Glycol Exposure Research Articles

Changes in ionised calcium in cases of ethylene glycol poisoning

Ethylene glycol is a toxic alcohol that occurs in a variety of chemical preparations. In patients poisoned with ethylene glycol, diagnosis is usually based on clinical suspicion and non-specific tests. Hypocalcaemia is often present and results from production of calcium oxalate crystals from oxalic acid. 
 Assess whether reduction in ionized calcium concentration is a common finding in ethylene glycol poisoning, whether it can be appropriate additional marker for the prognosis of outcome.
 Retrospective clinical records review of patients with a diagnosis of ethylene glycol poisoning at the Riga East University Hospital from 1 January 2012 to 31 December 2020. Ethylene glycol exposure was confirmed retrospectively, qualitatively in all patients. Results of blood gas samples and serum creatinine were analysed and abnormalities were compared amongst various groups.
 Ionized calcium concentration in arterial blood was below the normal range in 59% of cases at the time of presentation and more commonly associated with a blood pH < 7.3 in 79% of cases. The number of patients with low ionized calcium concentration increased over time. However, the number of patients with blood pH ≥7.3 fell during the same time period. Linear regression analysis did not show a significant correlation between low ionized calcium and blood pH. However, analysis of results from the time of presentation revealed a moderate negative correlation between low ionized calcium concentration and blood pH and lactate concentration. There was also a moderate correlation between low ionized calcium concentration and serum creatinine.
 A low ionised calcium concentration was a common finding in cases of ethylene glycol poisoning and was more commonly associated with patients exhibiting metabolic acidosis or developing acute kidney injury. Ionised calcium concentration and pH value may be additional markers for the diagnosis and risk stratification of severity from ethylene glycol poisoning.

Case report: Bovine ethylene glycol toxicosis

Acute death of 1-month-old calves on pasture that were accidentally exposed to an oil/antifreeze mix were investigated. Clinical signs were not observed and necropsy findings were non-specific. Histological diagnosis of calcium oxalate nephrosis with concurrent tubulointerstitial suppurative nephritis was supported by culture. Ethylene glycol exposure was confirmed via analytical methods.

Pathology and Epidemiology of Oxalate Nephrosis in Cheetahs.

To investigate cases of acute oxalate nephrosis without evidence of ethylene glycol exposure, archived data and tissues from cheetahs ( Acinonyx jubatus) from North America ( n = 297), southern Africa ( n = 257), and France ( n = 40) were evaluated. Renal and gastrointestinal tract lesions were characterized in a subset of animals with ( n = 100) and without ( n = 165) oxalate crystals at death. Crystals were confirmed as calcium oxalate by Raman spectroscopy in 45 of 47 cheetahs tested. Crystals were present in cheetahs from 3.7 months to 15.9 years old. Cheetahs younger than 1.5 years were less likely to have oxalates than older cheetahs ( P = .034), but young cheetahs with oxalates had more oxalate crystals than older cheetahs ( P < .001). Cheetahs with oxalate crystals were more likely to have renal amyloidosis, interstitial nephritis, or colitis and less likely to have glomerular loop thickening or gastritis than those without oxalates. Crystal number was positively associated with renal tubular necrosis ( P ≤ .001), regeneration ( P = .015), and casts ( P ≤ .001) but inversely associated with glomerulosclerosis, renal amyloidosis, and interstitial nephritis. Crystal number was unrelated to the presence or absence of colitis and was lower in southern African than American and European animals ( P = .01). This study found no evidence that coexisting chronic renal disease (amyloidosis, interstitial nephritis, or glomerulosclerosis), veno-occlusive disease, gastritis, or enterocolitis contributed significantly to oxalate nephrosis. Oxalate-related renal disease should be considered as a potential cause of acute renal failure, especially in young captive cheetahs. The role of location, diet, stress, and genetic predisposition in the pathogenesis of oxalate nephrosis in cheetahs warrants further study.

Dehydration-hydration reactivity of laumontite: analyses and tests for easy detection

AbstractHydration reactions are known to affect rock or aggregate stability in construction; laumontite is not usually considered to be a ‘problem-mineral’ though drill cores from the very low-grade metamorphic altered andesites and volcanoclastic rocks from Central Chile showed detachments of shotcrete in a tunnel exposed to periodic water flow, with expandable clay phases presumed to be responsible for the observed failure. Abundant laumontite detected in the cores may also be responsible for the detachment, however, resulting from the structural expansion and contraction in response to hydration and drying. Clay reactivity in construction projects is often tested on site by 30 days of ethylene glycol exposure, but adequate monitoring options for laumontite are not deployed. Options for laumontite characterization involving a combination of water immersion and slaking and modified oedometer-based expansibility tests were used here to observe the response to laumontite expansion pressure. All tests were formulated considering minimal implementation efforts for building sites or the easy availability of analytical and testing facilities.Laumontite was identified by optical microscopy, semiquantitative X-ray diffraction, and automated mineralogical analysis. A combination of the latter two methods provided reliable information about the presence of sub-microscopic laumontite and a visual impression of the textural arrangement of the zeolite in the rock.A slaking test based on four cycles of immersion followed by drying and final application of weight (simulated overburden) is best suited to indirect detection and for demonstrating rock reactivity due to the presence of laumontite. Rocks with laumontite show expansion when crushed, recompacted and fitted into an oedometer, but mineralogical information is required for adequate interpretation of the results.

Examination of the Physiological Effects of Ethylene Glycol Exposure on Muscle and Liver Tissue of the Leopard Frog, Rana pipiens

Newly developed and utilized industrial processes use anthropogenic agents that may adversely affect ecosystem biodiversity. Hydraulic fracturing technology involves the use of a fluid, composed of 98–99% water and 1–2% chemical additives, to break up shale reservoirs for access to natural gas and oil reserves. One of the chemical additives in fracturing fluid is ethylene glycol. To date, there is no information available of the effects of ethylene glycol exposure on aquatic organisms at concentrations used by the hydraulic fracturing industry (i.e., 0.14–15.8 mM). Therefore, the present study examined the physiological effects of ethylene glycol exposure on Leopard frogs, Rana pipiens. Frogs were exposed to control water or to water containing 5.7 mM ethylene glycol for five days. Ethylene glycol‐exposure significantly decreased the swimming time to exhaustion from 284.5±22.8 sec in control animals to 194.8±26.3 sec (P≤0.05, n=6 in each group). Moreover, contraction of isolated gastrocnemius muscles was significantly less in ethylene glycol‐exposed frogs at 3, 6, 12 and 24 V when compared to control animals. Mitochondrial membrane potential was also significantly decreased in ethylene glycol‐exposed frogs when compared to control animals, decreasing 40.1% and 42.4% in liver and muscle tissue, respectively. Culture of isolated satellite cells from skeletal muscle resulted in a dose‐dependent, ethylene glycol‐induced increase in cell proliferation and differentiation. Taken together, these data indicate that 5.7 mM ethylene glycol significantly reduced muscle and liver performance. Moreover, the activation and proliferation of the satellite cells when exposed to ethylene glycol suggests that the hydraulic fracturing agent is myotoxic to frog muscles. We believe that the agent is altering mitochondrial function by reducing the available ATP for cellular or organ system processes like cell volume regulation and muscle contraction.Support or Funding InformationThis research was supported by grants from Beta Beta Beta, the Bradley University Biology Department and the Bjorklund Endowment, and a Caterpillar Master's Fellowship to ANF.

Clinical Features of Reported Ethylene Glycol Exposures in the United States.

BackgroundEthylene glycol is highly toxic and represents an important cause of poisonings worldwide. Toxicity can result in central nervous system dysfunction, cardiovascular compromise, elevated anion gap metabolic acidosis and acute kidney injury. Many states have passed laws requiring addition of the bittering agent, denatonium benzoate, to ethylene glycol solutions to reduce severity of exposures. The objectives of this study were to identify differences between unintentional and intentional exposures and to evaluate the utility of denatonium benzoate as a deterrent.Methods and FindingsUsing the National Poison Data System, we performed a retrospective analysis of reported cases of ethylene glycol exposures from January 2006 to December 2013. Outcome classification was summed for intentionality and used as a basis for comparison of effect groups. There were 45,097 cases of ethylene glycol exposures resulting in 154 deaths. Individuals more likely to experience major effects or death were older, male, and presented with more severe symptoms requiring higher levels of care. Latitude and season did not correlate with increased exposures; however, there were more exposures in rural areas. Denatonium benzoate use appeared to have no effect on exposure severity or number.ConclusionDeaths due to ethylene glycol exposure were uncommon; however, there were major clinical effects and more exposures in rural areas. Addition of denatonium benzoate was not associated with a reduction in exposures. Alternative means to deter ingestion are needed. These findings suggest the need to consider replacing ethylene glycol with alternative and less toxic agents.

Insights on cryoprotectant toxicity from gene expression profiling of endothelial cells exposed to ethylene glycol

Cryopreservation consists of preserving living cells or tissues generally at −80 °C or below and has many current applications in cell and tissue banking, and future potential for organ banking. Cryoprotective agents such as ethylene glycol (EG) are required for successful cryopreservation of most living systems, but have toxic side effects whose mechanisms remain largely unknown. In this work, we investigated the mechanisms of toxicity of ethylene glycol in human umbilical vein endothelial cells (HUVECs) as a model of the vascular endothelium in perfused organs. Exposing cells to 60% v/v EG for 2 h at 4 °C resulted in only a slight decrease in subsequent cell growth, suggesting only modest toxicity of EG for this cell type. Gene expression analysis with whole genome microarrays revealed signatures indicative of a generalized stress response at 24 h after EG exposure and a trend toward partial recovery at 72 h. The observed changes involved signalling pathways, glycoproteins, and genes involved in extracellular and transmembrane functions, the latter suggesting potential effects of ethylene glycol on membranes. These results continue to develop a new paradigm for understanding cryoprotectant toxicity and reveal molecular signatures helpful for future experiments in more completely elucidating the toxic effects of ethylene glycol in vascular endothelial cells and other cell types.

L-Arginine attenuates the ethylene glycol induced urolithiasis in ininephrectomized hypertensive rats: role of KIM-1, NGAL, and NOs

Background: Ethylene glycol (EG) exposure caused formation of calcium oxalate crystal that led to renal failure, which is associated with higher prevalence of hypertension. l-Arginine is known to have an antioxidant and nephro-protective potential. Objective: To evaluate the effect of l-arginine against EG-induced urolithiasis in uninephrectomized hypertensive rats. Material and methods: Uninephrectomized male Wistar rats (180–200 g) were used to induce urinary calculi through oral administration of EG (0.75%) in distilled water. Rats were treated with either distilled water (10 mg/kg, p.o.) or telmisartan (10 mg/kg, p.o.) or Cystone (500 mg/kg, p.o.) or l-arginine (250, 500, and 1000 mg/kg, p.o.) for 28 days. Various hemodynamic, biochemical, molecular, and histological parameters were assessed in kidney and heart. Results: Rats treated with l-arginine (500 and 1000 mg/kg) significantly restored altered relative organ weight, urine output, urine density, urinary pH, and water intake. EG-induced alterations in electrocardiographic (QRS interval, HR, and ST height) and hemodynamic (SBP, DBP, MABP, and LVEDP) abnormalities were significantly restored by l-arginine (500 and 1000 mg/kg) treatment. It also significantly restored alteration in serum and urine biochemical parameters induced by EG. The elevated oxido-nitrosative stress was also significantly decreased by l-arginine (500 and 1000 mg/kg) treatment. It also significantly down-regulated EG-induced up-regulated renal KIM-1, NGAL, eNOS, and iNOs mRNA expressions. Histological aberrations induced in the renal and cardiac tissues were also ameliorated by l-arginine treatment. Conclusion: l-Arginine exerts its nephro- and cardio-protective potential in EG-induced urolithiasis in uninephrectomized hypertensive rats via modulation of KIM-1, NGAL, eNOS, and iNOs mRNA expression.

Challenges in the diagnosis of ethylene glycol poisoning

Ethylene glycol poisoning, while uncommon, is clinically significant due to the associated risk of severe morbidity or lethality and it continues to occur in many countries around the world. The clinical presentation of ethylene glycol toxicity, while classically described in three phases, varies widely and when combined with the range of differential diagnoses that must be considered makes diagnosis challenging. Early and accurate detection is important in these patients, however, as there is a need to start antidotal treatment early to prevent serious harm. In this article, we will review the literature and provide guidance regarding the diagnosis of ethylene glycol poisoning. While gas chromatography is the gold standard, the usefulness of this test is hampered by delays in access due to availability. Consequently, there are several surrogate markers that can give an indication of ethylene glycol exposure but these must be interpreted with caution and within the clinical context. An in-depth review of these tests, particularly the detection of a raised osmolar gap or an raised anion gap acidosis, will form the main focus of this article.

Water vapour measurements in natural gas in the presence of ethylene glycol

An investigation of hygrometers for monitoring of water vapour (moisture) in natural gas has been performed, with respect to response on ethylene glycol co-exposure. The tested hygrometers are based on: 1. capacitor sensor, 2. quartz crystal microbalance (QCM), 3. fibre-optic sensor and 4. conversion of water to ethyne, quantified by a gas chromatograph (CaC2-GC). The moisture concentration level in the test gas was 50 μmol/mol during the experiments, corresponding to a frost point of approximately −48 °C (atmospheric pressure). The experiments were performed in the laboratory, using nitrogen as matrix gas. The QCM hygrometer responded with a downward drift of the frost point readings in the presence of traces of ethylene glycol (0.25 μmol/mol and 0.66 μmol/mol, respectively). The drift increased initially when the ethylene glycol concentration increased, and the frost point readings from the QCM hygrometer decreased close to 5 °C during a total of 20 days of ethylene glycol exposure. The QCM hygrometer seemed to recover slowly from the ethylene glycol exposure, indicated by a decreasing upward drift as soon as the ethylene glycol exposure ended. Both tested capacitor hygrometers responded significantly to ethylene glycol exposure. The responses were not uniform, though, with one performing considerably better than the other one. The experiments also demonstrated the insufficiency of chilled mirror techniques for interpreting water frost points or water dew points, with subsequent moisture concentration calculation, in the presence of ethylene glycol, even at trace amounts. This made the chilled mirror technique totally unsuitable for reference measurements after the introduction of ethylene glycol to the test gas. The fibre-optic sensor hygrometer and the CaC2-GC hygrometer showed minor response for ethylene glycol. In general the results from this work demonstrate the need for careful evaluation of individual moisture monitoring applications, before choosing a hygrometer. A well-considered strategy for quality control of the moisture monitoring, regardless of the chosen hygrometer, is of utmost importance to establish a moisture monitoring system with high accuracy.

Preliminary evaluation of a quantitative ethylene glycol test in dogs and cats

Ethylene glycol (EG) toxicity is commonly encountered in dogs and cats. The purpose of the current study was to determine if the Catachem test kit (Catachem Inc., Oxford, Connecticut) could precisely and accurately detect the presence of EG added to serum and plasma from 6 dogs and 4 cats. Serum and plasma samples were spiked at various concentrations of EG (0, 20, 60, and 100 mg/dl) and analyzed using the Catachem kit. Twenty randomly selected samples were also submitted for gas chromatography-mass spectroscopy (GC-MS) analysis of EG concentration, which was considered the gold standard. Inter- and intra-assay coefficients of variation (CVs) were calculated. Bland-Altman analysis was performed to compare the Catachem results to the GC-MS analyses. Analysis of serum samples showed a bias of 8.48 mg/dl (95% limits of agreement: 17.8 to -0.9 mg/dl) while spiked plasma samples had a bias of 7.32 mg/dl (18.1 to -3.5 mg/dl). Intra-assay CV was 0.7%. Interassay CV ranged from 1.2% to 2.0%. For all samples, the Catachem kit read higher than GC-MS values and slightly overestimated in vitro concentrations. The Catachem test kit is an accurate quantitative test for EG in dogs and cats that may aid in timely recognition of EG exposure. Because of the positive bias in all samples, some pets may receive treatment unnecessarily. However, animals with blood EG concentrations at or above the published lethal serum or plasma concentration will be readily identified so that treatment may be initiated.

Effects of five cryoprotective agents on quality of sheep epididymal spermatozoa during pre-freezing

The objective of this study was to test five cryoprotective agents during ram epidydimal spermatozoa incubation (at 4°C), of up to 3h, typical equilibration time before the freezing step begins, in order to establish a starting point for future freezing and thawing protocols. The parameters analyzed were: progressive motility (PM), vitality, and the plasma membrane functional integrity by the hypoosmotic swelling (HOS) test. Testes and epididymides were collected immediately after death. The tail of both epididymides were isolated and spermatozoa were recovered constituting one sample (n=20). A Tes–Tris–Yolk extender was employed. The extender contained five alternative CPAs: Dimethylacetamide (DMA), Dimethyl sulfoxide (DMSO), Ethylene glycol (EG), Glycerol (GLY) and Propylene glycol (PG) at three final concentrations: 2.5%, 5.0% and 10.0%. Control groups consisted of samples mixed only with the extender, without any CPA. All sample groups were exposed to the CPAs for 1h or 3h at 4°C. EG exposure yielded better responses in both PM and HOS test parameters compared to extender only and also the other CPAs. There was no difference among all the treatments regarding vitality. EG (with best results at 2.5%) is thus proposed as a good CPA (followed by DMA as an explorable alternative) for the implementation of forthcoming ram epididymal spermatozoa freezing protocols.

Aluminum Citrate Prevents Renal Injury from Calcium Oxalate Crystal Deposition

Calcium oxalate monohydrate crystals are responsible for the kidney injury associated with exposure to ethylene glycol or severe hyperoxaluria. Current treatment strategies target the formation of calcium oxalate but not its interaction with kidney tissue. Because aluminum citrate blocks calcium oxalate binding and toxicity in human kidney cells, it may provide a different therapeutic approach to calcium oxalate-induced injury. Here, we tested the effects of aluminum citrate and sodium citrate in a Wistar rat model of acute high-dose ethylene glycol exposure. Aluminum citrate, but not sodium citrate, attenuated increases in urea nitrogen, creatinine, and the ratio of kidney to body weight in ethylene glycol-treated rats. Compared with ethylene glycol alone, the addition of aluminum citrate significantly increased the urinary excretion of both crystalline calcium and crystalline oxalate and decreased the deposition of crystals in renal tissue. In vitro, aluminum citrate interacted directly with oxalate crystals to inhibit their uptake by proximal tubule cells. These results suggest that treating with aluminum citrate attenuates renal injury in rats with severe ethylene glycol toxicity, apparently by inhibiting calcium oxalate's interaction with, and retention by, the kidney epithelium.

Methanol and ethylene glycol acute poisonings – predictors of mortality

Context. Methanol and ethylene glycol cause significant mortality post-ingestion. Predicting prognosis based on the biomarkers osmolal gap, anion gap and pH is beneficial. Objective. To evaluate the relationship between biomarkers, measured post-methanol and ethylene glycol exposure, and clinical outcomes. Methods. A review of the literature identified cases where methanol or ethylene glycol had been ingested and clinical outcomes were recorded. Biomarkers were extracted including osmolal gap, anion gap and pH, with clinical outcomes categorised as recovered, recovered with adverse sequelae and death. Biomarkers were analysed using the Mann–Whitney test for two samples; sensitivity and specificity were evaluated using receiver operating characteristic (ROC) curves. Results. In total, 119 cases of methanol and 88 of ethylene glycol poisoning were identified; 21 methanol and 19 ethylene glycol patients died. For methanol ingestion the mean values, for survival compared to death, were 48 (range: 6–138) and 90 (range: 49–159) mOsm/kg water for osmolal gap (p=0.0052), 31 (range: 11–50) and 41 (range: 30–53) mmol/L for anion gap (p=0.0065) and 7.21 (range: 6.60–7.50) and 6.70 (range: 6.34–7.22) for arterial pH (p<0.0001). The area under the ROC curve was highest for arterial pH, 0.94 (95% CI: 0.89–0.99). For ethylene glycol, these were 49 (range: 0–189) and 79 (range: 25–184) mOsm/kg water for osmolal gap (p=0.050), 28 (range: 6–48) and 38 (range: 20–66) mmol/L for anion gap (p=0.0037) and 7.08 (range: 6.46–7.39) and 6.98 (range: 6.50–7.16) for pH (p=0.072), for survival compared to death. The area under the ROC curve was highest for anion gap, 0.73 (95% CI: 0.60–0.87). Conclusion. Post-methanol ingestion a large osmolal gap, anion gap and low pH (<7.22) were associated with increased mortality; and pH has the highest predictive value. Post-ethylene glycol ingestion, both osmolal gap and anion gap were associated with increased mortality.

Involvement of urinary proteins in the rat strain difference in sensitivity to ethylene glycol-induced renal toxicity

Ethylene glycol (EG) exposure is a common model for kidney stones, because animals accumulate calcium oxalate monohydrate (COM) in kidneys. Wistar rats are more sensitive to EG than Fischer 344 (F344) rats, with greater COM deposition in kidneys. The mechanisms by which COM accumulates differently among strains are poorly understood. Urinary proteins inhibit COM adhesion to renal cells, which could alter COM deposition in kidneys. We hypothesize that COM accumulates more in Wistar rat kidneys because of lower levels of inhibitory proteins in urine. Wistar and F344 rats were treated with 0.75% EG in drinking water for 8 wk. Twenty-four-hour urine was collected every 2 wk for analysis of urinary proteins. Similar studies were conducted for 2 wk using 2% hydroxyproline (HP) as an alternative oxalate source. Total urinary protein was higher in F344 than Wistar rats at all times. Tamm-Horsfall protein was not different between strains. Osteopontin (OPN) levels in Wistar urine and kidney tissue were higher and were further increased by EG treatment. This increase in OPN occurred before renal COM accumulation. Untreated F344 rats showed greater CD45 and ED-1 staining in kidneys than untreated Wistars; in contrast, EG treatment increased CD45 and ED-1 staining in Wistars more than in F344 rats, indicating macrophage infiltration. This increase occurred in parallel with the increase in OPN and before COM accumulation. Like EG, HP induced markedly greater oxalate concentrations in the plasma and urine of Wistar rats compared with F344 rats. These results suggest that OPN upregulation and macrophage infiltration do not completely protect against COM accumulation and may be a response to crystal retention. Because the two oxalate precursors, EG and HP, produced similar elevations of oxalate, the strain difference in COM accumulation may result more so from metabolic differences between strains than from differences in urinary proteins or inflammatory responses.

Renal toxicity of ethylene glycol results from internalization of calcium oxalate crystals by proximal tubule cells

Ethylene glycol exposure can lead to the development of renal failure due to the metabolic formation of calcium oxalate monohydrate (COM) crystals. The renal damage is closely linked to the degree of COM accumulation in the kidney and most likely results from a COM-induced injury to proximal tubule (PT) cells. The present studies have measured the binding and internalization of COM by primary cultures of normal PT cells from humans and from Wistar and Fischer-344 rats in order to examine the roles of these uptake processes in the resulting cytotoxicity. Internalization was determined by incubation of cells with [ 14C]-COM at 37 °C, removal of bound COM with an EDTA incubation, followed by solubilization of cells, as well as by transmission electron microscopy of COM-exposed cells. COM crystals were internalized by PT cells in time- and concentration-dependent manners. COM crystals were bound to and internalized by rat cells about five times more than by human cells. Binding and internalization values were similar between PT cells from Wistar and Fischer-344 rats, indicating that a differential uptake of COM does not explain the known strain difference in sensitivity to ethylene glycol renal toxicity. Internalization of COM correlated highly with the degree of cell death, which is greater in rat cells than in human cells. Thus, surface binding and internalization of COM by cells play critical roles in cytotoxicity and explain why rat cells are more sensitive to COM crystals. At the same level of COM accumulation after ethylene glycol exposure or hyperoxaluria in vivo, rats would be more susceptible than humans to COM-induced damage.

Ethylene Glycol and Glycolic Acid in Postmortem Blood from Fatal Poisonings

Ethylene glycol (EG), a relatively infrequent cause of fatal intoxication, presents an analytical challenge for forensic confirmation in postmortem toxicology. We report EG and glycolic acid (GA) quantification in postmortem blood by gas chromatography coupled with ion trap mass spectrometry (GC-MS) analysis using a modification of a previously reported clinical method. The method is linear from 50 to 4000 mg/L with a limit of detection of 25 mg/L for both EG and GA. Interassay coefficient of variation (2.1-8.6%, 4.3-6.0%) and accuracy (96-101%, 92-105%) were determined for EG and GA, respectively. EG concentration by ion trap GC-MS correlated closely (R(2) = 0.995) with EG quantified by GC-flame-ionization detection. Analysis of blood from 20 autopsies with no evidence of EG exposure did not reveal detectable EG or GA. In 12 medical examiner cases with EG poisoning as cause of death, EG concentrations ranged widely from 58 to 7790 mg/L with a mean of 1830 mg/L, and the GA concentration averaged 1360 mg/L with a narrower range of 810-1770 mg/L. EG and GA levels correlate poorly (R(2) = 0.15) in postmortem blood with discordantly low EG concentrations in two cases. Birefringent oxylate crystals in renal tissue was a consistent finding. In conclusion, a sensitive and specific GC-MS method for detection and quantification of EG and GA has been validated and a study of fatal EG poisonings revealed forensic application of the method.

Strain differences in urinary factors that promote calcium oxalate crystal formation in the kidneys of ethylene glycol-treated rats

Ethylene glycol (EG)-induced hyperoxaluria is the most commonly employed experimental regimen as an animal model of calcium oxalate (CaOx) stone formation. The variant sensitivity to CaOx among different rat strains has not been fully explored, although the Wistar rat is known to accumulate more CaOx in kidney tissue after low-dose EG exposure than in the Fischer 344 (F344) rats. Supersaturation of CaOx in tubular fluid contributes to the amount of CaOx crystal formation in the kidney. We hypothesized that the urinary supersaturation of CaOx in Wistar rats is higher than that of F344 rats, thereby allowing for greater CaOx crystal deposition in the Wistar rat. Age-matched male Wistar and F344 rats were treated with 0.75% EG or drinking water for 8 wk. Twenty-four-hour urine was collected at 0, 2, 4, 6, and 8 wk for analysis of key electrolytes to calculate the CaOx supersaturation. Plasma oxalate level was also measured. Our data confirmed the different sensitivity to renal toxicity from EG between the two rat strains (Wistar > F344). After EG treatment, the plasma oxalate level and urine oxalate excretion were markedly greater in the Wistar rats than in the F344 rats, while urine calcium was slightly decreased in Wistars. Thus, the CaOx supersaturation in urine of Wistar rats was higher, which led to a greater crystal deposition in kidney in Wistar rats. These studies suggest that during EG treatment, changes in urine electrolytes and in CaOx supersaturation occur to a greater extent in the Wistar rat, in agreement with its greater sensitivity to EG toxicity.

Species‐specificity of ethylene glycol‐induced developmental toxicity: toxicokinetic and whole embryo culture studies in the rabbit

High-dose gavage exposure to ethylene glycol (EG) is teratogenic in rats, but not rabbits. To investigate the reason for this species difference, toxicokinetic and whole embryo culture (WEC) studies were conducted in gestation day 9 New Zealand White rabbits, and the data compared to very similar data previously generated in pregnant rats. In the toxicokinetic study, maximal levels of unchanged EG in rabbits were comparable to those reported for rats. However, maximal levels of EG's teratogenic metabolite, glycolic acid (GA), in rabbit maternal blood and embryo were only 46% and 10% of the respective levels in rats. The toxicokinetic profile suggested that the lower GA levels in rabbits were due to a slower rate of maternal metabolism of EG to GA, slow uptake of GA into the yolk sac cavity fluid which surrounds the embryo, and negligible transfer via the visceral yolk sac (VYS) placenta. In the WEC study, exposure of rabbit conceptuses to high concentrations (< or = 12.5 mM) of GA was without effect, which contrasts with reported effects in rat WEC at > or = 3 mM. Overall, these data implicate toxicokinetics as an important factor underlying the species difference, although intrinsic insensitivity of the rabbit embryo might also be involved. Integration of these findings with published human data suggest that the rabbit is the more relevant model for human EG exposure, based on the negligible role of the rabbit VYS in placental transfer (humans lack a VYS) and similar rates of EG metabolism and extraembryonic fluid turnover.

Permeability of human oocytes to ethylene glycol and their survival and spindle configurations after slow cooling cryopreservation

To develop novel cryopreservation methods, we estimated the permeability coefficients Lp (hydraulic conductivity) and P(EG) (cryoprotectant permeability) of mature human oocytes after exposure to ethylene glycol (EG) and tested the efficiency of a multi-step slow cooling protocol based on this cryoprotectant. Oocytes were perfused with 1.5 mol/l EG for 10 min. Oocyte volume at each time point was calculated and normalized to the original volume. Slow cooling was conducted by exposing oocytes to increasing EG concentrations (0.5, 1.0 and 1.5 mol/l n = 155) or 1.5 mol/l of propane-1,2-diol (PrOH) n = 102. Oocytes which survived cryopreservation n = 80 and fresh oocytes n = 73 were prepared for confocal microscopy analysis of the meiotic spindle. During EG exposure, oocytes underwent an abrupt 50% volume reduction. Complete recovery of the initial volume was not observed. From the values of a best fit plot, the coefficients Lp = 0.82 +/- 0.29 microm min(-1) atm(-1) (mean +/- SD) and P(EG) 0.10 +/- 0.01 microm s(-1) were generated. Survival rates after freezing with EG were lower than with PrOH (51.6 versus 71.5%, respectively, P < 0.05). The frequencies of normal spindle configuration were lower in frozen EG and frozen PrOH oocytes compared with fresh oocytes (53.8, 50.9 and 66.7%, respectively, P < 0.05). The oocyte plasmalemma possesses limited permeability to EG and EG exposure causes considerable osmotic stress. However, post-thaw rates of survival and normal meiotic spindle organization may be preserved by protocols which are designed in order to minimize osmotic stress.