrated a pooled sensitivity ranging from 51% (95% confidence interval [CI] 44-59%) to 86% (95% CI 70-95%) and a pooled specificity ranged from 55% (95% CI 38-70%) to 76% (95% CI 63-86%) for diagnosing sarcopenia defined by five different diagnostic criteria (11 studies, 7240 participants). The aspartate aminotransferase to alanine aminotransferase ratio demonstrated a pooled sensitivity of 62% (95% CI 56-67%) and a pooled specificity of 66% (95% CI 60-72%) (3 studies, 11,146 participants). The other 28 blood biomarkers exhibited low-to-moderate diagnostic accuracy for sarcopenia regardless of the reference standards. In conclusion, none of these biomarkers are optimal for screening or diagnosing sarcopenia. Well-designed studies are needed to explore and validate novel biomarkers for sarcopenia.

Progress in the Diagnostic and Predictive Evaluation of Crush Syndrome

Crush syndrome (CS), also known as traumatic rhabdomyolysis, is a syndrome with a wide clinical spectrum; it is caused by external compression, which often occurs in earthquakes, wars, and traffic accidents, especially in large-scale disasters. Crush syndrome is the second leading cause of death after direct trauma in earthquakes. A series of clinical complications caused by crush syndrome, including hyperkalemia, myoglobinuria, and, in particular, acute kidney injury (AKI), is the main cause of death in crush syndrome. The early diagnosis of crush syndrome, the correct evaluation of its severity, and accurate predictions of a poor prognosis can provide personalized suggestions for rescuers to carry out early treatments and reduce mortality. This review summarizes various methods for the diagnostic and predictive evaluation of crush syndrome, including urine dipstick tests for a large number of victims, traditional and emerging biomarkers, imaging-assisted diagnostic methods, and developed evaluation models, with the aim of providing materials for scholars in this research field.

The Role of Glutathione in Selected Viral Diseases

During inflammatory processes, immunocompetent cells are exposed to substantial amounts of free radicals and toxic compounds. Glutathione is a cysteine-containing tripeptide that is an important and ubiquitous antioxidant molecule produced in human organs. The intracellular content of GSH regulates the detoxifying capacity of cells, as well as the inflammatory and immune response. GSH is particularly important in the liver, where it serves as the major non-protein thiol involved in cellular antioxidant defense. There are numerous causes of hepatitis. The inflammation of the liver can be caused by a variety of infectious viruses. The relationship between oxidative stress and the hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis E virus (HEV) infection is not fully known. The aim of this study was to examine the relationship between hepatotropic viruses and glutathione status, including reduced glutathione (GSH) and oxidized glutathione (GSSG), as well as antioxidant enzymes, e.g., glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) in liver diseases.

Harnessing PUF-Based Reporters for Noninvasive Imaging of the MicroRNA Dynamics in Differentiation

Precise characterization of miRNA expression patterns is critical to exploit the complexity of miRNA regulation in biology. Herein, we developed a Pumilio/FBF (PUF) protein-based engineering luciferase reporter system, PUF/miR, to quantitatively and non-invasively sense miRNA activity in living cells and animal models. We verified the feasibility of this reporter by monitoring the expression of several types of miRNAs (miRNA-9, 124a, 1, and 133a) in neural and muscle differentiated cells as well as subcutaneous or tibial anterior muscles in mice. The quantitative RT-PCR also validated the reliability and quantitative consistency of bioluminescence imaging in detecting miRNA expression. We further effectively employed this reporter system to visualize the expression of miRNA-1 and miRNA-133a in mouse models of skeletal muscle injury. As a non-invasive and convenient innovative approach, our results have realized the positive bioluminescence imaging of endogenous miRNAs in vitro and in vivo using the PUF/miR system. We believe that this approach would provide a potential means for noninvasive monitoring of disease-related miRNAs and could facilitate a deeper understanding of miRNA biology.

Evaluation of circulating miR-216a and miR-217 as biomarkers of pancreatic damage in the L-arginine-induced acute pancreatitis mouse model

We investigated the usefulness of circulating miR-216a-5p and miR-217-5p that are pancreas-enriched micro RNAs (miRNAs) as biomarkers of acute pancreatic damage, and compared them with conventional pancreatic biomarkers in L-arginine-induced acute pancreatitis mouse model. As the results, amylase and lipase levels apparently increased and peaked on Day 3 when acute pancreatitis including acinar cell degeneration/necrosis and inflammatory cell infiltration reached its peak. In contrast, miR-216a-5p and miR-217-5p increased from Day 1 when histopathological findings in the acinar cells were limited to decreased zymogen granules, and the increases in ratios were much higher than those of amylase and lipase. The miRNAs remained at high levels until Day 5 when the pseudo-tubular complex and replacement of inflammatory cells and fibrotic cells were apparent instead of necrosis, whereas amylase and lipase levels decreased to the control levels. Furthermore, we examined the relationship between biomarker levels and histopathological degeneration/necrosis scores in the acinar cells. miR-216a-5p and miR-217-5p levels increased depending on the score of degeneration/necrosis, and all individual miRNAs exceeded the control levels from a score of 2 (focal necrosis), whereas all individual amylase and lipase levels exceeded the control levels at scores of 4 (lobular necrosis) and 3 (sublobular necrosis), respectively. In conclusion, we demonstrated that circulating miR-216a-5p and miR-217-5p could detect pancreatic damage earlier with greater magnitude, and the sensitivity to detect acinar cell degeneration/necrosis was superior to that of conventional biomarkers in the L-arginine-induced acute pancreatitis mouse model.

miRNA Profile Based on ART Delay in Vertically Infected HIV-1 Youths Is Associated With Inflammatory Biomarkers and Activation and Maturation Immune Levels

Early antiretroviral treatment (ART) in vertically acquired HIV-1-infection is associated with a rapid viral suppression, small HIV-1 reservoir, reduced morbimortality and preserved immune functions. We investigated the miRNA profile from vertically acquired HIV-1-infected young adults based on ART initiation delay and its association with the immune system activation. Using a microRNA panel and multiparametric flow cytometry, miRNome profile obtained from peripheral blood mononuclear cells and its association with adaptive and innate immune components were studied on vertically HIV-1-infected young adults who started ART early (EARLY, 0-53 weeks after birth) and later (LATE, 120-300 weeks). miR-1248 and miR-155-5p, were significantly upregulated in EARLY group compared with LATE group, while miR-501-3p, miR-548d-5p, miR-18a-3p and miR-296-5p were significantly downregulated in EARLY treated group of patients. Strong correlations were obtained between miRNAs levels and soluble biochemical biomarkers and immunological parameters including CD4 T-cell count and maturation by CD69 expression on CD4 T-cells and activation by HLA-DR on CD16^high NK cell subsets for miR-1248 and miR-155-5p. In this preliminary study, a distinct miRNA signature discriminates early treated HIV-1-infected young adults. The role of those miRNAs target genes in the modulation of HIV-1 replication and latency may reveal new host signaling pathways that could be manipulated in antiviral strategies. Correlations between miRNAs levels and inflammatory and immunological markers highlight those miRNAs as potential biomarkers for immune inflammation and activation in HIV-1-infected young adults who initiated a late ART.

Human Umbilical Cord Mesenchymal Stem Cell-Derived Small Extracellular Vesicles Ameliorated Insulin Resistance in Type 2 Diabetes Mellitus Rats

Human umbilical cord mesenchymal stem cell-derived small extracellular vesicle (hUC-MSCs-sEVs) therapy has shown promising results to treat diabetes mellitus in preclinical studies. However, the dosage of MSCs-sEVs in animal studies, up to 10 mg/kg, was considered high and may be impractical for future clinical application. This study aims to investigate the efficacy of low-dose hUC-MSCs-sEVs treatment on human skeletal muscle cells (HSkMCs) and type 2 diabetes mellitus (T2DM) rats. Treatment with hUC-MSCs-sEVs up to 100 μg/mL for 48 h showed no significant cytotoxicity. Interestingly, 20 μg/mL of hUC-MSCs-sEVs-treated HSkMCs increased glucose uptake by 80–90% compared to untreated cells. The hUC-MSCs-sEVs treatment at 1 mg/kg improved glucose tolerance in T2DM rats and showed a protective effect on complete blood count. Moreover, an improvement in serum HbA1c was observed in diabetic rats treated with 0.5 and 1 mg/kg of hUC-MSCs-sEVs, and hUC-MSCs. The biochemical tests of hUC-MSCs-sEVs treatment groups showed no significant creatinine changes, elevated alanine aminotransferase (ALT) and alkaline phosphatase (ALP) levels compared to the normal group. Histological analysis revealed that hUC-MSCs-sEVs relieved the structural damage to the pancreas, kidney and liver. The findings suggest that hUC-MSCs-sEVs could ameliorate insulin resistance and exert protective effects on T2DM rats. Therefore, hUC-MSCs-sEVs could serve as a potential therapy for diabetes mellitus.

A robust biostatistical method leverages informative but uncertainly determined qPCR data for biomarker detection, early diagnosis, and treatment

As a common medium-throughput technique, qPCR (quantitative real-time polymerase chain reaction) is widely used to measure levels of nucleic acids. In addition to accurate and complete data, experimenters have unavoidably observed some incomplete and uncertainly determined qPCR data because of intrinsically low overall amounts of biological materials, such as nucleic acids present in biofluids. When there are samples with uncertainly determined qPCR data, some investigators apply the statistical complete-case method by excluding the subset of samples with uncertainly determined data from analysis (CO), while others simply choose not to analyze (CNA) these datasets altogether. To include as many observations as possible in analysis for interesting differential changes between groups, some investigators set incomplete observations equal to the maximum quality qPCR cycle (MC), such as 32 and 40. Although straightforward, these methods may decrease the sample size, skew the data distribution, and compromise statistical power and research reproducibility across replicate qPCR studies. To overcome the shortcomings of the existing, commonly-used qPCR data analysis methods and to join the efforts in advancing statistical analysis in rigorous preclinical research, we propose a robust nonparametric statistical cycle-to-threshold method (CTOT) to analyze incomplete qPCR data for two-group comparisons. CTOT incorporates important characteristics of qPCR data and time-to-event statistical methodology, resulting in a novel analytical method for qPCR data that is built around good quality data from all subjects, certainly determined or not. Considering the benchmark full data (BFD), we compared the abilities of CTOT, CO, MC, and CNA statistical methods to detect interesting differential changes between groups with informative but uncertainly determined qPCR data. Our simulations and applications show that CTOT improves the power of detecting and confirming differential changes in many situations over the three commonly used methods without excess type I errors. The robust nonparametric statistical method of CTOT helps leverage qPCR technology and increase the power to detect differential changes that may assist decision making with respect to biomarker detection and early diagnosis, with the goal of improving the management of patient healthcare.

High Serum AST/ALT Ratio and Low Serum INS*PA Product Are Risk Factors and Can Diagnose Sarcopenia in Middle-Aged and Older Adults

BACKGROUND

Sarcopenia is an age-related clinical condition and associated with an increased risk of adverse outcomes. However, to date, there is no global standard for the diagnosis of sarcopenia, and fewer serum biomarkers have been suggested for the diagnosis of sarcopenia. It is, thus, important that sarcopenia-related serological diagnostic markers be explored. The present study was based on the Asian Working Group on Sarcopenia 2019 (AWGS 2019) criteria to assess whether aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio and fasting insulin*prealbumin (INS*PA) product are diagnostic markers associated with sarcopenia in various ethnic groups in western China.

METHODS

This cross-sectional study included 4,099 adults (1,471 men and 2,628 women) from the West China Health and Aging Trend (WCHAT) study. The value of serum biomarkers was based on laboratory data. The accompanying metabolic disorders and the associated parameters were evaluated. Logistic regression analysis was used to explore the association between markers and sarcopenia. Receiver operating characteristic curve (ROC) analysis was used to evaluate the diagnostic efficacy of the test in differentiating sarcopenia.

RESULTS

Binary regression analysis showed that high serum AST/ALT (OR = 2.247) and adrenal cortisol (PTC, OR = 1.511), low serum INS*PA (OR = 2.970), free triiodothyronine (FT3, OR = 1.313), 25-OH-VitD (VitD, in male participants, OR = 1.817), and diastolic blood pressure (DBP, in female subjects, OR = 1.250) were independent risk factors for sarcopenia (P < 0.05). AST/ALT and INS*PA were not affected by metabolic factors and had better diagnostic efficacy for sarcopenia. The AUC of the INS*PA was the highest (0.705, 0.706, and 0.701, respectively, P < 0.05), followed by that of the AST/ALT (0.680, 0.675, and 0.695, respectively, P < 0.05). The AUC of the AST/ALT/(INS*PA)*10,000 used to diagnose sarcopenia was 0.727.

CONCLUSION

Among middle-aged and older adults of multiple ethnicities in western China, we found that higher AST/ALT and lower INS*PA levels are associated with an increased prevalence of sarcopenia. Since these serum biomarkers are inexpensive and can be obtained easily from biochemical routine, regular follow-up of AST/ALT and INS*PA may be an effective strategy in sarcopenia screening and management.

The application of cytokeratin-18 as a biomarker for drug-induced liver injury

Drug-induced liver injury (DILI) is a frequent and dangerous adverse effect faced during preclinical and clinical drug therapy. DILI is a leading cause of candidate drug attrition, withdrawal and in clinic, is the primary cause of acute liver failure. Traditional diagnostic markers for DILI include alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP). Yet, these routinely used diagnostic markers have several noteworthy limitations, restricting their sensitivity, specificity and accuracy in diagnosing DILI. Consequently, new biomarkers for DILI need to be identified.A potential biomarker for DILI is cytokeratin-18 (CK18), an intermediate filament protein highly abundant in hepatocytes and cholangiocytes. Extensively researched in a variety of clinical settings, both full length and cleaved forms of CK18 can diagnose early-stage DILI and provide insight into the mechanism of hepatocellular injury compared to traditionally used diagnostic markers. However, relatively little research has been conducted on CK18 in preclinical models of DILI. In particular, CK18 and its relationship with DILI is yet to be characterised in an in vivo rat model. Such characterization of CK18 and ccCK18 responses may enable their use as translational biomarkers for hepatotoxicity and facilitate management of clinical DILI risk in drug development. The aim of this review is to discuss the application of CK18 as a biomarker for DILI. Specifically, this review will highlight the properties of CK18, summarise clinical research that utilised CK18 to diagnose DILI and examine the current challenges preventing the characterisation of CK18 in an in vivo rat model of DILI.

Systems analysis of miRNA biomarkers to inform drug safety

microRNAs (miRNAs or miRs) are short non-coding RNA molecules which have been shown to be dysregulated and released into the extracellular milieu as a result of many drug and non-drug-induced pathologies in different organ systems. Consequently, circulating miRs have been proposed as useful biomarkers of many disease states, including drug-induced tissue injury. miRs have shown potential to support or even replace the existing traditional biomarkers of drug-induced toxicity in terms of sensitivity and specificity, and there is some evidence for their improved diagnostic and prognostic value. However, several pre-analytical and analytical challenges, mainly associated with assay standardization, require solutions before circulating miRs can be successfully translated into the clinic. This review will consider the value and potential for the use of circulating miRs in drug-safety assessment and describe a systems approach to the analysis of the miRNAome in the discovery setting, as well as highlighting standardization issues that at this stage prevent their clinical use as biomarkers. Highlighting these challenges will hopefully drive future research into finding appropriate solutions, and eventually circulating miRs may be translated to the clinic where their undoubted biomarker potential can be used to benefit patients in rapid, easy to use, point-of-care test systems.

Universal Toxicity Gene Signatures for Early Identification of Drug-Induced Tissue Injuries in Rats

A new safety testing paradigm that relies on gene expression biomarker panels was developed to easily and quickly identify drug-induced injuries across tissues in rats prior to drug candidate selection. Here, we describe the development, qualification, and implementation of gene expression signatures that diagnose tissue degeneration/necrosis for use in early rat safety studies. Approximately 400 differentially expressed genes were first identified that were consistently regulated across 4 prioritized tissues (liver, kidney, heart, and skeletal muscle), following injuries induced by known toxicants. Hundred of these "universal" genes were chosen for quantitative PCR, and the most consistent and robustly responding transcripts selected, resulting in a final 22-gene set from which unique sets of 12 genes were chosen as optimal for each tissue. The approach was extended across 4 additional tissues (pancreas, gastrointestinal tract, bladder, and testes) where toxicities are less common. Mathematical algorithms were generated to convert each tissue's 12-gene expression values to a single metric, scaled between 0 and 1, and a positive threshold set. For liver, kidney, heart, and skeletal muscle, this was established using a training set of 22 compounds and performance determined by testing a set of approximately 100 additional compounds, resulting in 74%-94% sensitivity and 94%-100% specificity for liver, kidney, and skeletal muscle, and 54%-62% sensitivity and 95%-98% specificity for heart. Similar performance was observed across a set of 15 studies for pancreas, gastrointestinal tract, bladder, and testes. Bundled together, we have incorporated these tissue signatures into a 4-day rat study, providing a rapid assessment of commonly seen compound liabilities to guide selection of lead candidates without the necessity to perform time-consuming histopathologic analyses.

Methodological considerations for measuring biofluid-based microRNA biomarkers

MicroRNAs (miRNAs) are small non-coding RNA that regulate the expression of messenger RNA and are implicated in almost all cellular processes. Importantly, miRNAs can be released extracellularly and are stable in these matrices where they may serve as indicators of organ or cell-specific toxicity, disease, and biological status. There has thus been great enthusiasm for developing miRNAs as biomarkers of adverse outcomes for scientific, regulatory, and clinical purposes. Despite advances in measurement capabilities for miRNAs, miRNAs are still not routinely employed as noninvasive biomarkers. This is in part due to the lack of standard approaches for sample preparation and miRNA measurement and uncertainty in their biological interpretation. Members of the microRNA Biomarkers Workgroup within the Health and Environmental Sciences Institute's (HESI) Committee on Emerging Systems Toxicology for the Assessment of Risk (eSTAR) are a consortium of private- and public-sector scientists dedicated to developing miRNAs as applied biomarkers. Here, we explore major impediments to routine acceptance and use of miRNA biomarkers and case examples of successes and deficiencies in development. Finally, we provide insight on miRNA measurement, collection, and analysis tools to provide solid footing for addressing knowledge gaps toward routine biomarker use.

Recent progress in the use of microRNAs as biomarkers for drug-induced toxicities in contrast to traditional biomarkers: A comparative review

microRNAs (miRNAs) are small non-coding RNAs with 18-25 nucleotides. They play key regulatory roles in versatile biological process including development and apoptosis, and in disease pathogenesis, for example carcinogenesis, by negatively regulating gene expression. miRNAs often exhibit characteristics suitable for biomarkers such as tissue-specific expression patterns, high stability in serum/plasma, and change in abundance in circulation immediately after toxic injury. Since the discovery of circulating miRNAs in extracellular biological fluids in 2008, there have been many reports on the use of miRNAs as biomarkers for various diseases including cancer and organ injury in humans and experimental animals. In this review article, we have summarized the utility and limitation of circulating miRNAs as safety/toxicology biomarkers for specific tissue injuries including liver, skeletal muscle, heart, retina, and pancreas, by comparing them with conventional protein biomarkers. We have also covered the discovery of miRNAs in serum/plasma and their stability, the knowledge of which is essential for understanding the kinetics of miRNA biomarkers. Since numerous studies have reported the use of these circulating miRNAs as safety biomarkers with high sensitivity and specificity, we believe that circulating miRNAs can promote pre-clinical drug development and improve the monitoring of tissue injuries in clinical pharmacotherapy.

Reproducibility challenges for biomarker detection with uncertain but informative experimental data

Recent studies have revealed that circulating microRNAs are promising biomarkers for detecting toxicity or disease. Quantitative real-time polymerase chain reaction (qPCR) is often used to measure the levels of microRNAs. Besides complete and certain data, investigators inevitably have observed technically incomplete or uncertain qPCR data. Investigators usually set incomplete observations equal to the maximum quality number of qPCR cycles, apply the complete-observation method, or choose not to analyze targets with incomplete observations. Using biostatistical knowledge and published studies, we show that three commonly applied methods tend to cause biased inference and decrease reproducibility in biomarker detection. More efforts are needed to address the challenges to identify and detect reliable, novel circulating biomarkers in liquid biopsies.

Serum miR-206 as a biomarker for drug-induced skeletal muscle injury in rats

Creatine kinase (CK) and lactate dehydrogenase (LDH) serve as biomarkers for skeletal muscle injury in preclinical toxicity studies, but have a limitation regarding tissue specificity. Circulating miR-206 was recently reported to be a useful biomarker for skeletal muscle disorders in humans. Here, we sought to determine whether serum miR-206 can be used as a biomarker in preclinical toxicity studies to detect drug-induced skeletal muscle injury with higher sensitivity and specificity than the biomarkers CK, LDH, skeletal troponin I (sTnI), and myosin light chain 3 (Myl3). We established rat models of skeletal muscle injury through treatment with the muscle toxicant 2,3,5,6-tetramethyl-p-phenylenediamine (TMPD) as well as four in-house compounds. We found that serum miR-206 levels significantly increased after treatment with TMPD, and tended to be higher in rats treated with in-house compounds than in control rats. ROC analysis revealed that the specificity of serum miR-206 for detection of skeletal muscle injury was higher compared with those of other markers. Further, serum miR-206 levels were unchanged in rats with isoproterenol-induced cardiotoxicity. These findings demonstrate that serum miR-206 may serve as a highly specific biomarker for preclinical analysis of rats with drug-induced skeletal muscle injuries.

Circulating microRNA as biomarkers of canine mammary carcinoma in dogs

Background

Differentiating benign from canine malignant mammary tumors requires invasive surgical biopsy. Circulating microRNAs (miRNA) may represent promising minimally invasive cancer biomarkers in people and animals.

Objectives

To evaluate the serum mRNA profile between dogs with and without mammary carcinoma, and to determine if any of these markers have prognostic significance.

Animals

Ten healthy client‐owned female dogs (5 intact, 5 spayed) and 10 dogs with histologically confirmed mammary carcinoma were included; 9 were client‐owned, whereas 1 was a research colony dog.

Methods

Retrospective study. Serum miRNA was evaluated by RNA deep‐sequencing (RNAseq) and digital droplet PCR (dPCR).Expression of candidate biomarkers miR‐18a, miR‐19b, miR‐29b, miR‐34c, miR‐122, miR‐125a, and miR‐181a was compared with clinical characteristics, including grade, metastasis, and survival.

Results

452 unique serum miRNAs were detected by RNAseq. Sixty‐five individual miRNAs were differentially expressed (>±1.5‐fold) and statistically significant between groups. Serum miR‐19b (P = .003) and miR‐125a (P < .001) were significantly higher in the mammary carcinoma group by dPCR. Both had high accuracy based on receiver operator characteristic area under the curve (0.930 for miR‐125a; 0.880 for miR‐19b). Circulating miR‐18a by RNAseq was significantly higher in mammary carcinoma dogs with histologic evidence of lymphatic invasion (P = 0.03). There was no significant association with any miRNA and survival or inflammatory status.

Conclusions and Clinical Importance

Circulating miRNAs are differentially expressed in dogs with mammary carcinoma. Serum miR‐19b and miR‐18a represent candidate biomarkers for diagnosis and prognosis, respectively.

Abnormal liver function tests associated with severe rhabdomyolysis

Rhabdomyolysis is a syndrome of skeletal muscle injury with release of cellular constituents such as potassium, phosphate, urate and intracellular proteins such as myoglobin into the circulation, which may cause complications including acute kidney injury, electrolyte disturbance and cardiac instability. Abnormal liver function tests are frequently observed in cases of severe rhabdomyolysis. Typically, there is an increase in serum aminotransferases, namely aspartate aminotransferase and alanine aminotransferase. This raises the question of liver injury and often triggers a pathway of investigation which may lead to a liver biopsy. However, muscle can also be a source of the increased aminotransferase activity. This review discusses the dilemma of finding abnormal liver function tests in the setting of muscle injury and the potential implications of such an association. It delves into some of the clinical and experimental evidence for correlating muscle injury to raised aminotransferases, and discusses pathophysiological mechanisms such as oxidative stress which may cause actual liver injury. Serum aminotransferases lack tissue specificity to allow clinicians to distinguish primary liver injury from muscle injury. This review also explores potential approaches to improve the accuracy of our diagnostic tools, so that excessive or unnecessary liver investigations can be avoided.

A Cross-Sectional Study of the Relationship between Serum Creatine Kinase and Liver Biochemistry in Patients with Rhabdomyolysis

Abnormal liver function tests are commonly observed with rhabdomyolysis, but the nature of this association is not fully defined. This study aims to determine the functional relationship between serum creatine kinase, as a marker of rhabdomyolysis severity, and liver biochemistry. We used linear regression to model the relationship between liver biochemistry and peak serum creatine kinase. A total of 528 patients with a median age of 74 years were included. The distribution of creatine kinase, bilirubin, alkaline phosphatase, alanine aminotransferase, and γ-glutamyl transferase were significantly skewed, and these variables were log-transformed prior to regression. There was a positive linear correlation between log-alanine aminotransferase and log-creatine kinase. In the multiple regression analysis, log-creatine kinase, age, acute kidney injury stage, and chronic liver disease were independently associated with log-alanine aminotransferase. This model explained 46% of the variance of log-alanine aminotransferase. We found no correlation between the log-creatine kinase and the log-bilirubin, log-alkaline phosphatase, or log-γ-glutamyl transferase. Serum alanine aminotransferase was not associated with inpatient mortality but a higher creatine kinase-alanine aminotransferase ratio was associated with lower odds of mortality. In conclusion, an isolated elevation in alanine aminotransferase can occur in rhabdomyolysis, and it may be possible to anticipate the level of increase based on the peak creatine kinase.

Acetaminophen Overdose as a Potential Risk Factor for Parkinson's Disease

Four complementary approaches were used to investigate acetaminophen overdose as a risk factor for Parkinson's disease (PD). Circulating microRNAs (miRNAs) serum profiles from acetaminophen-overdosed patients were compared with patients with terminal PD, revealing four shared miRNAs. Similarities were found among molecular structures of dopamine (DA), acetaminophen, and two known PD inducers indicating affinity for dopaminergic transport. Potential interactions between acetaminophen and the human DA transporter were confirmed by molecular docking modeling and binding free energy calculations. Thus, it is plausible that acetaminophen is taken up by the dopaminergic transport system into the substantia nigra (SN). A ChEMBL query identified proteins that are similarly targeted by DA and acetaminophen. Here, we highlight CYP3A4, present in the SN, a predominant metabolizer of acetaminophen into its toxic metabolite N-acetyl-p-benzoquinone imine and shown to be regulated in PD. Overall, based on our results, we hypothesize that overdosing of acetaminophen is a potential risk factor for parkinsonism.

Evaluation of the Relative Performance of Pancreas-Specific MicroRNAs in Rat Plasma as Biomarkers of Pancreas Injury

Drug-induced pancreatic injury (DIPI) has become linked in recent years to many commonly prescribed medications from several pharmacological classes. Diagnosis is currently most often focused on identification of acute pancreatitis and generally based on subjective clinical assessment and serum amylase and lipase enzymatic activity, which have been criticized as being insufficiently sensitive and specific. The lack of novel noninvasive biomarkers of DIPI can impede the advancement of drug candidates through nonclinical development and translation into clinical settings. Pancreas-specific microRNAs (miRNAs) are currently being evaluated as biomarkers of DIPI that may outperform and/or add value to the interpretation of amylase and lipase. To assess the relative performance of these novel miRNAs, a comprehensive evaluation was conducted to determine the sensitivity and specificity of detecting DIPI in rats. Four miRNAs were evaluated (miR-216a-5p, miR-216b-5p, miR-217-5p, and miR-375-3p) in plasma from 10 studies in which rats were treated with known pancreatic toxicants to assess sensitivity, and from 10 different studies in which toxicity was evident in tissues other than pancreas to assess specificity. The candidate miRNA biomarker performance was compared with amylase and lipase, and receiver operator characteristics (ROC) were determined. Analysis of ROCs demonstrated that all four miRNAs outperformed amylase and lipase in monitoring acute pancreatic injury defined as acinar cell degeneration/necrosis. Specifically, miR-217-5p had the highest performance among all biomarkers assessed. The increased sensitivity and specificity of these miRNAs support their use as biomarkers of DIPI, thereby adding value to the interpretation of amylase and lipase measurements in nonclinical studies. The potential for miRNAs to serve as translational biomarkers in the clinic for the monitoring of DIPI is also supported by this investigation.