Effects of griseofulvin in medium-term liver carcinogenesis assay and peripheral blood micronucleus test in rat

Fluoride and endosulfan together potentiate cytogenetic effects in Swiss albino mice bone marrow cells

In this study, the cytotoxic potential of fluoride and endosulfan in combination was investigated in Swiss albino mice bone marrow cells using the chromosomal aberration (CA) and micronucleus (MN) test systems. Fluoride (25.1 mg kg^-1 body weight [bw] in water) and endosulfan (1.8 mg kg^-1 bw by oral intubation) were administered orally alone and in combination (fluoride 25.1 mg kg^-1 bw + endosulfan 1.8 mg kg^-1 bw) to male Swiss albino mice daily for 30 days. A significant (p < 0.01) increase in micronuclei (MNs) induction and decreased ratio (p < 0.01) of polychromatic to normonochromatic erythrocytes (indicators of cytotoxicity) were observed compared with saline controls when animals were given the combination of fluoride and endosulfan. A significant (p < 0.01) increase in MNs induction and no change in the polychromatic erythrocytes to erythrocyte ratio were also observed when endosulfan was given alone. CAs such as gaps, breaks, fragments, rings, exchanges, and polyploidy were recorded in the bone marrow cells. The mean percent frequency of CAs was increased (p < 0.01) in all the treated groups compared with the control saline group. In the combination group (F + E), the percent frequencies of CAs were significantly higher (13.875%) compared with those in the individual treatment groups of fluoride (4.375%) and endosulfan (6.25%). The mitotic index was calculated as percentage of dividing cells. A significant (p < 0.01) decrease in mitotic index was observed in all treated groups compared with controls. In the combination group (F + E), mitotic index was significantly less than (p < 0.01; 4.1 ± 0.49) the saline control (10.8 ± 0.98). These results indicated that repeated intake of endosulfan through various sources in fluoride affected areas resulted in increased cytotoxic effects. The greater effect in the combination group indicated additive interaction of fluoride and endosulfan in inducing cytotoxicity in Swiss albino mice.

A novel micronucleus in vitro assay utilizing human hematopoietic stem cells

The induction of micronucleated reticulocytes in the bone marrow is a sensitive indicator of chromosomal damage. Therefore, the micronucleus assay in rodents is widely used in genotoxicity and carcinogenicity testing. A test system based on cultured human primary cells could potentially provide better prediction compared to animal tests, increasing patient safety while also implementing the 3Rs principle, i.e. replace, reduce and refine. Hereby, we describe the development of an in vitro micronucleus assay based on animal-free ex vivo culture of human red blood cells from hematopoietic stem cells. To validate the method, five clastogens with direct action, three clastogens requiring metabolic activation, four aneugenic and three non-genotoxic compounds have been tested. Also, different metabolic systems have been applied. Flow cytometry was used for detection and enumeration of micronuclei. Altogether, the results were in agreement with the published data and indicated that a sensitive and cost effective in vitro assay to assess genotoxicity with a potential to high-throughput screening has been developed.

Protective action of curcumin and nano-curcumin against arsenic-induced genotoxicity in rats in vivo

We explored whether nanoformulation of curcumin can cause better protective effect than free curcumin against arsenic-induced genotoxicity. Curcumin-loaded Poly(lactic-co-glycolic acid) nanoparticles (CUR-NP) were prepared by emulsion technique. The CUR-NP were water soluble and showed biphasic release pattern. Rats were divided into 5 groups of 6 each. Group I served as the control. Group II rats were exposed to sodium arsenite (25 ppm) daily through drinking water for 42 days. Groups III, IV and V were maintained as in Group II, however, they were also administered empty nanoparticle, curcumin (100 mg/kg bw) and CUR-NP (100 mg/kg bw), respectively, by oral gavage during the last 14 days of arsenic exposure. On the 43rd day, genotoxic effects were evaluated in bone marrow cells. Arsenic increased chromosomal aberrations, micronuclei formation and DNA damage. Both free curcumin and CUR-NP attenuated these arsenic-mediated genotoxic effects. However, the result suggests that nanoformulation have better protective effect than free curcumin at the same dose level.

Establishment of a Stable Cell Line Expressing Green Fluorescence Protein-fused Hypoxia Inducible Factor-1α for Assessment of Carcinogenicity of Chemical Toxicants

Hypoxia inducible factor 1α (HIF-1α) is a potential marker of carcicnogenesis since it is overexpresssed in many human cancers such as brain, breast, and uterus, and its role has implicated in tumor cell growth and metastasis. In this study, we established a stable cell line that express green fluorescence protein (GFP)-fused hypoxia inducible factor 1α (HIF-1α) and evaluated the potential use of this cell line for assessment of carcinogenicity of chemical toxicants. Western blot analysis as well as fluorescence measurements showed that protein-level of GFP-HIF-1α was significantly enhanced in a dose-dependent manner upon treatment of hypoxia mimicking agents such as dexferrioxamine and CoCl₂. Well-Known tumor promoters such as mitomycin and methyl methane-sulfonate. significantly induced the fluorescence intensity of GFP-HIF-1α, whereas the known negative controls such as o-anthranilic acid and benzethonium chloride, did not. These results indicate that HIF-1α could be a biological parameter for detection of tumor initiators/promoters and suggest that the GFP-HIF-1α cell line is a useful system for screening of carcinogenic toxicants.

Automated image analysis in histopathology: a valuable tool in medical diagnostics

Virtual pathology, the process of assessing digital images of histological slides, is gaining momentum in today's laboratory environment. Indeed, digital image acquisition systems are becoming commonplace, and associated image analysis solutions are viewed by most as the next critical step in automated histological analysis. Here, we document the advances in the technology, with reference to past and current techniques in histological assessment. In addition, the demand for these technologies is analyzed with major players profiled. As there are several image analysis software programs focusing on the quantification of immunohistochemical staining, particular attention is paid to this application in this review. Oncology has been a primary target area for these approaches, with example studies in this therapeutic area being covered here. Toxicology-based image analysis solutions are also profiled as these are steadily increasing in popularity, especially within the pharmaceutical industry. Reinforced by the phenomenal growth of the virtual pathology field, it is envisioned that the market for automated image analysis tools will greatly expand over the next 10 years.

Veterinary pharmacovigilance. Part 6. Predictability of adverse reactions in animals from laboratory toxicology studies

Toxicological studies are conducted on constituents of veterinary medicinal products for a number of reasons. Aside from being a requirement of legislation, they are carried out for predictive purposes in the assessment of user safety or for the determination of consumer safety, for example, in the elaboration of maximum residue limits or tolerances. Alternatively, the results of toxicology studies may be available as they have been generated for registration of the drug for human medicinal purposes. This paper examines if the results of such studies have any predictive value for adverse reactions, which might occur during clinical use in animals. A number of adverse reactions, notably the Type A (toxicology or pharmacology dependent) should be predictable from these laboratory studies. However, as with human pharmaceutical products, they have less utility in predicting Type-B reactions (idiosyncratic in nature).