Creat membership Creat membership
Sign in

Forgot password?

Confirm
  • Forgot password?
    Sign Up
  • Confirm
    Sign In
home > search

Now showing items 1 - 16 of 273

  • Development of a curated Hershberger database

    Browne, P.   Kleinstreuer, N. C.   Ceger, P.   Deisenroth, C.   Baker, N.   Markey, K.   Thomas, R. S.   Judson, R. J.   Casey, W.  

    A systematic literature review was conducted to identify Hershberger bioassays for 3200 chemicals including those used to validate the OECD/US EPA guideline assay, US EPA's chemicals screened for endocrine activity, and the library of chemicals run in US EPA's ToxCast in vitro assays. For 134 chemicals that met pre-defined criteria, experimental results were extracted into a database used to characterize uncertainty in results and evaluate the concordance of the Hershberger assay with other in vivo rodent studies that measure androgen responsive endpoints. Of 25 chemicals tested in > 1 Hershberger study, 28% had disagreements between studies (i.e >=3D 1 positive and >=3D 1 negative study), and of the 65 chemicals tested in Hershberger studies and other in vivo studies with androgen-responsive endpoints, 43% indicated disagreements, though in some cases these may be explained by differences in study designs or physiology of the animal model. Ultimately, 49 chemicals were identified with reproducible androgen pathway responses confirmed in 2 in vivo rodent studies that could be considered reference chemicals useful for validating alternative methods.
    Download Collect
  • Evaluation of androgen assay results using a curated Hershberger database

    Kleinstreuer N.C.   Browne P.   Chang X.   Judson R.   Casey W.   Ceger P.   Deisenroth C.   Baker N.   Markey K.   Thomas R.S.  

    Download Collect
  • Evaluation of androgen assay results using a curated Hershberger database.

    Kleinstreuer, N C   Browne, P   Chang, X   Judson, R   Casey, W   Ceger, P   Deisenroth, C   Baker, N   Markey, K   Thomas, R S  

    A set of 39 reference chemicals with reproducible androgen pathway effects in vivo, identified in the companion manuscript [1], were used to interrogate the performance of the ToxCast/Tox 21 androgen receptor (AR) model based on 11 high throughput assays. Cytotoxicity data and specificity confirmation assays were used to distinguish assay loss-of-function from true antagonistic signaling suppression. Overall agreement was 66% (19/29), with ten additional inconclusive chemicals. Most discrepancies were explained using in vitro to in vivo extrapolation to estimate equivalent administered doses. The AR model had 100% positive predictive value for the in vivo response, i.e. there were no false positives, and chemicals with conclusive AR model results (agonist or antagonist) were consistently positive in vivo. Considering the lack of reproducibility of the in vivo Hershberger assay, the in vitro AR model may better predict specific AR interaction and can rapidly and cost-effectively screen thousands of chemicals without using animals. Published by Elsevier Inc.
    Download Collect
  • Evaluation of Triclosan in the Hershberger and H295R Steroidogenesis Assays

    Farmer, W.T.   Louis, G.W.   Buckalew, A.R.   Hallinger, D.R.   Stoker, T.E.  

    Download Collect
  • War, Peace and Social Conscience: Guy F. Hershberger and Mennonite Ethics

    Gerlof D. Homan  

    First page of article
    Download Collect
  • Assessing the antiandrogenic properties of propyl paraben using the Hershberger bioassay

    ?zdemir, Ecem   Barlas, Nurhayat   ?etinkaya, Mehmet Alper  

    Download Collect
  • Evaluation of the hamster Hershberger assay using reference androgens and antiandrogens

    Lidia Radko   Maria Minta   Sylwia Stypu?a-Tr?bas  

    Download Collect
  • Evaluation of the hamster Hershberger assay using reference androgens and antiandrogens

    Lidia Radko   Maria Minta   Sylwia Stypu?a-Tr?bas  

    Download Collect
  • The Songs of Insectsby Lang Elliott; Wil Hershberger

    Review by: Cate Hibbitt  

    Download Collect
  • The Songs of Insectsby Lang Elliott; Wil Hershberger

    Review by: Cate Hibbitt  

    Download Collect
  • Evaluation of (anti-)androgenic ability of formulated glyphosate by Hershberger assay

    M.C. Lozano   N.A. Valencia   C. Cáceres  

    Download Collect
  • Hershberger assay for antiandrogenic effects of phthalates

    Lee, Byrung Mu   Koo, Hyun Jung  

    The antiandrogenic effects of seven phthalates, di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), di-isononyl phthalate (DINP), di-isodecyl phthalate (DIDP), di-n-heptyl phthalate (DnHP), and mono-2-ethyhexyl phthalate (MEHP), were investigated by Hershberger assay in castrated male SD rats. An androgen agonist, testosterone (0.4 mg/kg/d), was administered for 10 consecutive days by subcutaneous (sc) injection as a positive control. Additionally, 20, 100, or 500 mg/kg body weight (bw)/d of 6 phthalates (DEHP, DBP, BBP, DINP, DIDP, or DnHP) or 10, 50, or 250 mg/kg bw/d of MEHP, the primary metabolite of DEHP, were also administered orally in combination with testosterone (0.4 mg/kg/d, sc) for 10 consecutive days, respectively. In the testosterone-treated groups, glans penis, seminal vesicles, ventral prostate, and levator ani/bulbocavernosus muscles (LABC) weights were found to be significantly increased. Ventral prostate weights were significantly decreased in animals treated with DEHP or DBP at doses of 20 mg/kg bw/d or above, 500 mg/kg bw/d DIDP, and 250 mg/kg bw/d MEHP. Seminal vesicles weights were also significantly decreased by DEHP at > 100 mg/kg bw/d, DINP at > 20 mg/kg bw/d, DIDP at 500 mg/kg bw/d, or MEHP at 50 or 250 mg/kg bw/d, respectively. In addition, LABC weights were decreased by DEHP at 500 mg/kg bw/d, DINP at 500 mg/kg bw/d, and MEHP at 50 or 100 mg/kg bw/d. These data suggest that some phthalates possess antiandrogenic activity, and that multiple cross-talk between androgen, estrogen, and steroid hormone receptors occurs.
    Download Collect
  • Hershberger Assay for Antiandrogenic Effects of Phthalates

    Lee, Byung Mu   Koo, Hyun Jung  

    Download Collect
  • How many imputations are needed? A comment on Hershberger and Fisher (2003)

    von Hippel, PT  

    Download Collect
  • Ability of the Hershberger assay protocol to detect thyroid function modulators

    Noda, S   Muroi, T   Takakura, S   Sakamoto, S   Takatsuki, M   Yamasaki, K   Tateyama, S   Yamaguchi, R  

    In vivo screening methods for detection of thyroid function modulators are now under development in many research laboratories. We assessed the applicability of the Hershberger assay protocol to screen for thyroid function modulators. In experiment 1, castrated male BrlHan WIST@Jcl (GALAS) rats were administered a potent thyroid peroxidase inhibitor, 3-amino-1,2,4-triazole (AT), in doses of 0, 40, 200, and 1,000 mg/kg/day with gravimetric endpoint, and in experiment 2, castrated and intact male rats were administered in doses of 0, 40, and 200 mg/kg/day, with quantification of the extent of hypertrophy of the thyroid epithelium, to assess the effects of castration, by gavage to 8-week-old for 10 consecutive days. At necropsy of both experiments, the thyroid glands and hypophysis were collected and fixed with 10% neutral-buffered formalin. To avoid crushing during weighing because of their fragility, the thyroid glands and hypophysis were weighed approximately 24 h after fixation with 10% neutral-buffered formalin. All animals were sacrificed approximately 24 h after the final dose. In experiment 2, the thyroid glands of all animals were stained with hematoxylin and eosin for histological examination and morphometry of follicular epithelial height. In experiment 1, absolute and relative thyroid weights in all of the AT groups were statistically increased in a dose-dependent manner, regardless of the testosterone propionate (TP)-injection. In experiment 2, the results showed a significant increase in thyroid weight in the 200 mg/kg groups of both castrated and intact rats. Hypophyseal weight was unaltered by AT, but comparison of vehicle-treated groups showed that the hypophyseal weight of the castrated rats was greater than that of the intact rats. Enlarged thyroid glands were observed in the AT-treated rats at necropsy. Histological examination of the thyroid glands of all the AT-treated animals showed hypertrophy and hyperplasia of the follicular epithelial cells, and the height of follicular epithelium of the thyroid glands increased in a dose-dependent manner in both the castrated and intact rats. In experiment 1, assessment of the (anti-) androgenic action of AT in seminal vesicle weight revealed a significant increase in the 200 and 1,000 mg/kg + TP groups in a dose-dependent manner. These results suggest that the effect of AT can be detected by the Hershberger assay 10-day administration protocol and may be useful for screening for thyroid function modulators regardless of whether the animals have been castrated.
    Download Collect
  • An Assessment of Androgenic/Anti-androgenic Effects of GH Transgenic Carp by Hershberger Assay

    Liu YuMei   Zhang WenZhong   Yong Ling   Zhao XiaoHong   Jia XuDong   Li Ning  

    Objective To evaluate the androgenic and anti-androgenic effects of GH (growth hormone) transgenic carp in male rats. Methods Hershberger assay was carried out in castrated male SD rats aged 4-5 weeks. Testosterone propionate (TP) (0.4 mg/kg BW) was administrated for a positive control, GH transgenic carp (3.0 g/kg BW)+TP (0.4 mg/kg BW), parental carp (3.0 g/kg BW) + TP (0.4 mg/kg BW), and flutamide (Flu) (3.0 g/kg BW) were used for negative controls, and vehicle was administered orally for a blank control. All groups were administrated for 10 consecutive days. At the end of the test, animals were anesthetized, then weights of accessory sex organ were measured. Serum testosterone (T), luteinizing hormone (LH), and Follicle-Stimulating Hormone (FSH) levels were detected. Results The weights ratios of the accessory sex organs and body weights showed no significant differences between the solvent control and the GH transgenic carp-treated groups. Serum concentrations of FSH, LH, and T of the rats treated with GH transgenic carp + TP showed no significant changes, compared with those treated with TP only. Conclusion GH transgenic carp does not have any androgenic agonist or antagonist properties in vivo screening tests.
    Download Collect
1 2 3 4 5 6 7 8 9 10

Contact

If you have any feedback, Please follow the official account to submit feedback.

Turn on your phone and scan

Submit Feedback