Induction of squamous cell carcinomas of the rat nasal cavity by inhalation exposure to formaldehyde vapor.

Groups of 120 male and 120 female rats were exposed by inhalation to 0, 2, 6, or 15 ppm formaldehyde vapor 6 hr/day, 5 days/week, for 18 months of a 24-month study. The present communication describes interim findings based on data available after 18 months of exposure. Squamous cell carcinomas occurred in the nasal cavities of 36 rats exposed to 15 ppm formaldehyde. The tumors ranged from small early carcinomas of the nasal turbinate to large invasive osteolytic neoplasms which extended into the subcutis of the premaxilla. Similar tumors were not detected in rats exposed for 18 months to 2 or 6 ppm or in mice exposed to 2, 6, or 15 ppm formaldehyde. Rhinitis, epithelial dysplasia, and squamous metaplasia occurred in rats from all exposure levels of formaldehyde; however, the severity and extent of the lesions were dose related. In contrast, papillary hyperplasia and squamous atypia occurred only in animals exposed to 15 ppm formaldehyde.

Carcinogenicity of formaldehyde in rats and mice after long-term inhalation exposure.

Groups of approximately 120 male and 120 female Fischer 344 rats and C57BL/6 X C3H F1 mice were exposed by inhalation to 0, 2.0, 5.6, and 14.3 ppm of formaldehyde gas 6 hr/day, 5 days/week, for 24 months. This exposure period was followed by up to 6 months of nonexposure. Interim sacrifices were conducted at 6, 12, 18, 24, 27, and 30 months. Significant formaldehyde-induced lesions were restricted to the nasal cavity and proximal trachea. The distribution and severity of these lesions were concentration dependent. Rhinitis, epithelial dysplasia, and squamous metaplasia occurred in all exposure groups of rats and in the intermediate and high exposure groups of mice. There was regression of rhinitis, dysplasia, and metaplasia at 27 months (3 months postexposure) in the 14.3- and 5.6-ppm groups of mice and in the 2.0- and 5.6-ppm groups of rats. Squamous cell carcinomas were observed in the nasal cavities of 103 rats (52 females and 51 males) and 2 male mice exposed to 14.3 ppm and in 2 rats (one male and one female) exposed to 5.6 ppm of formaldehyde gas. Formaldehyde inhalation was also weakly associated with an increase in the frequency of polypoid adenomas in the nasal cavity of male rats.

SR-12813 lowers plasma cholesterol in beagle dogs by decreasing cholesterol biosynthesis.

SR-12813 inhibits cholesterol biosynthesis in Hep G2 cells via an enhanced degradation of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. Here we also show that SR-12813 inhibits cholesterol biosynthesis in vivo. A sterol balance study was performed in normolipemic beagle dogs. The dogs were given SR-12813 orally at dosages of 10 and 25 mg/kg/day for a period of 9 days. After 7 days plasma cholesterol was decreased by 15% in the 10 mg/kg/day group and by 19% in the 25 mg/kg/day group. Using a dual isotope technique no effects on intestinal cholesterol absorption were observed. The sterol balance indicated that endogenous synthesis of cholesterol was reduced by 23% in the 10 mg/kg/day group and by 37% in the 25 mg/kg/day group. Plasma lathosterol-cholesterol levels in dogs treated with 25 mg/kg/day SR-12813 were reduced by 56%, confirming a reduction of the cholesterol biosynthesis. Treatment with SR-12813 or the HMG-CoA reductase inhibitor lovastatin resulted in a large decrease in low density lipoprotein (LDL) cholesterol. It is concluded that SR-12813 reduces cholesterol biosynthesis in the dog model which results in a decrease of bile acid excretion, cholesterol excretion and plasma cholesterol level. The in vivo profile of SR-12813 is very similar to that of direct HMG-CoA reductase inhibitors, although the mode of action of the compound is unique.

Evidence of foam cell and cholesterol crystal formation in macrophages incubated with oxidized LDL by fluorescence and electron microscopy.

Macrophage-derived foam cells are a prominent component of developing atherosclerotic lesions. We describe an in vitro model of foam cell formation which mimics some aspects of the evolution of foam cells in mature atherosclerotic lesions. Thioglycollate-elicited mouse peritoneal macrophages were incubated with copper-oxidized LDL (ox-LDL) for periods up to 168 hr. Identifiable foam cells were present after incubation with ox-LDL at 24, 72, and 168 hr. Control cells incubated without ox-LDL did not form foam cells. Fluorescence microscopy after staining with Nile red exhibited progressive accumulation of lipids, and transmission electron microscopy (TEM) showed distinct ultrastructural changes over time. Macrophages at 24 hr had a few non-membrane-bound lipid droplets but were otherwise identical to control cells. These lipid droplets fluoresced yellow-gold after Nile red staining. After 72 hr of incubation with ox-LDL, in addition to increased numbers of non-membrane-bound lipid inclusions, macrophages contained membrane-bound multilamellar lipoid structures. These multilamellar structures corresponded to areas of reddish-orange fluorescence after Nile red staining. In macrophages incubated with ox-LDL for 168 hr, the amount of cellular lipid was further increased and cholesterol crystal profiles were apparent within some multilamellar lipoid structures. Biochemical analysis showed that the total cholesterol content steadily increased over 168 hr. The increase in total cholesterol was accompanied by a dramatic increase in free cholesterol between 72 and 168 hr. These results demonstrate that long-term incubation of macrophages with ox-LDL increased lipid deposition in cultured cells and that, under the conditions studied, cholesterol crystals formed in macrophage foam cells. Moreover, this system allows investigation of the evolution of foam cells showing some characteristics of those found in atherosclerotic lesions.

A novel technique for mapping the lipid composition of atherosclerotic fatty streaks by en face fluorescence microscopy.

We introduce here a new fluorescence microscopy technique for en face analysis of the atherosclerotic fatty streaks (FS). This technique is semiquantitative and has the sensitivity and resolution to map lipids to individual cells in FS less than 100 microns in diameter. New Zealand White rabbits were fed an atherogenic diet for up to 26 weeks. Aortas were fixed in formalin and stained en bloc with the fluorescent dyes Nile red and filipin. Fluorescent staining was validated by correlating microfluorimetric and biochemical measurements of the lipid content in FS. To determine the cell types associated with the different staining patterns, FS were also evaluated by transmission electron microscopy (TEM) and immunohistochemistry (IH). Correlation of microfluorimetry, TEM, IH, and biochemical data indicated that regions rich in non-esterified cholesterol stained with filipin and fluoresced blue owing to accumulations of lipid vesicles and/or cholesterol crystals. Regions rich in neutral and polar lipids stained with Nile red and fluoresced yellow or orange, respectively, owing to accumulations of lipids in both macrophages and smooth muscle cells (SMC). Digital overlays of the filipin and Nile red images revealed that larger lesions (> 0.5 mm diameter) had a "nested" distribution of lipids, with a blue (filipin) fringe surrounding an orange (Nile red) fringe surrounding a yellow (Nile red) center.

In vivo inhibition of oxidative drug metabolism by, and acute toxicity of, 1-aminobenzotriazole (ABT). A tool for biochemical toxicology.

One hour following intravenous pretreatment of rats with 50 mg/kg of the cytochrome P-450 suicide substrate 1-aminobenzotriazole (ABT), the metabolism of phenacetin to acetaminophen is inhibited completely [B. A. Mico et al., Drug Metab. Dispos. 15, 274 (1987)]. Here we report an examination of the time-course of inhibition of phenacetin elimination by ABT, a demonstration of dose-dependent inhibition of phenacetin and antipyrine clearances by ABT, and an examination of the acute toxicity of ABT in rats, as well as the effect of ABT on phenacetin metabolism in beagles. After a 1-, 12-, 24- or 36-hr pretreatment of rats with ABT (50 mg/kg, i.v.), the clearance of phenacetin was decreased 85, 88, 81 and 48%, respectively, from control values. Twelve hours after intraperitoneal pretreatment of rats with 0.3, 1.0, 5.0, 20, and 50 mg/kg of ABT, the total systemic clearance of phenacetin was suppressed 39, 47, 60, 75, and 79%, respectively, from control values. The clearance of intravenously administered antipyrine was decreased 38 and 66% after a 12-hr intraperitoneal pretreatment of rats with 10 or 50 mg/kg of ABT. In rats, no hematological, clinical chemistry, macroscopic, or microscopic abnormalities were detected 1, 2, 3, and 9 days after a single i.v. dose of ABT (50 mg/kg). A 1-hr pretreatment of beagles with ABT (20 mg/kg) decreased the clearance of intravenous phenacetin 50% and completely prevented the formation of acetaminophen. These results demonstrate that ABT pretreatment causes long-lasting inhibition of oxidative drug metabolism without disruption of normal physiological processes. Profound inhibition of oxidation in two species suggests that ABT may have general utility as an inhibitor of oxidative drug metabolism in biochemical pharmacology and toxicology studies.

Altered hemostasis in male rats following administration of the ACAT inhibitor SKF-99085.

SKF-99085, an acyl-CoA:cholesterol acyltransferase (ACAT) was evaluated in male and female Sprague-Dawley rats at oral doses of 0, 10, 100, or 400 mg/kg/day for 6 months as part of the preclinical safety assessment of this drug candidate. In male rats given 400 mg/kg/day SKF-99085, hemorrhage and death were observed in males during the first month of the study, prompting collection of blood samples at weeks 6, 17, and 24 to monitor coagulation parameters. A dose-related increase in activated partial thromboplastin time (APTT) and Thrombotest clotting time (TCT) was observed in all male drug-treated groups. Mean APTT values for male rats given 10, 100, or 400 mg/kg/day were increased maximally to 17.5, 20.8, and 34.7 s (control, 15.4-16.0 s), and mean TCT values were increased to 86, 100, and >300 s (control, 71-74 s), respectively. Mean prothrombin times (PT) for male rats given 400 mg/kg/day were increased to 16.5 s (control, 12.9-13.1 s). Activities of factors II, VII, IX, and X were decreased in males at dosages of 10, 100, or 400 mg/kg/day. Factor V and VIII activities were unaffected. In summary, the drug-related hemorrhagic disorder observed in male rats given high doses of the ACAT inhibitor SKF 99085 was attributed to a reduction in the activity of vitamin-K-dependent coagulation factors. In contrast to humans and some other species, the APTT and TCT were more sensitive than the PT in detecting this effect.

Multiple organ mutation in the lacZ transgenic mouse (Muta mouse) 6 months after oral treatment (5 days) with benzo[a]pyrene.

We have recently demonstrated that not all organs with high rates of mutation in the lacZ transgene develop tumors using the Muta Mouse. To better understand the role of in vivo mutation in carcinogenesis, we examined the mutant frequencies (MF) of the lacZ transgene in tumor-bearing and non tumor-bearing organs. MF, recovered after 2 weeks (the data taken from our previous study) and after 26 weeks following oral doses of 125 mg kg-1 day-1 benzo[a]pyrene (BP) for five days were compared. The organs examined included the target organs (forestomach, spleen, and lung) and non-target organs (colon, glandular stomach, and liver) for BP carcinogenesis. The data indicated that lacZ MF were markedly increased over spontaneous frequencies in the organs examined and that the organ which showed the highest MF was the colon, followed by the forestomach>spleen>glandular stomach, liver, and lung in that order. These findings indicate that the MF of the lacZ transgene in each organ, even 26 weeks after the start of the treatment does not fully correlate with the known target organs of BP. Furthermore, the lacZ MF in a non-papilloma region of a forestomach with a papilloma was equivalent to the two highest MF observed in the healthy colon (non-target organ) of mice at 26 weeks. These observations also indicate that the generation of tumors requires the induction of mutations as well as other factor(s) specific to the target organs. These results clearly suggest that highly mutated organs do not always progress to tumors in the transgenic mouse.

The effect of hypertonic sodium and dantrolene on propranolol cardiotoxicity.

OBJECTIVE: To evaluate whether measures that lower cytosolic calcium (Ca) can reverse propranolol (PROP) toxicity in the isolated, perfused rat heart. METHODS: Isolated rat hearts were perfused on a Langendorff apparatus with Krebs-Henseleit-bicarbonate (KHB) buffer solution. Toxicity was produced by perfusing the hearts with PROP (5 micrograms/mL) for 30 minutes. Subsequently, the hearts were treated for 30 minutes with buffer containing PROP plus experimental treatment. Three treatments were chosen: hypertonic sodium (Na) (160 mmol), to stimulate Na-Ca exchange, dantrolene (DAN) (10 mumol), to inhibit Ca release from sarcoplasmic reticulum, and combined hypertonic Na and DAN. The hearts were paced after 20 minutes of treatment. Heart rate (HR), left ventricular peak systolic pressure (LVP), the first derivative of LVP (dP/dt), and coronary flow were measured. RESULTS: PROP decreased HR and rendered the hearts refractory to pacing. PROP did not alter dP/dt. PROP increased LVP consistent with increased cytosolic Ca. Combined hypertonic Na and DAN treatment restored the ability to pace PROP-toxic hearts to the basal HR. Individually, hypertonic Na or DAN treatment partially restored the ability to pace toxic hearts. As experimental treatments increased HR, dP/dt and LVP decreased, consistent with decreased cytosolic Ca availability. CONCLUSION: These data are consistent with the hypothesis that bradycardia during beta-blocker cardiotoxicity is mediated by altered Ca homeostasis.

Tolerability, pharmacokinetics and concentration-dependent hemodynamic effects of oral CF101, an A3 adenosine receptor agonist, in healthy young men.

OBJECTIVES: To assess safety, tolerability, pharmacokinetics and hemodynamic effects of oral CF 101, an A3 adenosine receptor (A3AR) agonist, in healthy men. METHODS: One single and 1 repeated dose, parallel-group, ascending dose, double-blind and placebo-controlled study in normal volunteers. In the single dose study, n = 15 subjects received 1, 5 or 10 mg oral CF101; in each group 1 subject received placebo, the remainder active CF101. In the repeat-dose study, n = 28 subjects received repeated 12-hourly oral doses of CF 101 (2, 3, 4 or 5 mg) for 7 days, in each group 2 subjects received placebo, the remainder active CF101. TEST MATERIALS: Single-dose study: CF101 in 30% Cremophor RH40. Multiple-dose sudy: CF101 in 0.5% methylcellulose suspension. Both studies: the corresponding vehicles were used as placebos. Galenicals were prepared remotely from the clinical study site to ensure double-blind nature of the study. RESULTS TOLERABILITY: Single doses up to 5 mg CF101 were safe and well-tolerated. However, the single dose of 10 mg CF101 was associated with flushing, tachycardia, nausea and vomiting, which were viewed as dose-limiting in normal volunteers. Single doses of CF101 (as well as the first of the multiple doses) were associated with increases in heart rate (8 - 24 beats/min after 5 mg and 18 - 55 beats/min after 10 mg). Multiple doses up to 4 mg 12-hourly for 7 days were safe and well-tolerated. However, the 5 mg multiple-dose group reported headache, drowsiness, hot flushes and dizziness on standing; this declined with dosing duration and was not dose-limiting in this study. Adverse events were commonest near t(max). RESULTS PHARMACOKINETICS: For oral CF101, the t(max) was always 1 - 2 h post-dose and t 1/2 about 9 h, in both the single- and multiple-dose studies. For a single 5 mg dose (mean +/- SD) C(max) = 81.6 +/- 23.6 ng/ml in the single dose study, and 63.6 +/- 22.0 ng/ml after the first of the multiple doses; AUC if was 904.0 +/- 221.9 ng.h/ml and 596.1 +/- 196.6 ng.h/ml for the 2 studies, respectively. After 7 days of multiple dosing there was little change, and AUC(0-24h) = 601.0 +/- 163.6 ng.h/ml. These pharmacokinetic parameters were linearly proportional to dose in the other treatment groups. RESULTS PHARMACODYNAMICS: Increases in heart rate were related to plasma concentration and evident only in the upper range of concentrations observed. There were no changes on ECG monitoring beyond sinus tachycardia, and, in particular, no evidence of PR prolongation in any subject (n = 43). In comparison with single doses, this response was almost absent after 7 days of dosing. Leucocytosis (increases up to about 1.5 x 10(9)/l after 5 and 10 mg) was similarly transient and reversible after multiple dosing. CONCLUSIONS: Single oral doses up to 5 mg CF101 and repeated doses up to 4 mg 12-hourly for 7 days were safe and well-tolerated. Multiple-dose CF101 pharmacokinetics were unchanged and predictable from single-dose estimates, and were linearly proportional to dose. Increases in heart rate and neutrophil count were reversible during multiple dosing and were not dose-limiting in the repeat dose study. CF101 warrants further study for its efficacy in treating human disease.

Beta-blocker and calcium channel blocker toxicity.

Toxicity from beta-blocker and calcium channel blocker drugs is a challenging medical emergency with steadily increasing incidence. Clinical manifestations of intoxication with these drugs are presented in light of known pharmacologic and pharmacokinetic properties, as well as the physiology of the beta-adrenoreceptor and calcium channel. Review of clinical and basic science literature provides the basis for specific management guidelines for beta-blocker and calcium channel blocker toxicity.

Airway obstruction following canebrake rattlesnake envenomation.

We report an unusual case of canebrake rattlesnake (Crotalus horridus atricaudatus) envenomation whose major manifestation was orolingual edema and airway compromise. The likely source of swelling was mucosal absorption of venom following the first aid technique of cutting and sucking the bite site. Except for airway compromise, the patient had mild local bite site effects (swelling) and mild systemic findings (depressed fibrinogen and elevated creatinine phosphokinase). He was managed with fiberoptic nasotracheal intubation and Crotalid antivenin with good outcome.

Cocaine-induced wide complex dysrhythmia.

Cocaine is a local anesthetic with the potential to induce dysrhythmia due to direct myocardial sodium channel antagonism similar to class I antidysrhythmic drugs. The hallmark of myocardial sodium channel poisoning is wide complex dysrhythmia, and the current accepted treatment is intravenous bicarbonate. Wide complex dysrhythmio due to cocaine in the absence of myocardial infarction is rare, and optimum management is undefined. We report three cases of acute cocaine intoxicating during which patients developed wide complex dysrhythmia consistent with sodium channel poisoning. In one case, wide complex tachycardia resolved without direct treatment. In the other cases, wide complex dysrhythmia resolved following intravenous bicarbonate therapy directed at reversing sodium channel blockade.

Incidence of aspiration pneumonia in intubated patients receiving activated charcoal.

Several case reports and animal studies raise concerns over the risk of aspiration pneumonia when administering activated charcoal (AC) to intubated patients. Therefore, we sought to determine the incidence of aspiration pneumonia in intubated overdose patients who then received AC. We conducted a retrospective review from January 1994 to April 1997 of intubated patients who then received AC. Patients were transferred to, or primarily treated at, an 843-bed tertiary medical center with an annual emergency department volume of 100,000 patients. Objective evidence of infiltrate on chest radiograph during initial 48 h of hospitalization was used to determine the incidence of aspiration pneumonia. Patients with known preexisting pneumonia or with administration of AC before intubation were excluded. There were 64 patients identified. Fourteen were excluded for clinical aspiration before intubation, receiving activated charcoal before intubation, or abnormal immediate post-intubation chest radiographs. The remaining 50 patients, ages 1-64 years, 33% male, overdosing on a large variety of substances, required acute intubation and then received AC. Only two patients of these 50 (4%) with initial negative radiographs developed a new infiltrate after intubation and AC. Administration of AC to intubated overdose patients is associated with a low incidence of aspiration pneumonia.

Protection against income loss during the first 6 months of illness or injury.

This note has reviewed the protection of workers against income loss during the first 6 months of illness or injury. The national income loss due to short-term sickness and disability during the first 6 months of illness, as expressed by pre-tax wages, was about $69.6 billion in 1991. Of this amount, about $46.5 billion (66.8 percent) was replaced by income-protection programs, including paid sick leave; group insurance; temporary disability insurance, under statutory State provisions; individual insurance; workers' compensation; general assistance; and the 6th month of the Social Security Disability Insurance program. In 1991, within the private sector, wage and salary workers lost $47.2 billion because of nonoccupational illnesses or injuries, of which $17.6 billion (or 37.3 percent) was replaced. Coverage against income lost because of illness in the U.S. workforce favors full-time professional and technical employees with longer service in large or medium firms, and especially favors public sector employees. The lowest level of coverage is provided to part-time employees with limited seniority who work in production and related areas in small, private establishments. About 70 percent of wage and salary workers in the private sector have some protection through their employment against earnings losses caused by short-term illness or injury; 44 percent of these workers have short-term disability insurance, and half have sick leave coverage.

Cash benefits for short-term sickness, 1970-94.

This note has reviewed the extent of protection of workers against income loss during the first 6 months of illness or injury. National income loss in 1994 was $81.1 billion, of which $49.4 billion (60.9 percent) was replaced by income-protection programs, including sick leave, group insurance, temporary disability insurance under statutory State provisions, individual insurance, workers' compensation, and (during the 6th month) the Social Security Disability Insurance program. In 1994, wage and salary workers in the private sector lost $55.2 billion because of nonoccupational illnesses or injuries, of which $19.0 billion (34.5 percent) was replaced. Wage replacement rates are higher for full-time professional and technical employees with longevity in large or medium firms, and especially public employees. The lowest level of coverage is given to part-time employees with limited seniority who work in production and related areas in small, private firms. Approximately 70 percent of wage and salary workers in the private sector have some protection through their employment against earnings losses caused by short-term illness. Forty-four percent of these workers have short-term disability insurance,and only half have sick-leave coverage.

Federal Employees' Retirement System Act of 1986.

In June, President Reagan signed the Federal Employees' Retirement System Act of 1986 (Public Law 99-335), which establishes the Federal Employees' Retirement System (FERS) for employees hired after December 31, 1983. The program, which goes into effect on January 1, 1987, features a defined benefit retirement plan to augment mandatory coverage under social security. It also permits FERS participants to contribute up to 10 percent of their earnings, on a tax-deferred basis, to a thrift savings plan, with partial matching by the Government. This article describes the provisions of the new system, including survivor annuities and disability benefits. It also explains how employees covered under the Civil Service Retirement System may freeze their earned benefits under that program and transfer to FERS during the period July-December 1987.

Private social welfare expenditures, 1972-85.

This article updates the private social welfare expenditures series with complete data for 1985 and information for most categories through 1986. In the United States, private sector expenditures play a substantial role in the provision of social welfare services. This article presents private social welfare expenditures in terms of the four major categories--health, education, welfare and related services, and income maintenance that includes private pensions, sickness and disability benefits, and group insurance. The private expenditures, which totaled $429.3 billion in 1985, are distributed by major category beginning in 1972 and are also related to public social welfare expenditures and gross national product.

Point of care testing provides an accurate measurement of creatinine, anion gap, and osmolal gap in ex-vivo whole blood samples with nitromethane.

CONTEXT: Nitromethane interferes with Jaffé measurements of creatinine, potentially mimicking acute kidney injury. OBJECTIVES: We determined the proportional contribution of nitromethane in blood samples to creatinine measured by the Jaffé colorimetric and the point-of-care (POC) reactions and determined whether the difference can reliably estimate the concentration of nitromethane. Additionally, we determined whether the presence of nitromethane interferes with anion/osmolal gaps and ascertained the stability of nitromethane in serum after 7 days. METHODS: Nitromethane was added to whole blood from four healthy volunteers to achieve concentrations of 0, 0.25, 0.5, 1, and 2 mmol/L. The following tests were performed: creatinine (Jaffé and POC), electrolytes (associated with Jaffé and POC), osmolality and nitromethane concentration (gas chromatography [GC]). Remaining samples were refrigerated and reanalyzed using GC at 7 days. Anion and osmolal gaps were calculated. Proportional recovery and degradation of nitromethane were measured using GC. Data were analyzed for agreement with single-factor ANOVA (p = 0.05). RESULTS: Mean creatinine for POC and Jaff methods were 0.93 vs. 0.76 mg/dL, respectively. Jaff creatinine concentrations increased linearly with increasing nitromethane concentrations (R(2) = 1, p = 0.01): measured creatinine (mg/dL) = 7.1*nitromethane (mmol/L) = 0.79. POC creatinine remained unchanged across the range of nitromethane concentrations (p = 0.99). Anion and osmolal gaps also remained unchanged. Nitromethane was reliably identified in all sample concentrations using GC on Day 0. Detection of 0.25 mmol/L nitromethane was not consistently recovered on Day 7. Nitromethane degradation was most pronounced at 2 mmol/L concentrations (81% recovery). CONCLUSIONS: Nitromethane alters apparent concentration of creatinine using the Jaffé reaction in a linear fashion but not when using the POC reaction. Measured difference between Jaffé and POC creatinine may identify the presence and estimate concentration of nitromethane. Presence of nitromethane did not alter the anion or osmolal gap; thus it would not potentially interfere with the diagnosis of co-exposure to a toxic alcohol.