Immunohistochemical characterization of oxidative stress in the lungs of rats exposed to the humidifier disinfectant polyhexamethylene guanidine hydrochloride.

Polyhexamethylene guanidine hydrochloride (PHMG-HCl), an antimicrobial additive in humidifier disinfectants, was associated with the pulmonary disease outbreak in South Korea. However, PHMG-mediated oxidative stress has only been studied in vitro. Here, we evaluated PHMG-induced oxidative stress in the lungs of rats exposed to PHMG-HCl. Male F344 rats were exposed to different concentrations of PHMG-HCl for 13-weeks via whole-body inhalation. Histopathological examination of the exposed rats showed the presence of lung lesions, including alveolar/interstitial fibrosis with inflammatory cell infiltration, bronchioalveolar hyperplasia, bronchiolar/alveolar squamous metaplasia, bronchial/bronchiolar epithelial detachment, and alveolar hemorrhage. Immunohistochemical analysis showed that 4-hydroxynonenal (4-HNE) was expressed in the bronchiolar epithelium, mainly in Clara cells and macrophages of the fibrotic tissue. The number of 4-HNE-positive cells increased significantly in a dose-dependent manner. This is the first in vivo study to report PHMG-induced oxidative stress. Our study provides clues to elucidate the mechanisms underlying PHMG-induced damage in patients affected by humidifier disinfectants.

N-methylformamide induces multiple organ toxicity in Fischer 344 rats.

N-Methylformamide (NMF) is a widely used chemical (CAS No.: 123-39-7) in several industries and its usage is continuously increasing. However, studies for NMF have been focused on hepatotoxicity from now. Its toxicity profile has not yet been established owing to limited toxicity data. Therefore, we evaluated systemic toxicity via NMF inhalation. We exposed 0, 30, 100, and 300 ppm NMF to Fischer 344 rats for 6 h/day, 5 days a week for 2 weeks. Clinical signs, body weights, food consumption, hematologic parameters, serum chemistry measurements, organ weights, necropsy, and histopathology were performed. Two females exposed to 300 ppm NMF died during exposure period. Decrease of food consumption and body weight in both sexes exposed to 300 ppm in females exposed to 100 ppm were noted during exposure period. Increased RBC and HGB were noted in females exposed to 300 ppm. A decrease in the levels of ALP and K and increase in the levels of TCHO and Na were observed in both sexes exposed to 300 and 100 ppm. Increased levels of ALT, AST, BUN and decreased levels of TP, ALB, Ca were observed in females exposed to 300 and 100 ppm. The relative liver weight was elevated in both sexes exposed to 300 and 100 ppm NMF. Hypertrophy in the liver and submandibular glands and nasal cavity injuries were noted in both sexes exposed to 300 and 100 ppm NMF. Tubular basophilia of the kidneys were noted in females exposed to 300 ppm NMF. We revealed that NMF affect several organs including the kidneys not only the liver and NMF-related toxicity is predominant in female rats. These results could contribute to the development of NMF toxicity profile and may help in developing strategies for the control of occupational environmental hazards related to NMF.

A four-week repeated study of intravenous toxicity of recombinant human interleukin-2 in Sprague-Dawley rats.

Interleukin-2 (IL-2) is a lymphokine with a potential role in cancer therapy. Many clinical trials of recombinant human IL-2 (rhIL-2) have been conducted to treat malignant renal carcinoma, melanoma, leukemia, lymphoma, multiple myeloma. BMI Korea has developed a method to manufacture rhIL-2 in bulk using Escherichia coli as a biosimilar. Prior to conducting human clinical trials, 4-week repeated toxicity study of rhIL-2 was conducted. In this study, rhIL-2 was administered intravenously to rats at doses of 9×10(6), 18×10(6), and 36×10(6)IU/kg/day over a period of 4 weeks. Adverse effects were observed in RBC, HGB, HCT, reticulocyte, mesenteric lymph node from middle dose, and changes of total bilirubin, femoral bone marrow, thymus, and clinical signs were observed at high dose. Local irritation was determined at low dose of female rats and at middle dose of male ones. Taken together, no observed adverse effect levels (NOAEL) was determined at dose of 9×10(6)IU/kg/day in male, and NOAEL was determined under the dose level in female rats. It suggests that present rhIL-2 is less toxic prior produced rhIL-2 and may be contribute more effective cancer-treatment strategy in human.

Evaluation of subchronic repeated administration toxicity of ammonium nitrate in rats.

Ammonium nitrate is a chemical mostly used in agriculture and munitions to produce fertilizers and explosives, respectively. Its annual production and consumption exceed ten million tons. Despite is diverse uses, large production and consumption, and occupational risk, information on the toxicity that results from oral exposure to ammonium nitrate is limited. In this study, the safety of ammonium nitrate was therefore evaluated by observing its subchronic toxicity in rats. Ammonium nitrate (0, 100, 300 and 1000 mg/kg/day) was orally administered by gavage to rats at 5 times/week for 13 weeks. Reversibility of the effects of 1000 mg/kg/day was assessed in rats after 2 weeks. Mortality, clinical signs, body weight, and food consumption were monitored. Hematology, serum chemistry, urinalysis, organ weight, necropsy, and histopathology were performed. Salivation was intermittently observed in both sexes receiving 300 and 1000 mg/kg/day ammonium nitrate, which normalized 2 weeks post-treatment. Urine volume increased in both sexes receiving 1000 mg/kg/day ammonium nitrate. Urine pH decreased in both sexes of all dosing groups when compared with the concurrent control group. Urinary changes normalized 2 weeks post-treatment. Blood urea nitrogen levels increased in males receiving 1000 mg/kg/day, but normalized 2 weeks later. Potassium level in males and sodium and chloride levels in both sexes receiving 1000 mg/kg/day ammonium nitrate decreased, but normalized 2 weeks later. Hypertrophy of zona glomerulosa in the adrenals was observed in both sexes receiving 1000 mg/kg/day and in females receiving 300 mg/kg/day ammonium nitrate. After a 2-week recovery period, the same lesion was observed in one female receiving 1000 mg/kg/day ammonium nitrate. Our results indicate that ammonium nitrate induces reversible salivation, increases BUN levels, induces acidic diuresis with decreases in sodium, potassium, and chloride levels, and induces ZG hypertrophy. These results shed light on the toxicity profile of ammonium nitrate.

Thirteen-week inhalation toxicity study of 1-methylnaphthalene in F344 rats.

1-Methylnaphthalene is generally utilized in solvents, as an intermediate in organic synthesis, a dye carrier, in resins, and others. There are some toxicological studies of 1-methylnaphthalene; however, inhalation toxicity studies are rare. Each of 10 male and female F344 rats was exposed to vapors of 1-methylnaphthalene for 13 weeks (6 h a day, 5 days per week) at concentrations of 0, 0.5, 4, and 30 ppm in a whole-body inhalation chamber system. The exposure concentrations were 0.52 ± 0.05, 4.08 ± 0.25, and 30.83 ± 1.28 ppm for the low-, middle-, and high-dose group, respectively. Body weight changes were not affected by exposure to 1-methylnaphthalene. Blood prothrombin time was delayed at 30 ppm in male and female groups, and activated partial thromboplastin time was also delayed at 30 ppm in the male group. Values of alanine aminotransferase in the serum were decreased and those of albumin were increased at 30 ppm in the male group. Differential cell counts and levels of lactate dehydrogenase in the bronchoalveolar lavage fluid were not affected. However, mucous cell hyperplasia in the nasopharyngeal tissues was found and the severity was correlated to exposure concentrations. In conclusion, 1-methylnaphthalene mainly affects the upper respiratory system and the no-observed-adverse-effect level is suggested to be 4 ppm on the basis of histopathological findings.

A thirteen-week oral toxicity study of So-ochim-tang-gami-bang, a traditional Korean medicine, in Sprague-Dawley rats.

ETHNOPHARMACOLOGICAL RELEVANCE: So-ochim-tang-gamibang (SOCG) is a traditional Korean medicine formulated to control internal energy flow (Qi) and has been prescribed to improve stress-induced depressive disorders. AIM OF THE STUDY: SOCG has been used in clinical practice for the last two decades and its efficacy against stress-induced thoracic pain has been suggested. Although SOCG has been used as an herbal formula in Korean medicine, its toxicity has not yet been evaluated. In this study, we evaluated the safety of SOCG through a 13-week general toxicity study in rats. MATERIAL AND METHODS: SOCG was administered by oral gavage to rats at doses of 0 (control), 800, 2000, and 5000mg/kg/day over a 13-week period. Toxicity testing was conducted by evaluating mortality, clinical signs, body weight, food consumption, urinalysis, hematology, serum biochemistry, organ weight, necropsy, and histopathology compared with the concurrent control. RESULTS: SOCG-related changes were noted in clinical signs and urinalysis. The observed clinical signs were compound-colored stool and salivation. Urinalysis results revealed brown or amber colored urine and elevated levels of protein. However, these changes were not considered to be adverse. CONCLUSIONS: The no-observed-adverse-effect-level of SOCG was determined to be above 5000mg/kg in both male and female rats. The result of this study can lay the foundation for the application of SOCG in humans and prove useful for detailed investigations on the toxicity or pharmacological effects of SOCG.

A 90-Day Inhalation Toxicity Study of Ethyl Formate in Rats.

Ethyl formate, a volatile solvent, has insecticidal and fungicidal properties and is suggested as a potential fumigant for stored crop and fruit. Its primary contact route is through the respiratory tract; however, reliable repeated toxicological studies focusing on the inhalation route have not been published to date. Therefore, the present study was conducted to investigate the safety of a 90-day repeated inhalation exposure in rats. Forty male and 40 female rats were exposed to ethyl formate vapor via inhalation at concentrations of 0, 66, 330, and 1,320 ppm for 6 hr/day, 5 days a week for 13 weeks. Clinical signs, body weights, food consumption, urinalysis, hematologic parameters, serum chemistry measurements, organ weights, necropsy, and histopathological findings were compared between the control and ethyl formate-exposed groups. Locomotor activity decreased during exposure and recovered afterward in male and female rats exposed to 1,320 ppm ethyl formate. Body weight and food consumption continuously decreased in both sexes exposed to 1,320 ppm ethyl formate from week 1 or 3 compared with the control values. The increases in adrenal weight and decreases in thymus weight were noted in both sexes exposed to ethyl formate at 1,320 ppm. Degeneration, squamous metaplasia of olfactory epithelium in the nasopharyngeal tissue, or both were noted in the male and female rats at 1,320 ppm and female rats at 330 ppm ethyl formate. Taken together, our results indicate that ethyl formate-induced changes were not observed in male and female rats at 330 and 66 ppm, respectively. This indicates that exposure to ethyl formate at concentrations below 66 ppm for 90 days is relatively safe in rats. This is the first report of a full-scale repeated inhalation toxicity assessment in rats and could contribute to controlling occupational environmental hazards related to ethyl formate.

Subchronic Oral Toxicity Study of Acanthopanax divaricatus var. albeofructus in Rats.

Acanthopanax divaricatus (Siebold & Zucc.) Seem. var. albeofructus (ADA), a traditional medical herb, has been used to treat arthritis and muscular injury, to strengthen muscle and bone, and to get vital energy. However, information regarding its toxicity is limited. ADA was administered by oral gavage to groups of rats at doses of 0 (control), 1,000, 1,500, 2,000, 2,500, and 3,000 mg/kg five times per week for 13 weeks. Mortality, clinical signs, body weights, food consumption, hematology, serum chemistry, urinalysis, organ weights, necropsy, histopathological finding, vaginal cytology, and sperm morphology were compared between control and ADA-treated groups. Salivation was intermittently observed in both sexes receiving 2,500 and 3,000 mg/kg directly after dosing. Absolute liver weights increased in females receiving 2,000, 2,500, and 3,000 mg/kg ADA (P < 0.05, P < 0.01, and P < 0.01, respectively) and so did the relative liver weights (P < 0.001). Salivation and increased liver weight were ADA-related changes but not considered to be adverse effects. Salivation was intermittent and transient, and the liver weight increase was minor and not accompanied by other changes such as hepatic morphological or functional alterations. The no-observed-adverse-effect-level was determined to be at least 3,000 mg/kg in both sexes of rats.

Subchronic toxicity of Acorus gramineus rhizoma in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Acorus gramineus rhizoma (AGR) is the dry rhizome of Acorus gramineus Solander from the family Araceae that has been used as sedative, analgesic, diuretic, digestive and antifungal agent. AIM OF THE STUDY: To evaluate the no-observed-adverse-effect level (NOAEL) and the toxicity of AGR, following repeated oral administration to rats for 13 weeks. MATERIALS AND METHODS: AGR was administered by oral gavage to groups of rats (10 per group, each sex) at doses of 0 (control), 25, 74, 222, 667, or 2,000mg/kg/day, 5 times per week for 13 weeks. Mortality, clinical signs, body weights, food consumption, hematology, serum chemistry, urinalysis, vaginal cytology, sperm motility, sperm morphology, organ weights, gross and histopathological findings were compared between control and AGR groups. RESULTS: No mortality or remarkable clinical signs were observed during this 13-week study. No adverse effects on body weight, food consumption, urinalysis, hematology, serum chemistry, organ weights, gross lesion, histopathology, vaginal cytology, sperm motility or deformity were observed in any of the male or female rats treated with AGR. CONCLUSIONS: On the basis of these results, the NOAEL of AGR is determined to be 2,000mg/kg/day for male and female rats.

Subchronic toxicity study of Coptidis rhizoma in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Coptidis Rhizoma (CR) is a medical herb from the family Ranunculacease that has been used to treat gastroenteritis, dysentery, diabetes mellitus, and severe skin diseases. AIM OF THE STUDY: To evaluate the no-observed-adverse-effect level (NOAEL) and the toxicity of CR, following repeat oral administration to rats for 13 weeks. MATERIALS AND METHODS: CR was administered by oral gavage to groups of rats (n=10/group, each sex) at dose levels of 0 (control), 25, 74, 222, 667 or 2000 mg/kg/day 5 times per week for 13 weeks. Mortality, clinical signs, body weights, food consumption, hematology, serum chemistry, urinalysis, vaginal cytology and sperm morphology, organ weights, gross and histopathological findings were compared between control and CR groups. RESULTS: Urinalysis showed a significant increase in N-acety1-ß-glucosaminidase in males in the 2000 mg/kg/day group (P<0.01). However, no mortality or remarkable clinical signs were observed during this 13-week study. No adverse effects on body weight, food consumption, hematology, serum chemistry, organ weights, gross lesion, histopathology, vaginal cytology, sperm motility, or deformity were observed in the males or female rats treated with CR. CONCLUSIONS: On the basis of these results, the NOAEL of CR is determined to be 667 mg/kg/day for males and 2000 mg/kg/day for females.

Subchronic oral toxicity of evodia fruit powder in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Evodia, a fruit from Evodia rutaecarpa, has been used in oriental medicine, and since its various pharmaceutical actions, including anti-cancer activity, have become known, evodia has been widely used as a dietary supplement. However, information regarding its toxicity is limited. MATERIALS AND METHODS: Evodia fruit from Evodia rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang (0, 25, 74, 222, 667, and 2000 mg/kg) was administered orally five times per week for 13 weeks. Clinical signs, body weight, food consumption, hematology, serum chemistry, urinalysis, vaginal cytology, sperm morphology, organ weight, and gross and histopathological findings were evaluated. RESULTS: Urinary ketone body excretion was detected in males at 667 and 2000 mg/kg and in females at 2000 mg/kg. An increase in absolute/relative liver weight was observed in both sexes at 2000 mg/kg. Although levels of serum alanine aminotransferase, glucose, total cholesterol, and triglycerides were significantly reduced in males and/or females at 200 and/or 667 and 2000 mg/kg, all values were within normal ranges and were considered non-adverse. In addition, no treatment-related differences in body weight, food consumption, hematology, vaginal cytology, sperm morphology, or gross and histopathological examination were detected. CONCLUSIONS: The subchronic no-observable-adverse-effect level for evodia fruit powder following oral administration in rats is greater than 2000 mg/kg.

Variation of nephrotoxicity biomarkers by urinary storage condition in rats.

Recently, there has been an increase in the use of several nephrotoxicity biomarkers in preclinical experiments. In addition, it has been indicated that the result may have been influenced by secondary factors, such as sample storage condition or storage period. In this study, we have assessed the variation in urinary nephrotoxicity biomarkers as a result of urine storage conditions and storage period of the urine. Urine was sampled from specific pathogen-free Sprague-Dawley rats (19 weeks old), which were housed individually in hanged stainless steel wire mesh cages. Urine was stored at 20℃, at 4℃, or at -70℃ after sampling. The levels of the biomarkers such as beta-2 microglobulin (B2M), cystatin-C (Cys-C), N-acetyl-ß- D-glucosaminidase (NAG), micro albumin (MA), micro protein (MP) were measured at 6, 24, 48 and 144 hr after sampling. The B2M level was significantly decreased at 6, 24, 48, and 144 hr compared to 0 hr at -70℃ (p < 0.05, p < 0.01, p < 0.05, and p < 0.05, respectively) and 24 and 144 hr at 20℃ (p < 0.01, p < 0.01, respectively). The Cys-C level was significantly decreased at 144 hr compared to 0 hr at 4℃ (p < 0.01), at 20℃ (p < 0.05) and at 70℃ (p < 0.01). MP and MA levels were not different for 144 hr in all storage conditions. Taken together, B2M and Cys-C levels were modulated by storage temperature and period. For the enhancement of test accuracy, it is suggested that strict protocols be established for samples to minimize the effects of the storage conditions on the detected levels of biomarkers.