Combined toxicity of methanol and formic acid: two cases of methanol poisoning

Assay of short-chain carboxylic acids in plasma and urine using gas chromatography after extractive alkylation

After extractive alkylation combined with plasma deproteinization, we used gas chromatography to assay for short-chain carboxylic acids from formic acid to valeric acid in plasma and urine. It was possible to provide highly sensitive analysis with 0.1-3.4 µg/mL as the limit of detection for plasma and 0.6-8.0 µg/mL for urine, with a correlation coefficient of 1.000 for the linear regression calibration curves. For plasma, deproteinization using ultrafiltration before extractive alkylation resulted in a higher sensitivity for acetic, propionic, butyric, and valeric acids compared with the method without deproteinization. The concentrations of formic acid and acetic acid were determined to be 6 µg/mL and 10 µg/mL, respectively, in the tested plasma, and 22 µg/mL and 32 µg/mL, respectively, in the tested urine. Concentrations from propionic acid to valeric acid were ≤ 1.3 µg/mL. In addition, high concentrations of sulfate, phosphate, hydrogen carbonate, ammonium, and/or sodium ions did not remarkably inhibit the derivatization of carboxylic acids, although hydrogen carbonate ions significantly inhibited that of formic acid.

Fatal methanol poisoning with different clinical and autopsy findings: Case report and literature review

Methanol poisoning is responsible for high morbidity and mortality, and the elevated concentration of methanol in the body is the major criteria for forensic diagnosis of methanol poisoning. However, in cases with lower methanol concentrations, diagnosis is mainly dependent on highly variable postmortem manifestations.Herein, we report a fatal methanol poisoning cases that two subjects ingested the same amount of methanol simultaneously, yet the subject one presented only non-specific gastrointestinal and mild central nervous system symptoms, while the other subject exhibited typical toxic manifestations with the exception of visual compromise. In autopsy, subject number 1 did not show typical pathological changes caused by methanol poisoning, except for the elevated levels of methanol in body fluids. On the contrary, bilateral basal ganglia hemorrhage and necrosis caused by methanol-induced brain lesion was observed in case number 2. Due to the complex and multifactorial process of methanol intoxication, many factors, including comprehensive autopsy, quantitative detection of methanol and formic acid, and genotype analysis, participate in its metabolism and toxicity, and can impact the clinical symptoms, prognosis and postmortem manifestations. Therefore, a combination of multiple diagnosis methods may more accurately contribute to the forensic diagnosis of methanol poisoning and should be tailored on an individual basis. This case report also reviews forensic diagnosis literature on methanol poisoning to provide a reference for forensic pathologists.

Methanol and ethylene glycol intoxication

Accidental or intentional ingestion of substances containing methanol and ethylene glycol can result in death, and some survivors are left with blindness, renal dysfunction, and chronic brain injury. However, even in large ingestions, a favorable outcome is possible if the patient arrives at the hospital early enough and the poisoning is identified and appropriately treated in a timely manner. This review covers the common circumstances of exposure, the involved toxic mechanisms, and the clinical manifestations, laboratory findings, and treatment of methanol and ethylene glycol intoxication.

Fatal methanol poisoning

Methanol poisoning has become a considerable problem in Iran. Liver can show some features of poisoning after methanol ingestion. Therefore, our concern was to examine liver tissue histopathology in fatal methanol poisoning cases in Iranian population. In this study, 44 cases of fatal methanol poisoning were identified in a year. The histological changes of the liver were reviewed. The most striking features of liver damage by light microscopy were micro-vesicular steatosis, macro-vesicular steatosis, focal hepatocyte necrosis, mild intra-hepatocyte bile stasis, feathery degeneration and hydropic degeneration. Blood and vitreous humor methanol concentrations were examined to confirm the proposed history of methanol poisoning. The majority of cases were men (86.36%). In conclusion, methanol poisoning can cause histological changes in liver tissues. Most importantly in cases with mean blood and vitreous humor methanol levels greater than 127 ± 38.9 mg/dL more than one pathologic features were detected.

Fatal methanol poisoning: features of liver histopathology

Methanol poisoning has become a considerable problem in Iran. Liver can show some features of poisoning after methanol ingestion. Therefore, our concern was to examine liver tissue histopathology in fatal methanol poisoning cases in Iranian population. In this study, 44 cases of fatal methanol poisoning were identified in a year. The histological changes of the liver were reviewed. The most striking features of liver damage by light microscopy were micro-vesicular steatosis, macro-vesicular steatosis, focal hepatocyte necrosis, mild intra-hepatocyte bile stasis, feathery degeneration and hydropic degeneration. Blood and vitreous humor methanol concentrations were examined to confirm the proposed history of methanol poisoning. The majority of cases were men (86.36%). In conclusion, methanol poisoning can cause histological changes in liver tissues. Most importantly in cases with mean blood and vitreous humor methanol levels greater than 127 ± 38.9 mg/dL more than one pathologic features were detected.

Metabolic acidosis in a patient with type 1 diabetes mellitus complicated by methanol and amitriptyline intoxication

Diabetic ketoacidosis (DKA) is a widely known acute metabolic complication of diabetes mellitus (DM), which can be potentially fatal. It is not difficult to diagnose when a patient with DM comes with symptoms such as coma, fruity breath, hyperglycemia, acidosis, and tachypnea. If the patient has not been diagnosed with DM before, then other sicknesses characterized by an increased anion gap should be considered. A 12-year-old boy with type 1 DM and repeated earlier admissions for DKA was admitted to the emergency department in another apparent case of DKA with coma, hyperglycemia, and profound metabolic acidosis. When his condition did not improve with initial treatment, intoxication was suspected as an alternate cause of his condition. Further laboratory tests detected methanol and amitriptyline. The patient underwent hemodialysis and recovered completely. This case illustrates that a seemingly obvious medical condition can mask serious intoxication. This report is the only publication on two different entities characterized by an increased anion gap and at the end the patient has been cured completely without any complications.

Glial fibrillary acidic protein (GFAP) and CD34 expression in the human optic nerve and brain in methanol toxicity

INTRODUCTION

The toxicity of methanol is as a result of its metabolites, formaldehyde and formic acid. Formic acid induces severe metabolic acidosis causing death, and is the primary agent responsible for ocular toxicity. Glial fibrillary acidic protein (GFAP) immunostaining is the most commonly used method for examining astrocyte proliferation and hypertrophy after various central nervous system injuries. The antigen CD34 is expressed widely on vascular endothelium, including that of the central nervous system and high endothelial venules.

METHODS

In this study, GFAP and CD34 were immunohistochemically localised in the post-mortem optic nerve head, and brain tissue (basal ganglia putamen) samples were collected from methanol-exposed and non-methanol-exposed (control) subjects.

RESULTS

There was a positive correlation between the GFAP and CD34 intensity of staining scores in the methanol-exposed group (P=0.711, P=0.010). Furthermore, there was also a positive correlation between the brain putamen and optic nerve head GFAP extent of staining in the methanol-exposed group (P=0.720, P=0.008). A statistically significant difference was found between the methanol-exposed group and the control group optic nerve CD34 intensity scores (P=0.014), but no significant difference was found between optic nerve CD34 and GFAP extent scores (P=0.05).

CONCLUSION

The study revealed that methanol affects brain putamen and the optic nerve selectively. We detected a positive significant correlation between brain and optic nerve GFAP expression. CD34 expression was markedly decreased by the toxic effects of methanol.

Methanol related deaths in Edirne

In this retrospective autopsy study, a detailed analysis of methanol related deaths in Trakya region of Turkey is presented and departmental autopsy records, toxicology and histopathology results are analyzed. We found that methanol poisonings comprise 2.83% of all forensic autopsies (n:18), 88.8% of the cases were male, most of the victims were aged between 41 and 45. Blood methanol concentrations range widely from 55 to 479 mg per 100ml. Ethyl alcohol was detected in 44.4% of the cases. Most of the cases died in hospital and were poisoned through the consumption of alcoholic beverages from illicit sources and colognes. It is important for physicians to be aware of methanol poisoning symptoms and for forensic pathologists to obtain samples for toxicology during autopsies. Some preventative strategies including to routine control of the stores, to prevent the production of illegal alcoholic beverages, etc. should be developed.

Simultaneous determination of formate and acetate in whole blood and urine from humans using gas chromatography–mass spectrometry

We devised a sensitive and simple method for simultaneous determination of formate and acetate in whole blood and urine from humans using gas chromatography-mass spectrometry. Formate and acetate were alkylated with pentafluorobenzyl bromide in the mixture of acetone and phosphate buffer (pH 6.8). The derivatives obtained were analyzed using gas chromatography-mass spectrometry in positive-ion electron ionization (EI) mode. The lower limit of detection for both compounds was 0.02mM. The calibration curves for formate and acetate were linear over the concentration range from 0.05 to 5.0mM. Accuracy and precision of the method were evaluated and the coefficients of variation were within 10%. With use of this method, levels of formate and acetate in whole blood can be determined in forensic cases.

The influence of L-carnitine on methanol biotransformation in rats

There persists a need for potent and safe inhibitors of alcohol dehydrogenase (ADH), to effectively treat methanol poisoning by slowing its rate of biotransformation to there toxic products, formaldehyde and formic acid. Only a few former papers have reported on the significant effectiveness of L-carnitine in treating ethanol poisoning as well as alcohol abuse. As are no reports on the effectiveness of L-carnitine in treating methanol poisoning till now, the current studies were conducted to investigate the influence of L-carnitine on both oxydative metabolism and elimination of methanol in rats. Male Sprague-Dawley rats, aged 3 months with the body weight of 200-230 g were divided into 6 groups at random, with two of the groups considered to be control. Rats were given drinking water (control) or methanol in two different doses of 3220 mg/kg b.m. or 6440 mg/kg b.m. intragastrically and 0.9% NaCl (control) or 6.2 mmol/kg b.m. of L-carnitine intraperitionelly. Within 96 hours after the administration of methanol and 0.9% NaCl or L-carnitine, the urine was collected and then the animals were decapitated. To determine methanol there were taken blood samples for clot, and to determine carnitine and its derivatives blood was taken into heparinized test tubes. During the autopsy liver was also secured. In all the experimental time points stated the methanol concentrations in blood, urine and liver homogenate were determined by a head-space gas chromatography.

Determination of formic acid tissue and fluid concentrations in three fatalities due to methanol poisoning

Three fatalities caused by methanol ingestion are reported. Admission blood methanol concentrations ranged from 0.28 to 4.6 g/L. Two patients had been admitted after a significant delay (>20 hours), and one patient was observed within 90 minutes following ingestion. Formic acid levels were determined in blood samples at admission and ranged from 302 to 680 mg/L. The patients died 44, 55, and 82 hours after poisoning. Formic acid determinations in postmortem tissues were performed by a gas chromatograph method. The authors found great variability in formic acid distribution among the patients and among organs.