Acute toxicity of polyethylene glycol p-isooctylphenol ether in Syrian hamsters exposed by inhalation or bronchopulmonary lavage

Dose-response studies were conducted with Syrian hamsters exposed to polyethylene glycol p-isooctylphenyl ether (Triton X-100) via inhalation or bronchopulmonary lavage. Syrian hamsters were exposed to an aerosol of Triton X-100 with a mass median aerodynamic diameter of 1.5 μm and a concentration of 3.0 mg/liter. Estimated initial lung burdens of Triton X-100 ranged from 800 to 3100 μg. Hamsters were lavaged with concentrations of Triton X-100 ranging from 0.01 to 0.10% in isotonic saline resulting in initial lung burdens of Triton X-100 that ranged from 300 to 3200 μg. The $\text{LD}\text{50}\text{7}$ values were 1700 μg (1300–2100 μg, 95% confidence limits) for the inhalation study and 2100 (1900–2700) μg for the lavage study. The difference between the $\text{LD}\text{50}\text{7}$ values for the two methods of exposure was not significant. However histopathological examination revealed differences in the nature and distribution of pathologic changes observed in animals exposed by the two routes of administration. Animals exposed by inhalation died as a result of ulcerative laryngitis and laryngeal edema with only minimal pulmonary pathologic alterations. Animals exposed by lavage, where the larynx was not exposed to Triton X-100, died from pulmonary edema and acute exudative pneumonia, these results demonstrate the need for careful selection of exposure methods to meet the specific objectives of a toxicology study.     

Correlation between histamine content in exudate and degree of edema produced by dextran

Edema was produced in the hind paws of rats by local subcutaneous injection of dextrans of four different molecular weights (7500, 28,000, 65,000 and 207,000), and the resultant exudate was assayed for histaminc content 15–240 min after injury. Each dextran produced paw edema, the degree of which depended on the concentration (0.2. 1.0 and 4.0%, $\text{w}\text{v}$). The maximum response was obtained 30–60 min after the injection. The highest concentration of histamine in the exudate collected from the inflamed paw was 3.7 to 6.9 $\text{μg}\text{ml}$, which was obtained in the initial stage before the peak of edema. When the edema was at its peak the concentration of histamine had already declined. Statistical analysis showed a significant correlation between the concentration or total amount of histamine in the exudate and the degree of edema produced by most of the dextrans. These results suggest that release of histamine is not the result but rather the cause of the edema formation produced by dextrans.     

Protection from paraquat-induced lung damage and lethality in adult rats pretreated with clofibrate

Pretreatment of adult rats with the hypolipidemic agent clofibrate (60 mg/kg/day × 6 days) resulted in a marked degree of protection from paraquat-induced lung toxicity and lethality. The 10-day survival of treated rats was $\text{39}\text{56}$ (70%) compared to $\text{21}\text{76}$ (28%) (LT₅₀ = 2.8 days) for controls (p < 0.001). Although clofibrate reportedly increases catalase activity in the liver, we found no increases in any of the antioxidant enzymes in the lung (catalase, superoxide dismutase, glutathione peroxidase, or G-6-PD) after clofibrate pretreatment. Lung lipid peroxidation at 24 and 48 hr post-paraquat was equivalent in both groups, although the clofibrate-pretreated rats showed significantly reduced lung edema and pathologic changes at these times. Blood paraquat levels were similar in both groups at 1, 3, and 24 hr postinjection. In two experiments, administration of clofibrate after paraquat injection afforded no protective effects. However, since pretreatment with clofibrate provided the best overall survival rate reported to date after a lethal dose of paraquat (35 mg/kg), further studies toward elucidating the mechanism(s) of action of this agent are warranted. Unraveling the protective mechanism(s) of the pretreatment regimen may still provide valuable clues to suggest effective post paraquat treatment approaches.     

Mercuric chloride stress on serum transaminase activity in Notopterus notopterus

Mercuric intoxication at sublethal levels ($\text{1}\text{5}$, $\text{1}\text{10}$, $\text{1}\text{15}$, $\text{1}\text{20}$ or $\text{1}\text{25}$ fractions of 96 h LC₅₀) produced alterations in the activity of serum glutamic oxalacetic transaminase (SGOT) and serum glutamic pyruvic transaminase (SGPT) of Notopterus notopterus. The difference between control and treated fish was found to be significant at P < 0.05, P < 0.01 and P < 0.001 levels. Maximum (81.75%) significant (P < 0.001) effect was observed in SGOT: maximum (69.23%) significant (P < 0.001) effect was observed in SGPT in fish exposed for 60 days.     

Reversion by vitamin K of aflatoxin B1 (AFB)-induced inhibition of oxygen uptake in three AFB-susceptible bacteria

The effect of Vitamin K, on the inhibition of oxygen uptake in Bacillus brevis (2611), Bacillus megaterium (1368) and Flavobacterium aurantiacum by aflatoxin B₁ (AFB) has been investigated.At 1.5 mM, vitamin K completely reversed oxygen inhibition by 10 $\text{μg}\text{ml}$ AFB in the three bacteria and by 50 $\text{μg}\text{ml}$ APB in B. brevis, the most susceptible of the three bacteria to AFB. Vitamin K did not reverse the inhibitory effect of 100 $\text{μg}\text{ml}$ AFB in any of the three bacteria except B. megaterium, neither did 1.5 mM 2,4-dinitrophenol (DNP) reverse the inhibition at 10 $\text{μg}\text{ml}$ and 100 $\text{μg}\text{ml}$ levels of AFB in any of the three bacteria.     

Circular dichroism and gel filtration study of binding of prochiral and chiral 1,4-benzodiazepin-2-ones to human serum albumin

Combining circular dichroism (c.d.) and gel filtration method in studying the binding of chiral $\text{((S)/R)-}\text{1}\text{)}\text{and prochiral}\text{(}\text{2}\text{.}\text{diazepam and}\text{3}$. desmethyldiazepam) benzodiazepines to human serum albumin (HSA), the following results were obtained: c.d. measurements revealed that both enantiomers of $\text{1}$ are bound by HSA with different affinities. Gel filtration measurements revealed the following data on binding; (a) the HSA affinity for ($\text{S)-}\text{1}$ is about 40 times higher than for ($\text{R)-}\text{1}$, (b) for ($\text{S)-}\text{1}$ exist two independent and nonequivalent sites of high affinity and for ($\text{R)-}\text{1}$ two independent equivalent sites of low affinity, (c) at equimolar concentrations of $\text{1}$ and HSA, (S)-enantiomer is bound up to 5 3 per cent, but (R)-enantiomer up to 18 per cent only; at the same ratio of ligand to protein prochiral $\text{3}$ was bound up to 56 per cent.     

Immunosuppressive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in strains of mice with different susceptibility to induction of aryl hydrocarbon hydroxylase

Mouse strains with different susceptibility to aryl hydrocarbon hydroxylase (AHH) induction and with different levels and/or affinity for a specific cytosolic binding protein (“receptor”) were used to investigate the immunosuppressive effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Humoral antibody production was strongly inhibited in $\text{C57B1}\text{6}$ and $\text{C3H}\text{HeN}$ mice (more susceptible strains) with very low, single doses of TCDD (1.2 μg/kg), while other strains ($\text{DBA}\text{2}$ and AKR) required higher doses (at least 6 μg/kg) to be partially suppressed. Longer exposure (8 weeks) did not increase the sensitivity of $\text{DBA}\text{2}$ mice. A good correlation between the degree of enzyme inducibility and immunosuppression was observed in studies with B6D2F1 mice and backcrosses. Similar results were obtained with 2,3,7,8-tetrachlorodibenzo-furan (TCDF), the most powerful competitor for TCDD “receptor” in vitro and in vivo. TCDD immnotoxic effects appeared to be associated with the presence of a specific cytosolic binding protein which mediates AHH induction.     

The blockade of bulbospinal inhibition by imipramine, desipramine and pargyline

Bulbospinal inhibition of the spinal cord monosynaptic reflex was antagonized by im-ipramine HCl (5 $\text{mg}\text{kg}$), desipramine HCl (4.8 $\text{mg}\text{kg}$) and pargyline HCl (30.0 $\text{mg}\text{kg}$) in unanaesthetized, decerebrate cats. The blocking action of imipramine was prevented in animals pretreated for three consecutive days with dl-p-chlorophenylalanine (300 $\text{mg}\text{kg}$) but not in animals pretreated with dl-α-methyl-p-tyrosine methyl ester HCl (125 $\text{mg}\text{kg}$) 16 and 4 hr prior to recording. These results do not support the proposal of Clineschmidt and Anderson (1970) that the bulbospinal inhibitory pathway contains a 5-hydroxytryptamine (5-HT) link. Rather, the findings suggest that 5-HT is involved in antagonizing bulbospinal inhibition of the monosynaptic reflex.     

Toxicity of N-(phosphonomethyl)glycine to chick embryo

The LD₅₀ values, 12.88 $\text{mg}\text{100 g egg}$ and 13.22 $\text{mg}\text{100 g egg}$, obtained when the N-phosphonomethyl derivative of glycine was injected into the air sacs of White Rock and White Leghorn eggs respectively, were significantly lower (P < 0.01) than the values, (24.72 $\text{mg}\text{100 g egg}$ for White Rocks and 25.44 $\text{mg}\text{100 g egg}$ for White Leghorns) obtained by injection into the yolk sac. These findings suggest that the toxicity of N-(phosphonomethyl)glycine (PMG) to the chick embryo depends on the route of injection.     

Sensitivity to suppression of cytotoxic T cell generation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is dependent on the Ah genotype of the murine host

Susceptibility of mice to a variety of toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is genetically determined by the Ah locus. To determine if immunotoxicity following TCDD exposure was also regulated by the Ah locus, we tested the ability of low dose TCDD (4 ng/kg) to suppress the generation of allospecific cytotoxic T cells (CTL) by lymphocytes from “susceptible” $\text{C57Bl}\text{6}$, and “resistant” $\text{DBA}\text{2}$, and from C57B1/6XDBA/2J F₁ hybrid mice in vitro. To determine if TCDD acted directly on the “susceptible” lymphoid cells, the immune response of $\text{C57B1}\text{6}\text{→}\text{DBA}\text{2}$ and $\text{DBA →}\text{C57B1}\text{6}$ bone marrow chimeras was also measured. $\text{C57B1}\text{6}$ and F₁ mice proved susceptible to suppression consistent with the dominant effect of Ah. Susceptibility to suppression in chimeric mice, however, was determined by the Ah genotype of the host and not by the genotype of the grafted lymphomyeloid cells. Mixing experiments demonstrated that suppression of CTL generation by TCDD was due to suppressor T cells. The frequency of CTL precursors was not affected by TCDD. These results are consistent with the idea that TCDD acts by an Ah locus-dependent mechanism to indirectly promote development of suppressor T cells that block the generation of CTL from their precursors.     

Mechanisms of hyperglycemic response to chlorpromazine administered into lateral ventricle in rats. I. Possible role of dopaminergic nervous system

Injection of a chlorpromazine(CPZ) dose of 0.5 $\text{mg}\text{kg}$ into the lateral ventricle caused a transient rise of about 50 per cent of the initial level in blood glucose of rat. The induced hyperglycemia was reduced by simultaneous injection of dopamine (0.02 $\text{mg}\text{kg}$) with CPZ into the ventricle or by pretreatment with l-DOPA (150 $\text{mg}\text{kg}$, i.p.) and diethyldithiocarbamate (DDC, 1 $\text{mg}\text{kg}$, intraventricularly). An increase of dopamine in brain per se did not significantly change the glucose levels. The inhibitory effect of dopamine injected into the ventricle was blocked by pretreatment withalpha-blockers(tolazoline, dibenamine, 0–05 $\text{mg}\text{rat}$) injected into the ventricle. Alpha-blockers per se did not cause any hyperglycemia. These results suggest that the sites of action of dopamine and alpha-blockers are similar and that of CPZ is different. An effect of beta-blockers on the inhibitory effect of dopamine was not obvious, because intraventricularly injected propranolol blocked the hyperglycemia induced by systemically administered epinephrine probably owing to a leak into extracerebral tissues. On the other hand, the combined administration of reserpine (1 $\text{mg}\text{kg}$, i.p.) and α-methyltyrosine (0.1 $\text{mg}\text{rat}$, intraventricularly) partially reduced the CPZ-induced hyperglycemia. 6-hydroxydopamine (6-OHDA) which caused a selective destruction of catecholamine-containing neurones, also reduced the CPZ-induced hyperglycemia, but this reduction was partially reversed after injecting simultaneously dopamine and CPZ.     

The use of urinary N-acetyl-beta-glucosaminidase in human renal toxicology. II. Elevation in human excretion after aspirin and sodium salicylate.

The copper-mobilizing effect of 16 substances has been studied in rats. Among these, sodium 2,3-dimercaptopropane-1-sulfonate (DMPS), d-penicillamine (PA), N-acetylpenicillamine (NAPA), and triethylenetetramine (TRIEN) showed the best efficacy. Combined treatment with $\text{DMPS}\text{PA}$, $\text{DMPS}\text{TRIEN}$, or $\text{TRIEN}\text{PA}$ was not superior to any one of the compounds in a corresponding dosage.     

In vitro transformation of hamster embryo cells by 3-(N-salicyloyl) amino-1,2,4-triazole

The in vitro carcinogenic activities of 3-(N-salicyloyl)amino-1,2,4-triazole (SAT) and its two components, 3-amino-1,2,4-triazole and phenyl salicylate were examined in a transformation assay with cryopreserved hamster embryo cells. SAT induced morphological transformation at certain doses between 10 $\text{μg}\text{ml}$ and 100 $\text{μg}\text{ml}$ in each of 5 repeated experiments, but gave a negative result in the Salmonella mutation assay. 3-Amino-1,2,4-triazole also induced transformation in 3 repeated experiments. Phenyl salicylate did not induce transformation at any of the doses tested in 3 consecutive experiments.     

A conditioned taste aversion induced by alpha-methyl-p-tyrosine

Rats treated with either four 50 $\text{mg}\text{kg}$ or 100 $\text{mg}\text{kg}$ injections of alpha methyl-p-tyrosine (α-MPT) spaced 12 hr apart acquired an aversion to a 0.1% saccharin solution in a two-bottle choice with water. Rats treated with either saline or four injections of 100 $\text{mg}\text{kg}$ of α-MPT without saccharin present exhibited a complete preference for the saccharin solution. In a subsequent experiment, the saccharin aversion induced by the four 100 $\text{mg}\text{kg}$ α-MPT injection procedure was found to persist after telencephalic norepinephrine had returned to normal levels. Thus, α-MPT was found to be a highly effective drug for inducing a taste aversion at dose levels which did not produce obvious signs of toxicity.     

Effects of apomorphine,TL-99 and 3-PPP on yawning in rats

Dopaminergic agonists, apomorphine (APO) (0.025–0.25 $\text{mg}\text{kg}$, s.c.), TL-99 (0.5–3 $\text{mg}\text{kg}$, s.c.) and 3-PPP (0.15–10 $\text{mg}\text{kg}$, s.c.) elicited yawning in rats and the dose-response curves of all 3 compounds showed a bell-shaped form. Haloperidol (0.02 $\text{mg}\text{kg}$, s.c.) reduced the yawning induced by DA-agonists to about 50%. The potencies of the DA-agonists in inducing yawning were APO > TL-99 > 3-PPP (comparable to potencies obtained in other in vivo tests, determining DA-ergic activity). The findings support the validity of the yawning phenomenon as a screening test for DA-agonists.Additionally, it was found that apomorphine induced yawning was significantly and dose-dependently enhanced by the β-agonist, formoterol. This effect was counteracted by scopolamine, not changed by metergoline and further increased by l-propranolol. These data support the hypothesis of cholinergic involvement in yawning and indicate a role, though unclear at present, of β -receptors in this behaviour.     

N-acetyl, 4-O-methyldopa,a major metabolite of L-4-O-methyldopa in man and rat

N-Acetyl, 4-O-methyldopa was identified as a major urinary metabolite of $\text{L}\text{-4-O-}\text{methyldopa}$, both in man and in the rat. The urinary metabolites were examined in man after oral and in rat after intraperitoneal administration of $\text{L}\text{-4-O-}\text{methyldopa}$, $\text{L}\text{-3-O-}\text{methyldopa}$, L-dopa and N-acetyl, 4-O-methyldopa. 4-Mdopa was found to be converted mainly to N-acetyl, 4-Mdopa and iso-HVA and very little to the corresponding pyruvic and lactic acids, whereas 3-Mdopa was metabolized to its pyruvic, lactic and acetic (HVA) derivatives and practically not acetylated. It is suggested therefore that the 3-hydroxy,4-methoxy group (the iso-vanyl structure) prevents transamination and that N-acetylation represents an alternative metabolic pathway. The lack of N-acetyl,4-O-methyldopa after the L-dopa loads shows that L-dopa is not 4-O-methylated and therefore that 4-O-methyldopa is not, or only in a minute amount if any, an in vivo metabolite of L-dopa. N-Acetyl,4-Mdopa administration to rats resulted in excretion of the compound almost unchanged. These results agree with a previous suggestion by the authors of partly distinct metabolic routes for the O-methyl catecholamines according to whether the methyl group is bound on the meta or on the para position and raises the question as to what extent iso-HVA levels in body fluids are representative of a para-O-methylation of dopamine, implicated in neuropsychiatric disorders.     

EEG-synchronizing effect of gamma-hydroxybutyrate and 1-hydroxy-3-amino-pyrrolidone-2 (HA-966) in relation to dopaminergic brain function.

The earlier finding that γ-hydroxybutyrate and HA-966-induced depression of the central nervous system was associated with the increase of dopamine concentration and block of its release, prompted this study of the influence which the monoaminergic system may have upon the electrocorticogram in rats.The synchronization induced by α-methyl-p-tyrosine began earlier than the decrease of the duration of arousal, indicating different sensitivities to the depressive drug action of structures responsible for synchronizing and for arousal.Five $\text{mg}\text{kg}$ HA-966 in diethyldithiocarbamate desynchronized animals increased the amplitude but the duration of arousal was unchanged. p-Chlorophenylalanine treatment of rats did not influence the synchronizing effect of HA-966 (10–20 $\text{mg}\text{kg}$) or the inhibitory effect upon the duration of arousal. Haloperidol (100 μg-4 $\text{mg}\text{kg}$) potentiated the synchronizing effect of y-hydroxybutyrate and HA-966. The number of phasic discharges in the electrocorticogram induced by treatment with anaesthetic doses of γ-hydroxybutyrate were increased by the low dose of haloperidol (100 $\text{μg}\text{kg}$), while the higher dose (4 $\text{mg}\text{kg}$) was ineffective.Animals with intact and lesioned substantia nigra compacta responded equally to the synchronizing activity of HA-966 and γ-hydroxybutyrate. Therefore, it is concluded that their effect is not due to the accumulation of dopamine in the nigrostriatal system.     

Induction of tumours of the urinary bladder in F344 rats by dietary administration of o-phenylphenol

o-Phenylphenol (OPP), a fungicide approved as a food additive in Japan, was given in pelleted diets at dietary levels of 0.156, 0.313, 0.625, 1.25 or 2.5% to groups of 11 or 12 F344/DuCrj rats of each sex for 13 wk, and 0.625, 1.25 or 2.5% to groups of 20–24 male F344/DuCrj rats for 91 wk. In the 13-wk study, transitional cell papillomas of the urinary bladder occurred in $\text{6}\text{12}$ (50%) of the male 1.25% group. In the 91-wk study, urinary bladder tumours appeared in $\text{23}\text{24}$ (96%) of the 1.25% and $\text{4}\text{23}$ (17%) of the 2.5% group. Among these tumours, transitional cell carcinomas were found in $\text{20}\text{23}$ (87%) of 1.25% and $\text{2}\text{4}$ (50%) of the 2.5% groups. A dose-related increase in the incidence of nephritic lesions was also observed in dosed rats in both the 13- and 91-wk study.     

Structure-activity relationships among some d-N-alkylated amphetamines

d-N-Alkylated amphetamines were synthesized in a series up to and including d-N-butylamphetamine and potencies of these compounds were compared in (1) rhesus monkeys allowed to respond for intravenous infusions of the drugs, (2) rats allowed to drink a milk solution for 15 minutes each day and (3) isolated, spontaneously beating guinea-pig atria. In the self-administration procedure, d-amphetamine (A), d-N-methylamphetamine (NMA), and d-N-ethylamphetamine (NEA) were self-administration procedure, saline levels at two or more doses by all animals. For these three drugs, maximal response rates were found at similar doses in all animals. However, maximal rates were generally higher in animals maintained on pentobarbital than in animals maintained on cocaine under control conditions. d-N-propylamphetamine (NPA) was self-administered above saline levels by three of four animals at one or more doses. Maximal response rates for NPA were about $\text{1}\text{2}$ of that A, NMA and NEA, and the dose-response curve was shifted to the right of these compounds by about 4 times. d-N-butylamphetamine (NBA) maintained responding above saline levels at two doses in only one of three animals. In rats, all of the compounds decreased milk intake in a dose-related manner. A, NMA and NEA were equipotent in disrupting intake, while NPA and NBA were, respectively, $\text{1}\text{4}$ and $\text{1}\text{6}$ as potent as the shorter-chain compounds. With the exception of NBA, all compounds increased the rate of beating of the guinea-pig atrium over the range of concentrations tested. In general, for substituents larger than ethyl, potency of d-N-alkylated amphetamines was inversely related to N-alkyl length.     

Effects of clophen A50, 3-methylcholanthrene,pregnenolone-16α-carbonitril and phenobarbital on the hepatic microsomal cytochrome P-450-dependen monooxygenase system in rainbow trout, Salmo gairdneri, of different age and sex

Four groups of rainbow trout (mature male and female, $\text{1}\text{2}\text{-}\text{year-old}$ juvenile, and $\text{1}\text{1}\text{2}\text{-}\text{year-old}$ juvenile) were injected ip at Days 0 and 3 with 20 mg/kg 3-methylcholanthrene (3-MC), 500 mg/kg Clophen A50 (Cl A50), 40 mg/kg pregnenolone-16α-carbonitrile (PCN), respectively, and examined at Day 14. Further, one group of $\text{1}\text{1}\text{2}\text{-}\text{year-old}$ juvenile was injected ip daily with 80 mg/kg phenobarbital (PB) and examined at Day 14. Only 3-MC and Cl A50 markedly elevated the total amount of cytochrome P-450 and the cytochrome P-450-dependent metabolism of paranitroanisole (PNA) and benzo(a)pyrene in the fish liver, whereas no such elevation were observed by PCN or PB. In order to characterize the hepatic cytochrome P-450-dependent metabolism, the Michaelis-Menten kinetic constants of PNA-O-demethylase and the responses of the reactions to α-naphtoflavone, metyrapone, and SKF 525A, in vitro, were studied. These studies (A) showed PCN to significantly elevate apparent K_m of PNA metabolism, whereas no alterations of apparent K_m were seen by 3-MC or Cl A50, (B) indicated the hepatic reactions to be mediated by several species of cytochrome P-450, (C) indicated the formation of alternative form(s) of cytochrome P-450 species in 3-MC- or Cl A50-induced fish when compared to control fish, (D) showed 3-MC- and Cl A50-induced reactions to be similar in character. The presence of differences due to age and sex in the response to the inducers and in the response to the inhibitors, in vitro, is indicated.