Hepatic damage and oxidative stress induced by Griseofulvin in mice

Erythropoietic Protoporphyria (EPP) is a disease associated with ferrochelatase deficiency, which produces accumulation of protoporphyrin IX (PROTO IX) in erythrocytes, liver and skin. In some cases, a severe hepatic failure and cholestasis was observed. Griseofulvin (Gris) develops an experimental EPP with hepatic manifestations in animals. The aim of this work was to further characterize this model studying its effect on different metabolisms in mice Gris feeding (0-2.5%, 7 and 14 days). PROTO IX accumulation in liver, blood and feces, induction of ALA-S activity, and a low rate of Holo/Apo tryptophan pyrrolase activity was produced, indicating a reduction of free heme pool. The progressive liver injury was reflected by the aspect and the enlargement of liver and the induction of hepatic damage. Liver redox balance was altered due to porphyrin high concentrations; as a consequence, the antioxidant defense system was disrupted. Heme oxygenase was also induced, however, at higher concentrations of antifungal, the free heme pool would be so depleted that this enzyme would not be necessary. In conclusion, our model of Protoporphyria produced liver alterations similar to those found in EPP patients.

SFTG international collaborative study on in vitro micronucleus test

In this report, are presented the results of an international collaborative study on the in vitro micronucleus assay, using CHL cells. Fourteen laboratories participated in this study which was coordinated by an organizing committee supported by the SFTG (the French branch of the European Environmental Mutagen Society). Nine coded substances, having different modes of action and at different levels were assessed in the in vitro micronucleus test, using a common protocol. Mitomycin C was used as a positive control. In order to help to define a standard protocol on CHL cells, short and long treatment periods followed by various recovery times, with or without cytochalasin B, were compared. After an evaluation of the acceptability of the assays, the tested chemicals were classified as negative, positive or equivocal. Mannitol and clofibrate were judged as negative in all treatment schedules. Bleomycin was positive in all the treatment schedules, with an increase in the number of micronucleated cells in both mononucleate and binucleate cells when using cytochalasin B. This was also shown for the aneugens colchicine, diethylstilboestrol and griseofulvin, as expected. Urethane was judged as equivocal only after long treatment with cytochalasin B, and negative in all other treatment schedules. In any case, no genotoxic compound would have been missed with schedules including a short and a long treatment time, whether the treatment was followed by a recovery period or not and whether cytochalasin B was used or not. Thus, these results show that CHL cells were suitable for accurately detecting clastogenic and aneugenic compounds of various types in the in vitro micronucleus test.

SFTG international collaborative study on in vitro micronucleus test I. General conditions and overall conclusions of the study

This study, coordinated by the SFTG (French branch of European Environmental Mutagen Society), included 38 participants from Europe, Japan and America. Clastogens (bleomycin, urethane), including base and nucleoside analogs (5-fluorouracil and cytosine arabinoside), aneugens and/or polyploidy inducers (colchicine, diethylstilboestrol, griseofulvin and thiabendazole), as well as non-genotoxic compounds (mannitol and clofibrate), were tested. Four cell types were used, i.e. human lymphocytes in the presence of cytochalasin B and CHO, CHL and L5178Y cell lines, in the presence or absence of cytochalasin B, with various treatment-recovery schedules. Mitomycin C was used as a positive control for all cell types. Mannitol and clofibrate were consistently negative in all cell types and with all treatment-recovery conditions. Urethane, known to induce questionable clastogenicity, was not found as positive. Bleomycin and mitomycin C were found positive in all treatment-recovery conditions. The base and nucleoside analogs were less easy to detect, especially 5-fluorouracil due to the interference with cytotoxicity, while cytosine arabinoside was detected in all cell types depending on the treatment-recovery schedule. Aneugens (colchicine, diethylstilboestrol and griseofulvin) were all detected in all cell types. In this study, the optimal detection was ensured when a short treatment followed by a long recovery was associated with a long continuous treatment without recovery. There was no impact of the presence or absence of cytochalasin B on the detection of micronucleated cells on cell lines. Scoring micronucleated cells in both mononucleated and binucleated cells when using cytochalasin B was confirmed to be useful for the detection and the identification of aneugens. In conclusion, these results, together with previously published validation studies, provide a useful contribution to the optimisation of a study protocol for the detection of both clastogens and aneugens in the in vitro micronucleus test.

SFTG international collaborative study on in vitro micronucleus test V. Using L5178Y cells

In this report, results are presented from an international study of the in vitro micronucleus assay using mouse lymphoma L5178Y cells. This study was coordinated by an organizing committee supported by the SFTG (the French branch of the European Environmental Mutagen Society). Test chemicals included mannitol, bleomycin, 5-fluorouracil, colchicine and griseofulvin. Mitomycin C was used as a positive control. Each chemical was evaluated in at least two laboratories following a variety of different protocols (short and long exposures, varying recovery times, with and without cytochalasin B) in order to help determine a standard protocol for routine testing in mouse lymphoma L5178Y cells. Mannitol was the only exception, being tested in only one laboratory. Mannitol was negative, while bleomycin induced a concentration-dependent increase in micronucleated cells. Equivocal results were obtained for 5-fluorouracil, colchicine and griseofulvin. High levels of cytotoxicity interfered with the assessment of aneuploidy for colchicine and griseofulvin, preventing the ability to obtain clear results in all the treatment schedules. Experiments with 5-fluorouracil, colchicine and griseofulvin showed that both short and long treatment times are required as each compound was detected using one or more treatment protocol. No clear differences were seen in the sensitivity or accuracy of the responses in the presence of absence of cytochalasin B. It was also found that a recovery period may help to detect compounds which induce a genotoxicity associated to a reduction in cell number or cell proliferation. Overall, the results of the present study show that mouse lymphoma L5178Y cells are suitable for the in vitro micronucleus assay.

Detection of numerical chromosomal aberrations by flow cytometry: a novel process for identifying aneugenic agents

Aneuploidy plays a significant role in adverse human health conditions including birth defects, pregnancy wastage, and cancer. Currently, there is no screening method sufficiently validated that can be used routinely to identify aneugenic agents in vitro because most conventional test systems rely on the labor-intensive microscopic assessment of the aneuploid cell population. Our laboratory has recently developed a flow cytometry-based procedure for assessing numerical chromosomal aberrations in mitotic populations of lymphocytes on the basis of DNA content. Studies were conducted in 24 h treated human lymphocyte cultures to determine the sensitivity of this flow cytometry-based procedure to detect aneugenic agents. A comparison between the microscopic and the flow cytometry-based procedures for scoring polyploidy shows a strong agreement exists between the two methods. Treatments with two known aneugenic agents, griseofulvin, and paclitaxel (taxol), resulted in a dose-related increase in the mitotic index, aneuploidy, and polyploidy. In contrast, results from the treatments with two known clastogenic agents, mitomycin-C, and etoposide, show a dose-related decrease in the mitotic index with a slight increase in the frequency of hypodiploidy at concentrations that produce severe chromosomal breakage. There were no increases in hyperdiploidy and polyploidy observed. In conclusion, the reproducibility of the results obtained in this study indicates that this flow cytometry-based procedure for assessing numerical chromosomal effects in mitotic populations on the basis of DNA content is promising for the routine detection and characterization of aneugenic agents.

Hepatic gene expression in protoporphyic Fech mice is associated with cholestatic injury but not a marked depletion of the heme regulatory pool

BALB/c Fech(m1Pas) mice have a mutated ferrochelatase gene resulting in protoporphyria that models the hepatic injury occurring sporadically in human erythropoietic protoporphyria. We used this mouse model to study the development of the injury and to compare the dysfunction of heme synthesis with hepatic gene expression of liver metabolism, oxidative stress, and cellular injury/inflammation. From an early age expression of total cytochrome P450 and many of its isoforms was significantly lower than in wild-type mice. However, despite massive accumulation of protoporphyrin in the liver, expression of the main genes controlling heme synthesis and catabolism (Alas1 and Hmox1, respectively) were only modestly affected even in the presence of the cytochrome P450-inducing CAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene. In contrast, in BALB/c mice exhibiting griseofulvin-induced hepatic protoporphyria with induction and destruction of cytochrome P450, both Alas1 and Hmox1 genes were markedly up-regulated. Other expression profiles in BALB/c Fech(m1Pas) mice identified roles for oxidative mechanisms in liver injury while modulated gene expression of hepatocyte transport proteins and cholesterol and bile acid synthesis illustrated the development of cholestasis. Subsequent inflammation and cirrhosis were also shown by the up-regulation of cytokine, cell cycling, and procollagen genes. Thus, gene expression profiles studied in Fech(m1Pas) mice may provide candidates for human polymorphisms that explain the sporadic hepatic consequences of erythropoietic protoporphyria.

Indirect mechanisms of genotoxicity

Indirect mechanisms of genotoxicity correspond to interactions of mutagens with non-DNA targets, and are expected to show threshold concentration-effect response curves. If these thresholds can be proven experimentally they may provide a third alternative for risk assessment, besides the No Effect Level/Safety Factor approach and the low dose linear extrapolation method. We contributed significantly to the in vitro assessment of thresholds in human lymphocytes exposed to the spindle inhibitors nocodazole and carbendazim showing dose dependency and existence of lower thresholds for induction of non-disjunction as compared to chromosome loss. Micronuclei correlated with p53-independent or p53-dependent apoptosis and elimination of aneuploid cells. Extrapolation from in vitro threshold values to the in vivo situation remains unsolved. Comparing the in vitro threshold values for griseofulvin in human and rat lymphocytes with in vivo NOAEL/LOAEL in bone marrow/gut/erythrocytes suggests that the in vitro human system is the most sensitive. The threshold for induction of non-disjunction in in vitro maturing, nocodazole-exposed mouse oocytes was in the same low range. Regulators (UK Committee on Mutagenicity, http://www.doh.gov.uk/com/com.htm) considered the importance of thresholds for indirect mechanisms of genotoxicity. Acceptance of a non-linear extrapolation for mutagens requires mechanistic studies identifying the mutagen/target interactions. Moreover appropriate risk evaluation will require additional studies on individual susceptibility for indirect mutagenic effects and on interactions of aneugens in complex mixtures.

Gene expression profiles associated with inflammation, fibrosis, and cholestasis in mouse liver after griseofulvin

Erythropoietic protoporphyria patients can develop cholestasis, severe hepatic damage, fibrosis, and cirrhosis. We modeled this hepatic pathology in C57BL/6J and BALB/c mice using griseofulvin and analyzed 3,127 genes for alteration of expression in the liver before and during the onset of protoporphyria, cholestasis, inflammation, and hepatic fibrosis. The two mouse strains developed different levels of pathologic damage in response to the griseofulvin. Characteristic gene expression profiles could be associated with griseofulvin-induced gene expression, disruption of lipid metabolism, and the pathologic states of inflammation, early fibrosis, and cholestasis. Additionally, some genes individually indicated an alteration of homeostasis. or pathologic state; for example, fibroblast proliferation was potentially indicated by increased calcyclin (SA100a6) expression. Changes in cytochrome P450 (Cyp) gene expression were particularly pronounced, with increased expression of the Cyp2a, Cyp2b, and Cyp3a families. Decreased Cyp4a10 and Cyp4a14 expression was observed that could be associated with early pathologic change. A potential decrease in bile acid and steroid biosynthesis was indicated by the decreased expression of Cyp7b1 and Hsd3b4, respectively. DNA damage was indicated by induction of GADD45. This study illustrates how transcriptional programs can be associated with different stimuli in the same experiment. The time course of change in the gene expression profile compared with changes in pathology and clinical chemistry shows the potential of this approach for modeling causative, predictive, and adaptive changes in gene expression during pathologic change.

Induction of aneuploidy in male mouse germ cells detected by the sperm-FISH assay: a review of the present data base

Multicolour fluorescence in situ hybridization (FISH) with chromosome-specific DNA-probes can be used to assess aneuploidy (disomy) and diploidy in sperm of any species provided the DNA-probes are available. In the present EU research project, DNA-probes for mouse chromosomes 8, X and Y were employed each labelled with different colours. Male mice were treated with the test chemicals and sperm were sampled from the Caudae epididymes 22-24 days later to allow spermatocytes exposed during meiosis to develop into mature sperm. At present, the data base comprises 10 chemicals: acrylamide (AA), carbendazim (CB), colchicine (COL), diazepam (DZ), griseofulvin (GF), omeprazole (OM), taxol (TX), thiobendazole (TB), trichlorfon (TF) and vinblastine (VBL). Of these, COL and TF induced disomic sperm only. DZ and GF induced disomic and diploid sperm, while CB and TB induced diploid sperm only. VBL gave contradictory results in repeated experiments in an inter-laboratory comparison. AA, OM and TX did not induce an increase in disomic or diploid sperm at the doses used. The induction of aneuploidy by DZ was also tested in humans. Sperm samples from patients after attempted suicide and from patients with chronic Valium((R)) abuse were evaluated using human DNA-probes specific for chromosomes 1,16, 21, X and Y. A quantitative comparison between mouse and man indicates that male meiosis in humans is 10-100 times more sensitive than in mice to aneuploidy induction by DZ. The positive response of mice to TF supports the hypothesis by Czeizel et al. [Lancet 341 (1993) 539] that TF may be causally related to the occurrence of congenital abnormality clusters in a Hungarian village.

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

Published data have suggested a possible link between the tumor promoting activity and the aneugenic properties of griseofulvin. The present study was conducted to explore this relationship. Griseofulvin was evaluated both for its potential promoting activity in liver carcinogenesis in partially hepatectomized F344 male rats initiated by diethylnitrosamine and for its genotoxic potential in the peripheral blood micronucleus assay. Rats were treated daily with 2,000 mg/kg body weight by oral gavage for 12 weeks in the medium-term carcinogenesis bioassay. GST-P-positive foci (mean number and surface area) and altered cell foci were compared in the liver of rats treated with griseofulvin alone, diethylnitrosamine alone,and griseofulvin in addition to diethylnitrosamine by using immunohistochemical and histopathological evaluation, respectively. This evaluation allowed the conclusion that griseofulvin did not initiate the carcinogenic process but rather had a potential in the liver for tumor promoting activity. Griseofulvin was found to be negative in the rat peripheral blood micronucleus test when given at a daily oral dose of 2,000 mg/kg body weight for at least 3 weeks.

Spontaneous and induced chromosome damage in somatic cells of sporadic and familial Alzheimer's disease patients

Alzheimer's disease (AD) is a neurodegenerative disorder of the elderly with a complex etiology due to the interaction between genetic and environmental factors. At least 15% of cases are inherited as an autosomal dominant mutation, but the majority are sporadic. We evaluated cytogenetic alterations, both spontaneous and chemical-induced [aluminium (Al) and griseofulvin (GF)], by means of the micronucleus (MN) test in lymphocytes or skin fibroblasts of 14 patients with sporadic and eight with familial Alzheimer's disease (FAD), respectively. The spontaneous MN frequencies of sporadic (20.8 +/- 9.2) and familial (20.7 +/- 4.6) AD patients are significantly higher than those of the respective control groups (9.0 +/- 6.8 and 6.7 +/- 3.4). In all AD patients, GF significantly increased the spontaneous MN frequency of somatic cells to a lesser extent (P < 0.05) as compared with the control group. Al treatment did not induce MN in AD patients. The results of the present study indicate that different types of somatic cells from sporadic and familial AD patients show comparable levels of spontaneous cytogenetic anomalies, and MN induction is partially reduced or lacking according to the type of chemical treatments.

Validation of single cell gel assay in human leukocytes with 18 reference compounds

To validate the alkaline single cell gel (SCG) assay as a tool for the detection of DNA damage in human leukocytes, we investigated the in vitro activity of 18 chemicals. Thirteen of these chemicals (pyrene (PY), benzo(a)pyrene (BaP), cyclophosphamide (CP), 4-nitroquinoline-1-oxide (4NQO), bleomycin (BLM), methylmercury chloride (MMC), mitomycin C (MTC), hydrogen peroxide (HP), diepoxybutane (DEB), glutaraldehyde (GA), formaldehyde (FA), griseofulvin (GF), sodium azide (NA)) are genotoxic in at least one cell system, while five compounds (ascorbic acid (AA), glucose (GL), D-mannitol (MAN), O-vanillin (VAN), chlorophyllin (CHL)) are classified as non-genotoxic. In this in vitro SCG assay, PY, BaP and CP were positive with exogeneous metabolic activation (rat S9 mix) while 4NQO, BLM, MMC, MTC, hydrogen peroxide, and diepoxbutane were positive in the absence of metabolic activation. CHL and VAN were unexpectedly found to induce a dose-dependent increase in DNA migration. AA, GL, and MAN were negative in a non-toxic range of doses. GF gave equivocal results, while FA and GA increased DNA migration at low doses and decreased DNA migration at higher doses. This behaviour is consistent with the known DNA damaging and crosslinking properties of these compounds. These data support the sensitivity and specificity of this assay for identifying genotoxic agents.

The application of the micronucleus test in Chinese hamster V79 cells to detect drug-induced photogenotoxicity

Recent reports on the photochemical carcinogenicity and photochemical genotoxicity of fluoroquinolone antibacterials led to an increasing awareness for the need of a standard approach to test for photochemical genotoxicity. In this study the micronucleus test using V79 cells was adapted to photogenotoxicity testing. Results of using different UVA/UVB relationships enabled us to identify a suitable irradiation regimen for the activation of different kinds of photosensitizers. Using this regimen, 8-methoxypsoralen and the fluoroquinolones lomefloxacin, grepafloxacin and Bay Y 3118 were identified to cause micronuclei and toxicity upon photochemical activation. Among the phenothiazines tested, chlorpromazine and 2-chlorophenothiazine, were positive for both endpoints, whereas triflupromazine was only slightly photoclastogenic in the presence of strong phototoxicity. Among the other potential human photosensitizers tested (oxytetracycline, doxycycline, metronidazole, emodin, hypericin, griseofulvin), only hypericin was slightly photogenotoxic. Photochemical toxicity in the absence of photochemical genotoxicity was noted for doxycycline and emodin. With the assay system described, it is possible to determine photochemical toxicity and photochemical genotoxicity concomitantly with sufficient reliability.

Quantitative in vitro assessment of drug phototoxicity by a chemiluminescence method

OBJECTIVE

To establish a test model for phototoxic agents using the method of chemiluminescence.

METHODS

The phototoxicity of pipemidic acid, doxycycline, griseofuvin and chlorpromazine was detected. These agents and distilled water were irradiated with ultraviolet A (UVA) in the presence of nicotinamide adenine dinucleotide reduced (NADH), and the duplicated samples were incubated in the dark as dark controls. Then luminol was added to the test samples, and the chemiluminescent value was counted and calculated.

RESULTS

Chemiluminescent values of pipemidic acid, doxycycline and griseofuvin were significantly higher than those in controls. The result of linear regression analysis showed that phototoxic intensity was linear correlated with UVA dosage. The regression coefficient for distilled water was 0.56, indicating that the luminescent value (LV) rose slightly after UVA irradiation. For pipemidic acid, griseofuvin and doxycycline, the regression coefficients reached 76.96, 254.33 and 92.61 respectively, significantly increased in comparison with those of negative controls (P < 0.01).

CONCLUSION

Phototoxicity of pipemidic acid, doxycycline and griseofuvin can be detected with the method of chemiluminescence.

Chemically induced micronucleus formation in V79 cells--comparison of three different test approaches

The in vitro micronucleus test (MNT) is a useful assay for the detection of mutagenic events on both the chromosomal and the genomic level. The main disadvantage for introducing the in vitro MNT into official test guidelines seems to be the disparity of existing protocols. To contribute to the aim of standardisation, three different methodological approaches of the in vitro MNT with V79 cells were compared: the standard assay using an asynchronically growing mixed cell population, the cytokinesis block (CB) assay and a modified MNT, the so-called mitotic shake-off (MSO) method. V79 cells were thus treated with two known aneugens (colcemide and griseofulvin) and two clastogens (mitomycin C and cyclophosphamide) over various time periods. The cultures of the CB assay were additionally exposed to cytochalasin B (Cyt-B), an inhibitor of cell, but not of nucleus division. After treatment, the cells were harvested and analysed for the appearance of micronuclei (MN). All three assays yielded positive results for all test substances. These results support the suitability of the MNT with V79 cells with regard to the ability to detect the genotoxic potential of both clastogens and aneugens independent of the test protocol applied. Thus, all three methods are appropriate for MN detection, but due to the fact that the application of Cyt-B has no advantages for a cell line like V79 in which nearly all cells undergo a normal cell cycle, its use is not recommended.

Mutation of a major keratin phosphorylation site predisposes to hepatotoxic injury in transgenic mice

Simple epithelia express keratins 8 (K8) and 18 (K18) as their major intermediate filament (IF) proteins. One important physiologic function of K8/18 is to protect hepatocytes from drug-induced liver injury. Although the mechanism of this protection is unknown, marked K8/18 hyperphosphorylation occurs in association with a variety of cell stresses and during mitosis. This increase in keratin phosphorylation involves multiple sites including human K18 serine-(ser)52, which is a major K18 phosphorylation site. We studied the significance of keratin hyperphosphorylation and focused on K18 ser52 by generating transgenic mice that overexpress a human genomic K18 ser52--> ala mutant (S52A) and compared them with mice that overexpress, at similar levels, wild-type (WT) human K18. Abrogation of K18 ser52 phosphorylation did not affect filament organization after partial hepatectomy nor the ability of mouse livers to regenerate. However, exposure of S52A-expressing mice to the hepatotoxins, griseofulvin or microcystin, which are associated with K18 ser52 and other keratin phosphorylation changes, resulted in more dramatic hepatotoxicity as compared with WT K18-expressing mice. Our results demonstrate that K18 ser52 phosphorylation plays a physiologic role in protecting hepatocytes from stress-induced liver injury. Since hepatotoxins are associated with increased keratin phosphorylation at multiple sites, it is likely that unique sites aside from K18 ser52, and phosphorylation sites on other IF proteins, also participate in protection from cell stress.

Enhancement of bioavailability of griseofulvin by its complexation with beta-cyclodextrin

Griseofulvin is a poorly soluble antifungal antibiotic drug, the solubility of which can be enhanced by complexation with beta-cyclodextrin. The inclusion complex was prepared by coprecipitation method in various molar ratios of 1:1, 2:1, 3:1, and 1:2 of the drug and beta-cyclodextrin, respectively. The inclusion complex was characterized and evaluated by UV-VIS spectral studies and FTIR. The in vitro drug release studies indicated that the 1:2 molar ratio complex form of the drug significantly increased the dissolution rate when compared to the free form. The acute toxicity studies clearly indicated that the beta-cyclodextrin complex was nontoxic and the safety range was close to other Griseofulvin formulations. The in vivo study of the beta-cyclodextrin was carried out in both animals and human beings by administering in four different rabbits and volunteers, respectively. Pellets made with Griseofulvin-beta-cyclodextrin complex also showed a significant increase in the dissolution of the drug, revealing that beta-cyclodextrin plays an important role in the solubilization of Griseofulvin.

Toxic effects of griseofulvin: disease models, mechanisms, and risk assessment

Griseofulvin (GF) has been in use for more than 30 years as a pharmaceutical drug in humans for the treatment of dermatomycoses. Animal studies give clear evidence that it causes a variety of acute and chronic toxic effects, including liver and thyroid cancer in rodents, abnormal germ cell maturation, teratogenicity, and embroyotoxicity in various species. No sufficient data from human studies are available at present to exclude a risk in humans: therefore, attempts were made to elucidate the mechanisms responsible for the toxic effects of GF and to address the question whether such effects might occur in humans undergoing GF therapy. It is well documented that GF acts as a spindle poison and its reproductive toxicity as well as the induction of numerical chromosome aberrations and of micronuclei in somatic cells possibly may result from disturbance of microtubuli formation. Likewise, a causal relationship between aneuploidy and cancer has been repeatedly postulated. However, a critical survey of the data available on aneuploidogenic chemicals revealed insufficient evidence for such an association. Conceivably, other mechanisms may be responsible for the carcinogenic effects of the drug. The induction of thyroid tumors in rats by GF is apparently a consequence of the decrease of thyroxin levels and it is unlikely that such effects occur in GF-exposed humans. The appearance of hepatocellular carcinomas (HCC) in mice on GF-supplemented diet is preceded by various biochemical and morphological changes in the liver. Among these, hepatic porphyria is prominent, it may result from inhibition of ferrochelatase and (compensatory) induction of ALA synthetase. GF-induced accumulation of porphyrins in mouse liver is followed by cell damage and necrotic and inflammatory processes. Similar changes are known from certain human porphyrias which are also associated with an increased risk for HCC. However, the porphyrogenic effect of GF therapy in humans is moderate compared with that in the mouse model, although more detailed studies should be performed in order to clarify this relationship on a quantitative basis. A further important effect of GF-feeding in mice is the formation of Mallory bodies (MBs) in hepatocytes. These cytoskeletal abnormalities occur also in humans, although under different conditions; their appearance is associated with the induction of liver disease and HCC. Chronic liver damage associated with porphyria and MB formation, enhanced cell proliferation, liver enlargement, and enzyme induction all may contribute to the hepatocarcinogenic effect of GF in mice. In conclusion, further investigation is required for adequate assessment of health risks to humans under GF therapy.

Stress, apoptosis, and mitosis induce phosphorylation of human keratin 8 at Ser-73 in tissues and cultured cells

Simple epithelia express keratins 8 (K8) and 18 (K18) as their major intermediate filament proteins. We previously showed that several types of cell stress such as heat and virus infection result in a distinct hyperphosphorylated form of K8 (termed HK8). To better characterize K8/18 phosphorylation, we generated monoclonal antibodies by immunizing mice with hyperphosphorylated keratins that were purified from colonic cultured human HT29 cells pretreated with okadaic acid. One antibody specifically recognized HK8, and the epitope was identified as 71LLpSPL which corresponds to K8 phosphorylation at Ser-73. Generation of HK8 occurs in mitotic HT29 cells, basal crypt mitotic cells in normal mouse intestine, and in regenerating mouse hepatocytes after partial hepatectomy. Prominent levels of HK8 were also generated in HT29 cells that were induced to undergo apoptosis using anisomycin or etoposide. In addition, mouse hepatotoxicity that is induced by chronic feeding with griseofulvin resulted in HK8 formation in the liver. Our results demonstrate that a "reverse immunological" approach, coupled with enhancing in vivo phosphorylation using phosphatase inhibitors, can result in the identification of physiologic phosphorylation states. As such, K8 Ser-73 phosphorylation generates a distinct HK8 species under a variety of in vivo conditions including mitosis, apoptosis, and cell stress. The low steady state levels of HK8 during mitosis, in contrast to stress and apoptosis, suggest that accumulation of HK8 may represent a physiologic stress marker for simple epithelia.

A new possible parameter for the detection of aneuploidy inducing substances: the analysis of qualitative and quantitative abnormalities of the spindle apparatus

In the present study, compared to other cytogenetic methods, we measured the number of aneuploid cells directly by analyzing anomalies of the mitotic spindle. Qualitative and quantitative abnormalities of the mitotic spindle apparatus in transformed and non-transformed cell lines in vitro were classified. We treated the different cell lines with well known aneugenic agents as Benomyl and Griseofulvin and investigated the mitotic spindle under different experimental conditions. The spindle apparatus was stained by indirect immunofluorescence and the chromatin was counterstained by fluorescent dyes. The mitotic spindle showed a great sensitivity to the aneuploidy-inducing substances used in our experiments. The spindle-disturbing effect of the tested substances was demonstrated to be dose- dependent. The morphological alterations appeared to be independent of the aneuploidy-inducing test substance used, but showed a relation to the dose and length of treatment. Thus, the analysis of the mitotic spindle may be a useful screening parameter for the detection of aneuploidy-inducing substances and further investigations will provide additional results to specific parameters.

Susceptibility to hepatotoxicity in transgenic mice that express a dominant-negative human keratin 18 mutant

Keratins 8 and 18 (K8/18) are intermediate filament phosphoglycoproteins that are expressed preferentially in simple-type epithelia. We recently described transgenic mice that express point-mutant human K18 (Ku, N.-O., S. Michie, R.G. Oshima, and M.B. Omary. 1995. J. Cell Biol. 131:1303-1314) and develop chronic hepatitis and hepatocyte fragility in association with hepatocyte keratin filament disruption. Here we show that mutant K18 expressing transgenic mice are highly susceptible to hepatotoxicity after acute administration of acetaminophen (400 mg/Kg) or chronic ingestion of griseofulvin (1.25% wt/wt of diet). The predisposition to hepatotoxicity results directly from the keratin mutation since nontransgenic or transgenic mice that express normal human K18 are more resistant. Hepatotoxicity was manifested by a significant difference in lethality, liver histopathology, and biochemical serum testing. Keratin glycosylation decreased in all griseofulvin-fed mice, whereas keratin phosphorylation increased dramatically preferentially in mice expressing normal K18. The phosphorylation increase in normal K18 after griseofulvin feeding appears to involve sites that are different to those that increase after partial hepatectomy. Our results indicate that hepatocyte intermediate filament disruption renders mice highly susceptible to hepatotoxicity, and raises the possibility that K18 mutations may predispose to drug hepatotoxicity. The dramatic phosphorylation increase in nonmutant keratins could provide survival advantage to hepatocytes.

Detection of the centromere in micronuclei by fluorescence in situ hybridization: its application to the human lymphocyte micronucleus assay after treatment with four suspected aneugens

The human lymphocyte micronucleus (MN) test combined with fluorescence in situ hybridization (FISH) of a centromeric probe is considered a useful screening assay to distinguish between clastogenic and aneugenic agents. Four suspected aneuploidy-inducing chemicals, acetaldehyde (AA), diethylstilbestrol (DES), diethylstilbestrol dipropionate (DESdp) and griseofulvin (GF), have been evaluated with the assay. All compounds induced a significant increase of MN at all doses tested. After the application of the FISH technique with a pancentromeric DNA sequence, DES, DESdp and GF showed a statistically significant increase in the percentage of positive signals compared with the control culture. GF induced the highest percentage of centromere-positive MN observed to date (>90% on average). AA did not show a significant difference in the percentage of centromere-positive MN. The results indicate that in human lymphocytes DES, DESdp and GF act primarily as aneugens, while AA seems capable of causing both chromosome breakage and aneuploidy.

Relationship between N-acetyltransferase (NAT) activity and liver protoporphyrin level in experimental porphyria

The results of our previous studies demonstrated that isonicotinic acid hydrazide (INH) can aggravate griseofulvin (GF)-induced protoporphyria in mice. To elucidate this phenomenon, we studied the relationship between liver protoporphyrin (PP) levels and N-acetyltransferase (NAT) activity, which is known to be a major catabolic enzyme of INH metabolism in the liver. The results revealed a significant correlation between liver PP levels and NAT activity in the mice fed 0.1% GF and 0.05% INH. In this group, mice with high NAT activity developed severe protoporphyria. There was no correlation, however, between liver PP levels and NAT activity in the mice fed GF alone or INH alone. The result suggested that INH metabolites formed by NAT enhance the hepatotoxicity of GF in mice.

Cytogenetic effect of griseofulvin in mouse spermatocytes

The genotoxic effects of griseofulvin (GF) in mouse primary spermatocytes at diakinesis metaphase I of meiosis were investigated. Griseofulvin was administered orally as a single dose of 500, 1000, 1500 and 2000 mg kg-1 body wt. and a multiple treatment with a daily dose of 1000 mg kg-1 body wt. for three and five successive doses. Both single and multiple treatment induced a statistically significant increase in the percentage of chromosomal aberrations which have a dose and time-dependent relationship. The frequency of chromosomal aberrations peaked 6 and 12 h post treatment; with the highest dose of the drug it reached 27.8% +/- 0.87 and 27.66% +/- 0.48 6 and 12 h respectively, compared with 5.6% +/- 0.39 and 5.2% +/- 0.48 for the control. The types of aberrations recorded were structural, including X-Y and autosomal univalent, gaps, breaks, fragments, chain IV and numerical in the form of diploid, triploid, tetraploid and aneuploid. The results of this study suggest that griseofulvin has a genotoxic effect in mouse spermatocytes.

Heat shock in vivo induces Mallory body formation in drug primed mouse liver

Perturbations in keratin intermediate filament organization and Mallory body (MB) formation are associated with alcoholic hepatitis. Inducible heat shock proteins (HSPs) are expressed in a variety of liver diseases including alcoholic liver disease. Therefore, we investigated whether heat shock protein induction can lead to MB formation. Mice were primed by a 5-month feeding of griseofulvin (GF) or diethyl 1,4-dehydro-2,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC) followed by drug withdrawal for 1 month. The animals were then subjected to an in vivo heat shock treatment or sham heat treatment. Liver morphology, HSP expression, liver regeneration (PCNA-labeled nuclei), and MB formation were monitored during a 7-day posttreatment period. Numerous MBs developed in the livers of mice exposed to GF or DDC for 5 months, but very few small MBs remained after 1-month withdrawal of either drug. No MBs were found at Day 1 post heat shock, whereas numerous MBs were observed at Day 7. The frequency of PCNA-labeled nuclei increased during the same period. At Day 1 posttreatment, a variable liver centrilobular necrosis was observed accompanied by a prominent increase in HSP-25 and HSP70 expression, but HSP-90 expression was not increased. In drug-primed mouse liver, a heat shock treatment induces the expression of specific HSPs prior to the formation of MBs, indicating that HSP expression may play a role in the pathogenesis of MB formation. We speculate that this role is through the protein unfolding function of HSP, which leads to the aggregation of the cytokeratins to form MBs as well as to polyubiquitin binding to these proteins in a manner analogous to amyloid formation.

Griseofulvin: generation time and ATP changes in the ciliate Tetrahymena pyriformis

Tetrahymena pyriformis GL populations (20,000 cells/ml and 50,000 cells/ml) were studied at various times after exposure to griseofulvin. Growth rates were significantly different between controls and treated samples 90 min after treatment. ATP levels decreased in treated samples after 45 min. No differences were observed between controls and populations treated with acetone used to dissolve griseofulvin.

Genotoxic effect of griseofulvin in somatic cells of Drosophila melanogaster

Griseofulvin (GF), a carcinogenic spindle poison, was tested in two types of somatic-cell assays of Drosophila melanogaster, one of which detects the induction of DNA damage and the other mutation/mitotic recombination. In both assays, GF was fed to tester larvae and genetic endpoints examined after emergence. In the wing spot test, trans-heterozygous flies carrying mwh and flr3 wing-hair mutations produced both significant and dose-dependent increases in the frequency of mwh single spots over the control level but no increase of twin spots. In the DNA repair test, double-mutant larvae carrying both mei-9(a) (excision repair-defective) and mei-41(D5) (postreplication repair-defective) mutations showed hypersensitivity to killing by GF compared with their DNA repair-proficient counterparts, suggesting that GF caused potentially lethal DNA damages which were efficiently repaired by the DNA repair-proficient but not -defective larvae. These lines of evidence clearly demonstrate that GF is genotoxic in somatic cells of Drosophila. It is noted that (1) GF-fed larvae showed a developmental delay and (2) surviving adult flies had morphological abnormalities in their eyes and wings.

Detection of aneuploidy-inducing carcinogens in the Syrian hamster embryo (SHE) cell transformation assay

As evidenced by the recent report of the Commission of the European Communities (CEEC) project (Detection of Aneugenic Chemicals-CEEC project, 1993), there currently is a great deal of effort towards developing and validating assays to detect aneuploidy-inducing chemicals. In this report, we describe the utility of the Syrian hamster embryo (SHE) cell transformation assay for detecting carcinogens with known or suspected aneuploidy-inducing activity. The following carcinogens were tested: asbestos, benomyl, cadmium chloride, chloral hydrate, diethylstilbestrol dipropionate, and griseofulvin. Thiabendazole, a noncarcinogen, was also tested. Chemicals of unknown or inconclusive carcinogenicity data, colcemid, diazepam, econazole nitrate, and pyrimethamine were also evaluated. All of the above chemicals except thiabendazole induced a significant increase in morphological transformation (MT) in SHE cells. Based on these results as well as those published in the literature previously, the SHE cell transformation assay appears to have utility for detecting carcinogens with known or suspected aneuploidy-inducing ability.

[Modification of the teratogenic effect of griseofulvin by heat shock in Drosophila melanogaster]

Modification of the teratogenic effect of griseofulvin by hyperthermia was demonstrated in line Canton-S of Drosophila melanogaster. Heat shock (37 degrees C for 45 min) during II instar larvae significantly decreased the frequency of chemomorphoses that phenocopy ey mutation (eyeless, 4:2.0).

OTC pharmaceuticals and genotoxicity testing: the paracetamol, anthraquinone, and griseofulvin cases

Genotoxic effects are hardly assessable in an exposed population but are generally considered to be serious due to their unpredictable effects on subsequent generations and to the link between genotoxicity and cancer. Lack of knowledge about a genotoxic/carcinogenic potential has to be stated for numerous compounds which are often in pharmaceutical use known for a long time. A thorough testing programme like it is done for new compounds is essential for such compounds that are not completely unsuspicious with respect to being reactive with macromolecules or that have the potential to generate reactive metabolites in the body. Paracetamol, anthraquinone-containing preparations, and griseofulvin are examples for pharmaceuticals that have been in use for a long time but for which genotoxicity testing revealed a possible deleterious potential only recently. The Federal Health Office/Federal Institute for Drugs and Medical Devices therefore imposed new studies upon companies marketing these compounds in the last years. These studies in part led to a more thorough description of possible adverse effects or even restrictions for use. Paracetamol exhibits a genotoxic potential in vitro and in vivo probably via indirect, cytotoxicity or enzyme inhibition-mediated effects. Further studies will have to clarify whether a threshold could be established and whether effects do not occur at therapeutic dose levels. Genotoxicity data on the mixed group of anthraquinones reveal positive and negative findings. Compounds such as lucidin, danthron, emodin supposedly have a genotoxic and carcinogenic potential. Further studies with anthraquinone-containing plant preparations will have to clarify the content and genotoxic activity of the preparations and the active ingredients. Lucidin- and danthron-containing preparations are currently no longer in use now whereas restrictions apply for other anthraquinone-containing laxatives. Griseofulvin is acknowledged in the meantime as an aneugen for somatic and germ cells. It is in vitro effective in concentrations that correspond to therapeutic plasma levels.

Induction of kinetochore-positive micronuclei in human lymphocytes by the anti-fungal drug griseofulvin

Griseofulvin (GF) is a widely used antifungal drug for the treatment of superficial dermatomycoses. However, because GF is carcinogenic and teratogenic in animal models there is considerable concern regarding its clinical application. Further, it produces numerical chromosome aberrations in human lymphocytes and cell lines. There are conflicting reports on the ability of GF to induce structural chromosomal aberrations. Here, we show GF induces micronucleus formation both in isolated peripheral lymphocytes and lymphocytes from whole blood cultures. An antikinetochore antibody was used to distinguish micronuclei with acentric chromosome fragments (kinetochore-negative) and from those containing whole chromosomes (kinetochore-positive). The micronuclei formed were 99% kinetochore-positive in isolated lymphocytes. In addition, GF was able to alter the cell cycle kinetics of lymphocytes, thereby increasing the percentage of triploid cells. We conclude that GF is a strong aneuploidy-inducing agent in peripheral human lymphocytes and produces effects at concentrations which should be detectable in the blood of persons undergoing therapy.

[Analysis of the mutagenic and teratogenic effect of griseofulvin in the mutagen-sensitive Drosophila melanogaster line mus(2)201G1]

The mutagenic effect of griseofulvin was demonstrated in a wing somatic mosaicism test (SMART) in different Drosophila lines. The mutagenic effect of this agent is accompanied by a pronounced toxic effect on Drosophila larvae and by a teratogenic effect, which is manifested in the reduction of ommatidia, phenocopying the mutation ey (eyeless-4:2.0). A relationship was shown between the level of the phenocopies and the dose of griseofulvin (GF), the genotypes of the treated larvae, the interval and duration of GF exposure, and also sexual differences. The lowest level of phenocopies is recorded for the line developed on the basis of the mutagen-sensitive mutation mus(2)201G1, which blocks excision repair.

Metabolic activation of four drugs in the eye mosaic assay measuring principally mitotic recombination in Drosophila melanogaster: differences in strain susceptibility and route of exposure

One mycotoxin and three therapeutic drugs widely used in developing countries were examined for genotoxic activity by means of the w/w + somatic recombination assay. Streptozotocin (SZ), an antibiotic antineoplastic agent, gave a frequency of light spots almost one order of magnitude higher than those obtained with the carcinogen mycotoxin sterigmatocystin (STC), the antiprotozoal and antimicrobial metronidazole (MNZ), and the antifungal griseofulvin (GF). Thus the order of response was SZ > STC > MNZ > GF. Chronic treatment turned out to be the better route of exposure for these genotoxins when compared with surface treatment. The performance of the insecticide-resistant strain Hikone-R was better than that of the wild genotype LS (Leiden Standard). The positive test results obtained with all four chemicals showed that the P450 system of Drosophila is capable of metabolizing these genotoxins into electrophilic intermediates.

Variation of mouse oocyte sensitivity to griseofulvin-induced aneuploidy and meiotic delay during the first meiotic division

The effects of varying the time of chemical treatment on the induction of aneuploidy and meiotic delay in metaphase II (MII) oocytes were studied by administering 1,500 mg/kg griseofulvin (GF) at 0, 2, 4, 6, or 8 hr after an injection of human chorionic gonadotrophin (HCG). The results show that the oocytes have a different sensitivity to GF-induced aneuploidy and meiotic delay during the course of meiotic maturation. Although not restricted to a particular period of meiotic maturation, the frequency of aneuploidy was highest (P < 0.05) when GF was given at 2, 4, or 6 hr after HCG. The maximum frequency of hyperploidy (42.4%) occurred at the 4-hr treatment time. Also, GF treatment resulted in the induction of meiotic delay as demonstrated by ovulated metaphase I (MI) and polyploid MII oocytes. The meiotic delay data depict a period of relative resistance between two periods of sensitivity in that the percentages of ovulated MI oocytes were 53.3, 21.3, 3.5, 6.7, and 25.7 when GF was given at 0, 2, 4, 6, and 8 hr after HCG, respectively. Also, at these treatment times the percentages of polyploid oocytes were 0.6, 1.7, 7.7, 20.1, and 15.4, respectively. Therefore, the oocytes seem to be more sensitive to GF-induced meiotic delay during the periods preceding and following meiotic spindle assembly. In conclusion, the results demonstrate that the time of chemical treatment influences the frequency of aneuploidy and the degree of meiotic delay. Also, the results emphasize that to thoroughly characterize the aneugenic potential of a specific chemical several treatment times may be needed.

Griseofulvin-induced aneuploidy and meiotic delay in mouse oocytes: effect of dose and harvest time

The in vivo mouse oocyte assay provides a useful system for studying both structural and numerical cytogenetic abnormalities induced by chemicals in mammalian germ cells. As part of the development of this assay for investigating chemically-induced numerical chromosome changes, the experimental and biological variables that can influence the outcome of the assay are being determined. In this study, we investigated the effect of griseofulvin (GF) administered by oral gavage on the induction of meiotic delay as measured by ovulated metaphase I (MI) oocytes and the induction of aneuploidy in metaphase II (MII) oocytes. The results indicate that GE significantly increased the frequencies of oocytes blocked in MI and of hyperploid MII oocytes compared to controls. The biological fate of delayed MI oocytes was investigated by harvesting oocytes at different times post treatment. With increasing harvest times, the frequency of MI oocytes decreased and, unexpectedly, the frequency of hyperploid MII oocytes also decreased. This suggests that some MI oocytes can overcome the GF-induced meiotic block, form a normal meiotic spindle, and progress to metaphase II as normal MII oocytes. The significance of these findings for the design and interpretation of in vivo mouse oocyte studies is discussed.

Induction of hepatocellular carcinomas in the Egyptian toad Bufo regularis by an antifungal drug (griseofulvin)

Neoplastic lesions (hepatocellular carcinomas) were induced in the liver in 18 of 100 experimental toads (Bufo regularis) force fed with the antifungal drug griseofulvin, at a dose level of 0.4 mg/50 g every day. Maximal time of exposure and observation was 12 weeks. The first tumors appeared in 2 male toads 4 weeks after the initiation of feeding.

Serial light and electron microscopic changes in renal glomeruli in mice fed griseofulvin

The renal glomerular mesangium in male, Swiss Webster mice, fed a diet containing 2.5 percent griseofulvin (GF), showed hypercellularity and mesangial thickening within three weeks. These changes gradually increased, peaking in prominence at 11 to 16 weeks and persisted up to 22 weeks. The tubular epithelium showed minimal light microscopic changes. There was focal hyperplasia of parietal cells of the Bowman's capsule. Ultrastructurally, the changes in the mesangial region of the glomeruli included increase in mesangial cells and mesangial matrix. The renal tubular epithelial cells showed dilatation of mitochondria and smooth endoplasmic reticulum. These changes, in addition to diverse cellular alterations in other organs previously reported, constitute the morphologic features of GF-induced renal disease.

Analysis of the six additional chemicals for in vitro assays of the European Economic Communities' EEC aneuploidy programme using Saccharomyces cerevisiae D61.M and the in vitro porcine brain tubulin assembly assay

We tested six additional chemicals (acetaldehyde, benomyl, diethylstilboestrol, diethylstilboestrol dipropionate, griseofulvin, and mercaptoethanol) for in vitro systems of the coordinated programme to study aneuploidy induction sponsored by the Commission of the European Communities in two in vitro test systems. Using Saccharomyces cerevisiae D61.M (mitotic chromosomal malsegregation assay), benomyl showed a dose-dependent increase in the frequency of chromosomal malsegregation with a lowest effective dose tested (LEDT) of 30 micrograms/ml (0.1 mM). Diethylstilboestrol (DES) showed solvent-dependent effects. DES dissolved in ethanol induced an increase in chromosomal malsegregation as well as in the frequency of total resistant colonies (mutations and recombinations) with a LEDT around 13 micrograms/ml (0.048 mM). Using dimethylsulfoxide as the solvent, no increases were observed with DES up to 333 micrograms/ml (1.24 mM). Acetaldehyde induced an increase in chromosomal malsegregation with the cold treatment protocol (LEDT: 1.25 microliters/ml (21 mM) and 0.75 microliters/ml (13 mM), respectively) but no increase with the overnight protocol (highest dose tested (HDT): 1.75 microliters/ml; 30 mM). Concerning the frequency of total cycloheximide-resistant colonies (mutations and recombinations) increases were obtained with both protocols. The other three compounds were negative when tested up to toxic doses (survival below 10%), up to the maximum solubility in the solvent used or up to heavy precipitation in the incubation mix. The HDT were 333 micrograms/ml (0.88 mM) for diethylstilboestrol dipropionate, 1,600 micrograms/ml (4.5 mM) for griseofulvin and 0.5 microliters/ml (7 mM) for mercaptoethanol. Concerning effects on porcine brain tubulin assembly in vitro, diethylstilboestrol and griseofulvin inhibited the assembly process. The IC30% (30% inhibition concentration) values were 12.5 microM and 100 microM for DES and griseofulvin, respectively. Mercaptoethanol showed no effects up to 50 mM.

Griseofulvin-induced aneuploidy and meiotic delay in female mouse germ cells. I. Cytogenetic analysis of metaphase II oocytes

Griseofulvin (GF) was tested in female mouse germ cells for the induction of aneuploidy and meiotic arrest. Superovulated mice were orally treated with 200, 666, 1332 or 2000 mg/kg in olive oil at the time of human chorionic gonadotrophin (HCG) injection and were sacrificed 18 h later. A dose-dependent increase in the frequency of metaphase I (M I) arrested oocytes was observed (maximum of 70%). Aneuploidy was not significantly induced. Also, the kinetics of meiotic progression up to the metaphase II (M II) stage was studied in untreated mice in order to correlate the time of treatment with the time of the first meiotic division. The results demonstrate that the majority of cells was treated with GF approximately 8 h before the M I stage. A second series of experiments were performed to test GF effects at a different treatment time. Doses of 200, 666 or 2000 mg/kg were administered 2 h post HCG. As in the first series of experiments, the animals were sacrificed 18 h post HCG. The results, compared with those obtained in the first experimental series, showed an inverse trend for meiotic arrest and aneuploidy induction. The frequency of M I arrested oocytes dropped from a maximum of 70% to a maximum of 20%, while, at the latest treatment time, a dose-dependent increase in the frequency of hyperploid oocytes was observed up to 56% aberrant cells at 2000 mg/kg. Altogether the results suggest that the arrest of meiotic division and the induction of aneuploidy by GF are caused by interaction with different targets or different developmental stages of the same target. In conclusion, GF has been shown to induce aneuploidy during the first meiotic division in a dose-related manner, together with other effects such as polyploidy, developmental delay and meiotic arrest. Also, these findings demonstrate that the sensitivity of the oocyte target(s) may be restricted to a specific time period and that a correct experimental protocol is critical for assessing the aneugenic activity of a chemical.

Griseofulvin-induced aneuploidy and meiotic delay in female mouse germ cells. II. Cytogenetic analysis of one-cell zygotes

The effects of griseofulvin (GF) upon the first meiotic division of female mouse germ cells were evaluated by cytogenetic analysis of first-cleavage (1-Cl) zygotes. The present study is an extension of an investigation that began with the cytogenetic analysis of metaphase II (M II) oocytes. Different doses (200, 666, 1332, 2000 mg/kg) were tested by oral administration of GF to superovulated animals either at the time of human chorionic gonadotrophin (HCG) injection or 2 h post HCG. When GF was given at the time of HCG, significant dose-dependent increases of different types of cytogenetically abnormal cells were found. These included zygotes containing ostensibly female-derived M I or M II arrested chromosomes and polyploid zygotes. The total yields of these aberrations were 2.9, 4.3, 26.2, 60.6, and 64.1% for control, 200, 666, 1332, and 2000 mg/kg, respectively. The origin of these zygotes was attributed to the fertilization of oocytes that had been previously arrested at M I. No significant induction of hyperploidy was detected. Developmentally abnormal zygotes were still observed when GF was administered 2 h post HCG, although their frequencies were significantly lower than in the first series of experiments. The yields of developmentally abnormal zygotes were 49, 10.2, and 23.6% at 200, 666, and 2000 mg/kg. Additionally, a dose-dependent increase in the frequency of hyperploid zygotes was detected up to a maximum of 36.5% at 2000 mg/kg. These results confirm the cytogenetic observations from M II oocytes after GF treatment under the same experimental conditions; namely, a dramatic change in the oocyte target susceptibility to GF occurred within a short time period. Also, the present study demonstrated that most of GF-induced aneuploid oocytes were fertilized and reached first-cleavage metaphase.

Inhibition of ferrochelatase and accumulation of porphyrins in mouse hepatocyte cultures exposed to porphyrinogenic chemicals

The ability of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC), 3,5-diethoxycarbonyl-4-ethyl-1,4-dihydro-2,6-dimethylpyridine (EDDC) and griseofulvin to induce porphyria in primary cultures of mouse hepatocytes has been examined. Exposure of cultured mouse hepatocytes to DDC, EDDC or griseofulvin resulted in a marked inhibition of ferrochelatase which was sustained over the 4-day exposure period. Maximal concentrations of DDC (25 microM), EDDC (25 microM) and griseofulvin (25 microM) resulted in 14-fold, 30-fold and 9-fold increases, respectively, in total porphyrin in the culture medium. Analysis of the porphyrins accumulating indicated a predominance of protoporphyrin with all three xenobiotics. Addition of 5-aminolaevulinic acid (ALA) to mouse hepatocyte cultures (10-1000 microM) resulted in much larger increases (up to 164-fold) in porphyrin accumulation in the medium and the porphyrin accumulating was predominantly uroporphyrin. These studies have demonstrated that primary cultures of mouse hepatocytes provide a valid mechanism-based in vitro model of the hepatic porphyrias produced by the dihydropyridines and griseofulvin in mice.

Distinctive infrared spectral features in liver tumor tissues of mice: evidence of structural modifications at the molecular level

Mice were treated with griseofulvin (GF) containing diet or control diet for 12 months. The livers from mice fed griseofulvin showed large tumors that were excised and used for analysis. The infrared spectra from control liver tissue and tumor tissue from GF livers were measured and compared as a function of pressure up to 27 kbar. Many changes in the infrared spectral features of the tumor tissue were observed. Results showed that neoplasm formation involved structural modifications of nucleic acids, lipids, carbohydrates, and proteins in the liver cells, which were detected from the abnormal vibrations of the functional groups in these biomolecules. The amount of glycogen was dramatically decreased in the tumor tissue compared to the control tissue. Important changes in the strength of hydrogen-bondings in the phosphodiester backbone of the nucleic acids and in the C-O groups of tissue proteins and carbohydrates were observed. Stronger interchain interactions and thus close interchain packing among the lipids in the GF liver were evident. These results showed very close similarities with those obtained with other types of tumors such as human colon cancer, suggesting that a common pattern of molecular changes has been identified in neoplastic transformation.

Changes of cytokeratin filament organization in human and murine Mallory body-containing livers as revealed by a panel of monoclonal antibodies

Mallory bodies (MBs) are characteristics morphologic features of alcoholic hepatitis and can be produced in mouse hepatocytes by chronic griseofulvin (GF) intoxication. The formation of MBs, which share some immunological, biochemical, and ultrastructural features with cytokeratin (CK) filaments of normal liver, is accompanied by derangement and even loss of the CK cytoskeleton of hepatocytes ("empty cells") as revealed by immunofluorescence microscopy. To clarify whether this diminution or lack of CK-related staining of MB-containing hepatocytes was due to loss of CK filaments or changes in antigenicity or accessibility of antigenic determinants immunohistochemical studies using a battery of monoclonal and polyclonal CK antibodies were performed. It could be shown that all these antibodies directed against different CK polypeptide components and antigenic determinants of CKs revealed a highly reduced or even undetectable cytoplasmic CK meshwork in most cells with fully developed large MBs. In the light of our present knowledge of the organization of CK intermediate filaments, these results indicate that the phenomenon of the "empty cells" reflects a diminution of CK meshwork rather than altered antigenic determinants.

Effect of ursodeoxycholic acid on experimental hepatic porphyria induced by griseofulvin

Griseofulvin(GF) has become the drug of choice as an antifungal agent for patients who suffer from many kinds of fungal infection. In order to clarify hepatic injury by griseofulvin(GF) overload and the effect of UDCA on GF-induced hepatic injury, the authors carried out biochemical, histologic, and ultrastructural studies of liver following treatment with griseofulvin and ursodeoxycholic acid(UDCA) in mice. Urine porphobilinogen excretion in the group treated with GF alone was significantly increased and reached the highest level in the 4th week and declined thereafter. Biochemical studies of the liver function showed no remarkable changes of serum bilirubin levels throughout the experimental period in all groups, except for SGPT and alkaline phosphatase activities which were significantly elevated and reached the highest level in the second week. Then they slightly decreased in GF treated groups(GF alone and GF plus UDCA) in comparison with the control group. Pathologic findings in the group treated with GF alone include focal liver cell necrosis(esp, zone 3), Mallory bodies in hepatocytes(esp, zone 1), Kupffer cell activation, and brown protoporphyrin pigments in the hepatocytes, bile canaliculi and interlobular bile ducts with a marked inflammatory cell infiltration in the portal tracts. Under the polarizing light microscope, bile ductular and canalicular thrombi showed a "Maltese cross" birefringence in mice treated with GF alone. There is no definite finding of fatty change in hepatocyte. Under the microscope, the liver appeared normal with an intact lobular architecture in the GF plus UDCA treated group. Electron microscopically, GF-induced changes include swelling of mitochondria, globular protoporphyrin crystals in the hepatocyte cytoplasm, markedly dilated bile cannaliculi and bile ducts and the formation of a Mallory hyaline bodies in the hepatocytes. There were no noticeable structural changes in the GF plus UDCA-treated group. Therefore the results suggest that GF causes hepatic injury, namely porphyria and cholestasis, and the treatment of UDCA may have cytoprotective and choleretic effects on GF-induced hepatic injuries.

On the three-dimensional structure of quick-frozen hepatic Mallory bodies with special reference to the appearance of cytoplasmic vesicles

Livers containing Mallory bodies (MBs, hyalin degenerative cytoplasmic inclusions) were examined using Heuser's and Van Harreveld's cryo-techniques. The tissues were collected from 1) a patient suffering from alcoholic hepatitis and 2) mice treated with griseofulvin (GF, an anti-mitotic drug). Normal mouse liver and isolated MBs from GF-treated mice were also analyzed by the same methods. Our results suggest that under the toxic influence of alcohol or GF on microtubular elements, MBs are generated by entanglement of elements of 10 nm filaments with microtubule elements. This in turn inhibits cellular transport processes. The reticular net of the ER-element which is usually observable in the normal tissue is changed into numerous small vesicles in the pathological and experimental tissues. The diameters of hepatocytes containing these vesicles were 1.5 to 2 times larger than control diameters. MBs have previously been described in thin sections as filamentous tangles. On replicas we found that they appear to be composed of pairs of filaments twisted in a roughly helical manner, each having a diameter less than 10 nm. The paired helical nature of the MB-filaments is reminiscent of other inclusion bodies, which are also composed of elements of 10 nm filaments, observable in various neurological diseases.

Toxicity of trichothecenes, moniliformin, zearalenone/ol, griseofulvin, patulin, PR toxin and rubratoxin B on protozoan tetrahymena pyriformis

The inhibitory effects of some fungal products from Fusarium, Trichothecium, Myrothecium and Penicillium were investigated on the protozoan Tetrahymena pyriformis. The dose of mycotoxin which decreased the protozoa growth by 50% in 24 h was defined as inhibitory dose 50 (ID50). The order of toxicity according to the ID50 values were: T-2 toxin greater than trichothecin greater than 4, 15-diacetylverrucarol greater than patulin greater than trichothecolone greater than verrucarol greater than zearalenone greater than PR toxin greater than 3 alpha-acetyldiacetoxyscirpenol greater than zearalenol greater than griseofulvin greater than acetyl T-2 greater than iso T-2 greater than T-2 triol greater than scirpentriol greater than rubratoxin B greater than T-2 tetraol greater than moniliformin. In analogous pairs of trichothecenes their toxicities depended upon the substituents at certain positions of the molecules. Thus, the order of toxicity by the substituents was: at C3 position, H greater than OH greater than OAc [e.g., verrucarol (H at C3) greater than scirpentriol (OH at C3); T-2 toxin (OH at C3) greater than acetyl T-2 (OAc at C3); 4,15-diacetylverrucarol (H at C3) greater than 3 alpha-acetyldiacetoxyscirpenol (OAc at C3)]; at C4 position, OAc greater than OH, and isocrotonyl greater than OH [e.g., acetyl T-2 (OAc at C4) greater than iso T-2 (OH at C4); trichothecin (isocrotonoyl at C4) greater than trichothecolone (OH at C4)]; at C8 position, H greater than isovaleryl greater than OH [e.g., 3 alpha-acetyldiacetoxyscirpenol (H at C8) greater than acetyl T-2 (isovaleryl at C8); T-2 triol isovaleryl at C8) greater than T-2 tetraol (OH at C8); scirpentriol (H at C8) greater than T-2 tetraol (OH at C8)]. Among trichothecenes (without ester groups) with H and OH substituents, the toxicity was inversely related to the number of OH groups in the molecule: verrucarol (2 OHs) greater than scirpentriol (3 OHs) greater than T-2 tetraol (4 OHs). Zearalenone was about 3 times more toxic than its analogue zearalenol. The Tetrahymena cultures exposed 1 d to mycotoxins had protozoa counts/microliters inversely related to doses, and the % transmittance and pH values were directly related to doses.

Elimination of permeability mutants from selections for drug resistance in mammalian cells

Chinese hamster ovary (CHO) cells exhibit increased sensitivity to a wide variety of microtubule inhibitory drugs when verapamil is present in the growth medium. The extent of this increased sensitivity is drug specific: some drugs such as taxol and vinblastine respond greatly to the presence of verapamil, whereas other drugs such as griseofulvin respond very poorly. For the majority of drugs examined, however, a 2- to 10-fold increase in drug sensitivity is observed in the presence of verapamil at 5 micrograms/ml. The effects of verapamil are even more dramatic when drug-resistant mutant cells with a presumed alteration in membrane permeability are examined. In the presence of appropriate levels of verapamil, these mutants demonstrate a level of drug sensitivity comparable to that of the wild-type parental cells. Drug-resistant cells from similar selections but with well-defined alterations in alpha- or beta-tubulin and no evidence of alterations in membrane permeability, however, continue to exhibit increased resistance to the selecting drug even in the presence of verapamil. These studies support the conclusion that verapamil affects the membrane permeability to or transport of a wide variety of hydrophobic drugs. In addition, we have used this information to devise selections that virtually eliminate the isolation of drug-resistant permeability mutants. This methodology should be generally applicable to genetic studies of drug action that are complicated by the isolation of large numbers of mutants with permeability alterations.

Griseofulvin

Griseofulvin (GF) is a mycotoxin produced by various species of Penicillium including P. griseofulvum Dierckx, P. janczewski (P. nigricans) and P. patulum. It is active against dermatophytic fungi of different species in the genera Microsporum, Trychophyton and Epidermophyton. Because of its capacity to concentrate in the keratinous layer of the epidermis and its relatively low toxicity in man, it has been extensively used in the therapy of dermatophytoses by oral administration. The biological activity of GF towards fungi is manifested as nuclear and mitotic abnormalities followed by distortions in the hyphal morphology. Mitotic segregation is also induced in fungi by GF treatment. In higher eukaryotes the cytostatic action of GF is essentially due to a mitotic arrest at late metaphase/early anaphase. The cytological effects observable both in vivo and in vitro on different plant and animal cell systems, include C-mitoses, multipolar mitoses and multinuclearity. Prolonged GF treatment in experimental animals provokes biochemical changes consisting mainly of disturbances of porphyrin metabolism, variation in the microsomal cytochrome levels and formation of Mallory bodies. In mice these alterations are followed by the development of multiple hepatomas. Evidence of tumor induction by GF has been obtained in mice and rats, but not in hamsters. GF may also act either as a promoting or a co-carcinogenic agent, depending on the circumstances of its administration. It has been found to increase the frequency of cell transformation induced by polyoma virus, but not to induce cell transformation per se. Induction of sperm abnormalities has been observed in GF-treated mice. The embryotoxic and teratogenic action of GF has been demonstrated in pregnant rats exposed during organogenesis. Genetic effects of GF have been investigated by the following tests: Salmonella/microsome mutagenicity assay, point mutations in mammalian and plant cells, DNA damage and repair, SCE, chromosome aberrations, micronuclei, dominant lethals, aneuploidy in lower and higher eukaryotes. A positive response has been obtained in the assays on numerical chromosome changes in all the systems analyzed; limited or inconclusive evidence has been obtained for SCE and structural chromosome changes. Doubled or highly polyploid sets can be detected in all types of cells during or immediately after GF treatment. A marked increase in chromosome number variation is observed at various times after withdrawal of the drug, with prevailing hyperdiploid and reduced sets in animal cells and plant cells respectively.(ABSTRACT TRUNCATED AT 400 WORDS)