bluuebunny/crossref_metadata_2025 huggingface dataset:
Preferential pericentric lesions and aneuploidy induced in mouse oocytes by the topoisomerase II inhibitor etoposide
Authors: Mailhes John B. , Marchetti Francesco , Phillips George L. , Barnhill Danny R.
Published: February 2006

Etoposide (VP‐16) is used as an antineoplastic drug in humans. It inhibits topoisomerase II (topo II) activity by forming a ternary complex (DNA‐etoposide‐topo II). This complex prevents the DNA‐strand rejoining activity of topo II, which results in DNA‐strand breaks and the formation of structural chromosome aberrations. Topo II activity is also required for removing regions of DNA catenation prior to chromosome segregation. The possibility exists that patients undergoing etoposide chemotherapy may incur genetic damage and, consequently, may be at a greater risk for developing secondary tumors and having genetically abnormal offspring. We studied the ability of etoposide for inducing both structural chromosome aberrations and aneuploidy in mouse oocytes. Different dosages of etoposide were given to female mice at various times before and after human choronic gonadotrophin injection, and ovulated oocytes were collected 17 h later. The proportions of chromatid acentric fragments and of hyperploid metaphase II oocytes were significantly higher (P < 0.01) in the etoposide groups than in concurrent controls. These results indicate that both structural and numerical aberrations can be induced without direct interaction with DNA or with the various organelles associated with chromosome segregation. Additionally, unlike other compounds (vinblastine, colchicine, benomyl, and griseofulvin) that induce both meiotic delay (ovulated metaphase I oocytes and polyploidy) and aneuploidy, etoposide did not cause meiotic delay in oocyte maturation. © 1994 Wiley‐Liss, Inc.
Changes in secondary structure of DNA of rat embryos following treatment with 1,2‐diethylhydrazine and dimethylnitrosamine in vivo
Authors: Huang Peter H. T. , Catalano Alberto
Published: February 2006

1,2‐Diethylhydrazine (DEH) and dimethylnitrosamine (DMN) are indirect acting carcinogens that require metabolic activation to exert their potency. DEH is a transplacental carcinogen and teratogen in Wistar rats when administered by i.p. injection on day 12 of gestation. DMN is embryotoxic during this period. In this study, gravid Wistar rats were injected i.v. with DEH (10, 15, or 20 mg/kg) or i.p. with DMN (10 or 30 mg/kg) and the effects on the embryos 24 hours later were observed. Controls were similarly injected with saline vehicle. The incidence of resorptions increased after treatment with 20 mg DEH/kg. DEH treatment also resulted in decreases in embryo wet weights and total DNA that were not dose dependent. Treatment with DMN did not affect embryonic wet weights and total embryonic DNA amount when compared to the saline‐treated controls. The effects of DEH and DMN on DNA synthesis in vivo were monitored by injecting [methyl‐14C]‐thymidine 1 hour prior to embryo death. DEH induced significant increases in thymidine incorporation into embryo DNA but the increases were not proportional to the doses administered. DNA synthesis was significantly decreased in embryos treated with 30 mg DMN/kg. The DNA of treated and control embryos was fractionated by benzoylated DEAE‐cellulose (BD‐cellulose) chromatography to determine differences in DNA secondary structure following treatment. BD‐cellulose chromatography separates double‐stranded DNA from DNA containing single‐stranded regions by step elution with 1 M NaCl solution and caffeine solution, respectively. Embryonic DNA was monitored by in vivo labelling with [methyl‐3H]‐thymidine on days 6 and 7 of gestation. Significant dose dependent increases in percentages of caffeine‐eluted DNA (%CE‐DNA) compared to controls were detected after treatment with 10, 15, and 20 mg DEH/kg and 10 and 30 mg DMN/kg. The relative %CE‐DNA is expressed as the ratio of %CE‐14C‐labelled DNA to %CE‐3H‐labelled DNA. Litters treated with 10, 15, and 20 mg DEH/kg had relative %CE‐DNA values significantly lower than controls. The results support the hypothesis that initiation mechanisms of transplacental carcinogenesis and teratogenesis are different. The pertinence of %CE‐DNA and relative %CE‐DNA values to the study of transplacental carcinogenesis and teratogenesis is discussed. © 1994 Wiley‐Liss, Inc.
Complementarity of genotoxic and nongenotoxic predictors of rodent carcinogenicity
Authors: Kitchin Kirk T. , Brown Janice L. , Kulkarni Arun P.
Published: February 2006

Twenty‐one chemicals carcinogenic in rodent bioassays were selected for study. The chemicals were administered by gavage in two dose levels to female Sprague‐Dawley rats. The effects of these 21 chemicals on four biochemical assays [hepatic DNA damage by alkaline elution (DD), hepatic ornithine decarboxylase activity (ODC), serum alanine aminotransferase activity (ALT), and hepatic cytochrome P‐450 content (P450)] were determined.

Available data from seven cancer predictors published by others [the Ames test (AMES), mutation in Salmonella typhimurium TA 1537 (TA 1537), structural alerts (SA), mutation in mouse lymphoma cells (MOLY), chromosomal aberrations in Chinese hamster ovary cells (ABS), sister chromatid exchange in hamster ovary cells (SCE), and the ke test (ke)] were also compiled for these 21 chemical carcinogens plus 28 carcinogens and 62 noncarcinogens already published by our laboratory. From the resulting 111 (chemicals) by 11 (individual cancer predictors) data matrix, the five operational characteristics (sensitivity, specificity, positive predictivity, negative predictivity, and concordance) of each of the 11 individual cancer predictors (four biochemical parameters of this study and seven cancer predictors of others) are presented.

Two examples of complementarity or synergy of composite cancer predictors were found. To obtain maximum concordance it was necessary to combine both genotoxic and nongenotoxic cancer predictors. The composite cancer predictor (DD or [ODC and P450] or [ODC and ALT]) had higher concordance than did any of the four individual cancer predictors from which it was constructed. Similarly, the composite cancer predictor (TA 1537 or DD or [ODC and P450] or [ODC and ALT]) had higher concordance than any of its five individual constituent cancer predictors. Complementarity or synergy has been demonstrated both (1) among genotoxic cancer predictors (DD and TA 1537) and (2) between nongenotoxic (ODC, P450, and ALT) and genotoxic cancer predictors (TA 1537 and DD). ©1993 Wiley‐Liss, Inc.

This article is a US Government work and, as suh, is in the public domain in the United States of America.
Teratogenic and reproductive studies of policosanol in the rat and rabbit
Authors: Rodríguez María D. , García Haydee
Published: February 2006

The present studies evaluated the teratogenic potential and reproductive toxicity of Policosanol, a new hypocholesterolemic drug. Policosanol was administered by oral gavage to Sprague‐Dawley rats and New Zealand White rabbits during the period of organogenesis at dosages up to 500 and 1,000 mg/kg/day, respectively. There was no evidence of teratogenicity or any other embryonal toxicity. In a fertility and reproductive study female rats were treated with Policosanol by oral gavage at dosages up to 500 mg/kg/day, 2 weeks prior to mating and throughout mating and pregnancy to day 21 of lactation. Males were given treatment 60 days before and during mating. Reproductive parameters of mothers were normal. There was no evidence that treatment affected the survival, postnatal growth, or behavior of the offspring. No maternal treatment‐related adverse side effects occurred in these studies. It is concluded that Policosanol was not teratogenic in either rats or rabbits, nor did it induce reproductive toxicity in rats. © 1994 Wiley‐Liss, Inc.
Embryotoxic effects of thalidomide derivatives in the non‐human primate Callithrix jacchus. IV. Teratogenicity of μg/kg doses of the EM12 enantiomers
Authors: Heger Wolfgang , Schmahl Hans‐Josef , Klug Stephan , Felies Annegret , Nau Heinz , Merker Hans‐Joachim , Neubert Diether
Published: February 2006

The dose‐response of the teratogenic potency of the thalidomide (Thd) derivative EM12 was evaluated in the common marmoset (Callithrix jacchus). The smallest daily dose found to be effective was 30 μg EM12/kg body wt. This is the lowest dose of a Thd derivative ever reported to induce severe skeletal abnormalities. Ten micrograms EM12/kg body wt may be considered the no‐observed‐adverse‐effect‐level (NOAEL) under the experimental conditions chosen.

The teratogenic potencies of the two EM12 enantiomers were tested at 100 μg/kg body wt, the dose which just induces an almost 100% effect in the case of the racemate. The S(−)‐EM12 was found to induce typical severe limb abnormalities such as amelia, phocomelia, and radius aplasia, and none of the exposed fetuses were devoid of skeletal defects. In contrast, only few and minor skeletal defects were observed after application of the R(+) enantiomer. Although a pronounced teratogenic potency of the R(+)‐EM12 can now largely be excluded, these low‐dose studies are not sufficient to completely rule out any teratogenic potential of this enantiomer, since racemisation to small amounts of the S(−) form may occur in vivo.

Further studies with Thd derivatives which are unable to racemise are necessary to prove the assumed complete ineffectiveness of the R(+) enantiomers. © 1994 Wiley‐Liss, Inc.
Genotoxic and embryotoxic effects of 5‐bromodeoxyuridine in the chick embryo
Authors: Novotná Božena , Hubálek František , Bednář Vladimír
Published: February 2006

Chick embryos were exposed intra‐amniotically to the thymidine analog bromodeoxyuridine (BrdU) in order to study its embryotoxic and genotoxic effects. Teratogenic effects were observed at doses of BrdU which failed to produce mitotic inhibition, clastogenic effects or any significant increase in sister chromatid exchanges. Clastogenic effects and depressed cell proliferation were observed only at high embryolethal doses. Thus, BrdU‐induced teratogenicity was independent of genotoxic effects manifested at chromosomal level. On the contrary, a significant increase of DNA single strand breaks was detected even 24 hours after the administration of teratogenic dose. BrdU incorporation in the DNA does not appear to prevent embryonic cells from mitotic proliferation. Whether the single strand breaks in DNA would ultimately lead to BrdU‐induced teratogenesis in chick embryos remained undetermined. © 1994 Wiley‐Liss, Inc.
Malformations persist after metamorphosis of Xenopus laevis tadpoles exposed to Ni2+, Co2+, or Cd2+ in FETAX assays
Authors: Plowman Marilyn C. , Grbac‐lvankovic Svetlana , Martin Jennifer , Hopfer Sidney M. , Sunderman F. William
Published: February 2006

This study was performed to determine whether malformations induced in Xenopus laevis embryos by exposures to divalent nickel, cobalt, or cadmium chlorides in FETAX assays persist after the tadpoles undergo metamorphosis to juvenile frogs. Embryos were exposed for four days to EC50 concentrations of Ni2+, Co2+, or Cd2+ under the standard conditions of FETAX assays; thereafter, the exposures were discontinued and the tadpoles were kept in aquaria through metamorphosis. Controls were treated similarly, without exposure to metals. At 13 weeks of age, surviving frogs were killed and examined for malformations. Control and metal‐exposed groups of Xenopus did not differ significantly in their median ages at metamorphosis, mean body weights, or survival at 13 weeks. Overall incidences of malformations found in Ni2+−, Co2+−, or Cd2+−exposed frogs at 13 weeks of age were 55, 40, and 51%, respectively (P <0.01 vs. 3% in controls). The malformations of metal‐exposed frogs included retinal depigmentation, diastematomyelia, scoliosis, kyphosis, phocomelia, sacro‐pelvic and hind‐limb deformities, and dysplasias of the heart, kidney, ovary, and gut. © 1994 Wiley‐Liss, Inc.
Progressive growth of rat bladder carcinomas after exposure to prolonged uracil‐induced urolithiasis
Authors: Shibata Masa‐Aki , Shirai Tomoyuki , Takahashi Satoru , Takesada Yasuko , Iwata Hiroyuki , Okumura Masanao , Fukushima Shoji
Published: February 2006

Dietary uracil at the 3% level induces urinary bladder tumors in rats through urolithiasis‐dependent mechanical irritation. In the present study, comparison of lesions induced by uracil administration over the different periods of 36 weeks (middle‐term) and up to 103 weeks (long‐term) revealed significant elevation of both incidences and multiplicity of transitional cell carcinomas (TCCs) in the long‐term group. Histopathological assessment in terms of tumor biology further demonstrated significantly higher grading on the basis of the degree of cellular and structural atypia, and greater depth of invasion in the long‐term group. Application of markers for cell proliferation activities including proliferating cell nuclear antigen (PCNA) and silver‐binding nucleolar organizer regions (AgNORs) also revealed significantly elevated AgNOR counts in the long‐term group TCC. AgNOR counts and PCNA rates in TCCs showed relation to the histological grades. Thus the present study demonstrated that prolonged uracil‐induced urolithiasis causes more biologically aggressive bladder carcinomas with invasive potential. Continuous stimulation of cell proliferation presumably has the potential to facilitate multiple genetic alterations leading to development of more malignant carcinomas. However, it should be borne in mind that the difference in bladder cancer development might also be related to the fact that the animals survived longer and that the early lesions therefore had more time to progress to more advanced stages. © 1994 Wiley‐Liss, Inc.
Lack of promoting effect of proline on bile duct cancer development in dimethylnitrosamine‐initiated hamster livers
Authors: Thamavit Witaya , Pairojkul Chawalit , Tiwawech Danai , Shirai Tomoyuki , Ito Nobuyuki
Published: February 2006

Bile duct hyperplasia caused by proline is believed to represent a chemical effect of the liver fluke, Fasciola hepatica, and the resultant cell division might be expected to play a role as a tumor promoter. To investigate the potential promoting effect of proline on bile duct cancer development, Syrian hamsters were therefore divided into 8 treatment groups: dimethylnitrosamine (DMN) + proline intraperitoneally (i.p.); DMN + proline s.c.; DMN + saline i.p.; DMN + saline s.c.; proline i.p.; proline s.c.; saline i.p.; and saline s.c. DMN was injected i.p. at 20 mg/kg to the animals 2 weeks prior to commencement of proline treatment, whereby 1 ml of a 2 M solution was given by i.p. or s.c. injection 3 times a week for 20 weeks. At the end of week 42, assessment of preneoplastic lesion development did not reveal any significant modulating influence of proline on DMN‐initiated lesion development nor did it itself cause persistent bile duct hyperplasia. © 1994 Wiley‐Liss, Inc.
Impact of higher doses of vitamin C in modulating pesticide genotoxicity
Authors: Khan Parimal Kumar , Sinha S. P.
Published: February 2006

The modulatory effect of higher doses of vitamin C (ascorbic acid) on the genotoxicity of the three pesticides (endosulfan, phosphamidon, and mancozeb) was assessed in the in vivo micronucleus test in Swiss albino mice. Concurrent administration of the vitamin in a dose (20 mg/kg bwt/day) equivalent to double the human therapeutic one, along with each of the three pesticides, was most effective as an antimutagen. The therapeutic dose (10 mg/kg bwt/day) was comparatively less so, and the quadruple (40 mg/kg bwt/day) of it did not show any further amelioration. © 1994 Wiley‐Liss, Inc.
Comparison of DNA adduct levels in human placenta from polychlorinated biphenyl exposed women and smokers in which CYP 1A1 levels are similarly elevated
Authors: Gallagher Jane E. , Everson Richard B. , Lewtas Joellen , George Michael , Lucier George W.
Published: February 2006

Previous studies demonstrated that cigarette smoking is associated with high elevations in levels of both cytochrome P450 1A1 (CYP 1A1) and DNA adducts in human placenta. To date, the identity of the smoking related DNA adducts is not known. The DNA adducts identified in placenta of smokers could result from chemicals present in cigarette smoke, substances formed by CYP 1A1 metabolic activation of endogenous compounds, non‐cigarette related exposures or a combination of these processes. Exposure to contaminated rice oil containing large doses of polychlorinated biphenyls (PCBs) and polychlorinated dibenzofurans (PCDFs) also resulted in massive elevation of CYP 1A1 in human placenta but formation of DNA adducts directly from this exposure has not previously been reported. The purpose for comparing the two populations was to test the hypothesis that if CYP 1A1 induction results in the metabolic activation of endogenous compounds, then DNA adducts should also be present in PCB/PCDF exposed tissues exhibiting high CYP 1A1 activity and some of the adducts detected in the placental DNA from smokers may be identified as those derived from the metabolic activation of endogenous compounds. To test this hypothesis, we measured DNA adducts using 32P‐postlabeling to analyze placental DNA from women exposed to PCB/PCDF and from cigarette smokers where levels of CYP 1A1 were similarly elevated. There was no evidence of DNA adducts among specimens obtained from PCB/PCDF exposed individuals. These data suggest that CYP 1A1 induction alone (in the absence of cigarette smoking) does not induce the formation of DNA adducts detectable by this approach, and that smoking related adducts are not a consequence of CYP 1A1 induction mediated activation of endogenous compounds or xenobiotics other than cigarette smoke. ©1993 Wiley‐Liss, Inc.

This Article is a US Government work and, as such, is in the public domain in the United States of America.
In utero exposure to caffeine causes delayed neural tube closure in rat embryos
Authors: Wilkinson Jenny M. , Pollard Irina
Published: February 2006

We have investigated the effect of caffeine on embryo growth and development. Caffeine (25 mg/kg) was administered on gestation day (g.d.) 8–9 and the embryos examined histologically 24 h after the final dose. The crown‐rump length of caffeine treated embryos (1.92 ± 0.08 mm) was significantly smaller (P<0.001) than the controls (2.91 ± 0.26 mm) as was the circumferential length (caffeine vs. controls, 3.79 ± 0.16 mm vs. 6.03 ± 0.61 mm;P<0.001). Additional measures, such as development of the heart, eye, and limb buds, were also reduced in the caffeine treated embryos. The most striking difference between the control and caffeine treated embryos was the larger proportion of treated embryos with regions of open neural tube. This was most marked in the caudal region of the embryos where 91% of treated embryos had regions of open neural tube compared with 14% of controls. The amount of open neural tube in any individual caffeine treated embryo did not relate to the crown‐rump or circumferential length of that embryo nor was the effect restricted to particular litters. These results indicate that caffeine had a significant effects on embryonic growth and development. © 1994 Wiley‐Liss, Inc.
Electromagnetic fields and brain tumours: A commentary
Authors: Hughes J. T.
Published: February 2006

Brain tumours are of different cell types, the commonest being tumours of glia called gliomas. Many etiological factors of gliomas have been suggested and certain industries have been implicated. Several epidemiological studies have linked electromagnetic fields (EMFs) to gliomas. Health effects of EMFs have been studied, both in humans and in experimental animals, mainly with negative findings. Positive experimental evidence linking EMFs to tumours is the effect of EMFs on melatonin production by the pineal gland. Removal of the pineal gland in rats increases the incidence of tumours. Further epidemiological and experimental evidence is required to elucidate this possible link between EMFs and brain tumours. © 1994 Wiley‐Liss, Inc.
Carcinogenicity of policosanol in sprague dawley rats: A 24 month study
Authors: Alemán Celia Luz , Ferreiro Rosa Más , Puig Miriam Noa , Guerra Idania Rodeiro , Ortega Caridad Hernández , Capote Amelia
Published: February 2006

The effects of policosanol (50–500 mg/kg) administered orally for 24 months to Sprague Dawley rats of both sexes were investigated. No differences related to daily clinical observations, weight gain, food consumption, or mortality (survival analysis) between groups were found. Histopathological study showed that the frequency of the occurrence of non‐neoplastic and neoplastic (benign and malignant) lesions was similar in the control and policosanol‐treated groups. The lesions observed in this study were similar to the spontaneous lesions reported in this species in previous studies. Since no drug‐related increase in the occurrence of malignant or benign neoplasms was found, nor acceleration in tumors growth in any specific group was observed, this study shows no evidence of policosanol induced carcinogenicity in this strain of rats. © 1994 Wiley‐Liss, Inc.
Human carcinogenic risk assessment based on hormonal effects in a carcinogenicity study in rats with the antifungal agent, fluconazole
Authors: Paulus G. , Longeart L. , Monro A. M.
Published: February 2006

Fluconazole is an orally active bis‐triazole antifungal agent that acts by selective inhibition of lanosterol 14α‐demethylase, a key enzyme for maintenance of the fungal cell wall. It is not genotoxic. In a 2 year carcinogenicity study in Sprague‐Dawley rats, fluconazole decreased mammary fibroadenomas in females and adrenal pheochromocytomas in males, and increased hepatic adenomas in males. The pattern of these changes is explicable in terms of a hormonal imbalance, corroborated in other studies with fluconazole in rats by changes in the weights of hormone‐sensitive organs and circulating levels of 17β‐estradiol. The decreases in mammary tumors are probably a consequence of aromatase inhibition by fluconazole at high dose levels. The tumor effects observed in this study are extremely unlikely to be of relevance to humans, since the hormone effects observed in this study do not occur in humans treated with therapeutic dose levels of fluconazole. This study illustrates the importance of seeking a mechanistic interpretation of rodent tumor findings, which may then be assessed for its relevance to the clinical use of a drug. © 1994 Wiley‐Liss, Inc.
Role of protein kinase C in the regulation of gap junctional communication
Authors: Budunova Irina V. , Mittelman Leonid A. , Miloszewska Joanna
Published: February 2006

We have examined the effect of protein kinase (PKC) depletion in SV40‐transformed Djungarian hamster fibroblasts (DM15 cells) on the level of gap junction permeability, C×43 electrophoretic mobility, and cell sensitivity to different uncoupling stimuli. After 24 hr exposure to 12‐O‐tetradecanoyl‐phorbol‐13‐acetate (TPA), the total PKC activity in DM15 cells was reduced to 20–25% in comparison with intact cells. In PKC‐depleted cells the level of dye coupling was 30–40% higher than in the same untreated cultures. Western blot analysis revealed multiple forms of the gap junction protein connexin 43, which correspond to known phosphorylated and dephosphorylated forms of this protein. No decrease in the level of connexin 43 phosphorylation after PKC depletion was observed. TPA (10−7 g/ml), mezerein (10−7 g/ml), teleocidin (10−8 g/ml), Ca‐ionophore A23187 (10−6 g/ml), insecticide 1,1,1‐trichloro‐2,2‐bis‐(p‐chlorphenyl)‐ethane (DDT) (10−4 g/ml), and nigericin (10−5 M in hydrolysate lactalbumin solution, pH 6.3) induced a four‐to six‐fold decrease in the number of recipient cells in the dye‐coupling assay. PKC‐depleted cells became almost completely resistant to the uncoupling effect of mezerein, teleocidin, and A23187, as well as to new exposure to TPA, and became partially resistant to the effect of DDT. Nigericin inhibited intercellular communication between PKC‐depleted cells to the same extent as between control cells. Thus, in the cell system studied, PKC plays a certain role in maintaining the basal level of gap junction permeability and has an important significance as a mediator of the uncoupling effects of such substances as TPA, mezerein, teleocidin, and Ca2+. © 1994 Wiley‐Liss, Inc.
Differences in teratogenic and toxic properties of alcohol dehydrogenase inhibitors pyrazole and 4‐methylpyrazole in Drosophila melanogaster: I. ADH allozymes in variable genetic backgrounds
Authors: Eisses Karel Th.
Published: February 2006

Pyrazole and 4‐methylpyrazole (4‐MP) are effective inhibitors of alcohol dehydrogenase (ADH) activity in mammals both in vivo and in vitro. 4‐MP has a tenfold higher inhibition specificity compared with pyrazole. Pyrazole proved a teratogenic compound in Drosophila melanogaster. Treatment of third instar larvae of D. melanogaster with pyrazole, in contrast with 4‐MP, produced an increase in the number of dorsocentral and scutellar macrochaetae and wing‐notches in the adult fly. A large difference in the penetrance of terata in males and females was observed. Similar effects were observed in flies lacking ADH molecules. The teratogenicity of pyrazole must be due to disturbance of processes other than ADH inhibition. Synergistic effects were observed between pyrazole and methoxyacetic acid (MAA), an in vitro inhibitor of sarcosine dehydrogenase activity. Each of these compounds, when fed to early third instar larvae, produced terata resembling the Notch mutant of D. melanogaster. © 1995 Wiley‐Liss, Inc.
Chemical skin carcinogenesis is prevented in mice by the induced expression of a TGF‐β related transgene
Authors: Blessing Manfred , Nanney Lillian B. , King Lloyd E. , Hogan Brigid L. M.
Published: February 2006

Skin papillomas and squamous cell carcinomas (SCCs) are induced in mice by tumor initiation with a carcinogen followed by tumor promotion with the phorbol ester 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). These usually arise from preneoplastic lesions characterized by epidermal proliferation and hyperplasia, dermal edema, and inflammation. To evaluate the role of polypeptide growth factors in chemically induced skin carcinogenesis, we used transgenic mice carrying the cDNA for a TGF‐β related molecule, bone morphogenetic protein‐4 (BMP‐4), under the control of the regulatory elements of the cytokeratin IV* gene in a skin carcinogenesis protocol.

Control non‐transgenic littermates and BMP‐4 transgenic mice were treated with a single dose of a carcinogen, N‐methyl‐N′‐nitrosoguanidine (MNNG), and biweekly with the tumor promoter TPA for 9 months. In control littermates TPA induced epidermal hyperproliferation, atypia with “dark” cells, and dermal inflammation, resulting in papillomas and SCCs in 13 of 26 animals tested. In BMP‐4 transgenic mice, TPA treatment induced the expression of the BMP‐4 transgene in interfollicular epidermis but only minimal epidermal thickening, hyperproliferation, and inflammation were noted after the initial dose of TPA. Furthermore, the mitotic indices in transgenic epidermis after 9 months of TPA treatment were significantly lower than the corresponding indices from untreated transgenic epidermis. Consequently, none of the 22 transgenic animals tested developed papillomas or SCCs. In conclusion, we have shown that the TPA induced expression of the BMP‐4 transgene blocks proliferation and inflammation in skin, steps that are critical to the subsequent formation of papillomas and SCCs and we characterized an inducible promotersystem which expresses polypeptides in interfollicular epidermis after exogenous stimulation. © 1995 Wiley‐Liss, Inc.
Periconceptional zinc deficiency affects uterine 3H‐estradiol binding in mice
Authors: Peters Jeffrey M. , Wiley Lynn M. , Zidenberg‐Cherr Sheri , Keen Carl L.
Published: February 2006

To better define the mechanisms by which zinc (Zn) deficiency influences periconceptional development, we examined the effects of this developmental insult on uterine estrogen metabolism. CD‐1 mice were assigned to 1 of 3 groups (Low Zn, LZ; Control, C; or Replete, R) and fed either a low Zn (⩽0.3 μg Zn/g) or control diet (47 μg Zn/g) 5 days prior to gestation day (GD) 0 and continuing up to GD 4 during early pregnancy. Mice in the R group were fed the low Zn diet until GD 1 after which they were fed the control diet. Uterine 3H‐estradiol binding in vivo was measured on GD 2, GD 3, and GD 4. Binding was similar among groups on GD 2 and GD 3, but was lower on GD 4 in LZ mice than in C and R mice (61% of control value). On GD 4, uterine 3H‐estradiol binding in vitro was measured and was lower in LZ mice than in C and R mice (63‐‐74% of control values); the reduction in binding was due to lower receptor number. Thus, Zn deficiency can result in a reduction in uterine estradiol receptors and estradiol binding. © 1995 Wiley‐Liss, Inc.
Novel electrophoretic protocol for collection of mutations in the lambda light chain immunoglobulin gene in a human B‐lymphoblastoid cell strain
Authors: McFarland Richard David , Smith Gary Joseph
Published: February 2006

Spontaneous and chemically induced mutation was examined in the lamba light chain immunoglobulin gene in a human B‐lymphoblastoid cell strain (T5‐1). The hemizygous lambda gene is a unique mutational target gene which codes for a protein that is both expressed on the cell membrane and secreted. Mutations in the lambda gene were detected by analysis of western blots of isoelectric focusing gel electrophoresis of T5‐1 cell conditioned culture medium. None of 5,841 individual clones established from vehicle‐exposed populations had detectable variations in the isoelectric banding pattern of the constitutively secreted lambda immunoglobulin protein. In contrast, 113 of 6,128 clonal populations established from N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG)‐exposed populations exhibited stable variations in expression of the lambda immunoglobulin: isoelectric variants (n = 3) and nonsecretors (n = 110). MNNG‐induced mutations in the lambda gene, which resulted in lambda immunoglobulin proteins with altered isoelectric points (pIs), occurred at a frequency of no less than 4.9 × 10−4 mutations/cell, indicating the mature rearranged lambda immunoglobulin gene is comparably sensitive to carcinogen induced mutation as other human autosomal target genes. Approximately one‐half of the MNNG‐induced non‐secretor mutant clones lacked lambda mRNA while one‐half maintained constitutive transcription and expression of the lambda immunoglobulin on the cell surface, demonstrating that carcinogen damage interdicted gene function at multiple points. © 1995 Wiley‐Liss, Inc.
Suppressing effect of WR‐2721 on micronuclei induced by cyclophosphamide in mice
Authors: Czyzewska Agnieszka , Mazur Lidia
Published: February 2006

The effect of WR‐2721 against cyclophosphamide‐induced clastogenicity was studied using the in vivo micronucleus assay. The frequency of micronuclei in polychromatic erythrocytes in the peripheral blood of mice treated with WR‐2721 and cyclophosphamide (CP), each of the compounds at a dose of 200 mg/kg body weight, was evaluated during the 15‐day period. The suppressing effect of WR‐2721, given 30 min prior to cyclophosphamide administration, on micronuclei induced by the alkylating agent was demonstrated. The number of micronuclei was increased on day 1 after CP application and declined thereafter with the frequency of micronucleated polychromatic erythrocytes remaining lower in WR‐2721 pre‐treated mice. The modulatory effect of WR‐2721 on the clastogenic activity of cyclophosphamide in the erythropoietic system by the mouse micronucleus test was shown. © 1995 Wiley‐Liss, Inc.
Interactive effects of alcohol and diabetes during pregnancy on the rat fetus
Authors: Lin Yi , Lee Melvin , Leichter Joseph
Published: February 2006

To determine the effect of maternal diabetes and alcohol intake, separately and in combination, on fetal growth and development, pregnant rats were divided into four groups: diabetic (D), diabetic plus alcohol (DA), control (C), and control plus alcohol (CA). Diabetes was induced by administration of streptozotocin before mating and alcohol was administered by gavage (2 g/kg body weight/day) on days 6‐‐11 of gestation. Both diabetic groups (D and DA) had significantly lower weight gain during pregnancy compared to the controls (C and CA), despite the fact that the former consumed more food and water. Alcohol treatment resulted in reduced water and food intake and lower weight gain in the diabetic rats (DA), but not in the non‐diabetic rats (CA), compared to their respective controls (D and C). On day 21 of gestation fetal body weights were significantly less and placental weights were significantly greater in the diabetic groups (D and DA) compared with the non‐diabetic groups (C and CA). Differences in fetal and placental weights between rats exposed and not exposed to alcohol (C vs. CA and D vs. DA) were not significant. The number of fetuses with external malformations was significantly greater in the litters of alcohol exposed diabetic (DA) than non‐alcohol exposed (D) animals. No external or skeletal malformations were observed in fetuses of non‐diabetic rats regardless of whether or not they received alcohol (C or CA). The skeletal development of fetuses of diabetic rats, judged by the number and size of ossification centers on day 21 of gestation, was retarded when compared with fetuses of non‐diabetic rats. Alcohol further retarded skeletal development of fetuses of diabetic animals (DA vs. D), but not of fetuses of non‐diabetic rats (CA vs. C). It is concluded that maternal alcohol administration potentiates the effects of maternal diabetes on the incidence of fetal malformations and the retardation of skeletal development. © 1995 Wiley‐Liss, Inc.
Embryotoxicity induced by alkylating agents: 10. Analysis of the combined teratogenic effects of methylnitrosourea and ethylmethanesulfonate in mice
Authors: Platzek Thomas , Bochert Gerd
Published: February 2006

In previous studies the direct‐acting alkylating model compounds methylnitrosourea (MNU) and ethylmethanesulfonate (EMS) were investigated with regard to dose‐response of teratogenicity as well as DNA adduct formation in mice. In this study the teratogenic effects induced by combined treatment with these substances were analyzed using doses which, following single treatment with either substance, were around the threshold level, i.e., no adverse effect level (NOAEL) and lowest observed adverse effect level (LAOEL).

Combined treatment of LAOELs resulted in a threshold‐like response, while the combination of the NOAEL of one substance with the LAOEL of the other increased the response rate dramatically to nearly 100%.

This phenomenon was further evaluated using biometrical methods. The dose‐response surface as well as isobolograms were calculated in order to describe the combination effect. In addition, a dose‐response model was fitted to the data. In conclusion, the initially surprising high combination effect revealed to be not so extraordinary when considering the steepness of the dose‐response relationships of the single substances. © 1995 Wiley‐Liss, Inc.
Lack of promoting activity of four pesticides on induction of preneoplastic liver cell foci in rats
Authors: Kato T. , Ogiso T. , Kato K. , Sano M. , Hasegawa R. , Shirai T. , Ito N.
Published: February 2006

Four pesticides were examined for hepatopromoting activity using a medium‐term bioassay based upon induction of glutathione S‐transferase placental form (GST‐P) positive foci in the rat liver. Male F344 rats were initially injected with diethylnitrosamine (DEN; 200 mg/kg body weight) intraperitoneally and 2 weeks later were treated with O‐ethyl O‐4‐nitrophenyl phenylphosphonothioate (EPN; 75 and 150 ppm), diazinon (500 and 1,000 ppm), phenthoate (500 and 1,000 ppm), or iprobenfos (500 and 1,000 ppm) in the diet for 6 weeks and then killed, all rats being subjected to partial hepatectomy at week 3. All of the pesticides gave negative results, the numbers and areas of GST‐P positive foci not exceeding the control values for animals given DEN alone. Indeed, a significant reduction of foci development was seen for EPN (75 ppm). These findings provide experimental evidence that the presently examined four pesticides do not have hepatocarcinogenic potential in rats © 1996 Wiley‐Liss, Inc.
Lack of carcinogenicity of daminozide, alone or in combination with its contaminant 1,1‐dimethylhydrazine, in a medium‐term bioassay
Authors: Cabral R. , Hakoi K. , Hoshiya T. , Hasegawa R. , Ito N.
Published: February 2006

The carcinogenicity of daminozide (succinic acid‐2,2‐dimethylhydrazide; Alar), a plant growth regulator used primarily in apple orchards, has been the subject of recent investigations by several national and international organizations because of contradictory study results. The aim of the present study was to assess the carcinogenicity of daminozide alone and in combination with 1,1‐dimethylhydrazine (UDMH), its major contaminant, in a novel medium‐term bioassay in Fischer 344 rats, the DEN‐PH model. Rats were given diethylnitrosamine (DEN) at 200 mg/kg body weight intraperitoneally and then 2 weeks later were given daminozide at 20,000 ppm or daminozide plus UDMH at 75, 150, or 300 ppm in the diet for 6 weeks and were then killed; all rats underwent a partial (two‐thirds) hepatectomy (PH) at week 3. Hepatocarcinogenic potential was assessed by comparing the number and area of preneoplastic foci positive for the glutathione S‐transferase placental form (GST‐P+) in the liver of treated rats, with those in controls given DEN alone. Daminozide, UDMH, and the combination were not carcinogenic in this model. This novel medium‐term bioassay for carcinogenicity is considered to be practical for the rapid evaluation of both agrochemical formulations and contaminants found in agrochemicals and other compounds. © 1996 Wiley‐Liss, Inc.
Sequencing the yeast genome: An international achievement
Authors: Levy J.
Published: February 2006

The yeast genome is currently being sequenced by a Consortium of European laboratories, in collaboration with a wider international network of researchers. It is expected that within the next two years Saccharomyces cerevisiae will become the first eukaryotic organism to have been completely genetically mapped and sequenced. This article traces the sequencing enterprise from its beginnings, outlining the intentions, the organisation, and the achievements so far. The tasks which remain are discussed, emphasising the follow‐on research into the evolution of primitive karyotypes, and, more particularly, into the nature of novel genes revealed during sequencing. The functional analysis of novel genes is attracting an ever wider community of yeast scientists, so that research which began with a decision to sequence a simple genome promises to remain a focus for international cooperation.
New heterologous modules for classical or PCR‐based gene disruptions in Saccharomyces cerevisiae
Authors: Wach Achim , Brachat Arndt , Pöhlmann Rainer , Philippsen Peter
Published: February 2006

We have constructed and tested a dominant resistance module, for selection of S. cerevisiae transformants, which entirely consists of heterologous DNA. This kanMX module contains the known kanr open reading‐frame of the E. coli transposon Tn903 fused to transcriptional and translational control sequences of the TEF gene of the filamentous fungus Ashbya gossypii. This hybrid module permits efficient selection of transformants resistant against geneticin (G418). We also constructed a lacZMT reporter module in which the open reading‐frame of the E. coli lacZ gene (lacking the first 9 codons) is fused at its 3′ end to the S. cerevisiae ADH1 terminator. KanMX and the lacZMT module, or both modules together, were cloned in the center of a new multiple cloning sequence comprising 18 unique restriction sites flanked by Not I sites. Using the double module for constructions of in‐frame substitutions of genes, only one transformation experiment is necessary to test the activity of the promotor and to search for phenotypes due to inactivation of this gene. To allow for repeated use of the G418 selection some kanMX modules are flanked by 470 bp direct repeats, promoting in vivo excision with frequencies of 10–3–10–4. The 1·4 kb kanMX module was also shown to be very useful for PCR based gene disruptions. In an experiment in which a gene disruption was done with DNA molecules carrying PCR‐added terminal sequences of only 35 bases homology to each target site, all twelve tested geneticin‐resistant colonies carried the correctly integrated kanMX module.
Stability of solitary waves for derivative nonlinear Schrödinger equation
Authors: Ohta Masahito , Colin Mathieu
Published: February 2006

This paper is concerned with the so-called Derivative Nonlinear Schrödinger equation. This equation is known to have a two-parameter family of solitary waves solutions. We prove orbital stability of these particular solutions for the whole range of parameters values by using variational methods.

Cet article concerne l'équation de Schrödinger Non Linéaire Dérivée. Cette équation possède une famille d'ondes solitaires dépendantes de deux paramètres. Nous prouvons la stabilité orbitale de ces solutions particulières pour toutes les valeurs des paramètres en utilisant des méthodes variationnelles.
The Cauchy problem for the Gross–Pitaevskii equation
Authors: Gérard P.
Published: February 2006

We prove global wellposedness of the two-dimensional and three-dimensional Gross–Pitaevskii equations in the natural energy space.

On établit que le problème de Cauchy pour l'équation de Gross–Pitaevskii est bien posé dans l'espace d'énergie naturel, en dimensions deux et trois.
Zoledronic acid is synergic with vinblastine to induce apoptosis in a multidrug resistance protein‐1 dependent way: An in vitro study*
Authors: Yildiz Mustafa , Celik‐Ozenci Ciler , Akan Selma , Akan Ilhan , Sati Leyla , Demir Ramazan , Savas Burhan , Ozben Tomris , Samur Mustafa , Ozdogan Mustafa , Artac Mehmet , Bozcuk Hakan
Published: February 2006

We have explored the action of zoledronic acid, which has an apoptotic effect and is used as an agent for treating skeletal metastases and osteoporosis, in the presence of vinblastine, and whether this effect is associated with MRP‐1 (multidrug resistance protein‐1) expression. HEK (human embryonic kidney) 293 cells were transfected to form the multidrug resistant cell line designated 293MRP (MRP‐1 expressing HEK293 cells). Both lines were treated with varying concentrations of vinblastine and zoledronic acid. Apoptosis was determined by the TUNEL (deoxyuridine triphosphate nick end‐labeling) method.

The type of treatment, MRP‐1 expression status, and the type of treatment with respect to MRP‐1 expression status significantly affected (P < 0.001) the degree of apoptosis. The largest increase in cytotoxicity was noted in HEK293 cells, when 100 μmol zoledronic acid was added to 4 μg/ml vinblastine (an increment of 80.3%, P < 0.001). This preliminary work shows that zoledronic acid acts synergistically with vinblastine to induce apoptosis in an MRP‐1 dependent way.
Being a parent of the adolescent with complex chronic pain: An interpretative phenomenological analysis
Authors: Jordan Abbie L. , Eccleston Christopher , Osborn Mike
Published: February 2006

BackgroundPrevious quantitative research has shown that parents of adolescents with chronic pain report elevated levels of emotional distress in addition to limitations in social and family functioning.

BackgroundThis study aimed to further explore this parental impact by employing qualitative methodology to investigate parental experiences of caring for an adolescent with chronic pain.

BackgroundA sample of 17 parents/carers of adolescents with chronic pain was selected from two UK tertiary clinic sites. Participants were 11 mothers, five fathers, and one grandmother (primary caregiver). Four focus groups with parents/carers were conducted to discuss the impact of caring for an adolescent with chronic pain on the parent/carer. Transcripts were analysed using interpretative phenomenological analysis (IPA).

BackgroundData analysis revealed two superordinate themes that captured the extensive, and largely negative, impact of being a parent of an adolescent with chronic pain. These themes were labelled ‘struggle for control and coherence’ and ‘a very different life’. Both themes represent a fundamental parental struggle to adapt to a life very different than expected, a life fraught with uncertainty, fear, distress and loss.

BackgroundParents who are unable to achieve the relief of their adolescent's chronic pain and suffering report significant personal distress that is exemplified by the repetitive search for legitimacy of their child's pain in ‘diagnosis'. In the absence of diagnosis parents reported an unwelcome suspension in an unusual pattern of parenting, resembling the infant phase of parenting.
A two component chitin‐binding protein from French bean – association of a proline‐rich protein with a cysteine‐rich polypeptide
Authors: Bindschedler Laurence V. , Whitelegge Julian P. , Millar David J. , Bolwell G. Paul
Published: February 2006

A 42 kDa chitin‐binding proline‐rich protein (PRP) from French bean has been previously characterised through its involvement in plant–pathogen interactions. It is located at the plasmalemma‐wall interface, intercellular spaces and binds to the pathogen Colletotrichum lindemuthianum in vitro and in planta. It is also present in cell wall appositions formed in response to an hrp mutant of Xanthomonas campestris. We now show that the 42 kDa protein is composed of two components, a 25 kDa polypeptide member of the PRP family of legumes and a 6.8 kDa cysteine‐rich peptide with high similarity to snakin‐2 from potato. Snakins bind to pathogens and are antimicrobial. Molecular cloning of the longest PRP corresponding to the N‐terminal sequence of the purified protein and the 6.8 kDa component is reported. The cognate mRNAs show coordinate expression. The two‐component protein complex has already been shown to be involved in binding and immobilising pathogens through oxidative cross‐linking of the PRP components but could also function as a two‐component chitin‐receptor involved in plant–pathogen interactions through antimicrobial activity and/or signalling.
Extracellular superoxide dismutase exists as an octamer
Authors: Due Anne V. , Petersen Steen V. , Valnickova Zuzana , Østergaard Louise , Oury Tim D. , Crapo James D. , Enghild Jan J.
Published: February 2006

Human extracellular superoxide dismutase (EC‐SOD) is involved in the defence against oxidative stress induced by the superoxide radical. The protein is a homotetramer stabilised by hydrophobic interactions within the N‐terminal region. During the purification of EC‐SOD from human aorta, we noticed that material with high affinity for heparin–Sepharose formed not only a tetramer but also an octamer. Analysis of the thermodynamic stability of the octamer suggested that the C‐terminal region is involved in formation of the quaternary structure. In addition, we show that the octamer is composed of both aEC‐SOD and iEC‐SOD folding variants. The presence of the EC‐SOD octamer with high affinity may represent a way to influence the local concentration of EC‐SOD to protect tissues specifically sensitive to oxidative damage.
A unique biotin carboxyl carrier protein in archaeon Sulfolobus tokodaii
Authors: Li Yan-Qiu , Sueda Shinji , Kondo Hiroki , Kawarabayasi Yutaka
Published: February 2006

Biotin carboxyl carrier protein (BCCP) is one subunit or domain of biotin‐dependent enzymes. BCCP becomes an active substrate for carboxylation and carboxyl transfer, after biotinylation of its canonical lysine residue by biotin protein ligase (BPL). BCCP carries a characteristic local sequence surrounding the canonical lysine residue, typically ‐M‐K‐M‐. Archaeon Sulfolobus tokodaii is unique in that its BCCP has serine replaced for the methionine C‐terminal to the lysine. This BCCP is biotinylated by its own BPL, but not by Escherichia coli BPL. Likewise, E. coli BCCP is not biotinylated by S. tokodaii BPL, indicating that the substrate specificity is different between the two organisms.