Cardiovascular risk assessment of atypical antipsychotic drugs in a zebrafish model.

The zebrafish model has been developed and evaluated for its ability to predict the toxicity of chemicals. Zebrafish additionally serve as an excellent model for assessing drug-induced cardiotoxicity, although zebrafish and mammalian hearts differ in structure. Recently, regulatory authorities have expressed concerns about a possible relationship between antipsychotics and risk of QTc interval prolongation, serious arrhythmia and sudden cardiac death. In the current study, we performed a cardiovascular risk assessment of six atypical antipsychotic drugs in zebrafish, specifically, aripiprazole, clozapine, olanzapine, quetiapine, risperidone and ziprasidone. Visual endpoints, such as lethality, edema (the presence of heart and trunk edema), hemorrhage (clustering of a pool of blood in an area outside the normal circulation), abnormal body shape (including bent or misshapen caudal region of the larvae) and motility, were evaluated as general toxicity endpoints, and the heart beat rate calculated as the cardiovascular toxicity endpoint. The zebrafish model facilitates determination of the heart beat rate, and may thus be an attractive screening tool for cardiovascular risk assessment of atypical antipsychotic drugs to understand the variations in response to QT-prolonging drugs.

Toxicity assessment of zebrafish following exposure to CdTe QDs.

CdTe quantum dots (QDs) are nanocrystals of unique composition and properties that have found many new commercial applications; therefore, their potential toxicity to aquatic organisms has become a hot research topic. The lab study was performed to determine the developmental and behavioral toxicities to zebrafish under continuous exposure to low concentrations of CdTe QDs (1-400 nM) coated with thioglycolic acid (TGA). The results show: (1) the 120 h LC(50) of 185.9 nM, (2) the lower hatch rate and body length, more malformations, and less heart beat and swimming speed of the exposed zebrafish, (3) the brief burst and a higher basal swimming rate of the exposed zebrafish larvae during a rapid transition from light-to-dark, and (4) the vascular hyperplasia, vascular bifurcation, vascular crossing and turbulence of the exposed FLI-1 transgenic zebrafish larvae.

Assessment of the developmental and reproductive toxicity of diiodomethyl-p-tolylsulfone in rats and rabbits.

Diiodomethyl-p-tolylsulfone (DIMPTS) was tested in developmental toxicity (DT) and reproductive toxicity studies. In the rat DT study, DIMPTS was administered at 0, 100, 300 or 1000 mg/kg/day. Maternal toxicity as evidenced by reductions in body weight gain or feed consumption at 1000 and, to a lesser extent, 300 mg/kg/day. The only developmental effect was umbilical hernia at 1000 mg/kg/day; therefore, NOELs for maternal and developmental toxicity were 100 and 300 mg/kg/day, respectively. In the rabbit DT study, NZW rabbits were gavaged with 0, 0.05, 0.5 and 2mg/kg/day DIMPTS. The NOEL for maternal toxicity was 0.5mg/kg/day, based on thyroid weight increase with histopathology. There were no observed developmental effects. In the two-generation study, CD rats were fed 0, 2.5, 10 or 40 mg/kg/day DIMPTS. Increased thyroid weight and histopathology were observed at all doses with associated pituitary findings in males. Reproductive toxicity at 40 mg/kg/day consisted of increased postimplantation loss, decreased gestation survival and two cases of dystocia, while litter size, pup survival/weight were affected at 10 and 40 mg/kg/day. The NOEL for parental toxicity could not be determined, while the NOEL for reproductive toxicity was 2.5mg/kg/day. The maternal thyroid and reproductive effects in this study were consistent with iodine toxicity.

Assessment of teratogenecity and embryotoxicity of sludge from textile industries at Pali (India) in Swiss albino mice exposed during organogenetic period.

The present investigation was carried out to assess the teratological effects of in-utero exposure of sludge leachate from textile and dyeing industries located in Pali, Rajasthan. Sludge was collected at the combined effluent treatment plant (CETP). Two groups of 10 pregnant Swiss albino mice each, were given sludge leachate of 1/10 and 1/100 dilutions with water ad libitum from 6th day to 15th day of gestation covering the critical period of organogenesis. Cesarean sections were performed on day 18 of gestation and all foetuses were examined for reproductive and teratological tests. Sludge induced maternal toxicity was evidenced by significant increase in leachate consumption, reduction in body weight gain and reduction in fur of the body. Developmental toxicity was evidenced by a significant decrease in foetal weight per litter increase in the number of resorptions and an increase in total number of foetuses showing bone retardation and skeletal variations (specially of skull, sternebrae and vertebrae). The leachate of the sludge that is being dumped in the open areas of the town Pall seems to elicit teratogenic as well as embryotoxic potential as indicated by the findings of the present investigation.

A toxicity and hazard assessment of fourteen pharmaceuticals to Xenopus laevis larvae.

The toxicity of fourteen widely used human pharmaceuticals was determined using the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Stage 9 Xenopus blastulae were exposed for 96 h to single concentrations of commonly prescribed selective serotonin reuptake inhibitors (SSRIs), statin blood lipid regulators, non-steroidal anti-inflammatories, antibiotics, a stimulant, and an anti-epileptic. Toxicity, teratogenicity, minimum concentration to inhibit growth, and types and severity of associated malformations were determined. EC(10)s ranged from 3.0 mg/l to >100 mg/l and LC(10)s ranged from 3.6 mg/l to >100 mg/l. Toxicity varied between and within compound class of pharmaceutical. The fluoroquinolones, stimulants, anti-epileptics, and antibiotics tested were determined to be nontoxic and non-teratogenic at singular, water-soluble concentrations. The hazard quotients (HQ) for the pharmaceuticals ranged from 6.10 x 10(-7 )to 1.6 x 10(-4), all of which are orders of magnitude below EPA's levels for concern for harm to aquatic animals. Thus, based on the data from the present study, concentrations of individual pharmaceuticals currently detected in surface water are far below concentrations of effective and lethal concentrations.

Vitamin A teratogenicity and risk assessment in the macaque retinoid model.

Studies were performed in the cynomolgus monkey (Macaca fascicularis) to provide risk assessment information on safe dose levels of Vitamin A during human pregnancy. Vitamin A palmitate was orally administered at 7500 IU/kg (2.25 mg/kg) to 80 000 IU/kg (24 mg/kg) body weight during early pregnancy (gestation day [GD] 16-27). The results indicated a dose-related increase in exposure (AUC) to retinyl esters and retinoic acids (RA) (all-trans-RA, all-trans-4-oxo-RA, 13-cis-RA, 13-cis-4-oxo-RA). There was also a dose-related increase in abortion and malformation that affected typical retinoid target tissues in the embryo, including the craniofacial region, heart, and thymus. The NOAEL and LOAEL for structural malformations were 7500 IU/kg and 20 000 IU/kg (6 mg/kg), respectively. A companion study involving oral administration of 13-cis-RA during the same gestational period established the NOAEL for malformations at 0.5 mg/kg/day, which is close to the human therapeutic dose range (0.5 to 1.5 mg/kg/day) associated with retinoid embryopathy. Based on the known similarities in teratogenic susceptibility to 13-cis-RA, the monkey NOAEL for Vitamin A (7500 IU/kg) was used to estimate safe levels of this nutrient in humans applying a safety factor of 10. This approach yielded safe levels of Vitamin A during human pregnancy in the range of approximately 25 000 to 37 000 IU/day.

Assessment of cerebral hemispheric symmetry in hatchling chickens exposed in ovo to polychlorinated biphenyl congeners.

Previous investigators have reported that exposure to a mixture of environmental contaminants, including polychlorinated biphenyls, results in morphologic asymmetry of the cerebral hemispheres in hatchling great blue herons (Ardea herodias) and have suggested that this asymmetry may be a useful biomarker for contamination. This study was made to determine whether exposure to PCB congeners 3,3',4,4'-tetrachlorobiphenyl (IUPAC #77) and 3,3',4,4',5-pentachlorobiphenyl (IUPAC #126) causes similar asymmetry in hatchling domestic chickens (Gallus domesticus). Eggs were injected at day 0 of incubation with either a high dose, low dose, or combination of each congener. At hatching, the chicks were perfused with 10% formalin-saline. The brains were removed, sectioned and stained with cresyl violet. Width and height measurements of each hemisphere were taken at eight locations, caudal to rostral, 400 microm apart starting at the level of the anterior commissure (CA) and ending at the lobus paraolfactorius (LPO). The absolute differences between measurements of the left and right sides were used to run a univariate split plot analysis of variance to determine if the amount of asymmetry present was associated with specific congeners or doses. Significant differences in asymmetry were found between noninjected control groups and vehicle-injected control groups (p

Assessment of the developmental toxicity of ethylene glycol applied cutaneously to CD-1 mice.

Ethylene glycol (EG; CAS No. 107-21-1) is teratogenic to mice by whole-body exposure to an aerosol at high concentrations, but results were confounded by possible exposure from ingestion after grooming and/or from percutaneous absorption. Therefore, CD-1 mice were exposed to EG on Gestational Days (GD) 6 through 15, 6 hr/day by occluded cutaneous application at 0, 12.5, 50, or 100% (undiluted) EG (0.1 ml/animal, equivalent to approximately 0, 404, 1677, or 3549 mg/kg/day [10 ml/kg, positive control gavage (PCGG)], 30 females/group. Dams were weighed and evaluated daily (including application site) for clinical signs and water consumption throughout gestation. On GD 18, maternal uterus, liver, and paired kidneys were weighed; kidneys of 0 and 100% and the PCGG were examined microscopically. Corpora lutea and implantation sites were recorded. Live fetuses were weighed, sexed, and examined for structural alterations. For cutaneously exposed dams, there was no treatment-related maternal, no differences in pre- or postimplantation loss in fetal body weights/litter, and no increased incidences of any fetal malformations. Two skeletal variations, increased at 100% may represent effects of restraint stress and/or findings due to chance. In the PCGG, 8 females (26.7%) died, water consumption was increased, fetal body weights/litter were reduced, and fetal malformations and variations were increased. PCGG kidneys exhibited tubular nephrosis and tubular cell degeneration, with no oxalate crystals, documenting renal toxicity at this oral dose in mice. Minimal-grade renal tubular lesions observed in 3 mice (of 30) at 100% EG may represent treatment-related or incidental findings. Therefore, exposure of pregnant CD-1 to 0, 12.5, 50 or 100% EG during organogenesis by occluded cutaneous application resulted in minimal or no observable maternal or developmental toxicity at 100% (approximately 3549 mg/kg/day), the NOEL.

Initial evaluation of developmental malformation as an end point in mixture toxicity hazard assessment for aquatic vertebrates.

The joint toxic action of three binary mixtures was determined for the embryo malformation endpoint of the aquatic FETAX (frog embryo teratogenesis assay: Xenopus) test system. Osteolathyrogenic compounds and short-chain carboxylic acids, representing separate, distinct modes of action for induction of malformation, were selected for testing in 96-hr, static-renewal tests. Three mixtures were tested for each combination, with each combination being tested on three separate occasions. Using toxic unit analysis, the combination of osteolathyrogens and the combination of carboxylic acids produced strictly additive (concentration addition) rates of malformation, while the combination of an osteolathyrogen and a carboxylic acid was less-than-additive (response addition) for induction of malformation. Therefore, developmental malformation may have value as an endpoint in mixture toxicity hazard assessment.

Prenatal and postnatal assessment of Maneb-exposed CD-1 mice.

Skeletons of CD-1 mice exposed in utero during days 6 to 15 of gestation by gavage of their dams with 1200 mg/kg/day of Maneb in 1.0% carboxymethylcellulose (CMC), were examined between 60 and 65 days postnatal (DPN) for the 88 variants of the skeletal variant assay system (SVAS). Of the 58 variants that appeared, 13 differed (P less than 0.01) from untreated (UNTD), and 15 from vehicle-treated (VEH), despite absence of malformations at birth, weaning, or time of sacrifice. Major changes in frequencies of Parted Frontals, Abnormal Metoptic Roots, Reduced Articular Processes of the Thoracic (Th) Vertebrae, and Carpal Fusions occurred. Several variants affecting the Spinous Process of Th2 occurred in significant proportions as an unusual effect of this compound. In a series of 20 Maneb-treated litters dissected at 18 days post coitus (DPC), of 168 live fetuses, 9 had minor abnormalities, one was exencephalic, and 14 showed growth retardation. Prenatal mortality (20%) was higher than in UNTD (7.5%); litter size and litter weight were not significantly reduced. Ossification of cervical vertebral centra, and caudal vertebrae were significantly reduced, sternebra and limb ossification were not. Occurrence of 14-Ribs was increased. Although maternal mortality complicates interpretation, both traditional prenatal and postnatal examination focusing primarily on the skeleton revealed effects of exposure in the absence of frank malformations.