A point-of-care paper-based fingerstick transaminase test: toward low-cost "lab-on-a-chip" technology for the developing world

Development of a µPAD for the point-of-care testing of serum glutamic oxaloacetic transaminase (SGOT)

A wax-patterned paper analytical device (µPAD) has been developed for point-of-care colourimetric testing of serum glutamic oxaloacetic transaminase (SGOT). The detection method was based on the transamination reaction of aspartate with α-ketoglutarate, leading to the formation of oxaloacetate which reacts with the reagent Fast Blue BB salt and forms a cavern pink colour. The intensity of the cavern pink colour grows as the concentration of SGOT increases. UV-visible spectroscopy was utilized to optimize reaction conditions, and the optimized reagents were dropped onto the wax-patterned paper. The coloured PADs, after the addition of SGOT, have been photographed, and a colour band has been generated to correlate the SGOT concentration visually. The images were used to calculate the intensity values using ImageJ software, which inturn was used to calculate the SGOT concentration. The PADs were also tested with serum samples, and SGOT spiked serum samples. The PAD could detect the SGOT concentration ranging from 5 to 200 U/L. The analysis yielded highly accurate results with less than 6% relative error compared to the clinical sample. This colourimetric test demonstrated exceptional selectivity in the presence of other biomolecules in the blood serum, with a detection limit of 2.77 U/L and a limit of quantification of 9.25 U/L. Additionally, a plasma separation membrane was integrated with the PAD to directly test SGOT from finger-prick blood samples.

Novel Assays to Solve the Clinical and Scientific Challenges of Chronic Hepatitis B

Chronic infection with Hepatitis B is a common, incurable, and deadly infection. Despite inexpensive laboratory tests for diagnosis and management that have been established for decades, the worldwide rate of diagnosis is only ∼10%, and ∼5% of people are under treatment. Novel assays have been developed to improve linkage to care by providing more flexible approaches to determine a patient's health status. Other assays have been established to better investigate intrahepatic host-virus interactions to support clinical trials for cure research. This review outlines the clinical and scientific challenges still to be solved and the upcoming methods used to address them.

A Paper-Based Photoelectrochemical Sensing Platform Based on In Situ Grown ZnO/ZnIn2S4 Heterojunctions onto Paper Fibers for Sensitively Detecting AFP

Nowadays, developing a cost-effective, easy-to-operate, and efficient signal amplification platform is of important to microfluidic paper-based analytical devices (μPAD) for end-use markets of point-of-care (POC) assay applications. Herein, an ultrasensitive, paper-based photoelectrochemical (PEC) bioassay platform is constructed by in situ grown ZnO/ZnIn2S4 heterojunctions onto paper fibers, which acted as photoactive signal amplification probes for enhancing the sensitivity of antibodies-based diagnostic assays, for the sensitive detection of alpha-fetoprotein (AFP) targets. The crystalline flake-like ZnIn2S4 composited with hexagonal nanorods (NRs) morphology of ZnO is an in situ grown, at the first time, onto cellulose fibers surface supported with Au nanoparticle (Au NP) modification to improve conductivity of the device working zone. The obtained composites on paper fibers are implemented as a flexible paper-based photoelectrode to realize remarkable performance of the fabricated μPAD, resulting from the enhanced PEC activity of heterojunctions with effective electron-hole pair separation for accelerating photoelectric conversion efficiency of the sensing process under light irradiation. Once the target AFP was introduced into the biosensing interface assistant, with a specific recognition interaction of AFP antibody, a drastically photocurrent response was generated, in view of the apparent steric effects. With the concentration increase of AFP targets, more immune conjugates could be confined onto the biosensing interface, eventually leading to the quantitative decrease of photocurrent intensity. Combined with an ingenious origami design and permitting the hydrophobic/hydrophilic conversion procedure in the bioassay process, the ultrasensitive PEC detection of AFP targets was realized. Under the optimized conditions, the level of AFP could be sensitively tracked by the prepared μPAD with a liner range from 0.1 to 100 ng mL-1 and limit of detection of 0.03 ng mL-1. This work provides a great potential application for highly selective and sensitive POC testing of AFP, and finally, developments for clinical disease diagnosis.

Development of a paper-based analytical device for the colourimetric detection of alanine transaminase and the application of deep learning for image analysis

A paper-based colourimetric assay for the detection of alanine transaminase has been developed. In the presence of alanine transaminase, 2,4-dinitrophenyl hydrazine changes to pyruvate hydrazone leading to a colour change from pale yellow to dark yellow. Reaction conditions were optimized using absorption spectroscopic studies. Hydrophobic patterns on the Whatman chromatographic paper were created by wax printing, and the reagents were drop cast at the reagent zone. On the paper device, the intensity of the yellow colour increases with ALT concentration in the range of 20-140 U/L in human serum. For the quantification of ALT, coloured images were captured using a digital camera and were processed with Image J software. The machine learning approach was also explored for the ALT analysis by training with colour images of the paper device and testing using a cross-validation procedure. The results obtained with real clinical samples on the paper device showed good accuracy of less than 5% relative error with the clinical lab results. Furthermore, the paper device shows high selectivity to ALT in the presence of various interfering species in blood serum with a sensitivity of 0.261 a.u/(U/L), a detection limit of 4.12 U/L, and precise results with an RSD of less than 7%. For the testing of whole blood, a plasma separation membrane was integrated with the patterned paper.

Key Enabling Technologies for Point-of-Care Diagnostics

A major trend in biomedical engineering is the development of reliable, self-contained point-of-care (POC) devices for diagnostics and in-field assays. The new generation of such platforms increasingly addresses the clinical and environmental needs. Moreover, they are becoming more and more integrated with everyday objects, such as smartphones, and their spread among unskilled common people, has the power to improve the quality of life, both in the developed world and in low-resource settings. The future success of these tools will depend on the integration of the relevant key enabling technologies on an industrial scale (microfluidics with microelectronics, highly sensitive detection methods and low-cost materials for easy-to-use tools). Here, recent advances and perspectives will be reviewed across the large spectrum of their applications.

Drug-induced liver injury: Do we know everything?

Interest in drug-induced liver injury (DILI) has dramatically increased over the past decade, and it has become a hot topic for clinicians, academics, pharmaceutical companies and regulatory bodies. By investigating the current state of the art, the latest scientific findings, controversies, and guidelines, this review will attempt to answer the question: Do we know everything? Since the first descriptions of hepatotoxicity over 70 years ago, more than 1000 drugs have been identified to date, however, much of our knowledge of diagnostic and pathophysiologic principles remains unchanged. Clinically ranging from asymptomatic transaminitis and acute or chronic hepatitis, to acute liver failure, DILI remains a leading causes of emergent liver transplant. The consumption of unregulated herbal and dietary supplements has introduced new challenges in epidemiological assessment and clinician management. As such, numerous registries have been created, including the United States Drug-Induced Liver Injury Network, to further our understanding of all aspects of DILI. The launch of LiverTox and other online hepatotoxicity resources has increased our awareness of DILI. In 2013, the first guidelines for the diagnosis and management of DILI, were offered by the Practice Parameters Committee of the American College of Gastroenterology, and along with the identification of risk factors and predictors of injury, novel mechanisms of injury, refined causality assessment tools, and targeted treatment options have come to define the current state of the art, however, gaps in our knowledge still undoubtedly remain.

Novel circulating- and imaging-based biomarkers to enhance the mechanistic understanding of human drug-induced liver injury

Liver safety biomarkers in current clinical practice are recognized to have certain shortcomings including their representation of general cell death and thus lacking in indicating the specific underlying mechanisms of injury. An informative panel of circulating- and imaging-based biomarkers, will allow a more complete understanding of the processes involved in the complex and multi-cellular disease of drug-induced liver injury; potentially preceding and therefore enabling prediction of disease progression as well as directing appropriate, existing or novel, therapeutic strategies. Several putative liver safety biomarkers are under investigation as discussed throughout this review, informing on a multitude of hepatocellular mechanisms including: early cell death (miR-122), necrosis (HMGB1, K18), apoptosis, (K18), inflammation (HMGB1), mitochondrial damage (GLDH, mtDNA), liver dysfunction (MRI, MSOT) and regeneration (CSF1). These biomarkers also hold translational value to provide important read across between in vitro-in vivo and clinical test systems. However, gaps in our knowledge remain requiring further focussed research and the ultimate qualification of key exploratory biomarkers. Relevance for patients: this novel multi-modal approach of assessing drug-induced liver injury could potentially enable better patient stratification and enhance treatment strategies. Ultimately, this could reduce unnecessary treatment, also decreasing hospital bed occupancy, whilst ensuring early and accurate identification of patients needing intervention.

Current and future directions in the treatment and prevention of drug-induced liver injury: a systematic review

While the pace of discovery of new agents, mechanisms and risk factors involved in drug-induced liver injury (DILI) remains brisk, advances in the treatment of acute DILI seems slow by comparison. In general, the key to treating suspected DILI is to stop using the drug prior to developing irreversible liver failure. However, predicting when to stop is an inexact science, and commonly used ALT monitoring is an ineffective strategy outside of clinical trials. The only specific antidote for acute DILI remains N-acetylcysteine (NAC) for acetaminophen poisoning, although NAC is proving to be beneficial in some cases of non-acetaminophen DILI in adults. Corticosteroids can be effective for DILI associated with autoimmune or systemic hypersensitivity features. Ursodeoxycholic acid, silymarin and glycyrrhizin have been used to treat DILI for decades, but success remains anecdotal. Bile acid washout regimens using cholestyramine appear to be more evidenced based, in particular for leflunomide toxicity. For drug-induced acute liver failure, the use of liver support systems is still investigational in the United States and emergency liver transplant remains limited by its availability. Primary prevention appears to be the key to avoiding DILI and the need for acute treatment. Pharmacogenomics, including human leukocyte antigen genotyping and the discovery of specific DILI biomarkers offers significant promise for the future. This article describes and summarizes the numerous and diverse treatment and prevention modalities that are currently available to manage DILI.

The Art and Science of Diagnosing and Managing Drug-induced Liver Injury in 2015 and Beyond

Drug-induced liver injury (DILI) remains a leading reason why new compounds are dropped from further study or are the subject of product warnings and regulatory actions. Hy's Law of drug-induced hepatocellular jaundice causing a case-fatality rate or need for transplant of 10% or higher has been validated in several large national registries, including the ongoing, prospective U.S. Drug-Induced Liver Injury Network. It serves as the basis for stopping rules in clinical trials and in clinical practice. Because DILI can mimic all known causes of acute and chronic liver disease, establishing causality can be difficult. Histopathologic findings are often nonspecific and rarely, if ever, considered pathognomonic. A daily drug dose >50-100 mg is more likely to be hepatotoxic than does <10 mg, especially if the compound is highly lipophilic or undergoes extensive hepatic metabolism. The quest for a predictive biomarker to replace alanine aminotransferase is ongoing. Markers of necrosis and apoptosis such as microRNA-122 and keratin 18 may prove useful in identifying patients at risk for severe injury when they initially present with a suspected acetaminophen overdose. Although a number of drugs causing idiosyncratic DILI have HLA associations that may allow for pre-prescription testing to prevent hepatotoxicity, the cost and relatively low frequency of injury among affected patients limit the current usefulness of such genome-wide association studies. Alanine aminotransferase monitoring is often recommended but has rarely been shown to be an effective method to prevent serious DILI. Guidelines on the diagnosis and management of DILI have recently been published, although specific therapies remain limited. The LiverTox Web site has been introduced as an interactive online virtual textbook that makes the latest information on more than 650 agents available to clinicians, regulators, and drug developers alike.

Performance of an Optimized Paper-Based Test for Rapid Visual Measurement of Alanine Aminotransferase (ALT) in Fingerstick and Venipuncture Samples

Background

A paper-based, multiplexed, microfluidic assay has been developed to visually measure alanine aminotransferase (ALT) in a fingerstick sample, generating rapid, semi-quantitative results. Prior studies indicated a need for improved accuracy; the device was subsequently optimized using an FDA-approved automated platform (Abaxis Piccolo Xpress) as a comparator. Here, we evaluated the performance of the optimized paper test for measurement of ALT in fingerstick blood and serum, as compared to Abaxis and Roche/Hitachi platforms. To evaluate feasibility of remote results interpretation, we also compared reading cell phone camera images of completed tests to reading the device in real time.

Methods

96 ambulatory patients with varied baseline ALT concentration underwent fingerstick testing using the paper device; cell phone images of completed devices were taken and texted to a blinded off-site reader. Venipuncture serum was obtained from 93/96 participants for routine clinical testing (Roche/Hitachi); subsequently, 88/93 serum samples were captured and applied to paper and Abaxis platforms. Paper test and reference standard results were compared by Bland-Altman analysis.

Findings

For serum, there was excellent agreement between paper test and Abaxis results, with negligible bias (+4.5 U/L). Abaxis results were systematically 8.6% lower than Roche/Hitachi results. ALT values in fingerstick samples tested on paper were systematically lower than values in paired serum tested on paper (bias -23.6 U/L) or Abaxis (bias -18.4 U/L); a correction factor was developed for the paper device to match fingerstick blood to serum. Visual reads of cell phone images closely matched reads made in real time (bias +5.5 U/L).

Conclusions

The paper ALT test is highly accurate for serum testing, matching the reference method against which it was optimized better than the reference methods matched each other. A systematic difference exists between ALT values in fingerstick and paired serum samples, and can be addressed by application of a correction factor to fingerstick values. Remote reading of this device is feasible.

Drug-induced liver injury: what was new in 2013?

INTRODUCTION

The year 2013 continued to highlight numerous aspects of drug-induced liver injury (DILI), with new information communicated via > 1500 publications. New reports of DILI were described and FDA warnings and alerts were issued for a number of products, emphasizing the risks related to hepatotoxicity.

AREAS COVERED

We provide a summary of the year's published reports of new causes of DILI, along with reviews and reports of established hepatotoxins, new and expanded DILI registries and the continuing emphasis placed on genetic and other risk factors. Several new analyses of data generated from the US DILI Network are included.

EXPERT OPINION

The clinical usefulness of pharmacogenetic testing remains to be determined; the number of patients who must be tested is large and the overall risk of DILI is quite small. The role that dose and hepatic metabolism play in causing idiosyncratic DILI was reviewed; daily doses > 50 - 100 mg of medications with high lipophilicity appear to be most predictive of severe DILI, but not in all cases. Restricting access to paracetamol in certain parts of the UK continues to demonstrate a successful reduction in the number of acute liver failure cases and patients listed for liver transplant.

Microfluidic chip-based technologies: emerging platforms for cancer diagnosis

The development of early and personalized diagnostic protocols is considered the most promising avenue to decrease mortality from cancer and improve outcome. The emerging microfluidic-based analyzing platforms hold high promises to fulfill high-throughput and high-precision screening with reduced equipment cost and low analysis time, as compared to traditional bulky counterparts in bench-top laboratories. This article overviewed the potential applications of microfluidic technologies for detection and monitoring of cancer through nucleic acid and protein biomarker analysis. The implications of the technologies in cancer cytology that can provide functional personalized diagnosis were highlighted. Finally, the future niches for using microfluidic-based systems in tumor screening were briefly discussed.