Genetic Variations in the Promoter of the APE1 Gene Are Associated with DMF-Induced Abnormal Liver Function: A Case-Control Study in a Chinese Population

Acute or long-term exposure to N,N-dimethylformamide (DMF) can induce abnormal liver function. It is well known that DMF is mainly metabolized in the liver and thereby produces reactive oxygen species (ROS). The base excision repair (BER) pathway is regarded as a very important pathway involved in repairing ROS-induced DNA damage. Several studies have explored the associations between GSTM1, GSTT1, CYP2E1 polymorphisms and DMF-induced abnormal liver function; however, little is known about how common hOGG1, XRCC1 and APE1 polymorphisms and DMF induce abnormal liver function. The purpose of this study was to investigate whether the polymorphisms in the hOGG1 (rs159153 and rs2072668), XRCC1 (rs25487, rs25489, and rs1799782), APE1 (rs1130409 and 1760944) genes in the human BER pathway were associated with the susceptibility to DMF-induced abnormal liver function in a Chinese population. These polymorphisms were genotyped in 123 workers with DMF-induced abnormal liver function and 123 workers with normal liver function. We found that workers with the APE1 rs1760944 TG/GG genotypes had a reduced risk of abnormal liver function, which was more pronounced in the subgroups that were exposed to DMF for <10 years, exposed to ≥10 mg/m³ DMF, never smoked and never drank. In summary, our study supported the hypothesis that the APE1 rs1760944 T > G polymorphism may be associated with DMF-induced abnormal liver function in the Chinese Han population.

Potential mechanisms by which a single drink of alcohol can increase transdermal absorption of topically applied chemicals

BACKGROUND

Both chronic and acute ethanol consumption increase transdermal penetration of topically applied xenobiotics. The mechanisms by which this enhancement occurs are unknown. We hypothesized that either the vasodilatory effects of ethanol or its ability to disrupt the lipid bilayer via lipid peroxidation, may be contributing to the increased transdermal absorption observed in alcohol consuming animals.

METHODS

Male Wistar rats were gavaged with 1.5, 3, 4.3, 6 or 10 g/kg ethanol or saline control or were treated with either the vasoconstrictor epinephrine or with the vasodilator prilocaine. Dermal blood flow, transepidermal water loss (TEWL), and skin moisture were non-invasively measured. Transdermal penetration was then determined for four xenobiotics (paraquat, dimethyl formamide (DMF), 2,4-dichlorophenoxyacetic acid (2,4-D) and N,N-diethyl-m-toluamide (DEET)). Lipid peroxidation was also determined by monitoring the formation of malondialdehyde.

RESULTS

Dermal blood flow increased by approximately 27% (p<0.05), TEWL increased 1.12+/-0.2-fold while skin lipid peroxidation increased 1.4-fold (p<0.05) 2h after gavage with 10 g/kg alcohol. Transdermal penetration of paraquat was increased by prilocaine (ER=2.1+/-0.4, p<0.05), but the absorption of DEET, 2,4-D and DMF were not influenced by greater blood flow. Reducing dermal blood flow with epinephrine did not cause any significant changes in transdermal penetration.

CONCLUSIONS

Vasodilation triggered by a single episode of ethanol ingestion is not responsible for the observed increase in transdermal absorption. Ethanol induced changes in lipid peroxidation and TEWL demonstrate that drinking alcohol induces transdermal absorption of xenobiotics.

Evaluation of the effectiveness of personal protective equipment against occupational exposure to N,N-dimethylformamide

The objectives of this study were to evaluate the protective effectiveness of various personal protective equipment and the respective exposure contributions from respiratory and skin exposures of N,N-dimethylformamide (DMF) with a self-comparison study design. Two high-, four intermediate- and four low-DMF exposure workers from a synthetic leather factory were monitored in airborne DMF concentrations and N-methylformamide (NMF) concentrations in urine across four consecutive days. The workers were designated to wear no personal protective equipment on the first day. The barrier cream, rubber gloves and rubber gloves plus respirator were used on the second, third and fourth days, respectively. Person-to-personal observation was performed in the field to record all high and low exposure tasks during work for each subject. Protective effectiveness index (PEI) was used to evaluate different glove effectiveness. We concluded that the direct skin contact to the strong skin penetrates like DMF could be a more significant exposure source than the respiratory exposure in the actual occupational environment. The provision of protective equipment from skin exposure could be more important than that from respiratory exposure. The application of barrier cream could be as effective as wearing impermeable rubber gloves in the prevention from the skin penetrate in the occupational settings.

Carcinogenicity and Chronic Toxicity after Inhalation Exposure of Rats and Mice to N,N ‐Dimethylformamide

Carcinogenicity and chronic toxicity of N,N-Dimethylformamide (DMF) were examined by inhalation exposure of groups of 50 rats and 50 mice of both sexes to DMF vapor at a concentration of 0, 200, 400 or 800 ppm (v/v) for 6 h/d, 5 d/wk, for 104 wk. In rats, incidences of hepatocellular adenomas and carcinomas significantly increased in the 400 and 800 ppm-exposed groups and in the 800 ppm-exposed group, respectively. The hepatocellular adenoma did not increase significantly in the 400 ppm-exposed female rats, but its incidence exceeded a range of historical control data in the Japan Bioassay Research Center (JBRC). In mice, incidences of hepatocellular adenomas and carcinomas significantly increased in all the DMF-exposed groups. Incidence of hepatoblastomas significantly increased in the 200 and 400 ppm-exposed male mice, and 4 cases of hepatoblastomas in the 400 ppm-exposed female mice and the 800 ppm-exposed male mice exceeded the range of historical control data of the JBRC. Incidences of altered cell foci increased in the liver of exposed rats and mice in an exposure concentration-related manner, and those foci were causally related to the hepatocellular tumors. Liver weights increased in both rats and mice exposed to DMF at 200 ppm and above. Increased levels of gamma-GTP, ALT, AST and total bilirubin in exposed rats of both sexes and AST and ALT in exposed mice of both sexes were noted. It was concluded that 2-yr inhalation exposure to DMF increased incidences of hepatocellular adenomas and carcinomas in rats and incidences of hepatocellular adenomas, carcinomas and hepatoblastomas in mice, and that hepatocarcinogenicity of DMF was more potent in mice than in rats.

Thirteen-week inhalation toxicity of N,N-dimethylformamide in F344/N rats and B6C3F1 mice

Male and female F-344 rats and B6C3F1 mice (10/sex/group) were exposed to N,N-dimethylformamide (DMF) by whole body inhalation exposure at 0, 50, 100, 200, 400, or 800 ppm, 6 h/day, 5 days/week, for 13 weeks. A concentration-dependent depression in body weight occurred in rats of both sexes at 400 (6-11%) and 800 ppm (20-22%). In contrast, all weight changes in both sexes of mice were within 10% of controls. No rats died, while 5 mice died from nonexposure-related causes. Relative liver weights were significantly increased at all DMF concentrations in both sexes and both species. Activities of serum sorbitol dehydrogenase (SDH) were statistically increased in male and female rats (200 to 800 ppm) on study days 4, 24, and 91 (13 weeks). Activities of alanine aminotransferase (ALT) and isocitrate dehydrogenase (ICD) were statistically increased in both sexes of rats exposed to 800 ppm DMF at all time points. Cholesterol (CHOL) levels were statistically increased in male and female rats (50-800 ppm) at all sampling time points. Levels of total bile acids (TBA) were statistically increased in both sexes of rats (400-800 ppm) on days 24 and 91. Centrilobular hepatocellular necrosis (minimal to moderate) was seen in rats of both sexes exposed at 400 and 800 ppm, with the lesions more severe in females. Centrilobular hepatocellular hypertrophy (minimal to mild) was found in all groups of DMF-exposed male mice, and in female mice exposed at 100-800 ppm. For male and female rats the no-observed-adverse-effect concentration (NOAEC) for microscopic liver injury was 200 ppm. The NOAEC was 50 ppm for female mice, but an NOAEC based upon the absence of microscopic liver injury was not determined in male mice.

Does the polymorphism of cytochrome P-450 2E1 affect the metabolism of N,N-dimethylformamide? Comparison of the half-lives of urinary N-methylformamide

The aim of this study was to clarify whether phenotypic variation exists when subjects with different genotypes of cytochrome P450 2E1 (CYP2E1) are exposed to N,N-dimethylformamide (DMF). The genotypes of CYP2E1 were confirmed in 123 healthy male volunteer subjects. Of the 123 subjects, the numbers of c1 homozygotes, c2 heterozygotes, and c2 homozygotes were 77, 45, and 1, respectively. Seven of the c1 homozygotes, five of the c2 heterozygotes, and the one c2 homozygote (mean age: 22.7 years, range: 20-27 years) were exposed to DMF vapor twice, once via the skin and once via the lung, for a total of 8 h per subject at a concentration below 10 ppm, the occupational exposure limit recommended by the Japan Society for Occupational Health, the American Conference of Governmental and Industrial Hygienists, and Deutsche Forschungsgemeinschaft, at 27 degrees C and 44% relative humidity. Exposure levels were 6.2+/-1.0 ppm in dermal exposure and 7.1+/-1.0 ppm in inhalation exposure. Urine samples were collected until 72 h after exposure. The half-lives of urinary N-methylformamide (NMF) were obtained as the phenotype. The average urinary NMF half-lives of the c1 homozygotes, the c2 heterozygotes, and the c2 homozygote were 3.86+/-1.90, 4.38+/-1.53, and 4.2 h after dermal exposure, and 1.58+/-0.42, 1.84+/-0.61, and 3.2 h after respiratory exposure. The NMF half-lives of the c1 homozygotes were not significantly different from those of the c2 heterozygotes, and there were no differences between the NMF half-lives on the subjects with and without the c2 allele. Even though the data were obtained from only one c2 homozygote, it is noteworthy that the NMF half-life of this subject was slightly less than that of the c1 homozygotes after respiratory exposure.

Enhancer aided in vitro permeation of atenolol and prazosin hydrochloride through mice skin

Effect of penetration enhancers were studied on the permeation of antihypertensive drugs prazosin hydrochloride and atenolol through full thickness skin of swiss albino mice. Atenolol was delivered to skin from saturated alcoholic solution containing 5% of 1-decanol and alcohol alone, while prazosin hydrochloride was saturated in dimethyl formamide(DMF, 5% v/v in water) and dimethyl sulfoxide(DMSO, 5% v/v in water). Atenolol permeation was augmented significantly in decanolic solution and also in pure alcohol. In case of prazosin hydrochloride, significant enhancement of permeation was shown by DMSO but not by DMF.

Characterization of the antinociceptive and sedative effect of amitraz in horses

Amitraz, an acaricide used to control ectoparasites in animals has a complex pharmacological activity, including alpha2-adrenergic agonist action. The purpose of this research was to investigate the possible antinociceptive and/or sedative effect of amitraz in horses. The sedative effect of the intravenous (i.v.) injection of dimethylformamide (DMF, 5 mL, control) or amitraz (0.05, 0.10, 0.15 mg/kg), was investigated on the head ptosis test. The participation of alpha2-adrenergic receptors in the sedative effect provoked by amitraz was studied by dosing yohimbine (0.12 mg/kg, i.v.). To measure the antinociception, xylazine hydrochloride (1 mg/kg, i.v., positive control) and the same doses of amitraz and DMF were used. A focused radiant light/heat directed onto the fetlock and withers of a horse were used as a noxious stimulus to measure the hoof withdrawal reflex latency (HWRL) and the skin twitch reflex latency (STRL). The three doses of amitraz used (0.05, 0.10 and 0.15 mg/kg) provoked a dose-dependent relaxation of the cervical muscles. The experiments with amitraz and xylazine on the HWRL showed that after i.v. administration of all doses of amitraz there was a significant increase of HWRL up to 150 min after the injections. Additionally, there was a significant difference between control (DMF) and positive control (xylazine) values up to 30 min after drug injection. On the other hand, the experiments on the STRL show that after administration of amitraz at the dose of 0.15 mg/kg, a significant increase in STRL was observed when compared with the control group. This effect lasted up to 120 min after injection. However, no significant antinociceptive effect was observed with the 0.05 and 0.10 mg/kg doses of amitraz or at the 1.0 mg/kg dose of xylazine.

Assessment of the developmental toxicity, metabolism, and placental transfer of N,N-dimethylformamide administered to pregnant rats

This study evaluates the developmental toxicity and placental and milk transfer of N,N-dimethylformamide (DMF) in rats. Sprague-Dawley rats were given 0, 50, 100, 200, and 300 mg DMF/kg/day, by gavage, on Gestational Days (GD) 6 through 20. Maternal toxicity was indicated by depressions in weight gain and food consumption at doses >/=100 mg/kg. Fetal toxicity was indicated by decreased fetal body weight at doses >/=100 mg/kg, and by increased incidences of two skeletal variations (absent or poorly ossified supraoccipital and sternebrae) at 200 and 300 mg/kg. Thus, the maternal and developmental no-observed-adverse-effect level was 50 mg/kg/day. The time course disposition of [14C]DMF was examined over a 48-hr period in GD12- and GD18-pregnant rats after a single oral dose of 100 mg [14C]DMF/kg. Peak concentrations of radiocarbon occurred within 1 hr after dosing. Embryonic (GD12) and fetal (GD18) tissues accounted for 0.15 and 6% of the administered dose, respectively. Levels of radiocarbon in embryonic and fetal tissues were equal or slightly less than in maternal plasma up to 8 and 24 hr, respectively, and higher thereafter. HPLC analysis performed at intervals from 1 to 8 hr on GD12 and 1-24 hr on GD18 indicated that unchanged DMF and metabolites were readily transferred to the embryonic and fetal tissues, where their levels were generally equal to those in maternal plasma. The parent compound accounted for most of the radioactivity until 4-8 hr and then decreased. N-Hydroxymethyl-N-methylformamide (HMMF) and N-methylformamide (NMF) were the predominent metabolites and increased with time. Much lower concentrations were found for formamide and N-acetyl-S-(N-methylcarbamoyl)cysteine. Transfer of radioactivity into milk was studied in dams given a single oral administration of 100 mg [14C]DMF on Lactation Day 14. DMF, HMMF, and NMF were found in the milk at concentrations equal to those in plasma.

Hepatotoxicity of N, N-dimethylformamide in rats following intraperitoneal or inhalation routes of administration

Male Sprague-Dawley rats were administered a single intraperitoneal injection of N, N-dimethylformamide (DMF, 0.01-1.5 g kg-1) or were exposed for 4 h to DMF vapours (75-900 ppm). The serum activities of the enzymes sorbitol deshydrogenase and glutamate deshydrogenase were used as indicators of liver damage, and were determined at 24, 48 or 72 h post-treatment. Following either route of administration DMF caused concentration-dependent elevations in enzyme activities, the maxima of which occurred later after administration of higher concentrations of DMF than after lower concentrations.

Chronic toxicity/oncogenicity of dimethylformamide in rats and mice following inhalation exposure

The potential chronic toxicity and oncogenicity of dimethyl-formamide (DMF) was evaluated by exposing male and female rats and mice to 0, 25, 100, or 400 ppm DMF for 6 hr/day, 5 days/week for 18 months (mice) or 2 years (rats). Clinical pathology was evaluated at 3, 6, 12, 18, and 24 (rats only) months. An interim euthanasia for rats occurred at 12 months and hepatic cell proliferation in rats and mice was examined at 2 weeks, 3 months, and 12 months. No compound-related effects on clinical observations or survival were observed. Body weights of rats exposed to 100 (males only) and 400 ppm were reduced. Conversely, body weights were increased in 400 ppm mice. No hematologic changes were observed in either species. Serum sorbitol dehydrogenase activity was increased in rats exposed to 100 or 400 ppm. There were no compound-related effects on the estrous cycle of rats or mice at any concentration. Compound-related morphological changes were observed only in the liver. In rats, exposure to 100 and 400 ppm produced increased relative liver weights, centrilobular hepatocellular hypertrophy, lipofuscin/hemosiderin accumulation in Kupffer cells, and centrilobular single cell necrosis (400 ppm only). In mice, increased liver weights (100 ppm males, 400 ppm both sexes), centrilobular hepatocellular hypertrophy, accumulation of lipofuscin/hemosiderin in Kupffer cells, and centrilobular single cell necrosis were observed in all exposure groups. These observations occurred in a dose-response fashion and were minimal at 25 ppm. No increase in hepatic cell proliferation was seen in mice or female rats. Slightly higher proliferation was seen in male rats exposed to 400 ppm at 2 weeks and 3 months but not at 12 months. Dimethylformamide was not oncogenic under these experimental conditions in either the rat or mouse.

Acute intravenous toxicity of dimethyl sulfoxide, polyethylene glycol 400, dimethylformamide, absolute ethanol, and benzyl alcohol in inbred mouse strains

Acute intravenous toxicity of some solvents, i.e. dimethyl sulfoxide (DMSO), polyethylene glycol 400 (PEG 400), dimethylformamide (DMF), absolute ethanol (EtOH) and benzyl alcohol (BeOH), was determined in three inbred (CD2F1, B6D2F1 and C57BL/6N) mouse strains used in many preclinical tests, mainly in oncology and toxicology. Haemolytic and precipitation potential tests in vitro were performed to assess the blood compatibility of the investigated solvents and its relationship with the observed symptoms. The single tested solvents did not show any major differences in acute toxicity in the three tested strains with the exclusion of DMSO (less toxic in CD2F1) and BeOH and EtOH (less toxic in B6D2F1). The tested dose ranges in the three strains (in ml/kg) were 1.0-5.66 for DMSO, 2.0-8.0 for PEG 400, 1.0-4.0 for DMF, 0.75-4.24 for EtOH, 0.025-0.4 for BeOH. The lowest tested dose was a safe dose and the highest one was the dose causing mortality in no more than half the animals in each group. The in vitro results suggest avoiding the use of BeOH (which also is more toxic than the other solvents in the in vivo test) and DMSO and using PEG400, EtOH and DMF even though the latter induced a body weight decrease in the B6D2F1 mouse strain. As a general conclusion, dilution of these solvents in water is suggested to ameliorate their blood compatibility and the use of doses not higher than the lowest dose tested in this study is recommended.

Dimethylformamide pharmacokinetics following inhalation exposure in monkeys

Male and female cynomolgus monkeys received whole-body inhalation exposures to dimethylformamide (DMF) at concentrations of 30, 100, and 500 ppm for 6 hours a day, 5 days a week over a 13-week period. Serial blood samples were drawn at the conclusion of the first day of exposure and following 15, 29, 57, and 85 days of testing. Area under the plasma concentration curve (AUC) values were determined for DMF and "NMF" [N-methylformamide (NMF) plus N-(hydroxymethyl)-N-methylformamide (DMF-OH)]. Urine samples were also collected and assayed for DMF, NMF and DMF-OH. The systemic exposure to DMF increased disproportionately as the airborne DMF concentrations increased. DMF AUC values increased 19- to 37-fold in male and 35- to 54-fold in female monkeys as the inhalation concentrations increased 5-fold (100 to 500 ppm). These data are consistent with saturation of DMF metabolism as inhaled DMF concentrations increased from 100 to 500 ppm. AUC values, peak plasma concentrations, and plasma half-lives were essentially unaltered over the duration of the study within each exposure concentration tested. Estimated plasma half-lives ranged from 1 to 2 hours and 4 to 15 hours for DMF and "NMF" respectively. DMF was rapidly converted to "NMF" following 30 ppm exposures, with "NMF" plasma concentrations higher than DMF plasma concentrations at the 0.5 hour time-point. In plasma samples simultaneously assayed for DMF-OH and NMF, the concentration of DMF-OH exceeded, was equal to, or was less than NMF concentrations depending upon the plasma sample. DMF-OH was always the main urinary metabolite (56 to 95 percent) regardless of exposure level or time on study.

Dimethylformamide pharmacokinetics following inhalation exposures to rats and mice

Whole-body inhalation exposures to N,N-dimethylformamide (DMF) were conducted with rats and mice. The exposure concentrations were 10, 250, and 500 ppm DMF. The exposure routines consisted of single 1-, 3-, or 6-hour exposures and ten 6-hour exposures (ten exposure days in 2 weeks). Area under the plasma concentration curve (AUC) values were determined following exposure for DMF and "N-methylformamide" ["NMF" represented N-methylformamide plus N-(hydroxymethyl)-N-methylformamide (DMF-OH)]. The DMF AUC values increased 8- and 29-fold for rats and mice, respectively, following single six-hour exposures to 250 and 500 ppm DMF. These data are indicative of saturation of DMF metabolism. Peak "NMF" plasma concentrations for rats and mice, following single 6-hour exposures, did not increase as DMF exposure concentrations increased from 250 to 500 ppm. In addition, the "NMF" plasma levels in rats following a single 6-hour 500 ppm DMF exposure did not decay by 24 hours post exposure. These "NMF" plasma data also indicate saturation of DMF metabolism. Multiple exposures to 500 ppm DMF resulted in a 3- and 4-fold reduction in DMF AUC values for rats and mice, respectively, compared to AUC values following a single six-hour 500 ppm DMF exposure. This indicates enhanced metabolism of DMF resulting from multiple 500 ppm DMF exposures and together with saturation of DMF metabolism suggest using exposure levels below 500 ppm in a chronic bioassay. Selected plasma samples were simultaneously assayed for NMF and DMF-OH. The "NMF" values consisted of between 30 to 60 percent DMF-OH depending upon the exposure group (conversely NMF represented 30 to 60 percent of the "NMF" levels). Urinary analysis of all samples revealed DMF-OH represented over 90 percent of the summed DMF, DMF-OH and NMF quantities.

Developmental toxicity of dimethylformamide in the rat following inhalation exposure

Dimethylformamide (DMF) is a widely used industrial solvent. DMF has been reported to be a developmental toxin when given to rodents by injection or following dermal administration. In this study, groups of pregnant rats were exposed by inhalation to either 0 (control), 30, or 300 ppm DMF from gestation day 6 through 15. In the 300 ppm rats, both maternal weight gain during gestation and fetal weights were lower than those of the controls. Fetal resorptions were not increased in this group. No significant differences among either maternal or fetal rats were seen in the 30 ppm group compared to controls. Both fetal and maternal toxicity were noted at 300 ppm and the no observed effect level under these experimental conditions was 30 ppm for both the dams and the conceptuses. DMF did not produce malformations in the rat fetus even at a level that was toxic to the dam.

Studies on the prenatal toxicity of N,N-dimethylformamide in mice, rats and rabbits

Prenatal toxicity studies with N,N-dimethylformamide (DMF) in rabbits, rats and mice were carried out using the oral (gavage), dermal, inhalation and ip injection routes of administration. Administration of DMF by gavage led to an increase in malformations in rats and mice in the absence of overt maternal toxicity. The lowest-observable-effect level was 182 mg/kg body weight/day in mice and 166 mg/kg body weight/day in rats. After dermal administration a dose-dependent incidence of teratogenicity was observed in rats at 94-944 mg/kg/body weight/day in the absence of overt maternal toxicity. In rabbits dermal administration led to a steeper increase in the dose-response relationship and at 400 mg/kg body weight/day to a clear teratogenic effect in the presence of slight maternal toxicity. The 200 mg/kg body weight/day dose appeared to be the no-adverse-effect level. Inhalation in rats caused foetotoxicity and embryolethality at 287 ppm. A clear teratogenic effect was shown in rabbits at 450 ppm and a marginal effect at 150 ppm. The no-effect level for does and foetuses was 50 ppm. Ip injection in mice caused clear teratogenicity at 944 mg/kg body weight/day and slight embryotoxicity at 378 mg/kg body weight/day. The rabbit appears to be more sensitive than the rat to DMF-related prenatal toxicity and should, therefore, be used as the basis for the evaluation of teratogenic risk in humans.

Carvedilol (Kredex) reduces infarct size in a canine model of acute myocardial infarction

Carvedilol (Kredex) is a multiple action, antihypertensive agent that may also prove to be useful in the treatment of angina and congestive heart failure. Carvedilol combines in one molecule both beta-adrenoceptor blocking and vasodilating activities. Inasmuch as beta-adrenoceptor blocking agents are known to be cardioprotective and thereby reduce infarct size, it is logical to assume that carvedilol, likewise, would possess this desirable activity. Furthermore, the additional vasodilating activity of carvedilol could contribute to further reductions in infarct size by reducing myocardial work (and therefore myocardial oxygen demand) through reductions in both afterload and myocardial wall tension. As such, we have investigated the ability of carvedilol to reduce infarct size in a canine model of acute myocardial infarction. Carvedilol (1 mg/kg i.v.) or its vehicle, dimethylformamide, were administered 15 min before left circumflex coronary artery (LCX) occlusion. Following 1 h of LCX occlusion, dogs were reperfused through a critical stenosis and then allowed to recover for 24 h. Carvedilol-treated animals exhibited a 78% reduction in infarct size compared to vehicle controls, such that the percentage of the left ventricle infarcted was reduced significantly from 16.2 +/- 4.1% in control animals to 3.6 +/- 1.3% in animals treated with carvedilol (p = 0.017, n = 6). Stained tissue sections of the left ventricle were photographed, digitized and color-enhanced using an Image Analysis Computer System, and three-dimensional reconstruction of the left ventricle, including the infarcted areas, was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Embryotoxicity and teratogenicity study in rats dosed epicutaneously with dimethylformamide (DMF)

The reproductive effect of N,N-dimethylformamide (DMF) administered epicutaneously to rats was examined. The rats were dosed on gestation days 6-15 or on gestation days 1-20 at dose levels of up to 2 ml DMF kg-1 body weight. Body weight, weight gain and pregnancy rate were reduced in those rats receiving 2 ml DMF kg-1 body weight per day on days 6-15. A reduction in the number of live fetuses and in fetal weight, as well as an increase in postimplantation loss, were also observed at this dose level. Similar but more pronounced effects were observed in rats dosed on days 1-20 with 2 ml DMF kg-1 body weight. The lowest effect level was 1 ml DMF kg-1 body weight. No other dose-related effects were found in this study.

Fulminant hepatic failure in poisoning due to ingestion of T 61, a veterinary euthanasia drug

A patient developed fulminant hepatic failure 48 h after the ingestion of T 61, a veterinary euthanasia drug which contains both general and local anesthetics, a neuromuscular blocking agent, and dimethylformamide (DMF) as a solvent. This is the first report of such severe hepatic manifestation in T 61 poisoning, the most common symptoms of which are early coma and respiratory failure due to the anesthetic and the neuromuscular blocking agent. In a very few cases mild and transitory symptoms of hepatic insufficiency have been observed. In this case the fulminant hepatic failure was due to the high dose (0.6 ml/kg) ingestion of DMF.

Triple combination of retinoic acid plus actinomycin D plus dimethylformamide induces differentiation of human acute myeloid leukaemic blasts in primary culture

Differentiation induction therapy provides an alternative for treatment of acute myeloid leukaemia (AML) patients who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy. The effect of a triple combination of retinoic acid (RA) + actinomycin D (Act-D) + dimethylformamide (DMF) on differentiation of blasts from 24 AML patients was studied. Non-adherent mononuclear cells were seeded at a concentration of 5 x 10(5) cells/ml in 24-well tissue-culture plates containing RPMI 1640 culture medium with 20% fetal calf serum, 10% autologous serum and 10% 5637-conditioned medium and incubated with 10(-6) M retinoic acid, 5 nM actinomycin D and/or 100 mM dimethylformamide alone and in combination with each other for 6 days at 37 degrees C in a humidified incubator and an atmosphere containing 5% CO2. The triple combination of 10(-6) M retinoic acid + 5 nM actinomycin D + 100 mM dimethylformamide induced 90% of the blasts from 22 of the 24 AML patients to differentiate. The combination of N-methylformamide (a compound similar to dimethylformamide) with cyclophosphamide significantly increased the in vivo activity with no concomitant increase in its reversible hepatotoxicity. Since several polar compounds related to dimethyl-formamide, e.g. hexamethylene bisacetamide and N-methylformamide, are currently undergoing phase II clinical trials, it may be feasible to combine one of these with retinoic acid and/or actinomycin D in the treatment of AML patients.

Triple combination of retinoic acid, low concentration of cytarabine and dimethylformamide induces differentiation of human acute myeloid leukaemic blasts

Differentiation induction therapy provides an alternative for treatment of patients with acute myeloid leukaemia (AML) who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy. The effect of a triple combination of retinoic acid (RA) + low concentration of cytarabine (Ara-C) + dimethylformamide (DMF) on the differentiation of blasts from 24 AML patients was studied. Nonadherent mononuclear cells were cultured at a concentration of 5 x 10(5) cells/ml in 24-well tissue culture plates containing RPMI 1640 culture medium with 20% fetal calf serum, 10% autologous serum and 10% 5637-conditioned medium and incubated with 10(-6) M RA, 10(-6) M Ara-C and/or 100 mM DMF alone and in combination with each other for 6 days in primary culture at 37 degrees C in a humidified incubator under 5% CO2. The triple combination of 10(-6) M RA + 10(-6) M Ara-C + 100 mM DMF induced 90% of blasts from 22 out of 24 AML patients to differentiate. These highly effective results justify a clinical trial of this triple combination for AML patients who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy.

Triple combination of retinoic acid+aclacinomycin A+ dimethylformamide induces differentiation of human acute myeloid leukaemic blasts in primary culture

Differentiation induction therapy provides unalternative for treatment of acute myeloid leukaemia (AML) patients who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy. The effect of a triple combination of retinoic acid(RA)+aclacinomycin A (ACM)+dimethylformamide (DMF) on differentiation of blasts from 24 AML patients was studied. Non-adherent mononuclear cells were seeded at a concentration of 5 x 10(5) cells/ml in 24-well tissue culture plates containing RPM11640 culture medium with 20% fetal calf serum and 10% 5637-conditioned medium and incubated with 10(-6) M retinoic acid, 80nM aclacinomycin A and/or 100mM dimethylformamide alone and in combinations with each other for six days at 37 degrees C in a humidified incubator under 5% CO2. Morphological, cytochemical and functional differentiation into mature cells were induced in blasts from 22 out of the 24 AML patients after exposure to the triple combination of 10(-6)M RA+80nM ACM+100mM DMF for 6 days in primary culture. These highly effective results justify a clinical trial of this triple combination for AML patients who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy.

The organic solvents acetone, ethanol and dimethylformamide potentiate the mutagenic activity of N-methyl-N'-nitro-N-nitrosoguanidine, but have no effect on the mutagenic potential of N-methyl-N-nitrosourea

The frequency of recessive chlorophyll and embryonic lethals included by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Arabidopsis thaliana was markedly increased when exposure of the seeds to MNNG (3 h) was carried out in the presence of 4-12% acetone, 4-16% ethanol or 8-32% dimethylformamide. The enhancement of MNNG mutagenicity was proportional to the concentrations of these organic solvents. In contrast, neither of them, applied at the same conditions and doses, influenced the mutagenic activity of N-methyl-N-nitrosourea. The solvents without mutagens did not influence the spontaneous rate of mutations and revealed no or very weak toxic effect as measured by the seed germination.

Acute and subchronic toxicity of dimethylformamide and dimethylacetamide following various routes of administration

Dimethylformamide (DMF, CAS No. 68-12-2) and dimethylacetamide (DMAC, CAS No. 127-19-5) are widely used for their superior solvent properties. A series of single and multiple dose experiments in rodents were conducted to determine the target organs, and to establish doses which, under various routes of administration, produced those changes. DMF produced moderate irritation in the rabbit eye, with the corneal response clearing in 2 to 4 weeks. DMAC produced only mild, quickly reversible conjunctival irritation. Oral doses of DMF to the rat of 2,250 mg/kg or greater produced lethality which was associated with liver damage. Lethality occurred following oral doses of 4,500 mg/kg DMAC with LD50's for male and female rats of 5,809 and 4,930 mg/kg, respectively. The 1 hour LC50 by inhalation for DMAC in the rat was 2,475 ppm or greater. Sensory irritation was produced in the mouse at concentrations of 1,658 ppm or greater for DMF. Repeated oral doses of 450 mg DMF/kg to rats produced reduced body weight gain and liver injury with both changes being reversible. DMAC tested similarly produced body weight effects, liver injury, and testicular changes in the rat with all changes again being readily reversible. Dermal doses of 2,000 mg/kg of either DMF or DMAC were poorly tolerated by rabbits. DMAC was slightly more toxic with all treated rabbits dying of acute hepatic necrosis. Repeated inhalation of 2,000-2,500 ppm produced mortality in rats exposed to DMF but not DMAC. Liver injury was seen with DMF, testicular changes with DMAC. DMF and DMAC both produced slight anemia and leukocytosis in rats during 90 days of feeding. Liver weights were elevated in rats fed DMF, but not DMAC, at a level of 1,000 ppm. The "no-observed effect level" in rats fed DMF for 90 days was 200 ppm. The overall toxicologic profiles of both DMAC and DMF are similar with the target organ being the liver.

Hepatotoxicity of dimethylformamide and dimethylsulfoxide at and above the levels used in some aflatoxin studies

Albino rats were each treated with a single intraperitoneal injection of dimethylformamide (DMF) or dimethysulfoxide (DMSO). The doses of DMF administered were 0.6, 0.9, and 1.2 ml. per kg. and those of DMSO were 1.2, 2.4, 3.6, and 4.8 ml. per kg. The animals were sacrificed at 24, 48, 72, and 120 hours following administration of each dose. The liver was investigated in all cases. Treatment with DMF at 0.6 ml. per kg. indicated some histologic lesions of the liver which became well defined at 0.9 and 1.2 ml. per kg. causing severe central phlebitis with centrilobular coagulative necrosis of the cells associated with a heavy inflammatory infiltrate. Maximal liver lesions occurred at 48 hours and started to regress after 72 hours. However, cellular atypism became a consistent finding after this inflammatory phase. DMSO-treated animals showed minimal histologic lesions of the liver at 1.2 and 2.4 ml. per kg. Higher doses caused fatty infiltration with a predominatly periportal distribution. It tended to produce its maximal effect in 12 hours which then regressed rapidly after 24 hours. The development of histologic lesions in the liver even at 0.6 ml. per kg. suggests that DMF is not a suitable solvent for aflatoxin studies, and hence the results obtained from such studies need cautious interpretation. DMSO appears to be an ideal alternative for toxicologic studies at a much higher dose level compared to DMF.