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)