Intestinal injury in paracetamol overdose (ATOM-8)

BACKGROUND AND AIM

Paracetamol, a widely used medication, is known for its delayed hepatotoxicity in cases of overdose. However, the potential for intestinal toxicity resulting from very high paracetamol concentrations during absorption is not well explored. This study aims to investigate the presence of intestinal toxicity and its correlation with observations in early and late paracetamol toxicity.

METHODS

Serial samples of 30 patients with acute paracetamol overdose (> 10 g or 200 mg/kg) were prospectively tested. Markers of enterocyte damage, including plasma intestinal fatty acid binding protein (IFABP) and selected gut-related microRNAs (miR-21, miR-122, miR-194, and miR-215), were analyzed. Sub-analysis was performed on patients presenting with hyperlactatemia defined as a lactate greater than 2 mmol/L within 12 h post ingestion.

RESULTS

In paracetamol overdose patients, median plasma IFABP was significantly elevated compared with healthy controls (720 μg/L [interquartile range, IQR, 533-1644] vs 270 μg/L [IQR 153-558], P < 0.001). Four patients had early hyperlactatemia and had significantly higher median plasma IFABP compared with those without early hyperlactatemia (3028 μg/L [IQR 1399-3556] vs 574 μg/L [IQR 526-943], P = 0.007). Furthermore, two microRNAs (miR-122 and miR-215) were downregulated in early hyperlactatemia (P = 0.019 and P = 0.006, respectively). Plasma IFABP concentrations correlated with paracetamol concentration (Spearman's r = 0.55) and lactate (r = 0.60).

CONCLUSIONS

Paracetamol overdose causes concentration-related intestinal toxicity, and this is a possible explanation for the early hyperlactatemia syndrome. Intestinal toxicity has potential impacts on pharmacokinetics of other agents ingested and on the evolution of hepatotoxicity. Further studies are required to explore the mechanisms and prognostic implications of intestinal toxicity.

Investigating the role of lipid genes in liver disease using fatty liver models of alcohol and high fat in zebrafish (Danio rerio)

BACKGROUND

Accumulation of lipid in the liver is the first hallmark of both alcohol-related liver disease (ALD) and non-alcohol-related fatty liver disease (NAFLD). Recent studies indicate that specific mutations in lipid genes confer risk and might influence disease progression to irreversible liver cirrhosis. This study aimed to understand the function/s of lipid risk genes driving disease development in zebrafish genetic models of alcohol-related and non-alcohol-related fatty liver.

METHODS

We used zebrafish larvae to investigate the effect of alcohol and high fat to model fatty liver and tested the utility of this model to study lipid risk gene functions. CRISPR/Cas9 gene editing was used to create knockdowns in 5 days post-fertilisation zebrafish larvae for the available orthologs of human cirrhosis risk genes (pnpla3, faf2, tm6sf2). To establish fatty liver models, larvae were exposed to ethanol and a high-fat diet (HFD) consisting of chicken egg yolk. Changes in morphology (imaging), survival, liver injury (biochemical tests, histopathology), gene expression (qPCR) and lipid accumulation (dye-specific live imaging) were analysed across treatment groups to test the functions of these genes.

RESULTS

Exposure of 5-day post-fertilisation (dpf) WT larvae to 2% ethanol or HFD for 48 h developed measurable hepatic steatosis. CRISPR-Cas9 genome editing depleted pnpla3, faf2 and tm6sf2 gene expression in these CRISPR knockdown larvae (crispants). Depletion significantly increased the effects of ethanol and HFD toxicity by increasing hepatic steatosis and hepatic neutrophil recruitment ≥2-fold in all three crispants. Furthermore, ethanol or HFD exposure significantly altered the expression of genes associated with ethanol metabolism (cyp2y3) and lipid metabolism-related gene expression, including atgl (triglyceride hydrolysis), axox1, echs1 (fatty acid β-oxidation), fabp10a (transport), hmgcra (metabolism), notch1 (signalling) and srebp1 (lipid synthesis), in all three pnpla3, faf2 and tm6sf2 crispants. Nile Red staining in all three crispants revealed significantly increased lipid droplet size and triglyceride accumulation in the livers following exposure to ethanol or HFD.

CONCLUSIONS

We identified roles for pnpla3, faf2 and tm6sf2 genes in triglyceride accumulation and fatty acid oxidation pathways in a zebrafish larvae model of fatty liver.

MicroRNAs Signature Panel Identifies Heavy Drinkers with Alcohol-Associated Cirrhosis from Heavy Drinkers without Liver Injury

Background: Alcohol-associated liver disease (ALD) is the most common disorder of prolonged drinking. Mechanisms underlying cirrhosis in such patients remain unclear. MicroRNAs play regulatory role in several diseases, are affected by alcohol and may be important players in alcohol use disorders, such as cirrhosis. Methods: We investigated serum samples from heavy chronic alcohol users (80 g/day (male) and 50 g/day (female) for ≥10 years) that were available from our previously reported GenomALC study. A subset of GenomALC drinkers with liver cirrhosis (cases, n = 24) and those without significant liver disease (drinking controls, n = 23) were included. Global microRNA profiling was performed using high-throughput real-time quantitative PCR to identify the microRNA signatures associated with cirrhosis. Ingenuity Pathway Analysis (IPA) software was utilized to identify target mRNAs of significantly altered microRNAs, and molecular pathways were analysed. Identified microRNAs were analysed for correlation with traditional liver disease biomarkers and risk gene variants previously reported from GenomALC genome-wide association study. Results: The expression of 21 microRNAs was significantly downregulated in cases compared to drinking controls (p < 0.05, ∆∆Ct > 1.5-fold). Seven microRNAs (miR-16, miR-19a, miR-27a, miR-29b, miR-101, miR-130a, and miR-191) had a highly significant correlation (p < 0.001) with INR, bilirubin and MELD score. Three microRNAs (miR-27a, miR-130a and miR-191) significantly predicted cases with AUC-ROC 0.8, 0.78 and 0.85, respectively (p < 0.020); however, INR performed best (0.97, p < 0.001). A different set of six microRNAs (miR-19a, miR-26a, miR-101, miR-151-3p, miR-221, and miR-301) showed positive correlation (ranging from 0.32 to 0.51, p < 0.05) with rs10433937:HSD17B13 gene variant, associated with the risk of cirrhosis. IPA analysis revealed mRNA targets of the significantly altered microRNAs associated with cell death/necrosis, fibrosis and increased steatosis, particularly triglyceride metabolism. Conclusions: MicroRNA signatures in drinkers distinguished those with liver cirrhosis from drinkers without liver disease. We identified mRNA targets in liver functions that were enriched for disease pathogenesis pathways.

Relationship Between Alcohol Co-Ingestion and Clinical Outcome in Pesticide Self-Poisoning: A Systematic Review and Meta-Analysis

AIM

Alcohol is a commonly co-ingested compound during self-poisoning with pesticides. Clinical experiences suggest alcohol co-ingestion (or withdrawal) makes patient management more difficult after self-poisoning and may contribute to poor clinical outcomes. We aimed to systematically review the world literature to explore the relationship between alcohol co-ingestion and outcome in pesticide self-poisoning.

METHODS

We searched 13 electronic databases and Google scholar, conducted citation searching and a review of reference lists to find studies which investigated the relationship of alcohol with clinical outcome of pesticide self-poisoning in different countries. Thirteen studies, including 11 case series/reports and two cohort studies were considered for inclusion.

RESULTS

Meta-analysis showed that alcohol co-ingestion in pesticide self-poisoning was associated with increased risk of death [odds ratio (OR) 4.9, 95% confidence interval (CI) 2.9-8.2 P<0.0001] and that alcohol co-ingested group required intubation eight times more often than non-co-ingested group in organophosphorus insecticide self-poisoning (OR 8.0, 95% CI 4.9-13.0 P<0.0001). Cases who co-ingested alcohol were older than non-alcohol group in two studies. One cohort study demonstrated that alcohol co-ingestion was associated with larger pesticide ingestions but did not itself affect the outcome.

CONCLUSIONS

This systematic review indicates that alcohol co-ingestion may worsen clinical outcome in pesticide self-poisoning.

Urinary microRNAs as non-invasive biomarkers for toxic acute kidney injury in humans

MicroRNAs in biofluids are potential biomarkers for detecting kidney and other organ injuries. We profiled microRNAs in urine samples from patients with Russell's viper envenoming or acute self-poisoning following paraquat, glyphosate, or oxalic acid [with and without acute kidney injury (AKI)] and on healthy controls. Discovery analysis profiled for 754 microRNAs using TaqMan OpenArray qPCR with three patients per group (12 samples in each toxic agent). From these, 53 microRNAs were selected and validated in a larger cohort of patients (Russell's viper envenoming = 53, paraquat = 51, glyphosate = 51, oxalic acid = 40) and 27 healthy controls. Urinary microRNAs had significantly higher expression in patients poisoned/envenomed by different nephrotoxic agents in both discovery and validation cohorts. Seven microRNAs discriminated severe AKI patients from no AKI for all four nephrotoxic agents. Four microRNAs (miR-30a-3p, miR-30a-5p, miR-92a, and miR-204) had > 17 fold change (p < 0.0001) and receiver operator characteristics area-under-curve (ROC-AUC) > 0.72. Pathway analysis of target mRNAs of these differentially expressed microRNAs showed association with the regulation of different nephrotoxic signaling pathways. In conclusion, human urinary microRNAs could identify toxic AKI early after acute injury. These urinary microRNAs have potential clinical application as early non-invasive diagnostic AKI biomarkers.

MicroRNAs in toxic acute kidney injury: Systematic scoping review of the current status

Acute kidney injury induced by nephrotoxic agents is common, increasing in incidence and associated with considerable morbidity and mortality in developing countries. MicroRNAs are stable biomarkers that can be detected in extracellular fluids. This systematic scoping review aims to describe published research on urinary and circulating microRNAs in toxic acute kidney injury in both animal and human studies. We conducted a literature search, using EMBASE and Medline, for articles on urinary and circulating microRNA in nephrotoxic injuries to February 2020. A total of 21 publications studied acute kidney injury from 12 different toxic agents. Cisplatin was the most common nephrotoxic agent (n = 10), followed by antibiotics (n = 4). There were no randomized controlled trials. An increase in urinary miR-218 predicted acute kidney injury in six different studies, suggesting it is a promising biomarker for nephrotoxin-induced acute kidney injury. There were many factors that prevented a more comprehensive synthesis of microRNA performance including highly variable models, no consistent protocols for RNA isolation, cDNA synthesis and PCR amplification, and variability in normalization methods using reference controls. In conclusion, while microRNAs are promising biomarkers to study nephrotoxic acute kidney injury, the replication of most positive findings is not assessable due to deficient reporting of negative outcomes. A very narrow range of poisons have been studied, and more human data are required. In particular, further studies are needed on the most important causes of nephrotoxic injury, such as pesticides, chemicals, snake envenoming, and medicines other than aminoglycosides and cisplatin.

Urinary versus serum microRNAs in human oxalic acid poisoning: Contrasting signals and performance

MicroRNAs are key regulators of the normal kidney function and development, and altered in acute kidney injury (AKI). However, there is a lack of studies comparing serum and urine miRNA expression in toxic AKI in humans. We aimed to compare the global signature of urinary and serum microRNAs, with and without kidney injury, after human oxalic acid poisoning. We profiled urinary microRNAs in patients who ingested oxalic acid and developed no injury (No AKI n = 3), moderate injury (AKIN2 n = 3) or severe injury (AKIN3 n = 3) and healthy controls (n = 3). We validated a signature of 30 urinary microRNAs identified in the discovery profiling, in a second cohort of individuals exposed to oxalic acid (No AKI n = 15, AKIN2 n=11 & AKIN3 n= 18) and healthy controls (n=-27) and we compared the results with previously published serum data. Global profiling in toxic AKI patients showed a higher expression of urinary microRNAs and lower expression of serum microRNAs. Most urine microRNA in the validation cohort were significantly upregulated (25/30, fold change >2.8 and p < 0.05) in AKIN2/3 patients compared to No AKI. Four urinary microRNAs (miR-191, miR-19b, miR-20a and miR-30b) had good diagnostic performance (AUC greater than 0.8) to predict AKIN2/3 between 4-8 hours post ingestion. Poisoning irrespective of AKI led to significantly lower expression of many microRNAs in serum but relatively few changes in urinary miRNA expression. In conclusion, urinary microRNA signature provides a stronger measure of AKI in oxalic acid poisoning compared to serum microRNA. Kidney injury has the greatest impact on urinary microRNA, while poisoning itself was better reflected in serum miRNA. Plasma and urinary microRNAs signatures provide complementary information in toxic kidney injury.

Cellular injury leading to oxidative stress in acute poisoning with potassium permanganate/oxalic acid, paraquat, and glyphosate surfactant herbicide

Previous studies on human acute kidney injury (AKI) following poisoning with potassium permanganate/oxalic acid (KMnO4/H2C2O4), paraquat, and glyphosate surfactant herbicide (GPSH) have shown rapid and large increases in serum creatinine (sCr) that cannot be entirely explained by direct nephrotoxicity. One plausible mechanism for a rapid increase in sCr is oxidative stress. Thus, we aimed to explore biomarkers of oxidative stress, cellular injury, and their relationship with sCr, after acute KMnO4/H2C2O4, paraquat, and GPSH poisonings. Serum biomarkers [sCr, creatine (sCn), cystatin C (sCysC)] and urinary biomarkers [cytochrome C (CytoC), 8-isoprostane (8-IsoPs)] were evaluated in 105 patients [H2C2O4/KMnO4 (N = 57), paraquat, (N = 21), GPSH (N = 27)] recruited to a multicenter cohort study. We used area under the receiver operating characteristics curve (AUC-ROC) to quantify the extent of prediction of moderate to severe AKI (acute kidney injury network stage 2/3 (AKIN2/3)). Patients with AKIN2/3 showed increased levels of CytoC. Early high CytoC predicted AKIN2/3 in poisoning with KMnO4/H2C2O4 (AUC-ROC4-8h: 0.81), paraquat (AUC-ROC4-8h: 1.00), and GPSH (AUC-ROC4-8h: 0.91). 8-Isoprostane levels were not significantly elevated. Reduced sCn and increased sCr/sCn ratios were observed for 48 h post KMnO4/H2C2O4 ingestion. Paraquat exhibited a similar pattern (N = 11), however only 3 were included in our study. Increased CytoC suggests there is mitochondrial injury coupled with energy depletion. The increased sCr within 24 h could be due to increased conversion of cellular creatine to creatinine during the process of adenosine triphosphate (ATP) generation and then efflux from cells. Later increases of sCr are more likely to represent a true decrease in kidney function.

Circulating human microRNA biomarkers of oxalic acid-induced acute kidney injury

Oxalic acid-induced nephrotoxicity and acute kidney injury result from formation of calcium oxalate crystals. Oxalic acid-induced acute kidney injury is a significant problem in many parts of the world. Circulating biomarkers that can accurately and reproducibly detect acute kidney injury are highly desirable. We used a high sensitivity discovery platform to identify signature microRNAs to distinguish healthy individuals never exposed to oxalic acid (n = 4) from those who were exposed to oxalic acid but had no injury (NOAKI; n = 4), moderate injury (AKIN2; n = 4) or severe injury (AKIN3; n = 4). Longitudinal analyses identified 4-8 h post-ingestion as the best time to detect AKIN2/3. We validated a signature of 53 microRNAs identified in the discovery, in a second cohort of individuals exposed to oxalic acid (NOAKI = 11, AKIN2 = 8 and AKIN3 = 18) and healthy controls (n = 19). Thirteen microRNAs were significantly downregulated in acute kidney injury patients compared to NOAKI within 8-h post-ingestion. Five microRNAs (miR-20a, miR-92a, miR-93, miR-195, miR-451) had a highly significant correlation with normalized urinary albumin, serum creatinine at 24 h and creatinine clearance. Logistic regression of these microRNAs had AUC-ROC of 0.85 predicting AKIN2/3 and discriminated patients from healthy controls (AUC-ROC = 0.93). mRNA targets of these microRNAs identified oxidative stress pathways of nephrotoxicity in proximal tubule and glomeruli nephrotoxicity. In conclusion, the downregulation of multiple circulating microRNAs in patients correlated with the severity of oxalic acid-induced acute kidney injury. A set of microRNAs (miR-20a, miR-92a, miR-93, miR-195, miR-451) could be promising biomarkers for early detection of oxalic acid-induced acute kidney injury.

Comparison of Serum Cystatin C and Creatinine Levels among Individuals with Persisting Proteinuria in Farming Communities of Rural Sri Lanka

Background

Chronic kidney disease of uncertain aetiology (CKDu) is one of the major health concerns among agricultural communities in Sri Lanka. Individuals involved in severe agricultural works for their livelihood are highly vulnerable for this disease and patients have been detected with persisting proteinuria at community-level screening. The current study was designed to evaluate the diagnosis of two functional markers of kidney damage using individuals with persisting proteinuria as the baseline.

Methods

One hundred and fifty hard-working agricultural farmers from high-prevalence area for CKDu (Madawachchiya) were screened three times for proteinuria; 66 proteinuric and 21 non-proteinuric were identified as the baseline classification. Selected individuals were analysed further for creatinine, protein and cystatin C in urine and creatinine, cystatin C in serum. Urine protein-to-creatinine ratio (UP/UC) was calculated.

Results

Based on creatinine and cystatin C cut-off levels in serum, individuals were classified as high or normal. Diagnosis of two functional markers (creatinine and cystatin C) were evaluated using receiver operating characteristic (ROC) curve and in terms of sensitivity and specificity using UP/UC as the baseline. Creatinine and cystatin C-based eGFR (estimated Glomerular filtration rate) levels were calculated, and Pearson’s correlation coefficient was determined between different eGFR measurements using UP/UC. Mean (SD) UP/UC ratio, serum creatinine, and serum cystatin C levels of the proteinuric subjects were 129.0 (18.4) mg/mmol, 1.35 (0.39) mg/dL, 1.69 (0.58) mg/L. For non-proteniuric individuals, the results were found to be 14.4 (2.28), 1.22 (0.40) mg/dL, 0.82 (0.25) mg/L. The ROC analysis showed excellent accuracy in using cystatin C for identifying proteinuric patients than creatinine area under the curve (AUC): 0.9675, P < 0.001). Cut-off points were identified as 1.015 mg/dL for serum creatinine and 0.930mg/L for cystatin C. Furthermore, cystatin C based Hoek formula showed the better correlation (0.635, P < 0.001) with UP/UC compared with creatinine based modification of diet in renal disease (MDRD) formula.

Conclusion

The study showed elevated serum cystatin C in patients with persisting proteinuria compared with non-responding serum creatinine. Moreover, cystatin C-based eGFR equations were more accurate to determine the kidney function than serum creatinine in proteinuric patients who are vulnerable for CKDu in high-prevalence areas.

Albuminuria and other renal damage biomarkers detect acute kidney injury soon after acute ingestion of oxalic acid and potassium permanganate

BACKGROUND

Deliberate self-poisoning with a combination washing powder containing oxalic acid (H₂C₂O₄) and potassium permanganate (KMnO₄) is a significant medical problem in the Southern Province of Sri Lanka. Acute kidney injury (AKI) is a frequent consequence. Biomarkers for early diagnosis of nephrotoxicity could guide appropriate supportive therapies.

METHODS

We investigated the performance of three serum biomarkers and nine urinary biomarkers in 85 patients in an ongoing multicenter prospective cohort study in Sri Lanka exploring AKI following poisoning.

RESULTS

Sixty two (62/85, 73%) patients developed AKI (acute kidney injury network, AKIN, criteria). Early and rapid increases in serum creatinine (sCr) peaking on day 3 were observed in AKIN stage 2 and 3 patients. In these patients, serum cystatin C (sCysC) rose more gradually but also peaked on day 3. Biomarker concentrations (normalized to urinary creatinine) of urinary albumin (uAlbumin), clusterin (uClusterin), beta-2-microglobulin (uB2M), osteopontin (uOPN), neutrophil gelatinase-associated lipocalin (uNGAL) and kidney injury molecule-1 (uKIM-1) in the AKIN2/3 group increased above the 95th centile concentration of the healthy population. Within 8 h of ingestion, the normalized uAlbumin and sCysC predicted AKIN2/3 with respective area under receiver operating characteristic curve, AUC-ROC values, of 0.94 (95% CI 0.86-1.00) and 0.85 (95% CI 0.76-0.95).

CONCLUSIONS

Urinary albumin was the best performing AKI biomarker following ingestion of H₂C₂O₄/KMnO₄. This may reflect glomerular injury and/or proximal tubular injury. The urinary albumin concentrations observed in this study could generally be detected using albumin specific dipstick methods, easily available even in resource poor settings.

Serum creatinine and cystatin C provide conflicting evidence of acute kidney injury following acute ingestion of potassium permanganate and oxalic acid

AIM

Acute kidney injury (AKI) is common following deliberate self-poisoning with a combination washing powder containing oxalic acid (H₂C₂O₄) and potassium permanganate (KMnO₄). Early and rapid increases in serum creatinine (sCr) follow severe poisoning. We investigated the relationship of these increases with direct nephrotoxicity in an ongoing multicenter prospective cohort study in Sri Lanka exploring AKI following poisoning.

METHODS

Multiple measures of change in kidney function were evaluated in 48 consenting patients who had serial sCr and serum cystatin C (sCysC) data available.

RESULTS

Thirty-eight (38/48, 79%) patients developed AKI (AKIN criteria). Twenty-eight (58%) had AKIN stage 2 or 3. Initial increases in urine creatinine (uCr) excretion were followed by a substantial loss of renal function. The AKIN stage 2 and 3 (AKIN2/3) group had very rapid rises in sCr (a median of 118% at 24 h and by 400% at 72 h post ingestion). We excluded the possibility that the rapid rise resulted from the assay used or muscle damage. In contrast, the average sCysC increase was 65% by 72 h.

CONCLUSIONS

In most AKI, sCysC increases to the same extent but more rapidly than sCr, as sCysC has a shorter half-life. This suggests either a reduction in Cystatin C production or, conversely, that the rapid early rise of sCr results from increased production of creatine and creatinine to meet energy demands following severe oxidative stress mediated by H₂C₂O₄ and KMnO₄. Increased early creatinine excretion supports the latter explanation, since creatinine excretion usually decreases transiently in AKIN2/3 from other causes.

Performance of the 20-minute whole blood clotting test in detecting venom induced consumption coagulopathy from Russell's viper (Daboia russelii) bites

The 20-minute whole blood clotting test (WBCT20) is used as a bedside diagnostic test for coagulopathic snake envenoming. We aimed to assess the performance of the WBCT20 in diagnosis of venom induced consumption coagulopathy (VICC) in Russell's viper envenoming. Adult patients admitted with suspected snake bites were recruited from two hospitals. WBCT20 and prothrombin time (PT) test were performed on admission. WBCT20 was done by trained clinical research assistants using 1 ml whole blood in a 5 ml borosilicate glass tube with a 10 mm internal diameter. The PT was measured by a semi-automated coagulation system and international normalised ratio (INR) calculated. VICC was defined as present if the INR was >1.4. The diagnostic utility of WBCT20 was determined by calculating the sensitivity and specificity of the WBCT20 on admission for detecting VICC. There were 987 snake bites where both WBCT20 and PT were done on admission samples. This included 79 patients (8 %) with VICC. The WBCT20 was positive in 65/79 patients with VICC (sensitivity 82 %; 95 % confidence interval [CI]: 72-90 %) and was falsely positive in 13/908 with no coagulopathy. The WBCT20 was negative in 895/908 snake bites with no coagulopathy (specificity: 98 % 95 % CI: 97-99 %) and was falsely negative in 14/79 with VICC. Using trained clinical staff, the WBCT20 test had a relatively good sensitivity for the detection of VICC, but still missed almost one fifth of cases where antivenom was potentially indicated.

Mechanism-specific injury biomarkers predict nephrotoxicity early following glyphosate surfactant herbicide (GPSH) poisoning

Acute kidney injury (AKI) is common following glyphosate surfactant herbicide (GPSH) self-poisoning. Serum creatinine (sCr) is the most widely used renal biomarker for diagnosis of AKI although a recent study in rats suggested that urinary kidney injury molecule-1 predicted AKI earlier and better after GPSH-induced nephrotoxicity. We explored the utility of a panel of biomarkers to diagnose GPSH-induced nephrotoxicity in humans. In a prospective multi-centre observational study, serial urine and blood samples were collected until discharge and at follow-up. The diagnostic performance of each biomarker at various time points was assessed. AKI was diagnosed using the Acute Kidney Injury Network (AKIN) definitions. The added value of each biomarker to sCr to diagnose AKI was assessed by the integrated discrimination improvement (IDI) metric. Of 90 symptomatic patients, 51% developed AKI and 5 patients who developed AKIN≥2 died. Increased sCr at 8 and 16h predicted moderate to severe AKI and death. None of the 10 urinary biomarkers tested increased above normal range in patients who did not develop AKI or had mild AKI (AKIN1); most of these patients also had only minor clinical toxicity. Absolute concentrations of serum and urinary cystatin C, urinary interleukin-18 (IL-18), Cytochrome C (CytoC) and NGAL increased many fold within 8h in patients who developed AKIN≥2. Maximum 8 and 16h concentrations of these biomarkers showed an excellent diagnostic performance (AUC-ROC ≥0.8) to diagnose AKIN≥2. However, of these biomarkers only uCytoC added value to sCr to diagnose AKI when assessed by IDI metrics. GPSH-induced nephrotoxicity can be diagnosed within 24h by sCr. Increases in uCytoC and uIL-18 confirm GPSH-induces apoptosis and causes mitochondrial toxicity. Use of these biomarkers may help to identify mechanism specific targeted therapies for GPSH nephrotoxicity in clinical trials.

A bedside test for methemoglobinemia, Sri Lanka

Problem

Propanil is an aniline herbicide that is widely used for rice cultivation, but is also used for self-poisoning. Toxicity from propanil is largely due to methemoglobinemia. In resource-poor settings, the capacity to determine methemoglobin concentration is insufficient and prevents effective case management, which results in increased deaths from propanil poisoning.

Approach

Blood with a methemoglobin concentration greater than 15% of total haemoglobin levels appears brownish in colour. We introduced a colour reference chart that can be used to semiquantitatively determine methemoglobinemia. Each ward in three rural hospitals received a chart. Ward staff, medical officers and trainee doctors were given a presentation describing the test method and how it should be used with the relevant national treatment guidelines.

Local setting

In three rural hospitals in Sri Lanka, 401 patients were admitted with a diagnosis of propanil poisoning before the introduction of this test (2003–2007) and 262 patients after it was introduced (2008–2014), 46 of 663 patients died.

Relevant changes

The chart can be freely produced with any good-quality colour printer. In three rural hospitals, deaths from propanil poisoning fell from 10% of those admitted with this diagnosis in 2003–2007 (38/401) to 3% (8/262) in 2008–2014 and the use of methylene blue increased from 10% (13/136) to 55% (59/107) over this period.

Lessons learnt

This simple bedside test was associated with increased use of the first line treatment for propanil poisoning and improved survival. In 2011, the test was included in the national guidelines for the management of propanil poisoning.

Mechanisms underlying early rapid increases in creatinine in paraquat poisoning

Background

Acute kidney injury (AKI) is common after severe paraquat poisoning and usually heralds a fatal outcome. The rapid large increases in serum creatinine (Cr) exceed that which can be explained by creatinine kinetics based on loss of glomerular filtration rate (GFR).

Methods and Findings

This prospective multi-centre study compared the kinetics of two surrogate markers of GFR, serum creatinine and serum cystatin C (CysC), following paraquat poisoning to understand and assess renal functional loss after paraquat poisoning. Sixty-six acute paraquat poisoning patients admitted to medical units of five hospitals were included. Relative changes in creatinine and CysC were monitored in serial blood and urine samples, and influences of non-renal factors were also studied.

Results

Forty-eight of 66 patients developed AKI (AKIN criteria), with 37 (56%) developing moderate to severe AKI (AKIN stage 2 or 3). The 37 patients showed rapid increases in creatinine of >100% within 24 hours, >200% within 48 hours and >300% by 72 hours and 17 of the 37 died. CysC concentration increased by 50% at 24 hours in the same 37 patients and then remained constant. The creatinine/CysC ratio increased 8 fold over 72 hours. There was a modest fall in urinary creatinine and serum/urine creatinine ratios and a moderate increase in urinary paraquat during first three days.

Conclusion

Loss of renal function contributes modestly to the large increases in creatinine following paraquat poisoning. The rapid rise in serum creatinine most probably represents increased production of creatine and creatinine to meet the energy demand following severe oxidative stress. Minor contributions include increased cyclisation of creatine to creatinine because of acidosis and competitive or non-competitive inhibition of creatinine secretion. Creatinine is not a good marker of renal functional loss after paraquat poisoning and renal injury should be evaluated using more specific biomarkers of renal injury.

Method of stabilizing blood for the determination of methemoglobin

Methemoglobin (MetHb) is a significant clinical problem for some poisonings. Its measurement is a problem as both formation and reduction of MetHb can occur even after sampling with time. The objective of this study was to discover a method to stabilize the blood samples for the determination of MetHb. First, hemolysates were prepared by diluting the MetHb blood samples with phosphate buffers under different pH values. The samples were stored at 4-8 °C and a day-to-day variability in the amount of MetHb was determined using the method described by Evelyn and Malloy. The results show that there is a significantchange in the amount of MetHbstored in both KH2PO4/Na2HPO4 and KH2PO4/Na2HPO4 .2H2O buffer solutions at pH of 6.7 and 6.9. Buffer solution containing phosphate composition of KH2PO4/Na2HPO4 ·2H2O (pH=7.0) gives relatively stable values for MetHb during the storage and the amount of MetHb samples in the buffer solution retain constant up to 9 days. Therefore, stabilized MetHb blood samples can be prepared using KH2PO4/Na2HPO4 ·2H2O buffer solution (pH=7) with non-ionic detergent and the samples can be stored for several days at 4-8 °C.

A modified low-cost colorimetric method for paracetamol (acetaminophen) measurement in plasma

BACKGROUND

Despite a significant increase in the number of patients with paracetamol poisoning in the developing world, plasma paracetamol assays are not widely available. The purpose of this study was to assess a low-cost modified colorimetric paracetamol assay that has the potential to be performed in small laboratories with restricted resources.

METHODS

The paracetamol assay used in this study was based on the Glynn and Kendal colorimetric method with a few modifications to decrease the production of nitrous gas and thereby reduce infrastructure costs. Preliminary validation studies were performed using spiked aqueous samples with known concentrations of paracetamol. Subsequently, the results from the colorimetric method for 114 stored clinical samples from patients with paracetamol poisoning were compared with those from the current gold-standard high-performance liquid chromatography method. A prospective survey, assessing the clinical use of the paracetamol assay, was performed on all patients with paracetamol poisoning attending the Peradeniya General Hospital, Sri Lanka, over a 10-month period.

RESULTS

The recovery study showed an excellent correlation (r(2) > 0.998) for paracetamol concentrations from 25 to 400 mg/L. The final yellow color was stable for at least 10 min at room temperature. There was also excellent correlation with the high-performance liquid chromatography method (r(2) = 0.9758). In the clinical cohort study, use of the antidote N-acetylcysteine was avoided in over a third of patients who had the plasma paracetamol concentration measured. The cost of consumables used per assay was $0.50 (US).

CONCLUSIONS

This colorimetric paracetamol assay is reliable and accurate and can be performed rapidly, easily, and economically. Use of this assay in resource-poor clinical settings has the potential to have a significant clinical and economic impact on the management of paracetamol poisoning.