Browsing by Author "Hughes, CL"

Now showing 1 - 6 of 6
  • Thumbnail Image
    ItemOpen Access
    An approach to the development of quantitative models to assess the effects of exposure to environmentally relevant levels of endocrine disruptors on homeostasis in adults.
    (Environmental health perspectives, 1999-08) Ben-Jonathan, N; Cooper, RL; Foster, P; Hughes, CL; Hoyer, PB; Klotz, D; Kohn, M; Lamb, DJ; Stancel, GM
    The workshop "Characterizing the Effects of Endocrine Disruptors on Human Health at Environmental Exposure Levels" was held to provide a forum for discussions and recommendations of methods and data needed to improve risk assessments of endocrine disruptors. This article was produced by a working group charged with determining the basic mechanistic information that should be considered when designing models to quantitatively assess potential risks of environmental endocrine disruptors in adults. To reach this goal, we initially identified a set of potential organ system toxicities in males and females on the basis of known and/or suspected effects of endocrine disruptors on estrogen, androgen, and thyroid hormone systems. We used this integrated, systems-level approach because endocrine disruptors have the potential to exert toxicities at many levels and by many molecular mechanisms. Because a detailed analysis of all these untoward effects was beyond the scope of this workshop, we selected the specific end point of testicular function for a more detailed analysis. The goal was to identify the information required to develop a quantitative model(s) of the effects of endocrine disruptors on this system while focusing on spermatogenesis, sperm characteristics, and testicular steroidogenesis as specific markers. Testicular function was selected because it is a prototypical integrated end point that can be affected adversely by individual endocrine disruptors or chemical mixtures acting at one specific site or at multiple sites. Our specific objective was to gather the information needed to develop models in the adult organism containing functional homeostatic mechanisms, and for this reason we did not consider possible developmental toxicities. Homeostatic mechanisms have the potential to ameliorate or lessen the effects of endocrine disruptors, but these pathways are also potential target sites for the actions of these chemicals.
  • Thumbnail Image
    ItemOpen Access
    Effects of dietary allicin on health and growth performance of weanling piglets and reduction in attractiveness of faeces to flies.
    (Animal : an international journal of animal bioscience, 2011-02) Huang, RH; Qiu, XS; Shi, FX; Hughes, CL; Lu, ZF; Zhu, WY
    To investigate the effect of dietary allicin on health and growth performance of weanling piglets, at 21 days of age. Two hundred and twenty-five piglets were weaned and randomly allocated into five groups. Piglets in the control group were fed diets supplemented with antibiotics. Those in the treatment groups were fed diets without antibiotics, but supplemented with allicin product (25% pure allicin oil) in the proportion of 0.10 g/kg, 0.15 g/kg, 0.20 g/kg and 0.25 g/kg in the diet, respectively. During the 28 days of the experiment, average daily weight gain increased linearly (P < 0.0001) and quadratically (P = 0.0014) as the level of dietary allicin increased. The feed gain ratio decreased linearly (P < 0.0001) and quadratically (P < 0.0001). As the dietary allicin level increased, the incidence of diarrhoea in the treatment piglets, especially female piglets decreased linearly (P = 0.0003) and tended to decrease quadratically (P = 0.0716). The number of flies alighting on the surface of the faeces of the piglets at each counting time point decreased linearly (P < 0.0001), quadratically (P < 0.0001) and cubically (P < 0.0001) as the dietary allicin level increased. In conclusion, supplementation of the diet with allicin may improve growth performance, reduce the incidence of diarrhoea and possibly improve their local environmental conditions by reducing the attractiveness of faeces to flies.
  • Thumbnail Image
    ItemOpen Access
    Effects of Dietary Chromium Methionine on Growth Performance, Carcass Composition, Meat Colour and Expression of the Colour-related Gene Myoglobin of Growing-finishing Pigs.
    (Asian-Australasian journal of animal sciences, 2013-07) Li, YS; Zhu, NH; Niu, PP; Shi, FX; Hughes, CL; Tian, GX; Huang, RH
    To investigate the effect of dietary chromium (Cr) as Cr methionine (CrMet) on growth performance, carcass traits, pork quality, meat colour and expression of meat colour-related genes in growing-finishing pigs, 189 crossbred Duroc×(Landrace×Yorkshire) growing-finishing pigs (male, castrated, average initial BW 74.58±1.52 kg) were selected and randomly allocated into four groups. Dietary treatments per kg of feed were as follows: 0 (CT), 0.3 mg/kg (T1), 0.6 mg/kg (T2) and 0.9 mg/kg (T3) Cr (in the form of CrMet; as-fed basis), and each treatment was replicated five times with 8 to 10 pigs per replicate pen. During the 28 d of the experiment, both the ADG and the ADFI increased linearly (p<0.05) as the level of dietary Cr increased. The F/G ratio decreased linearly (p<0.05). As dietary Cr increased, loin muscle areas (linear, p = 0.013) and average backfat thickness (linear, p = 0.072) decreased. Shear force (linear, p = 0.070) and Commission Internationale de I'Éclairage (CIE) redness (quadratic, p = 0.028) were increased. In addition, CIE Lightness (quadratic, p = 0.053) were decreased as dietary Cr increased. As dietary Cr increased, total myglobin (Mb) content (quadratic, p = 0.015) and the mb mRNA levels (quadratic, p = 0.046) in longissimus muscles of pigs were up-regulated. In conclusion, supplementation of dietary Cr improved growth and meat colour, but increased shear force and decreased IMF reduced palatability of longissimus muscles. Moreover, the increasing total Mb content and mb mRNA levels indicated that CrMet dietary supplementation may improve meat colour via up-regulating expression of the mb gene.
  • Thumbnail Image
    ItemOpen Access
    Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens.
    (Environmental health perspectives, 1988-06) Hughes, CL
    Plants have physical and chemical mechanisms for defense from attack by animals. Phytochemical defenses that protect plants from attack by insects include antifeedants, insecticides, and insect growth regulators. Phytochemical options exist by which plants can modulate the fertility of the other major group of plant predators, vertebrate herbivores, and thereby reduce cumulative attacks by those herbivores. The success of such a defense depends upon phytochemical mimicry of vertebrate reproductive hormones. Phytoestrogens do mimic reproductive hormones and are proposed to be defensive substances produced by plants to modulate the fertility of herbivores.
  • Thumbnail Image
    ItemUnknown
    The Impact of Endometriosis across the Lifespan of Women: Foreseeable Research and Therapeutic Prospects.
    (BioMed research international, 2015-01) Hughes, CL; Foster, WG; Agarwal, SK
    In addition to estrogen dependence, endometriosis is characterized by chronic pelvic inflammation. The impact of the chronic pelvic inflammatory state on other organ systems and women's health is unclear. Endometriosis associated chronic inflammation and potential adverse health effects across the lifespan render it imperative for renewed research vigor into the identification of novel biomarkers of disease and therapeutic options. Herein we propose a number of opportunities for research and development of new therapeutics to address the unmet needs in the treatment of endometriosis per se and its ancillary risks for other diseases in women across the lifespan.
  • Thumbnail Image
    ItemUnknown
    Workshop to identify critical windows of exposure for children's health: reproductive health in children and adolescents work group summary.
    (Environmental health perspectives, 2000-06) Lemasters, GK; Perreault, SD; Hales, BF; Hatch, M; Hirshfield, AN; Hughes, CL; Kimmel, GL; Lamb, JC; Pryor, JL; Rubin, C; Seed, JG
    This work group report addresses the central question: What are the critical windows during development (preconception through puberty) when exposure to xenobiotics may have the greatest adverse impact on subsequent reproductive health? The reproductive system develops in stages, with sex-specific organogenesis occurring prenatally and further maturational events occurring in the perinatal period and at puberty. Complex endocrine signals as well as other regulatory factors (genetics, growth factors) are involved at all stages. Evidence from animal models and human studies indicates that many specific events can be perturbed by a variety of toxicants, with endocrine-mediated mechanisms being the more widely studied. Prioritized research needs include basic studies on the cellular-molecular and endocrine regulation of sexual differentiation and development; increased efforts regarding potential adverse effects on development in females, including breast development; expanded animal studies on different classes of chemicals, comparing responses during development (prenatal and postnatal) with responses in adults; and, more extensive explorations regarding the reproductive biology and toxicology of puberty in humans.