Characterizing concentrations of diethylene glycol and suspected metabolites in human serum, urine, and cerebrospinal fluid samples from the Panama DEG mass poisoning

Variable sensitivity to diethylene glycol poisoning is related to differences in the uptake transporter for the toxic metabolite diglycolic acid

INTRODUCTION/CONTEXT

Poisonings with diethylene glycol are characterized by acute kidney injury and peripheral neuropathy. In animal studies on the toxicities of diethylene glycol and its metabolite diglycolic acid, remarkable differences in susceptibility to acute kidney injury were observed in identically-dosed rats. In those studies, only about 60% showed acute kidney injury, yet all rats with acute kidney injury showed marked diglycolic acid accumulation in tissues, while no diglycolic acid accumulated in rats without injury. Diglycolic acid is taken into renal cells via sodium-dependent dicarboxylate transporters. When sodium-dependent dicarboxylate transporter-1 is inhibited or knocked down in human kidney cells, diglycolic acid uptake and toxicity are reduced. We hypothesize that the variation in sensitivity to tissue diglycolic acid retention and to diethylene glycol/diglycolic acid toxicity is explained by differential expression of sodium-dependent dicarboxylate transporter-1 in rat kidneys.

METHODS

Using kidney tissue from previous studies, we performed rt-PCR analysis of sodium-dependent dicarboxylate transporter-1 mRNA. In those studies, Wistar-Han rats were either gavage with diethylene glycol 6 g/kg every 12 h for 7 days or with single doses of diglycolic acid 300 mg/kg. Kidney tissue was harvested after euthanasia and preserved in formalin. Tissue slices were homogenized and RNA was isolated using an RNAstorm FFPE RNA Isolation Kit. The expression of sodium-dependent dicarboxylate transporter-1 mRNA was compared between groups that showed diglycolic acid accumulation and acute renal injury with those that showed no diglycolic acid accumulation or toxicity.

RESULTS

Significantly higher expression of sodium-dependent dicarboxylate transporter-1 mRNA was present in the kidneys of rats with acute kidney injury and diglycolic acid accumulation compared to those in rats that had no diglycolic acid in their kidneys and no acute kidney injury.

DISCUSSION

The likelihood of acute kidney injury after dosing of rats with diethylene glycol or diglycolic acid is linked with an enhanced ability to take up diglycolic acid into renal cells via the sodium-dependent dicarboxylate transporter-1. The variability in diethylene glycol toxicity in humans, as reported in epidemiological studies, may also be linked with differences in tissue uptake of diglycolic acid.

CONCLUSIONS

Animals with acute kidney injury after exposure to diethylene glycol or diglycolic acid had higher sodium-dependent dicarboxylate transporter-1 expression and greater diglycolic acid accumulation in renal tissues than animals without acute kidney injury.

Lack of efflux of diglycolic acid from proximal tubule cells leads to its accumulation and to toxicity of diethylene glycol

Diethylene glycol (DEG) mass poisonings have resulted from ingestion of adulterated pharmaceuticals, leading to proximal tubular necrosis and acute kidney injury. Diglycolic acid (DGA), one of the primary metabolites, accumulates greatly in kidney tissue and its direct administration results in toxicity identical to that in DEG-treated rats. DGA is a dicarboxylic acid, similar in structure to Krebs cycle intermediates such as succinate. Previous studies have shown that DGA is taken into kidney cells via the succinate-related dicarboxylate transporters. These studies have assessed whether the DGA that is taken up by primary cultures of human proximal tubule (HPT) cells is effluxed. In addition, a possible mechanism for efflux, via organic anion transporters (OATs) that exchange external organic anions for dicarboxylates inside the cell, was assessed using transformed cell lines that actively express OAT activities. When HPT cells were cultured on membrane inserts, then loaded with DGA and treated with the OAT4/5 substrate estrone sulfate or the OAT1/3 substrate para-aminohippurate, no DGA efflux was seen. A repeat of this experiment utilizing RPTEC/TERT1 cells with overexpressed OAT1 and OAT3 had similar results. In these cells, but not in HPT cells, co-incubation with succinate increased the uptake of PAH, confirming the presence of OAT activity in the RPTEC/TERT1 cells. Thus, despite OATs stimulation in cells with OAT activity, there was little to no efflux of DGA from the cells. This study concluded that DGA is poorly transported out of cells and that stimulation of OAT transporters is not a viable target for reducing DGA accumulation in cells.

Role of plasma membrane dicarboxylate transporters in the uptake and toxicity of diglycolic acid, a metabolite of diethylene glycol, in human proximal tubule cells

Diethylene glycol (DEG) mass poisonings have resulted from ingestion of pharmaceuticals mistakenly adulterated with DEG, typically leading to proximal tubular necrosis and acute kidney injury. The metabolite, diglycolic acid (DGA) accumulates greatly in kidney tissue and its direct administration results in toxicity identical to that in DEG-treated rats. DGA is a dicarboxylic acid, similar in structure to metabolites like succinate. These studies have assessed the mechanism for cellular accumulation of DGA, specifically whether DGA is taken into primary cultures of human proximal tubule (HPT) cells via sodium dicarboxylate transporters (NaDC-1 or NaDC-3) like those responsible for succinate uptake. When HPT cells were cultured on membrane inserts, sodium dependent succinate uptake was observed from both apical and basolateral directions. Pretreatment with the NaDC-1 inhibitor N-(p-amylcinnamoyl)anthranilic acid (ACA) markedly reduced apical uptakes of both succinate and DGA. Basolateral uptake of both succinate and DGA were decreased similarly following combined treatment with ACA and the NaDC-3 inhibitor 2,3-dimethylsuccinate. When the cells were pre-treated with siRNA to knockdown NaDC-1 function, apical uptake of succinate and toxicity of apically applied DGA were reduced, while the reduction in basolateral succinate uptake and basolateral DGA toxicity was marginal with NaDC-3 knockdown. DGA reduced apical uptake of succinate, but not basolateral uptake. This study confirmed that primary HPT cells retain sodium dicarboxylate transport functionality and that DGA was taken up by these transporters. This study identified NaDC-1 as a likely and NaDC-3 as a possible molecular target to reduce uptake of this toxic metabolite by the kidney.

Diethylene glycol produces nephrotoxic and neurotoxic effects in female rats

CONTEXT

Diethylene glycol (DEG) is an organic compound found in household products but also as a counterfeit solvent in medicines. DEG poisonings are characterized by acute kidney injury (AKI) and by neurological sequelae such as decreased reflexes or face and limb weakness. Previous studies in male rats have demonstrated that neurotoxic effects develop only with the establishment of AKI, but the dose sensitivity of females to DEG toxicity is unknown.

OBJECTIVES

Assessing whether subacute administration of DEG in female rats would delineate any sex-differences in neuropathy or in kidney injury.

METHODS

Female Wistar-Han rats were orally administered doses of 4 - 6 g/kg DEG every 12 h and monitored for 7 days. Urine was collected every 12 h and endpoint blood and cerebrospinal fluid (CSF) were collected for renal plasma parameters and total protein estimation, respectively. Motor function tests were conducted before and after treatment. Kidney and brain tissue were analyzed for metabolite content.

RESULTS

Of 12 animals treated with DEG, 3 developed AKI as confirmed by increased BUN and creatinine concentrations. Renal and brain DGA contents were increased in animals that developed AKI compared to animals without AKI. Total CSF protein content in animals with AKI was markedly elevated compared to control and to treated animals without AKI. Decreases in forelimb grip strength and in locomotor and rearing activity were observed in animals with AKI compared to control and to animals without AKI.

DISCUSSION

Repeated dosing with DEG in a female model produced nephrotoxic effects at a dose similar to that in males. The decrease in motor function and increase in CSF protein were only present in females that developed AKI. However, kidney and neurologic effects were assessed only at the end of the treatments, thus limiting determination of which effect occurs first. Limb function and coordination were measured globally and more sensitive tests such as nerve conduction studies might offer a detailed neurotoxicity assessment of the effects of DEG.

CONCLUSIONS

These studies show that DEG toxicity does not appear to be sex-specific and that, in males and females, neurological symptoms are present only when DGA accumulation and kidney injury also occur.

Diethylene glycol and its metabolites induce cell death in SH-SY5Y neuronal cells in vitro

Diethylene glycol (DEG) intoxication results in metabolic acidosis, renal and hepatic dysfunction, and late-stage neurotoxicity. Though the renal and hepatic toxicity of DEG and its metabolites 2-hydroxyethoxyacetic acid (2-HEAA) and diglycolic acid (DGA) have been well characterized, the resultant neurotoxicity has not. SH-SY5Y neuroblastoma cells were incubated with all 3 compounds at increasing concentrations for 24, 48, or 120 h. At all 3 time points, 50 mmol/L DGA and 100 mmol/L DEG showed significant Annexin V and propidium iodide (PI) staining with additional concentrations showing similar staining patterns at 24 h (100 mmol/L DGA) and 48 h (50 mmol/L DEG, 100 mmol/L DGA). Only the 200 mmol/L 2-HEAA concentration induced SH-SY5Y cell death. Interestingly at 24 and 48 h, 100 mmol/L DEG induced significant increases in apoptotic cell death markers, which progressed to necrosis at 120 h. Similar to DEG, 50 mmol/L DGA induced significant increases in SH-SY5Y cell apoptosis and necrosis markers at both 24 and 48 h. As expected, high DGA concentrations (100 mmol/L) at 120 h induced significant SH-SY5Y cell necrosis with no apoptosis detected. However, at 120 h lower DGA concentrations (20 mmol/L) significantly increased oligonucleosome formation alone and in combination with 2-HEAA or DEG. Taken together, these results indicate that DGA and DEG at threshold concentrations induce neurotoxicity in SH-SY5Y cells.

Neurotoxic effects of nephrotoxic compound diethylene glycol

CONTEXT

Diethylene glycol (DEG) is an organic compound found in household products but also as an adulterant in medicines by acting as a counterfeit solvent. DEG poisonings have been characterized predominately by acute kidney injury (AKI), but also by delayed neurological sequelae such as decreased reflexes or face and limb weakness.

OBJECTIVES

Characterizing the neurological symptoms of DEG poisoning in a subacute animal model would create a clearer picture of overall toxicity and possibly make mechanistic connections between kidney injury and neuropathy.

METHODS

Male Wistar-Han rats were orally administered doses of 4 - 6 g/kg DEG every 12 or 24 h and monitored for 7 days. Urine was collected every 12 h and endpoint blood and cerebrospinal fluid (CSF) were collected for a renal plasma panel and total protein estimation, respectively. Motor function tests were conducted before and after treatment. Kidney and brain tissue was harvested for metabolic analysis.

RESULTS

Of the 43 animals treated with DEG, 11 developed AKI as confirmed by increased BUN and creatinine levels. Renal and brain DGA accumulation was markedly increased in animals that developed AKI compared to animals without AKI. The total protein content in CSF in animals with kidney injury was markedly elevated compared to control and to treated animals without AKI. Significant decreases in forelimb grip strength and decreases in locomotor and rearing activity were observed in animals with AKI compared to control and to animals without AKI.

DISCUSSION

Repeated dosing with DEG in an animal model produced nephrotoxic effects like those in studies with acute DEG administration. The decrease in motor function and increase in CSF protein were only present in animals that developed AKI.

CONCLUSIONS

These studies show development of neurotoxicity in this DEG animal model and suggest that neurological symptoms are observed only when DGA accumulation and kidney injury also occur.

Analysis of Diglycolic Acid After Mass Poisoning by Diethylene Glycol

In December 2019, unusual cases of acute renal failure with neurological changes were observed in the State of Minas Gerais, Brazil. Criminal investigations indicated cases of intoxication after consumption of beers contaminated with diethylene glycol (DEG). The elimination of DEG by the body is fast, but its metabolite, diglycolic acid (DA), may persist for a long time. To assess the level of intoxicated victims who consumed the contaminated beers, qualitative and quantitative methods were developed to determine DA in biological matrices by gas chromatography coupled to a mass spectrometer (GC-MS) and gas chromatography coupled to a mass spectrometer with triple-quadrupole mass filter (GC-MS/MS), respectively. The validated qualitative method presents good selectivity and limit of detection of 1 µg/mL (whole blood, urine, vitreous humor and cerebrospinal fluid) and 5 µg/g (liver and kidney). A quantitative method for whole blood presented satisfactory performance to determine DA. Twelve victims presented positive results for DA in whole blood, with concentrations ranging from 2 to 108 µg/mL. The toxicology laboratory of the Institute of Forensic Medicine of Minas Gerais was the first governmental agency to identify DA in whole blood, vitreous humor, cerebrospinal fluid, kidney and urine in victims affected by this contaminant. The results of this study legally supported the prohibition to the continued consumption of the beer and avoided further intoxications. Our results showed, for real cases of human intoxication, that it can still be detected in alternative matrices, even when non-detectable in blood, demonstrating the importance of collecting different kinds of samples for a proper investigation.

1,4-Dioxane as an emerging water contaminant: State of the science and evaluation of research needs

1,4-Dioxane has historically been used to stabilize chlorinated solvents and more recently has been found as a contaminant of numerous consumer and food products. Once discharged into the environment, its physical and chemical characteristics facilitate migration in groundwater, resulting in widespread contamination of drinking water supplies. Over one-fifth of U.S. public drinking water supplies contain detectable levels of 1,4-dioxane. Remediation efforts using common adsorption and membrane filtration techniques have been ineffective, highlighting the need for alternative removal approaches. While the data evaluating human exposure and health effects are limited, animal studies have shown chronic exposure to cause carcinogenic responses in the liver across multiple species and routes of exposure. Based on this experimental evidence, the U.S. Environmental Protection Agency has listed 1,4-dioxane as a high priority chemical and classified it as a probable human carcinogen. Despite these health concerns, there are no federal or state maximum contaminant levels for 1,4-dioxane. Effective public health policy for this emerging contaminant requires additional information about human health effects, chemical interactions, environmental fate, analytical detection, and treatment technologies. This review highlights the current state of knowledge, key uncertainties, and data needs for future research on 1,4-dioxane.

Structure-based investigation on the association between perfluoroalkyl acids exposure and both gestational diabetes mellitus and glucose homeostasis in pregnant women

BACKGROUND

Biomonitoring studies have shown the presence of structurally diverse perfluoroalkyl acids (PFAAs) in humans but only a few studies are available regarding the differential structural effects of PFAAs on human health.

OBJECTIVE

The specific association between different structural PFAAs and both gestational diabetes mellitus (GDM) and glucose homeostasis in pregnant women was investigated.

METHODS

A prospective nested case-control study including 439 women was conducted during 2013-2015 in Beijing, China. First trimester maternal serum was collected and analyzed for 25 diverse PFAAs with varying carbon chain lengths, linear/branched isomers and carboxylate or sulfonate functional groups. The analyzed PFAAs were grouped into different exposure variables depending on structure characteristics. GDM cases were diagnosed at 24-28 weeks of gestation and individually matched in a 1:2 ratio to controls. Conditional logistic and linear regression was used to evaluate the association between structurally grouped PFAAs and both GDM risk and glucose homeostasis parameters.

RESULTS

Among the 25 PFAAs, 12 perfluoroalkyl carboxylates (PFCAs) and 8 perfluoroalkyl sulfonates (PFSAs) were detected in >55.0% of samples and were respectively grouped into different structural groups. The structural-based effect was observed for PFCAs, where short-chain (C4-C7) PFCAs continuous level was significantly associated with GDM with an estimated odds ratio (OR) of 1.99 (95% CI: 1.29, 3.09), and the multivariable-adjusted ORs (95% CI) of GDM for increasing tertiles of short-chain PFCAs were 1.00 (ref.), 1.82 (0.80, 4.16) and 3.01 (1.31, 6.94), P trend = 0.011. Additionally, increased concentration of short-chain PFCAs was significantly associated with higher postprandial glucose levels (P < 0.05). Non-significant association was observed between structure grouped PFSAs and GDM as well as glucose homeostasis.

CONCLUSION

This investigation suggests a structure-specific association between short-chain PFCAs exposure and both GDM risk and impaired glucose homeostasis in pregnant women. These findings warrant further investigation with larger samples and a wide range of short-chain PFCAs exposure.

Modeling the Accumulation of Degradable Polymer Drug Carriers in the Brain

The blood-brain barrier (BBB) limits the access of drugs to the brain. Intensive research is being conducted on the development of nanoparticulate drug carriers that mediate transfer across the BBB. A question that has been neglected so far is the potential accumulation of the carrier in the brain upon long-term exposure. Here, we address this question by implementing a kinetic model to relate drug loading, required concentration of drug in the brain, and drug clearance to the degradation half-life of the carrier. As a test case with clinical relevance we chose poly-lactic-co-glycolic-acid (PLGA) as a carrier material and a chemotherapeutic for which the required parameters could be recovered from the literature. For methotrexate with a drug load of 8.5 %, a required concentration of free drug of 1 μm, a release from PLGA of 6 hours, a drug clearance from the brain of 3 hours and a half-life of polymer degradation of 28 days, a steady-state accumulation of 1.3 g polymer would be reached in the brain (1.5 L) after seven months. While this number is surprisingly small, further physiological research is warranted to assess to which degree this will be in a tolerable range.

Basal Ganglion Hemorrhage as Delayed Complication of Diethylene Glycol Ingestion

Diethylene glycol (DEG), an organic compound (HOCH2CH2)2O is a commonly used solvent. Mass poisoning outbreaks have been reported because of frequent contaminations. A PubMed search for diethylene resulted in 795 publications with 151 specifically discussing the toxicity. Of the 151 reported toxicity reviews/case reports, only 6 publications discussed the long-term neurological effects of diethylene toxicity. We report a fatal case of oral ingestion of DEG with complications from delayed toxicity. She died 7 days after the second admission. Autopsy disclosed a right basal ganglia hemorrhage within the brain and microscopic deposits of polarizable crystals into small cerebral blood vessels. Both kidneys illustrate tubular necrosis with scattered tubular deposition of polarizable calcium oxalate crystals. PubMed search leads to only 2 reported cases of basal ganglia hemorrhage (based on radiological findings) after ethylene glycol intoxication. Our case is the first reportable case of basal ganglia hemorrhage after DEG ingestion.

Identification and quantification of acidosis inducing metabolites in cases of alcohols intoxication by GC-MS for emergency toxicology

A simple, cost effective, and fast gas chromatography method with mass spectrometry detection (GC-MS) for simultaneous measurement of formic acid, glycolic acid, methoxyacetic acid, ethoxyacetic acid and 2-hydroxyethoxyacetic acid in serum and urine was developed and validated. This multi-analyte method is highly suitable for clinical and emergency toxicology laboratory diagnostic, allowing identification and quantification of five most common acidosis inducing organic acids present in cases of alcohol intoxication. Furthermore, when patients are admitted to emergency unit at late stage of toxic alcohol intoxication, the concentration of parent compound may be already low or not detectable. This new method employs a relatively less used class of derivatization agents - alkyl chloroformates, allowing the efficient and rapid derivatization of carboxylic acids within seconds. The entire sample preparation procedure is completed within 5 min. The optimal conditions of derivatization procedure have been found using chemometric approach (design of experiment). The calibration dependence of the method was proved to be quadratic in the range of 25-3000 mg L(-1), with adequate accuracy (97.3-108.0%) and precision (<12.8%). The method was successfully applied for identification and quantification of the selected compounds in serum of patients from emergency units.

The chemical components of electronic cigarette cartridges and refill fluids: review of analytical methods

INTRODUCTION

To date, several concerns have been raised on the purity of ingredients employed in the manufacturing processes of refill fluids and cartridges, the device functionality, and the quality control of electronic cigarettes. This article reviews analytical methods so far described for the analysis of liquids to detect their chemical components and to investigate the presence of toxicants and carcinogens that can potentially occur as impurities of ingredients or as a consequence of their degradation.

RESULTS AND DISCUSSION

Based on the scientific literature, high-performance liquid chromatography with diode-array detection (HPLC/DAD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) are most appropriate for determining nicotine and related compounds in fluids and cartridges, whereas LC-MS/MS has been successfully used to determine nitrosamines. Content analyses of glycols have been performed using gas chromatography equipped with flame ionization detector or gas chromatography/mass spectrometry (GC/MS), whereas carbonyl and other volatile organic compounds determinations have been performed by HPLC/DAD and GC/MS, respectively. Content analyses of heavy metals have been performed by inductively coupled plasma optical emission spectroscopy or inductively coupled plasma mass spectrometry. Since new potentially toxic substances may be created during heating, it is also necessary to investigate the chemical composition of generated aerosol. In this case, similar methods applied for tobacco smoke can be adopted.

CONCLUSIONS

A broad range of analytical techniques are available for the detection of constituents and toxicants in e-liquids and cartridges. Analyses of liquids have been performed with pharmacopeia procedures and methods (International Organization for Standardization, Environmental Protection Agency, and American Public Health Association) developed for other matrices but applicable to e-liquids. Because new potentially harmful substances may be produced during heating process, analyses of aerosol are needed to correlate its composition to the chemical components of liquids.

Diethylene glycol-induced toxicities show marked threshold dose response in rats

Diethylene glycol (DEG) exposure poses risks to human health because of widespread industrial use and accidental exposures from contaminated products. To enhance the understanding of the mechanistic role of metabolites in DEG toxicity, this study used a dose response paradigm to determine a rat model that would best mimic DEG exposure in humans. Wistar and Fischer-344 (F-344) rats were treated by oral gavage with 0, 2, 5, or 10g/kg DEG and blood, kidney and liver tissues were collected at 48h. Both rat strains treated with 10g/kg DEG had equivalent degrees of metabolic acidosis, renal toxicity (increased BUN and creatinine and cortical necrosis) and liver toxicity (increased serum enzyme levels, centrilobular necrosis and severe glycogen depletion). There was no liver or kidney toxicity at the lower DEG doses (2 and 5g/kg) regardless of strain, demonstrating a steep threshold dose response. Kidney diglycolic acid (DGA), the presumed nephrotoxic metabolite of DEG, was markedly elevated in both rat strains administered 10g/kg DEG, but no DGA was present at 2 or 5g/kg, asserting its necessary role in DEG-induced toxicity. These results indicate that mechanistically in order to produce toxicity, metabolism to and significant target organ accumulation of DGA are required and that both strains would be useful for DEG risk assessments.

Neurological manifestation of recreational fatal and near-fatal diethylene glycol poisonings: case series and review of literature

Diethylene glycol is a common industrial solvent which is responsible for accidental and epidemic poisoning as early as the 1930s. Due to the unavailability and unaffordability of ethanol, people in Qatar among the low income group are consuming household chemicals, some of which contain diethylene glycol, for recreational purposes.The history of ingestion is usually not volunteered and the initial clinical presentation is usually nonspecific, making it difficult to diagnose from the clinical presentation. Moreover, the biochemical profile varies with time, making the diagnosis more difficult. The neurological course and toxicity is less well characterized than its renal counterpart. Moreover, reports in the literature of such recreational poisoning is lacking particularly in the region.Three cases of recreational diethylene glycol poisoning seen in Hamad General Hospital, Doha, Qatar from 2009 to 2012 are detailed here.These illustrate the clinical course with emphasis on the neurological sequelae that include encephalopathy and multiple cranial and peripheral neuropathies with fatal and near-fatal outcomes. Neuroimaging in 2 were initially normal, but follow-up imaging showed brain atrophy. The third patient's neuroimaging showed diffuse brain edema with evidence of transtentorial herniation. Nerve conduction studies were performed in 2 of the 3 cases and showed evidence of mixed sensorimotor neuropathy. The outcomes were death in 1 and severe neurological morbidity and disability in 2 cases.Diethylene glycol is a dangerous substance when ingested and can result in mortality and severe morbidity, particularly from the renal and neurological manifestations. Whereas the mechanism of damage is less well known, the damage is likely dose related. The typical clinical pattern of evolution of the poisoning in the absence of cost-effective ways to detect it in the serum can help clinicians in making the diagnosis.Neurological manifestations may include encephalopathy and multiple cranial and peripheral neuropathies with subsequent brain atrophy. Public awareness of the danger of such recreational use should be raised.

Long-term renal and neurologic outcomes among survivors of diethylene glycol poisoning

IMPORTANCE

At least 13 medication-associated diethylene glycol (DEG) mass poisonings have occurred since 1937. To our knowledge, this is the first longitudinal study characterizing long-term health outcomes among survivors beyond the acute poisoning period.

OBJECTIVE

To characterize renal and neurologic outcomes among survivors of a 2006 DEG mass-poisoning event in Panama for 2 years after exposure.

DESIGN, SETTING, AND PARTICIPANTS

This prospective longitudinal study used descriptive statistics and mixed-effects repeated-measures analysis to evaluate DEG-poisoned survivors at 4 consecutive 6-month intervals (0, 6, 12, and 18 months). Case patients included outbreak survivors with a history of (1) ingestion of DEG-contaminated medication, (2) hospitalization for DEG poisoning, and (3) an unexplained serum creatinine level of 1.5 mg/dL or higher (to convert to micromoles per liter, multiply by 88.4) during acute illness or unexplained exacerbation of preexisting end-stage renal disease.

MAIN OUTCOMES AND MEASURES

Demographics, mortality, dialysis dependence, renal function, neurologic signs and symptoms, and nerve conduction studies.

RESULTS

Of the 32 patients enrolled, 5 (15.6%) died and 1 was lost to follow-up, leaving 26 patients at 18 months. Three (9.4%) missed 1 or more evaluations. The median age was 62 years (range, 15-88 years), and 59.4% were female. Three (9.4%) patients had preexisting renal failure. Enrollment evaluations occurred at a median of 108 days (range, 65-154 days) after acute illness. The median serum creatinine level for the 22 patients who were not dialysis dependent at time 0 was 5.9 mg/dL (range, 1.8-17.1 mg/dL) during acute illness and 1.8 mg/dL (range, 0.9-5.9 mg/dL) at time 0. Among non-dialysis-dependent patients, there were no significant differences in the log of serum creatinine or estimated glomerular filtration rate over time. The number of patients with subjective generalized weakness declined significantly over time (P < .001). A similar finding was observed for any sensory loss (P = .05). The most common deficits at enrollment were bilateral lower extremity numbness in 13 patients (40.6%) and peripheral facial nerve motor deficits in 7 (21.9%). All patients with neurologic deficits at enrollment demonstrated improvement in motor function over time. Among 28 patients (90.3%) with abnormal nerve conduction study findings at enrollment, 10 (35.7%) had motor axonal involvement, the most common primary abnormality.

CONCLUSIONS AND RELEVANCE

Neurologic findings of survivors tended to improve over time. Renal function generally improved among non-dialysis-dependent patients between acute illness and the first evaluation with little variability thereafter. No evidence of delayed-onset neurologic or renal disease was observed.

Quantitation of diethylene glycol and its metabolites by gas chromatography mass spectrometry or ion chromatography mass spectrometry in rat and human biological samples

The misuse of the commonly used chemical diethylene glycol (DEG) has lead to many poisonings worldwide. Methods were developed for analysis of DEG and its potential metabolites; ethylene glycol, glycolic acid, oxalic acid, diglycolic acid and hydroxyethoxy acetic acid in human urine, serum and cerebrospinal fluid samples, collected following a DEG-associated poisoning in the Republic of Panama during 2006. In addition, methods were developed for rat blood, urine, kidney and liver tissue to support toxicokinetic analysis during the conduct of DEG acute toxicity studies in the rat. Sample analysis was conducted using two techniques; ion chromatography with suppressed conductivity and negative ion electrospray ionization with MS detection or with gas chromatography using electron impact ionization or methane negative chemical ionization with MS detection. Stable-isotope-labeled analogs of each analyte were employed as quantitative internal standards in the assays.