bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of reproductive tract glutathione enhancement and depletion on ethyl methanesulfonate‐induced dominant lethal mutations in Sprague‐Dawley rats
Authors: Gandy J. , Bates H. K. , Conder L. A. , Harbison R. D.
Published: February 2006

The effects of altering glutathione (GSH) levels in the male reproductive tract have been studied in an attempt to establish a link between chemical‐induced perturbations in glutathione and susceptibility of spermatozoa to chemical insult. Tissue GSH levels were enhanced by a treatment regimen of N‐acetylcysteine (NAC) (250 mg/kg, 4 treatments at 2 h intervals). With this treatment, GSH levels in liver, testis, caput epididymis, and cauda epididymis were elevated to 126%, 110%, 178%, and 136% of control values. Sexually mature male rats were then treated with NAC and challenged with a dose of EMS (100 mg/kg) to determine if enhanced tissue GSH would protect against EMS‐in‐duced dominant lethal mutations. Pretreatment with NAC significantly decreased the post‐implantation loss from 7.05 ± 0.57 with EMS alone to 5.28 ± 0.47. Conversely, a dominant lethal assay was conducted using different doses of phorone pretreatment to determine the relative contribution of hepatic versus reproductive tract GSH in protecting against EMS‐induced dominant lethal resorptions. Doses of 100 mg/kg and 250 mg/kg phorone significantly lowered both hepatic and reproductive tract GSH while 25 mg/kg lowered only hepatic GSH. These three dose levels were used as pretreatments in a dominant lethal study followed by a challenge administration of EMS (50 mg/kg), which is a threshold dose of EMS for producing dominant lethal mutations. Comparison against controls demonstrated a significant potentiation of fetal resorptions in all groups receiving phorone pretreatment, including the 25 mg/kg pretreatment group which only lowered hepatic GSH prior to EMS challenge. The results of these experiments indicate that GHS reserve in the male reproductive tract are insufficient to protect developing spermatozoa from damage by alkylating agents in the absence of hepatic GSH. © 1992 Wiley‐Liss, Inc.
Lack of synergism among DMAB, BOP, and MNU in induction of carcinomas of the rat ventral prostate
Authors: Shirai Tomoyuki , Yamamoto Atsushi , Imaida Katsumi , Tamano Seiko , Mori Toshio , Hasegawa Ryohei
Published: February 2006

The present experiment was undertaken to investigate possible synergism in induction of rat prostate tumor. F344 rats were repeatedly administered the prostate carcinogens 3,2′ ‐dimethyl‐4‐aminobiphenyl (DMAB), N‐nitrosobis(2‐oxopropyl)amine(BOP), and N‐methylnitrosourea (MNU) sequentially or together at times of hormonal castration induced regenerative cell proliferation of prostate epithelial cells. Group 1 animals received two 100 mg/kg doses of DMAB, two 20 mg/kg applications of BOP, and two times 15 mg/kg of MNU. Groups 2,3, and 4, respectively, received each of the carcinogen treatment alone. Group 5 was given 6 applications of all three in combination, each at one‐third the dose administered to the other groups. The results showed a clear synergism in enhanced tumor development in the colon but not in the prostate, in which the incidence of lesions induced by the three carcinogens was similar to that with DMAB alone. © 1992 Wiley‐Liss, Inc.
Identification of kinetochores and DNA synthesis in micronuclei induced by mitomycin C and colchicine in chinese hamster ovary cells
Authors: Majone Franca , Tonetto Sabina , Soligo Carla , Panozzo Marina
Published: February 2006

The presence of kinetochore and DNA synthesis in micronuclei (MN) induced in Chinese hamster ovary (CHO) cells by clastogenic and aneuploidogenic substances such as mitomycin C (MMC) and colchicine was determined by immunofluorescence technique using CREST antikinetochore antibodies and anti‐bromodeoxyuridine (BrdUrd) antibodies. A cytofluorimetric analysis was also performed. Colchicine significantly increased micronucleated cells at least up to 96 h from the end of treatment. As expected, among colchicine‐induced micronucleated cells the majority contained at least one CREST + MN. MMC induced a significant increase in micronucleated cells up to 120 h from the end of treatment and the great majority of MN lacked kinetochore fluorescence, indicating that MMC‐induced MN were derived from acentric fragments. However, colchicine and MMC at 48 and 72 h from the end of treatment induced a significant increase of CREST— and CREST + MN, respectively, suggesting an induction of clastogenicity by colchicine and aneuploidy by MMC. The clastogenic effect of colchicine after 48 h was also confirmed by the presence of chromatid fragments in metaphase cells. A cytofluorimetric analysis indicated that, as aspected, colchicine and MMC interfere with the G2/M and S phases, respectively; however, a slight interference of colchicine with the S phase was also observed. DNA synthesis was present in MN and it was in most cases synchronous with synthesis in the main nucleus. The frequency of cells with MN in S phase observed in untreated or MMC‐treated cells is in agreement with the proportion of cells without MN showing DNA synthesis. On the contrary, the frequency of cells with MN in S phase observed in colchicine‐treated cells was significantly lower than that observed in control and MMC‐treated cells. © 1992 Wiley‐Liss, Inc.
Influence of periconceptional zinc deficiency on embryonic plasma membrane function in mice
Authors: Peters Jeffrey M. , Wiley Lynn M. , Zidenberg‐Cherr Sheri , Keen Carl L.
Published: February 2006

Periconceptional Zn deprivation can affect development of 2‐ and 4‐cell mouse embryos in vitro as evidenced by fewer cells per embryo and delayed blastocyst development after 72 h in culture. One mechanism by which this could be occurring is through changes in oocyte and embryonic membrane structure/function. To test this idea, 3H‐glycine uptake was measured in unfertilized oocytes and preimplantation embryos recovered from mice fed control ( + Zn; 50 μg Zn/g diet) or low Zn ( − Zn; ⩽O.4 μg Zn/g diet) diets for 6 days. In a second experiment, we assessed the in vitro development of preimplantation embryos in medium designed to inhibit cavitation through changes in membrane‐associated sodium flux. Preimplantation embryos from − Zn and + Zn mice recovered on day 1 of gestation were cultured in medium containing 147.2 mM sodium (normal) or 123 mM sodium (low sodium) for 48 h. In experiment 1, glycine uptake was similar in embryos from + Zn and − Zn mice, suggesting that the impaired in vitro development of embryos from − Zn mice is not due to gross changes in sodium‐dependent cell membrane function. In experiment 2, embryos recovered from − Zn mice and cultured in normal sodium medium contained fewer cells than controls. Embryos from both groups cultured in low sodium medium contained fewer cells than their normal sodium controls; the percent difference in cell number was 50 ± 8% and 56 ± 11% for embryos from + Zn and − Zn mice, respectively. The lack of an exacerbation of Zn deficiency‐induced impairment of in vitro development with the low sodium challenge further supports the idea that the reduction in embryonic cell number is not due to gross alterations in membrane structure and/or function. ©1993 Wiley‐Liss, Inc.
Developmental toxicity and teratogenicity of trichosanthin, a ribosome‐inactivating protein, in mice
Authors: Chan W. Y. , Ng T. B. , Wu P. J. , Yeung H. W.
Published: February 2006

The embryotoxic and teratogenic effects of trichosanthin (TCS), a protein isolated from tubers of Trichosanthes kirilowii (family Cucurbitaceae), were studied both in vivo and in vitro. The protein was administered i.p. to ICR mice on day 8.0 of pregnancy, and the animals were sacrificed 1 day before parturition. The fetuses were fixed and subsequently sectioned. At the highest TCS dose employed (7.5 mg/kg body weight), the viability of fetuses declined to 70.2%, compared with 96.5% in the saline‐treated control group. The number of resorbed fetuses increased, and the crown‐rump length of the surviving fetuses was reduced. At the doses of 5.0 and 7.5 mg TCS/kg body weight, 2.3% and 9.0%, respectively, of the surviving fetuses were found to be abnormal. The abnormalities observed included exencephaly, micromelia, and short tail. When mouse embryos at the early organogenesis stage were cultured with TCS at a dose of 200 μg/ml or above, a significantly larger number of embryos were found to be abnormal as compared with the controls. The abnormalities were observed in the head, trunk, and limb regions. Hence, TCS produced adverse effects on prenatal development both in vivo and in vitro. ©1993 Wiley‐Liss, Inc.
Teratogenicity and carcinogenicity in a twin exposed in utero to cyclophosphamide
Authors: Zemlickis Donna , Lishner Michael , Erlich Robert , Koren Gideon
Published: February 2006

A 29‐year‐old pregnant woman diagnosed with acute lymphocytic leukemia maintained remission with daily cyclophosphamide and intermittent prednisone treatment. She delivered a male twin with multiple congenital abnormalities who was diagnosed with papillary thyroid cancer at 11 years of age and stage III neuroblastoma at 14 years of age. The female twin was unaffected and has exhibited normal development to date. First trimester exposure to cylcophosphamide has been associated with major malformations. Metabolites of cyclophosphamide have been demonstrated to be teratogens and carcinogens in animals. Differences in placental or fetal hepatic cytochrome P‐450 may account for the variability in response between the twins. In addition, disparity between the twins may be the result of differences in metabolite inactivating enzymes present either in fetal liver or placenta. The risk of second malignancies caused by alkylating agents such as cyclophosphamide has been well documented in adults and children but to the best of our knowledge this is the first description of transplacental second cancer. ©1993 Wiley‐Liss, Inc.
Teratogenic effect of hyperthermia during early organogenesis period in mice
Authors: Hande M. Prakash , Veena K.
Published: February 2006

Pregnant Swiss albino mice were subjected to 41, 42, or 43°C temperature for 10 minutes on day 6.5 of gestation. Another group of animals treated at 37°C was used as control. All animals were killed on the 18th day of gestation and fetuses were examined for prenatal mortality, growth retardation, and microphthalmia incidence. Results indicated a dose dependent increase in the mortality rates with a 42% death in the 43°C group. Treatment with the higher temperatures (42 and 43°C) resulted in a significant increase in the number of growth retarded fetuses and in the incidence of microphthalmia. Reduction in head length and decrease in brain weight were observed in the group exposed to 43°C, particularly in the growth retarded fetuses. However, the percent brain weight(g)‐body weight(g) ratio did not show any significant difference from the control values. ©1993 Wiley‐Liss, Inc.
Interception of reactive, DNA adduct‐forming metabolites present in rodent serum following carcinogen exposure: Implications for use of body fluids in biomonitoring
Authors: Garg Achal , Beach Andrew C. , Gupta Ramesh C.
Published: February 2006

The detection of adduct‐forming metabolites in the serum of carcinogen treated animals by 32P‐postlabeling was evaluated as a novel approach to overcome the stringent requirement of obtaining DNA from tissues in human biomonitoring assessments. Benzo[a]pyrene (BP) was given i.p. to B6C3F1, C57B1/6, ICR, and DBA/2 mouse strains as well as Sprague‐Dawley rats. Three adducts related to BP were detected in the liver and/or lung of Sprague‐Dawley rats or B6C3F1), C57B1/6, and ICR mice; a single adduct was detected in the liver and lung of the DBA/2 mouse strain. Adducts chromatographically similar to those found in these tissues were also detected when salmon sperm DNA was incubated with the serum of BP‐treated animals. Benzidine treatment induced the formation of one adduct in the liver of B6C3F1 mice, which was chromatographically similar to dG‐C8‐N′‐acetylbenzidine. An identical adduct was detected in the salmon sperm DNA incubated with the serum of these mice. Cyclopenta[cd]pyrene treatment produced four major and three minor adducts in the liver or lung of B6C3F1 mice, all but two of which were detected in DNA incubated with serum of cyclopenta[cd]pyrene‐treated animals. Large interstrain differences in the serum level of BP adduct‐forming metabolites as well as tissue DNA adducts were found which correlated with previously observed strain‐specific trends in sensitivity to PAH‐mediated carcinogenesis. Thus, levels of BP adduct‐forming metabolites were found in the following descending order: B6C3F1, C57B1/6, ICR, and DBA/2. BP‐derived adduct‐forming metabolites were detectable as late as 2 d and 5 d post‐treatment in the serum of C57B1/6 mice or Sprague‐Dawley rats, respectively, which seems to coincide well with the reported species‐specific turnover of serum albumin; a protein know to be involved in the transport of reactive metabolites throughout the systemic circulation. The results obtained clearly indicate the presence of adduct‐forming carcinogen metabolites in the serum of treated animals, which seemingly irrespective of their chemical nature, can be intercepted with exogenous DNA and detected by 32P‐postlabeling. Successful application of a serumbased approach coupled with the use of the generally applicable, ultrasensitive 32P‐postlabeling assay could evade the need for obtaining DNA from tissues, currently the major impediment in human biomonitoring studies. ©1993 Wiley‐Liss, Inc.
Relationship between blood group‐A antigen expression and malignant potential in hamster pancreatic cancers
Authors: Hirota Masahiko , Egami Hiroshi , Mogaki Masatoshi , Kazakoff Katherine , Chaney William G. , Pour Parviz M.
Published: February 2006

The loss of expression of the ABH blood group antigens is suggested to be associated with more aggressive behavior of cancers. We have compared the growth behaviors of two hamster pancreatic cancer cell lines with different blood group‐Aexpressions. PC‐1.0 cells, which expressed blood group‐A antigen poorly, showed a faster growth in vitro and in vivo when implanted into the pancreas of homologous animals, whereas PC‐1.2 cells, all of which express the antigen, had a slower growth rate both in vitro and in vivo. PC‐1.0 also tended to metastasize, whereas PC‐1.2 cells grew primarily locally. The allografts of both PC‐1.2 cells (PC‐1.2AG) and PC‐1.0 cells (PC‐1.0AG) and the metastases of PC‐1.0 cells expressed blood group A antigen in a similar rate. There was no significant difference in the number of A‐antigen positive cells (A +) between the PC‐1.2AG and PC‐1.0AG, although the expression of A antigen in PC‐1.0AG showed a greater heterogeneity. The combined immunohistochemistry and autoradiography did not show any significant differences in the labeling index of A + or A− cells between the two allografts. Thus, the results indicate that blood group A antigen expression is unrelated to malignancy in this model. The faster growth rate of PC‐1.0 cells may be due to their shorter cell cycle. ©1993 Wiley‐Liss, Inc.
Time‐dependent differences in the development of somites of four different mouse strains
Authors: Thiel Renate , Chahoud Ibrahim , Jürgens Maike , Neubert Diether
Published: February 2006

In studies on reproductive toxicity and especially teratogenicity, animals are often treated at defined stages of pregnancy. As a result the exposure to a certain teratogen can lead to striking differences in the formation of abnormalities in different strains of the same species. As a contribution to the discussion about the reasons for these differences, we examined the somite development of four different strains of mice during organogenesis. The embryos of pregnant females of the inbred strains DBA/2J, BALB/cJ, and C57BL/6J and of the outbred strain Han:NMRI were studied on days 9, 10, 11, or 12 of gestation. As a criterion for development the somite pairs were evaluated on the respective days. There were remarkable differences in the somite number, even within one litter. The largest variation (minimum vs. maximum) was 14 pairs of somites. The regression curves did not exhibit major differences in the speed of somite development from day 9 to day 12 between the four strains. We have to conclude from our results that the individual embryonic stages within one litter may vary by nearly 1 day, and that there may be a delay of half a day in the embryonic development between different strains of mice. ©1993 Wiley‐Liss, Inc.
Radiation dose‐dependent variations of micronuclei production in cytochalasin B‐blocked human lymphocytes
Authors: Lee Tung‐Kwang , Wiley Albert L. , Esinhart James D. , Blackburn Lisa D.
Published: February 2006

Using the cytokinesis‐block technique, lymphocytes from healthy volunteers (n = 9) were evaluated for (1) the radiation dose‐response curve for micronuclei (MN) expression; (2) technique variables on the yield of MN; and (3) the shortest lymphocyte incubation time required for the MN assay. We found that the best fitting of relationships between increasing MN production and increasing irradiation dose (0–4.0 Gy) was the linear‐quadratic model as expressed by the yield equation Y = C + αD + βD2 (P = 0.0003). When lymphocytes were irradiated in vitro with 2.0 Gy and harvested at various time intervals, MN increased during the entire 84 hr culture time. The radiation caused a division delay in lymphocyte as indicated by an increased frequency of mononucleated cells and a decreased number of mitotic indices. The data showed that a shortened culture time (60 hr) for the MN assay is possible and that binucleated cells with ⩾ 3 MN were found only in cells irradiated at ⩾ 2.0 Gy. These findings suggest that scoring of MN in lymphocytes may be a practical biological dosimeter for the rapid screening of accidental radiation exposure victims, especially when their clinical manifestations are not obvious. © 1994 Wiley‐Liss, Inc.
Congenital malformations in the offspring of male mice treated with ethylnitrosourea at the embryonic stage
Authors: Wada Azusa , Sato Masako , Takashima Hiromasa , Nagao Tetsuji
Published: February 2006

Ethylnitrosourea (ENU) was i.p. injected into ICR female mice at 25 or 50 mg/kg on day 10 of gestation, and male newborns treated with ENU at the embryonic stage were obtained. The treated males were aged for 10 weeks and then mated to untreated females of the same strain. The male germ cells used in the copulation correspond to primordial germ cells (PGC) at the time of ENU treatment. The F1 offspring were sampled as fetuses on day 18 of gestation and inspected for external and skeletal malformations. Evidence of F1 teratogenesis due to the mutagenized PGC was obtained when the fetuses from the males treated with 25 mg ENU/kg were inspected the frequencies of skeletally malformed fetuses in the ENU‐treated series and the control being, respectively, 1.0% (14/1,360) and 0.3% (3/1,017). The fetuses from 50 mg/kg‐treated males did not show a significant increase in malformations, most probably reflecting a high vulnerability of PGC to the killing effect of ENU. The findings in this study suggest that germ cell stage at PGC is at risk for the induction of congenital malformations by environmental chemicals. © 1994 Wiley‐Liss, Inc.
Comparison of dexamethasone‐induced embryotoxicity in vitro in mouse and rat embryos
Authors: Hansen Deborah K. , Grafton Thomas F.
Published: February 2006

Previous work demonstrated that rat embryos were more susceptible to the growth retardation effect of the synthetic glucocorticoid dexamethasone (DEX) in vivo than were mouse embryos. The purpose of this study was to examine this species difference using an in vitro system. Embryos of CD rats and CD‐1 mice were cultured in a whole embryo culture system with concentrations of DEX from 5 to 250 μg/ml. Rat embryos were explanted on day 9 of gestation (GD 9: plug day = GD 0), while mouse embryos were removed on GD 8. After 48 h in culture, each viable embryo was evaluated for morphological score, and the number of somite pairs, crown‐rump, and head lengths, as well as DNA and protein concentrations were determined. A reduced morphological score was observed for mouse embryos at 5 μg DEX/ml, but a significant decrease in this parameter was only observed at DEX concentrations of ⩾ 100 μg/ml in rat embryos. Significant reductions in the number of somite pairs were observed at 25 μg/ml for mouse embryos and 100 μg/ml for rat embryos. Crown‐rump and head lengths as well as DNA and protein concentrations were significantly decreased at 100 μg/ml in mouse embryos and 150 μg/ml in rat embryos. Therefore, in vitro mouse embryos were adversely affected by lower concentrations of DEX than were rat embryos for each of the six end points examined in this study. This species sensitivity in vitro could be due to inherent genetic differences or to the slightly different developmental stages evaluated using the culture system. The species sensitivity observed in vivo may be due to a maternal difference in the pharmacodynamics of the drug. © 1994 Wiley‐Liss, Inc.

This article is a US Government work and, as suh, is in the public domain in the United States of America.
Differences in teratogenic and toxic properties of alcohol dehydrogenase inhibitors pyrazole and 4‐methylpyrazole in Drosophila melanogaster. II. ADH allozymes in an isogenic background
Authors: Eisses Karel Th.
Published: February 2006

Pyrazole and 4‐methylpyrazole (4‐MP) are in vivo and in vitro inhibitors of alcohol dehydrogenase activity in mammals. The fruitfly Drosophila melanogaster has been used to demonstrate the influence of genetic variation in alcohol dehydrogenase alleles on the results of larval treatment with pyrazole and 4‐MP. Genetic polymorphism of organisms involved in experiments with teratogenic and toxic agents is not often considered. Administration of pyrazole to larvae of isogenic D. melanogaster strains, differing mainly in their Adh alleles, caused large Notch‐like teratogenic aberrations, macrochaetae multiplication, and pupal mortality. The level of teratogenicity and developmental‐toxicity of pyrazole was both concentration and Adh‐genotype‐dependent. The strain with the highest ADH activity showed smaller effects after the treatments with the two concentrations used. 4‐MP does not cause morphological aberrations, although treatment of larvae with an isogenic background caused a high pupal mortality due to non‐differentiated material in the pupal case. © 1994 Wiley‐Liss, Inc.
Measurement of DNA integrity and structure in Xenopus embryos in the presence of hydroxyurea, actinomycin‐D, and triethylenemelamine using the fluorescent probe hoechst 33258
Authors: Stringer Bradley K. , Blankemeyer James T.
Published: February 2006

Cell health assay of water quality (CHAWQ) is an assay using intracellular biomarkers measured by optical techniques. CHAWQ uses embryos of the South African clawed frog, Xenopus laevis, and optical transducers of intracellular biomarkers to obtain rapid assessment of toxicity to frog embryos. Since the biomarkers are common to all cells, CHAWQ can indicate toxicity of different classes of chemicals. Among the biomarkers used are (1) the change in synthesis rate, (2) the structure, or (3) the environment of DNA. Measurement of DNA to detect genotoxicants has previously used extracted DNA or flow cytometry to detect alterations in DNA content or configuration. We report the use of viable frog embryos and the fluorescent probe Hoechst 33258 to detect the effect of three DNA‐active chemicals—actinomycin‐D, hydroxyurea, and triethylenemelamine (TEM)—on DNA in intact embryos. We found that we can detect changes in the DNA in the presence of toxicants at concentrations comparable to longer‐term assays but following a much shorter time of drug exposure. Actinomycin‐D caused a fluorescence decrease, TEM caused a fluorescence increase, whereas hydroxyurea gave a biphasic response. Hydroxyurea caused a decrease at low concentrations and an increase at higher concentrations. Concentration‐response data for TEM, hydroxyurea, and actinomycin‐D generated EC50 values of 0.1 mg/ml, 1.4 mg/ml, and 6.34 μg/ml, respectively. © 1995 Wiley‐Liss, Inc.
Embryotoxicity induced by alkylating agents: 9. Low dose prenatal‐toxic risk estimation of ethylmethanesulfonate based on No‐observed‐adverse‐effect‐level risk factor approach, dose‐response relationships, and molecular dosimetry
Authors: Platzek Thomas , Bochert Gerd , Meister Reinhard
Published: February 2006

Analogously to an earlier study using methylnitrosourea (MNU) the prenatal‐toxic risk of low doses of ethylmethanesulfonate (EMS) was estimated using different procedures, comparatively. First, the risk of low doses was estimated using linear extrapolation to zero. When using the variable “all gross structural abnormalities” the lowest effective dose in the experiment was 150 mg/kg body wt (5.6% incidence), the additional risk over background was calculated to be 5.0%, and the hypothetical incidence 0.1% was associated with the dose 3 mg/kg EMS. When evaluating “gross structural limb abnormalities,” which are not observed in controls, the dose associated with the hypothetical incidence 0.1% was 17.4 mg/kg EMS.

Furthermore, derived from a dose‐response study of teratogenicity extrapolation to the possible risk of low doses was performed using nonlinear mathematical models. In this case, the results obtained are dependent on the dose response variable as well as from the statistical approach which was chosen. As an example, the values obtained from one evaluation are given: all gross structural abnormalities, Weibull transformation, jackknife approach: ED0.1% = 72 mg/kg EMS.

For comparison a “virtually safe dose” was calculated by use of the no‐observed‐adverse‐effect‐level (NOAEL) risk factor approach. The NOAEL under our experimental conditions was 100 mg per kg body wt. By using an arbitrarily chosen risk factor of 100 a “safe dose” of 1 mg EMS per kg body wt was obtained.

In addition, molecular dosimetry of the DNA adduct rate of O6‐ethylguanine in the 11‐day‐old embryos was used. Based on the assumption that a linear correlation exists between this specific adduct rate and the incidence of teratogenic effects, the hypothetical incidence of 0.1% was associated with a dose of 99 mg/kg EMS. This value is quite similar to that obtained by extrapolation using probit analysis which is in contrast to the results obtained with MNU. © 1995 Wiley‐Liss, Inc.
2‐aminofluorene bioactivation by human term placental peroxidase
Authors: Murthy K. R. , Joseph P. , Kulkarni Arun P.
Published: February 2006

Earlier investigations from our laboratory demonstrated that human term placental peroxidase (HTPP) is capable of metabolism of xenobiotics and endogenous compounds. In this study, purified HTPP was found to bioactivate 2‐aminofluorene (2‐AF) in the presence of H2O2. 2‐AF oxidation was studied spectrophotometrically while radiometry was employed to assess the bioactivation. The rate of oxidation and covalent binding to protein and DNA was dependent upon the pH of the reaction medium and the concentration of 2‐AF, the enzyme, and H2O2. To observe maximal enzyme velocity of oxidation, the presence of 16.5 μM H2O2, 100 μM 2‐AF, 37 γg of the enzyme protein/ml, and pH 7.2 was required. Under optimal assay conditions, the range of specific activity between 130 and 165 nmol of 2‐AF oxidized/min/mg HTPP was observed. Using similar assay conditions, the magnitude of covalent binding of [3H]‐2‐AF to protein (BSA) and calf thymus DNA was found to be about 508 pmol bound/min/mg HTPP/mg BSA and 84 pmol bound/min/mg HTPP/mg DNA, respectively. Potassium cyanide and sodium azide, the known inhibitors of different peroxidases, significantly blocked both the oxidation and covalent binding of 2‐AF in a dose dependent manner. These results strongly suggest that peroxidase may be one of the important pathways responsible for the bioactivation of arylamines in human term placenta. © 1995 Wiley‐Liss, Inc.
Modulatory influence of arecanut on the mouse hepatic xenobiotic detoxication system and skin papillomagenesis
Authors: Singh Anjali , Rao A. R.
Published: February 2006

The modulatory influence of arecanut, a masticatory in several human populations, on the levels of biotransformation system enzymes in mouse liver has been studied. Swiss albino mice of either sex (4 weeks old) were fed on diets containing 0.25%, 0.5%, or 1% arecanut (w/w) for 5 weeks. In addition, a group of mice received a 1% arecanut diet for 36 weeks. The findings revealed a significant increase in hepatic levels of cytochrome b5, cytochrome P‐450, malondialdehyde (MDA), and glutathione S‐transferase (GST). The hepatic –SH content was depressed by 0.5% and 1% arecanut diets. Long‐term feeding of a 1% arecanut diet elicited changes similar to those seen following treatment for 5 weeks. Arecanut‐modulated profiles of biotransformation enzymes and antioxidant levels are suggestive of its influence in the process of carcinogenesis induced by bioactivated electrophilic species of potential chemical carcinogens among habitual arecanut chewers. Arecanut was also tested for its potency either to induce or to alter 7,12‐dimethylbenz[a]anthracene (DMBA)‐induced papillomagenesis in the skin of the mouse. Animals put on a 1% arecanut diet and treated with a standard two‐stage protocol for tumor induction developed a 5.41 tumor burden (control value: 5.76) along with 100% incidence of mice bearing papillomas (control value: 94.4%), thus signifying that dietary intake of 1% arecanut for 18 weeks could not induce/alter the mouse skin tumorigenesis pattern. © 1995 Wiley‐Liss, Inc.
Covalent binding of carbon tetrachloride reactive metabolites to liver microsomal and nuclear lipid and phospholipid classes from sprague dawley and osborne mendel male rats
Authors: Fanelli S. L. , Castro J. A.
Published: February 2006

The interaction between carbon tetrachloride (CCl4)‐reactive metabolites and liver microsomal or nuclear lipids (covalent binding = CB) was studied in male rats from Osborne Mendel (OM) and Sprague Dawley (SD), strains with different cancer susceptibility. The in vitro or in vivo CB was more intense in OM than in SD.

Most of the CB was with phospholipid (PL; SD > OM). The CB to cholesterol (CH) and cholesterol esters (CHE) was OM > SD. We also observed the presence of specific adducts only present in lipids from either OM or SD strains.

The results were related to the well‐known role of PL and CH derivatives in gene function control and cell growth. © 1995 Wiley‐Liss, Inc.
Susceptibility to vinblastine‐induced aneuploidy and preferential chromosome segregation during meiosis I in Robertsonian heterozygous mice
Authors: Pacchierotti Francesca , Tiveron Cecilia , Mailhes John B. , Davisson Muriel T.
Published: February 2006

Chromosome segregation at meiosis I was studied in oocytes and spermatocytes of four different Robertsonian (Rb) heterozygous mouse stocks by cytogenetic analysis of meiotic products. Two Rb heterozygotes spontaneously yielded high frequencies of unbalanced oocytes. In one case, Rb(2.18)Rma, the excess hyperploidy was mainly accounted for by nondisjunction of normal bivalents, suggesting a generalized impairment of meiotic segregation. In each stock, frequencies of hyperploid spermatocytes were either not significantly different or significantly lower than the corresponding frequencies in the oocytes. This confirmed the greater risk of segregational errors in female than in male carriers of the same Rb metacentric. The hypothesis that an error prone system of meiotic segregation, such as the trivalent configuration of single Rb heterozygous oocytes, could be hypersensitive to chemically induced malsegregation was tested by injecting Rb heterozygous females with low doses of vinblastine (VBL). An intraperitoneal injection of 0.06 or 0.09 mg/kg VBL before the first meiotic division significantly increased the spontaneous frequency of hyperploid oocytes, inducing segregational errors of both the trivalent and normal bivalents. The comparison of these data with VBL effects in B6C3F1 mice showed that single Rb heterozygous oocytes are more sensitive to VBL‐induced meiotic aneuploidy than oocytes with a standard karyotype.

Although segregation distortion has been repeatedly shown in the progeny of Rb heterozygous mice with a significant excess of all telocentric balanced offspring, it has never been demonstrated whether this is a primary event occurring during meiotic segregation or a consequence of selective postconceptional death. In this study, we showed that preferential segregation occurred during female meiosis in all the Rb stocks tested. When segregation distortion was analyzed separately in balanced and unbalanced oocytes, the latter did not show preferential segregation, suggesting that, when the two telocentrics segregated from each other, then the metacentric was randomly directed to the ovum or the polar body © 1996 Wiley‐Liss, Inc.
Mouse embryonic development and tumor cell growth under the influence of recombinant trichosanthin (a ribosome inactivating protein) and its muteins
Authors: Chan W. Y. , Ng T. B. , Shaw P. C.
Published: February 2006

Trichosanthin, a ribosome inactivating protein, is known to possess embryotoxic and antiproliferative activities. In the present study recombinant trichosanthin and its muteins produced by site‐directed mutagenesis were tested for these activities using whole embryo culture and cell culture. The results revealed that when Glu 160 in trichosanthin was mutated to alanine or aspartate, the two aforementioned activities underwent a substantial decrease. However, the former mutein had a higher potency than the latter mutein. When both Glu 160 and Glu 189 were mutated, the resultant mutant possessed very low antiproliferative and yet considerable embryotoxic activity, indicating the contribution from other amino acids in stabilizing the transition state complex of trichosanthin © 1996 Wiley‐Liss, Inc.
Chronic Feeding Study of deoxynivalenol in B6C3F1 male and female mice
Authors: Iverson Frank , Armstrong Cheryl , Nera Eduardo , Truelove John , Fernie Susan , Scott Peter , Stapley Robert , Hayward Stephen , Gunner Sol
Published: February 2006

A 2 year feeding study was conducted with male and female B6C3F1 mice that consumed diets containing 0, 1, 5, or 10 ppm deoxynivalenol (DON). Survivability was good and, while the test animals gained less weight with increasing levels of DON in the diet, there were no consistent toxic manifestations associated with DON consumption. There was some evidence for an increase in serum IgA and IgG in females, and there were sporadic changes noted in the clinical chemistry and hematology parameters conducted at the terminal sacrifice. However, these changes were not considered to be biologically significant. The pathology results provided statistically significant dose‐related evidence for a decrease in liver preneoplastic and neoplastic lesions as the dose level of DON increased. This negative trend probably results from the known positive correlation between body weight and the appearance of spontaneous hepatic neoplasms in this strain of mouse. © 1996 Wiley‐Liss, Inc.
Neoplastic transformation by quartz in the BALB/3T3/A31‐1‐1 cell line and the effects of associated minerals
Authors: Saffiotti Umberto , Ahmed Nadera
Published: February 2006

Quartz, the most common form of crystalline silica, was tested quantitatively for neoplastic transformation in the mouse embryo cell line, BALB/3T3/A31‐1‐1. Five quartz dust samples of respirable size [Min‐U‐Sil 5 (MQZ); hydrofluoric‐acid‐etched MQZ (HFMQZ); Chinese standard quartz (CSQZ); DQ12; and F600] all induced significant levels of neoplastic transformation, showing dose‐dependent increases in the frequency of morphologically transformed foci at lower tested doses and a plateau level of response at higher doses. The plateau levels reached by the five tested samples did not differ substantially (maximum transformation frequencies per 105 cells ranging from 53.2 for MQZ to 28.3 for HFMQZ). F600 had minimal cytotoxicity but transforming activity comparable to the other samples. Cells from all tested transformed foci, when injected s.c. in nude mice, grew as sarcomas. Cytogenetic analysis showed that all tested silica‐transformed cell lines had acquired one to five additional marker chromosomes, of types not seen in untreated control lines, indicative of induced chromosomal translocations and amplification. Increased expression of one or more of five genes (p53, myc, H‐ras, K‐ras, and abl) was observed in several quartz‐transformed cell lines. No transforming activity was found for hematite and anatase (both nontoxic), and for rutile (more toxic than MQZ). Combined exposure (1:1 w/w per unit culture area) of each of these dusts with MQZ showed that hematite and anatase inhibited MQZ toxicity as well as transformation, whereas rutile markedly enhanced MQZ toxicity but not MQZ‐induced transformation. © 1996 Wiley‐Liss, Inc.
Another brick in the wall? Recent developments concerning the yeast cell envelope
Authors: Stratford Malcolm
Published: February 2006

To a yeast, the cell wall is an important living organelle performing a number of vital functions, including osmotic and physical protection, selective permeability barrier, immobilized enzyme support and cell‐cell recognition and adhesion. Our basic model of wall structure involves attachment of secreted mannoproteins to a fibrillar inner layer of β‐glucan. Recent work has emphasised the importance of chitin in lateral walls, examined the mechanisms of attachment of mannoproteins to the various cell wall glucan fractions and elucidated the pathway of β‐glucan synthesis, by means of resistance to glucan‐binding killer toxins. The conventional view of wall structure has been challenged by the discovery of a class of GPI‐anchored, serine/threonine‐rich wall‐proteins. It has been suggested, that these proteins are anchored in the plasma membrane, spanning the wall with extended O‐glycosylated structures and protruding out into the medium. Examination of these proteins shows a diversity of structures, sizes and behaviour that makes it improbable that these represent a new class of wall proteins. The possible roles of one of these proteins associated with flocculation, Flo1p, are discussed.
Intact acute cardiorenal and humoral responsiveness following chronic subcutaneous administration of the cardiac peptide BNP in experimental heart failure
Authors: Chen Horng H. , Schirger John A. , Cataliotti Alessandro , Burnett John C.
Published: February 2006

Background:

BNP is a cardiac peptide with vasodilating, lusitropic and natriuretic properties mediated by the second messenger cGMP. We have previously shown that chronic subcutaneous (SQ) administration of BNP in experimental CHF resulted in improved haemodynamics and unloading of the heart. However, it is unknown if this will lead to the development of tolerance to exogenous BNP.

Methods:

The current study extends our previous study and compares the cardiorenal effects of acute administration of SQ BNP (5 μg/kg) in a group of dogs (n = 5) with rapid ventricular pacing induced CHF (180 bpm for 10 days) to a separate group of CHF dogs (n = 6), who received chronic SQ BNP (5 μg/kg) three times a day for 10 days.

Results:

Acute administration of SQ BNP resulted in similar increases in both plasma cGMP (35 ± 5 vs. 29 + 2 pmol/ml) and urinary cGMP excretion (UcGMPV) (6000 ±1000 vs. 4000 ± 600 pmol/min) in both the Chronic SQ BNP treated and the Untreated CHF groups (P>0.05). These were associated with decreased cardiac filling pressures and increased urine flow, which were also similar in both groups.

Conclusion:

In experimental CHF, chronic SQ BNP administration did not result in the development of tolerance as demonstrated by increases in both plasma cGMP and UcGMPV following acute administration of SQ BNP. This may have important clinical implications, suggesting that chronic BNP administration does not lead to the development of tolerance to acute BNP administration.
Conserved cis‐elements in the Xenopus red opsin promoter necessary for cone‐specific expression
Authors: Babu S. , McIlvain V. , Whitaker S.L. , Knox B.E.
Published: February 2006

The long‐wavelength sensitive (red) opsin genes encode proteins which play a central role in daytime and color vision in vertebrates. We used transgenic Xenopus to identify 5′ cis‐elements in the red cone opsin promoter necessary for cone‐specific expression. We found a highly conserved extended region (−725 to −173) that was required for restricting GFP transgene expression to cones. We further identified a short element (5′‐CCAATTAAGAGAT‐3′) highly conserved amongst tetrapods, including humans, necessary to restrict expression to cones in the retina. These results identify novel conserved elements that regulate spatial expression of tetrapod red cone opsin genes.
Isoprenoid biosynthesis in plant chloroplasts via the MEP pathway: Direct thylakoid/ferredoxin‐dependent photoreduction of GcpE/IspG
Authors: Seemann Myriam , Tse Sum Bui Bernadette , Wolff Murielle , Miginiac-Maslow Myroslawa , Rohmer Michel
Published: February 2006

In the methylerythritol phosphate pathway for isoprenoid biosynthesis, the GcpE/IspG enzyme catalyzes the conversion of 2‐C‐methyl‐d‐erythritol 2,4‐cyclodiphosphate into (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate. This reaction requires a double one‐electron transfer involving a [4Fe–4S] cluster. A thylakoid preparation from spinach chloroplasts was capable in the presence of light to act as sole electron donor for the plant GcpE Arabidopsis thaliana in the absence of any pyridine nucleotide. This is in sharp contrast with the bacterial Escherichia coli GcpE, which requires flavodoxin/flavodoxin reductase and NADPH as reducing system and represents the first proof that the electron flow from photosynthesis can directly act in phototrophic organisms as reducer in the 2‐C‐methyl‐d‐erythritol 4‐phosphate pathway, most probably via ferredoxin, in the absence of any reducing cofactor. In the dark, the plant GcpE catalysis requires in addition of ferredoxin NADP+/ferredoxin oxido‐reductase and NADPH as electron shuttle.
Body weight, sexual maturity, and spinal deformity in strains and families of Atlantic cod (Gadus morhua) at two years of age at different locations along the Norwegian coast
Authors: Kolstad K. , Thorland I. , Refstie T. , Gjerde B.
Published: February 2006

Body weight, occurrence of spinal deformity, and sexual maturity were recorded in 51 full-sib families of the strains coastal and Arctic cod at two years of age. The family groups were located at three sites along the Norwegian coast including Hordaland, Møre and Romsdal (M&R), and Nordland County to detect genetic variation in important production traits and to investigate interactions between genetic composition and production environment. Body weight varied among locations partly owing to different production conditions. There were also large differences among the locations with respect to spinal deformity. M&R had the highest occurrence of spinal deformity (p < 0.001). Comparison of sexual maturity among the locations was made difficult owing to the different ways the trait was recorded. Only small differences were found between coastal and Arctic cod in spinal deformity (p < 0.05 in Hordaland) and sexual maturity (p = 0.06 in M&R), while no differences were found for body weight. Heritability estimates for body weight (0.51), spinal deformity (0.27), and sexual maturity (0.21) indicate the potential for improvement of all three traits by selective breeding using a family-based selection programme. Final recordings at the end of the growing period will provide further information. Genetic correlations estimated between weight and occurrence of spinal deformity (rg = 0.50) suggest that caution be used when selecting for growth, and that a need exists for including spinal deformity in the selection index. No significant correlations were found between these two traits and the incidence of sexual maturity.
Bone resorption activity of osteolytic metastatic lung and breast cancers
Authors: Shih Lih‐Yuann , Shih Hsin‐Nung , Chen Tien‐Hsiung
Published: February 2006

Production of bone resorption mediators and bone resorption activity were compared among osteolytic metastatic cancers, normal bone tissues, and soft tissue metastatic cancers to search for the possible factors leading to cancer‐induced bone resorption. Twenty‐five patients with untreated osteolytic metastatic breast or non‐small cell lung cancers consisted of the study group. Normal bone tissues obtained from the same patient were used as internal controls; and tumor tissues from patients with soft tissue metastasis were used as external controls. Serum and urinary bone turnover markers were measured. Tissues harvested during surgery were subjected to tissue culture. The levels of prostaglandin E2 (PGE2), tumor necrosis factor‐α (TNF‐α), and interleukin‐6 (IL‐6) in the supernatant after 72 h of culture were measured. Bone resorption activity was measured by calcium release from cultured calvarias, and bone volume as well as osteoclast number in bone sections. Patients with osteolytic metastatic cancers showed significantly decreased serum osteocalcin, increased serum alkaline phosphatase, and urinary deoxypyridinoline levels. Osteolytic metastatic cancers produced significantly more PGE2 than both controls. Conditioned medium from osteolytic metastatic tumors showed significantly enhanced bone resorption activity, and indomethacin significantly reduced this activity. Levels of PGE2, and bone resorption activity increased in osteolytic tumor tissues than soft tissue metastatic tissues in the same patient indicated that the same tumor cells might respond differently to different microenvironments. Our observation showed that PGE2 was produced by osteolytic metastatic cancers and stimulated bone resorption in mice calvarias. PGE2 inhibitor may be applicable in reducing bone resorption by osteolytic metastatic cancers. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Early cementing does not increase debond energy of grit blasted interfaces
Authors: Mann Kenneth A. , Damron Leatha A. , Race Amos , Ayers David C.
Published: February 2006

A fracture mechanics based approach was used to determine the debond energy or fracture toughness of the stem–cement interface for a variety of conditions. The goals of the study were to determine if early cementing of stems increased the debond energy of grit blasted stem–cement interfaces and if debond energy was dependent on mold type. Early (2 min) and late (6 min) times of cementation were considered for two different grit blasted surface finishes (16 and 60 grit, Ra = 5.7 or 2.3 μm). Specimen fabrication was performed using a relatively simple, unconstrained rectangular mold and a mold that more closely simulated in vivo conditions. The rectangular mold was used with all components at room temperature whereas the in vivo simulated mold had a body that resembled the femoral canal in shape and was warmed to body temperature. Early cementing did not increase the debond energy using the in vivo simulated mold. Extensive porosity was found at the interface, and porosity had a strong negative effect on debond energy. When the simpler, rectangular mold was used, early cementing did result in higher debond energies, but few voids were found at the interface. It appears that porosity at the interface was the major factor affecting the debond energy. The results from this study do not support the concept that improved stem–cement interface strength can be obtained by application of the cement while it is in a low viscosity state. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.