Dose-response hapatotoxicity of the peroxisome proliferator, perfluorodecanoic acid and the relationship to phospholipid metabolism in rats.

Perfluorodecanoic acid (PFDA) is a potent peroxisome proliferator that causes hepatotoxicity but lacks tumor-promoting activity in rats. We previously showed that a single dose of PFDA at 50 mg/kg (approximately LD50) causes an elevation in liver phosphocholine (PCho) and other effects related to phospholipid metabolism. In this study, we examined metabolic effects in the dose range 2-50 mg/kg in rats. At doses < or =20 mg/kg, PFDA is significantly less hepatotoxic than the LD50 as manifested by electron microscopy and measurements of daily food consumption and body weight. At 50 mg/kg rat serum tumor necrosis factor (TNF)-alpha concentration was increased 8-fold, while at 15 mg/kg there was no apparent increase in this cytokine. This lower dose, however, induces metabolic effects similar to those seen at the LD50. Liver fatty acyl-CoA oxidase activity showed a dose-dependent increase from 5-25 mg/kg PFDA. Treatments at 15 and 50 mg/kg caused a significant increase in liver phosphatidylcholine (28 and 66%) and phosphatidylethanolamine (31 and 74%). Both doses caused a significant increase in liver PCho but did not affect liver ATP levels, as manifested in 31P nuclear magnetic resonance (NMR) spectra from rat livers in vivo. These data suggest that the increase in liver [PCho] observed following PFDA exposure in rats represents a specific metabolic response, rather than a broad-range hepatotoxic effect.     

In vivo micronucleus assay and GST activity in assessing genotoxicity of plumbagin in Swiss albino mice

Information available on the mutagenicity of a large number of indigenous drugs commonly employed in the Siddha and Ayurveda systems of medicine is scanty. In this context, the current investigation on plumbagin, 5-hydroxy-2methyl-1,4-napthoquinone, an active principle in the roots of Plumbago zeylanica used in Siddha and Ayurveda for various ailments, was carried out; 16 mg/kg b.w. (LD(50)) was fixed as the maximum dose. Subsequent dose levels were fixed as 50% and 25% of LD(50) amounting to 8 mg and 4 mg/kg b.w., respectively, and given orally for 5 consecutive days in 1% Carboxyl Methyl Cellulose (CMC) to Swiss albino mice weighing 25-30 g. The micronucleus assay was done in mouse bone marrow. Plumbagin was found to induce micronuclei at all the doses studied (4 mg/kg, 8 mg/kg, 16 mg/kg b.w.), and it proves to be toxic to bone marrow cells of Swiss albino mice. Animal treated with cyclophosphamide (40 mg/kg b.w.) served as positive control. In addition, glutathione S-transferase (GST) activity was observed in control, plumbagin (4 mg, 8 mg, 16 mg/kg b.w., respectively), and genotoxin-treated experimental group of animals. No significant change in GST activity was observed with plumbagin dose of 4 mg/kg b.w., whereas GST activity was significantly inhibited by higher doses of plumbagin (8 mg and 16 mg/kg b.w.) and cyclophosphamide.     

Acute and repeat-dose toxicity studies of the (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH), an albumin-binding prodrug of the anticancer agent doxorubicin

The (6-maleimidocaproyl)hydrazone derivative of doxorubicin (DOXO-EMCH) is an albumin-binding prodrug of doxorubicin with acid-sensitive properties that demonstrates superior antitumor efficacy in murine tumor models, and has been evaluated in a phase I study. In order to establish the toxicity profile of this prodrug, acute and repeat-dose toxicity studies were performed with DOXO-EMCH in CD1-mice, Sprague-Dawley rats and Beagle dogs. Although the objective of the acute toxicity studies was not the determination of LD50 values, the LD50 of DOXO-EMCH was >60 mg/kg doxorubicin equivalents in both male and female mice (the LD50 of doxorubicin in CD-1 mice is -12 mg/kg). In Sprague-Dawley rats, the LD50 was 23.4 and 45.9 mg/kg doxorubicin equivalents for males and females, respectively. For comparison, the LD50 of doxorubicin in Sprague-Dawley rats is -10.5 mg/kg. The major clinical sign noted following intravenous administration of DOXO-EMCH in mice and rats was a dose-dependent peripheral neuropathy which, in general, developed as a delayed toxicity 1-3 weeks after application. The observed neurotoxicity has been well documented for Sprague-Dawley rats treated with doxorubicin at a dose of 5 and 10 mg/kg. In Beagle dogs, LD10 was not reached for DOXO-EMCH at 4.5 mg/kg doxorubicin equivalents. A four-cycle intravenous study with DOXO-EMCH at dose levels of 4 x 2.5, 5.0 or 7.5 mg/kg doxorubicin equivalents in rats revealed approximately three-fold less side effects on the hemolymphoreticular system when compared to 4 x 2.5 mg/kg doxorubicin dose, whereas effects on the testes/oligospermia seem to be comparable between both drugs at equitoxic dose. A No Observable Adverse Effect Level (NOAEL) for DOXO-EMCH of 4 x 2.5 mg/kg doxorubicin equivalents was established in this study. This dose is equivalent to the maximum tolerated dose (MTD) of doxorubicin in rats. In a two-cycle study over a period of 6 weeks in Beagle dogs (intravenous administration of DOXO-EMCH at dose levels of 1.5, 3.0 or 4.5 mg/kg doxorubicin equivalents), dose-related systemic histamine-like reactions within the first 3 hours after injection were noted in all treated groups. Only transient and temporary effects on hematology, urinary function, as well as on histopathology in mid- and/or high-dose animals, were observed. The low dose of 2 x 1.5 mg/kg was considered to be the NOAEL in this study, which is equivalent to twice the MTD o f doxorubicin i nBeagle dogs. In summary, the toxicity studies with DOXO-EMCH in mice, rats or dogs have not identified any other special toxicity when compared to the toxicity data for doxorubicin. Preclinical tolerance of DOXO-EMCH was higher in mice, rats and dogs compared to doxorubicin. A dose of 20 mg/m2 doxorubicin equivalents was recommended as the starting dose for a phase I study with DOXO-EMCH.     

Comparison of lung injury induced in 4 strains of mice by butylated hydroxytoluene

Butylated hydroxytoluene (BHT) is a phenolic antioxidant which induces lung injury in all strains of mice which have been tested, but not in any other species. The mortality of mice treated with BHT is also highly strain-dependent, with LD50s ranging from 138 to 1739 mg/kg. Despite this wide range of toxic doses, the relationship between lung damage and dose has not been well studied. The data presented here demonstrate that BALB/c, ICR and C57BL/6NHsd mice, with LD50s of 1739, 1243 and 917 respectively, exhibit similar time courses of repair (as assessed by the incorporation of radiolabelled thymidine into DNA) and pulmonary fibrosis (as assessed by lung hydroxyproline content) when given a single 400 mg/kg dose of BHT. SSIn mice, with an LD50 of approximately 350 mg/kg, also exhibited a similar time course of repair when given a single dose of 300 mg/kg BHT, although fibrosis did not develop in these animals. These data indicate that all strains of mice develop similar levels of lung injury at equivalent doses and that the extent of lung damage produced in mice does not correlate with the lethal dose.     

A comparison of the pulmonary toxicity produced by metal-free and copper-complexed analogs of bleomycin and phleomycin

The purpose of this study was to evaluate the acute and subchronic toxicology of trichloroethylene (TCE) in the mouse. The oral LD50 in female mice was 2443 mg/kg (95% confidence limits of 1839–3779 mg/kg) and in male mice was 2402 mg/kg (95% confidence limits of 2065–2771 mg/kg). After determination of the LD50 by the oral route, a 14-day study was done in male CD-1 mice in which TCE was administered daily by gavage at 24 and 240 mg/kg. A subchronic drinking water study was designed based on these data, in which TCE at concentrations of 0.1, 1.0, 2.5, and 5.0 mg/ml was used, and mice of both sexes were exposed for 4 or 6 months. There was a decreased body weight gain at the highest dose, which could be attributed to a decrease in fluid consumption. The most significant effects attributable to TCE were an increase in liver weight in both sexes accompanied by increased nonprotein sulfhydryl levels in the males, and an increase in kidney weight in both sexes accompanied by increases in protein and ketones in the urine. TCE failed to elicit any other adverse effects.     

Antiviral effect of 1-morpholinomethyl-tetrahydro-2(1H)-pyrimidinone (DD-13) in experimental alphaviral infections in white mice

1-Morpholinomethyl-tetrahydro-2(1H)-pyrimidinone (DD-13), a selective inhibitor of the alphaviral reproduction in vitro, manifests a pronounced antiviral activity in experimental infections with Semliki forest virus (SFV) and Sindbis virus in white mice (intraperitoneally inoculated with 10-10 000 LD50). Introduced subcutaneously in mice infected with SFV the compound was effective within the dose range of 4.7-300 mg/kg. The effective dose (ED)50 value of DD-13 is about 18.7 mg/kg and the maximum effect is reached with a 150-300 mg/kg dose. The protection index reached 80% and the mean survival time from approximately 7 days in the placebo group was lengthened to 26 days. This high antiviral effect is distinguished by its high selectivity, the selectivity ratio (LD50/ED50) being 385 (LD50 = 7200 mg/kg) and is manifested in infections with massive viral inocula (100-1000 LD50). The effective treatment schedule was determined: two divided daily doses of 37.5-150 mg/kg, beginning on the 3rd day after infection to the 8th day. After intravenous administration of DD-13 in mice infected with SFV a high protective effect was also observed, which was equal to that of the subcutaneous application, but with doses several times lower: in the 3-40 mg/kg. ED50 is about 3.5 mg/kg and the optimal effective dose is 10-20 mg/kg, i.e. 1/12-1/6 of LD50 (116 mg/kg). The selectivity ratio is about 33. The most effective treatment course is accomplished by a 10-20 mg/kg daily dose (in two applications) starting on the 2nd day after the virus inoculation up to the 8th day.(ABSTRACT TRUNCATED AT 250 WORDS)     

敌枯双致畸危害性的评价指标

本文提出以β-二项分布模型处理具有窝别效应的致畸实验资料。并将由此模型求得的tD_(50)(半数致畸效量)作为致畸强度的指标。将母体LD_(50)与仔代tD_(50)的比值LD_(50)/tD_(50)作为相对致畸强度指数(RTPI),用于不同化学物质间致畸强度比较。将tD_(01)作为最小致畸效量的估计值。将母体LD_(01)与仔代tD_(01)的比值LD_(01)/tD_(01)作为相对致畸危害性指数(RTHI)用于不同化学物质间的比较。讨论了选择上述指标的理由。敌枯双tD_(50)为3.80mg/kg,95％可信限范围2.53-6.68mg/kg,tD_(01)为0.22mg/kg(0.03-0.52mg/kg)。相对致畸强度指数(RTPI)为67±15.相对致畸危害性指数(RTHI)为660±432,并将β-二项分布模型所得结果与概率单位模型和以窝为观察单位的计算结果作了比较。与文献报道的化学物质相应的参数亦作了初步比较。     

Effects of lindane on spontaneous behavior of rats analyzed by multivariate statistics

The effects of subconvulsant doses (10, 15, 30 mg/kg) of the organochlorine insecticide gamma-hexachlorocyclohexane (lindane) on the spontaneous activity of male Wistar rats were assessed in an automated wheel-shaped activity monitor in 4 hr sessions. Most of the activity variables defined on the raw data showed statistically significant differences among treatment groups. These data can be interpreted as a lindane-induced change in the temporal distribution of the activity. The multivariate statistical technique principal component analysis was used to obtain a composite variable that measured this change. The variable obtained was found to be well correlated with dose levels and brain concentration of lindane and was used to estimate a minimal effective dose (MED) of 1.85 mg/kg and a upper limit for a minimal effective concentration (MEC) in brain of 0.84 micrograms/g by a log-linear regression approach. The results obtained with this approach further support the conclusion that the behavioral effects of lindane can be significant at exposure levels far below its LD50.     

The protective effect of hydrated sodium calcium aluminosilicate against haematological, biochemical and pathological changes induced by Zearalenone in mice.

Hydrated sodium calcium aluminosilicate (HSCAS), an anticaking agent for mixed feed, was added alone or simultaneously with a toxic Zearalenone (ZEN) dose to balb/c mice and was evaluated for its ability to restore damages induced by ZEN. The latter is a mycotoxin produced by fusarium genera; it is mainly known to induce several toxic effects such as hepatotoxicity, immunotoxicity and nephrotoxicity on animals and humans. The experimental approach consisted of eight treatments of six mice each by 400 mg/kg bw or 5 g/kg bw of HSCAS. Two experimental groups have received respectively ZEN alone at 40 (8% of LD50) and at 500 mg/kg bw (LD50). Two other groups have received ZEN at 40 or 500 mg/kg bw combined respectively with HSCAS at 400 mg/kg bw and 5 g/kg bw. The control groups received water or olive oil. Forty-eight hours after treatment, blood samples were collected for haematological and serum biochemical parameters measurements. ZEN treatment significantly increased hematocrit, haemoglobin, white blood cells: lymphocytes, eosinophils, neutrophils, monocytes and the most of biochemical serum parameters; it significantly reduced platelets and induced degenerative changes in the hepatic and renal tissues; while, the mixture of HSCAS with ZEN induced a reestablishment of haematological parameters, levels of serum biochemical enzyme activities and histological pictures of both liver and kidney. It also prevented general toxicity of ZEN. This was observed by the shift of LD50 for this toxin. Thus, our data strongly suggested that deleterious effects of ZEN could be overcome or, at least, significantly were diminished by HSCAS. Moreover, this sorbent by itself did not show any toxic effects.     

Biological Markers of Acute Acrylonitrile Intoxication in Rats as a Function of Dose and Time

Three markers of acute acrylonitrile (AN) intoxication, namely,tissue glutathione (GSH), tissue cyanide (CN), and covalentbinding to tissue protein, were studied as a function of doseand time. Doses administered and responses expected were 20mg/kg (LD0), 50 mg/kg (LD10), 80 mg/kg (LD50), and 115 mg/kg(LD90). Liver GSH was the most sensitive marker of AN exposure.At 80 mg/kg AN, virtually complete depletion of liver GSH wasobserved within 30 min with no recovery through 120 mm. KidneyGSH showed a similar, but less intense depletion; while bloodand brain GSH were more refractory to AN. Whole blood and brainCN rose progressively during the first 60 mm in a dose-dependentfashion. At the lowest dose, CN levels decreased thereafter,whereas, at the three higher doses, CN levels were maintainedor continued to increase through 120 min. At the highest dose,blood and brain CN remained at acutely toxic levels through240 mm. Covalent binding increased rapidly in all tissues duringthe first 30 mm at all doses. At the lowest dose, little additionalcovalent binding was observed beyond 30 mm, while at the threehigher doses, covalent binding increased, although at a slowerrate. The data indicate that these three biologic markers ofacute AN intoxication respond dramatically in a time-dependentmanner in the toxic dosage range. Furthermore, the data provideevidence that AN toxicity is gated by GSH depletion in liverwith the resultant termination of AN detoxification.     

Acute toxicity of bemithyl and bromithyl

The experiments on rats showed for bemithyl LD50 = 581.48 (350.17-965.57) mg/kg and for bromithyl LD50 = 1750.30 (1463.07-2093.92) mg/kg (males) and 1584.29 (1280.46-1960.22) mg/kg (females). The therapeutic ratios are 4-6 for both drugs, while the toxicity index is 10-15 for bemithyl and 20 <196> 22 for bromithyl. It was established that ergotropic effects prevail in the toxicity of bemithyl administered in the 20-80 mg/kg dose range, while trophotropic effects are dominating at doses above 100 mg/kg. Bromithyl exhibits a dose-dependent trophotropic effect in the entire dose range.     

The Effect of Thiabendazole on Pain Threshold

Abstract: Thiabendazole significantly increased the reaction time to thermal stimulus. However, in mice treated with morphine, the reaction time was not in any way different from those treated with combined doses of thiabendazole and morphine. Thiabendazole was found to have an antinociceptive action. The protective dose for 50% of animal (ED50) against p–benzoquinone–induced writhing reflex was found to be 310 mg/kg. The ED50 for aspirin alone was 140 mg/kg. When the ED50 of aspirin was determined in combination with different dose levels of thiabendazole, it showed a marked reduction in the values reaching 50 mg/kg, when 300 mg of thiabendazole was used in combination. Toxicological studies revealed that the oral LD50 for thiabendazole in mice was 2200 mg/kg, and when combined with 140 mg/kg of aspirin, the LD50 was reduced to 900 mg/kg. These findings indicate that thiabendazole possesses an analgesic activity which is potentiated by aspirin, though aspirin was found to significantly enhance its toxicity     

Intraperitoneal injection of dipyridamole increases the life span of tumor bearing mice treated with fluorouracil.

This study was carried out to investigate the effect of the Fluorouracil (5-FU) and Dipyridamole (DP) combination on the growth of P388 murine lymphoid neoplasms. The first stage was to determine the lethal dose (LD 50) for each compound (5-FU, DP) to normal B6D2F1 mice after intraperitoneal (i.p.) injection. The LD 50 were 700 and 54 mg/kg for DP and 5-FU respectively. B6D2F1 mice bearing P388 ascitic tumors and receiving a 4-day schedule of 5-FU (2 mg/kg/day) with DP (100 mg/kg/day) 1 hr before each 5-FU dose were studied. DP was found to lower significantly (p < 0.0001) the mortality of 5-FU in tumor bearing mice by nearly 2.5 fold. This study aims at defining the best dose combination of intraperitoneal injection of 5-FU in conjunction with DP. These data allow a prospective evaluation of 4-day, i.p. 5-FU and DP with an increase of life span without toxic death.     

Toxicity Studies with Fluindarol, 2-[p-(trifluoromethyl)phenyl]1, 3-indandione,an Agent with Anticoagulant Properties (BS 7616 D)

The phenylindandione derivative fluindarol was subjected to a toxicological investigation in view of its possible use as an anticoagulant in man. The acute oral LD50 in rats and rabbits was 198 and 123 mg/kg, respectively. The acute intraperitoneal LD50 in the rat was 125 mg/kg. Dogs survived single oral doses of up to 2810 mg/kg; if the drug was given for four consecutive days, an oral LD50 of 118 mg/kg was obtained. In a four-week experiment in the rat, doses ranging from 108 to 7 mg/kg caused mortality which occurred sooner and more frequently in the females than the males; the organs showed haemorrhages and at the higher dose levels the liver showed parenchymal necrosis. Similar results were obtained with chlorindione, which tended to be somewhat less toxic. It was confirmed that a distinction should be made between the “toxicity” of an anticoagulant which is due to its pharmacological properties and true organ toxicity. Fluindarol was considered too toxic for clinical use.     

Experimental assessment of the protective activity of diazepam on the acute toxicity of chloroquine

The dose of diazepam that reduces the mortality rate of acute intoxications with chloroquine was determined: The oral LD 50 of chloroquine (330 mg/kg) was administered and immediately thereafter diazepam was injected intraperitoneally to male and female rats at dose levels of 2.5, 7.5, 20, 55, and 148 mg/kg. An untreated group served as control. A significant decrease of the mortality rate was observed at the dose levels 7.5, 20, and 55 mg/kg with optimal effect at 20 mg/kg. This mortality rate was analysed by analysis of variance. The occurrence of two types of symptoms: convulsions and respiratory disturbances was analysed by the chi square method.     

Renal, hepatic, cardiac and thymic acute toxicity afforded by bis(helenalinyl)malonate in BDF1 mice

Bis(helenalinyl)malonate [BHM], a pharmacologically active sesquiterpene lactone potentially useful as an antineoplastic agent, proved to be less toxic than its parent compound, helenalin. Its LD50 in BDF1 mice, i.p. was more than twice that of helenalin. Its lower toxicity allowed a higher therapeutic dose (15 mg/kg/day vs. 8 mg/kg/day for helenalin) which, in turn, afforded a greater T/C% (261 vs. 161). When BHM was employed at its therapeutic dose of 15 mg/kg/day, no marked toxicity was evident after three daily doses. However, continuation of treatment at this level led to both kidney and liver toxicity as measured by clinical chemistry parameters. Histological lesions in the thymus and kidney were demonstrated within 48 h at 25 mg/kg as a single dose. Apparently the toxicity was delayed with BHM but accumulated over time. Transient cardiotoxicity occurred with the drug and the agent was suspected of causing intestinal blockage.     

New hepato-protective agents. I. Maleopimaric acid-4alpha-carboxamides.

A number of amide derivatives of maleopimaric acid were synthesised and preliminary results on their protective activity against galactosamine-induced liver damage in the rat are described. The compounds (2, 6, 9 and 15) were found to display the highest level of protective activity producing significant lowering of serum GOT and GPT levels at a daily dose of 250-300 mg/kg. The LD50 of these compounds was typically in excess of 2000 mg/kg.     

New hepato-protective agents. II. Maleopimaridyl morpholides.

A further series of derivatives of maleopimaric acid, the maleopimaridyl morpholides, has been prepared and results on their protection against galactosamine-inducted liver damage in the rat are described. The compounds (3, 4, 8 and 10) were found to display the highest levels of hepato-protective activity in the series. Compound 8 (LD50 greater than 10 g/kg) which exhibited significant, dose-related protection at a daily dose in the range of 50-400 mg/kg, was selected for detailed investigation.     

β-Adrenergic agonists,potent nonspecific inhibitors of circulatory shock in rats

The activity of a series of nine β-adrenergic agonists was studied in the potassium cyanide (KCN; 5.00 mg/kg i.v.) and the compound 48/80 (0.50 mg/kg i.v.) lethality tests in rats. All compounds were found active in both tests. The ED50 values in mg/kg for protection against KCN-induced lethality were as follows: clenbuterol (0.0047), zinterol (0.0055), hexoprenaline (0.0093), fenoterol (0.012), isoproterenol (0.014), colterol (0.019), salbutamol (0.028), terbutaline (0.14), and metaproterenol (0.33). The obtained results illustrate that KCN antagonism in rats is a general property of β-adrenergic agonists and that their potency is in agreement with previously reported data for β-adrenergic stimulation. By increasing the dose levels, the protective activity of some of the compounds disappeared and LD50s at which lethality to KCN was restored could be calculated. The protective dose range, which is defined as the ratio of the LD50 and the ED50, greatly varies among the test compounds. Protection from compound 48/80 induced lethality was also obtained with all compounds. This protection occurred at higher dose levels than in the KCN test, but persisted at agonist doses that had lost protective effect against KCN. Protection from KCN-induced lethality seems to be due to an increased tissue perfusion and to occur as long as myocardial activity is not markedly changed from normal by the test compound.     

Effects of acute and repeated oral exposure to the organophosphate insecticide chlorpyrifos on open-field activity in chicks

The effects of the organophosphate insecticide chlorpyrifos on 5min open-field activity were examined in a 7-15 days old chick model. Chlorpyrifos was acutely administered taking into account cholinesterase inhibition and determination of the acute (24h) median lethal dose (LD50). The oral LD50 value of chlorpyrifos in chicks was 18.14mg/kg, with cholinergic toxicosis observed on intoxicated chicks. Chlorpyrifos at the dose rates of 5,10 and 20mg/kg orally produced within 2h signs of cholinergic toxicosis in the chicks and significantly inhibited plasma (40-70%), whole brain (43-69%) and liver (31-46%) cholinesterase activities in a dose-dependent manner. Chlorpyrifos at 2 and 4mg/kg, orally did not produce overt signs of cholinergic toxicosis, but decreased (30, 60 and 90min after dosing) the general locomotor activity of the chicks as seen by a significant increase in the latency to move from the central square of the open-field arena, decreases in the numbers of lines crossed and vocalization score. Repeated daily chlorpyrifos treatments (2 and 4mg/kg, orally) for seven consecutive days also caused hypoactivity in chicks in the open-field behavioral paradigm. Only the high dose of chlorpyrifos (4mg/kg, orally) given repeatedly for 7 days caused significant cholinesterase inhibition in the whole brain (37%) and the liver (22%). In conclusion, chlorpyrifos at single or short-term repeated doses-induced behavioral changes in 7-15 days old chicks, in a model that could be used for further neurobehavioral studies involving subtle effects of organophosphates on chicks.