Energy Metabolism and Leptin: Effects on Neuroendocrine Regulation of Reproduction in the Gilt and Sow

It is well established that reproductive function is metabolically gated. However, the mechanisms whereby energy stores and metabolic cues influence appetite, energy homeostasis and fertility are yet to be completely understood. Adipose tissue is no longer considered as only a depot to store excess energy. Recent findings have identified numerous genes, several neurotrophic factors, interleukins, insulin-like growth factor binding protein-5, ciliary neurotrophic factor and neuropeptide Y (NPY) as being expressed by adipose tissue during pubertal development. These studies demonstrated for the first time the expression of several major adipokines or cytokines in pig adipose tissue which may influence local and central metabolism and growth. Leptin appears to be the primary metabolic signal and is part of the adipose tissue-hypothalamic regulatory loop in the control of appetite, energy homeostasis and luteinizing hormone (LH) secretion. Leptin's actions on appetite regulation are mediated by inhibition of hypothalamic NPY and stimulation of proopiomelanocortin. Its effects on gonadotropin-releasing hormone (GnRH)/LH secretion are mediated by NPY and kisspeptin. Thus, leptin appears to be an important link between metabolic status, the neuroendocrine axis and subsequent fertility in the gilt and sow.     

Surface transport of 2,4-D from small turf plots: observations compared with GLEAMS and PRZM-2 model simulations

A three-year field study was conducted using twelve 7.4×3.7 m plots and simulated rainfall to investigate pesticide run-off following application to a golf course fairway. The plots were sprigged with ‘Tifway 419’ bermudagrass (Cynodon dactylon×C transvaalensis). The dimethylamine salt of 2,4-D [(2,4-dichlorophenoxy)acetic acid] was applied as foliar sprays at a rate of 2.24 kg AI ha⁻¹. Simulated rainfall was applied at an intensity of 29 mm h⁻¹ one day before and 1, 2, 4, and 8 days after the pesticide applications for 0.92, 1.75. 1.75, 0.92, and 0.92 h, respectively. Water run-off was measured using a tipping-bucket apparatus and sub-samples were analyzed for pesticide residues. Data collected from the study were also compared with the GLEAMS and PRZM-2 model simulations for surface water and 2,4-D run-off. Mass and concentration of 2,4-D in run-off decreased rapidly, with 74.5% of the total run-off of 2,4-D occurring in the first run-off event after treatment. When calibrated to the site-specific characteristics, the GLEAMS and the PRZM-2 models adequately simulated the average of surface water run-off over all plots, with normalized root mean square error (NRMSE) and coefficient of determination for linear regression (R²) being 22.8% and 0.917 for GLEAMS, and 23.7% and 0.879 for PRZM-2, respectively. However, both GLEAMS (NRMSE=82.1%, R²=0.776) and PRZM-2 (NRMSE=125.8%, R²=0.513) less accurately simulated 2,4-D concentrations in run-off. © 1999 Society of Chemical Industry     

The Current State of Solar Modeling

Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.     

Stochastic variation of system component variables in a network analysis

A deterministic network simulation was reformulated to include the uncertainty of various parameters. Then, by the recording values obtained for each pathway or system in the network for a set of stochastic parameters and then choosing another set of stochastic parameters and recording the values obtained from that simulation, an average value and standard deviation for any system in the network can be determined. In the decision-making process of choosing from one system over another, the manager will have a better understanding of the complex interactions involved by knowing the effects that uncertainty in the system can cause.     

The Role of Estrogens in the Pathogenesis of Canine Hip Dysplasia. Metabolism of Exogenous Estrogens

Abstract— —Urinary estradiol-17β was measured by gas chromatography in each of 22 normal or dysplastic dogs that had received intramuscular injections of estradiol. Measurable quantities of estradiol-17β were not found in urine from these dogs prior to administration of the exogenous hormone. The level of urinary estradiol-17β was lower in normal dogs than in dysplastic dogs after injection of the hormone. Larger quantities of the hormone occurred in the urine of older dogs of dysplastic lineage after estradiol-17 β injection. These results indicate dogs with hereditary hip dysplasia have a lower than normal capacity to metabolize biologically-active estradiol. Résumé— —L'estradiol-17β urinaire a été mésuré par gas-chromatographie dans chaque des 22 chiens normaux ou dysplastiques qui ont roçu des injections intramusculaires d'estradiol. Des quantités mesurables d'estradiol-17β n'ont pas été trouvées dans Purine de ces chiens avant 1'administration de hormone exogéne. Le niveau d'estradiol-17β urinaire était plus bas chez les chiens normaux que chez les chiens dysplastiques, après l'injection de l'hormone. Des quantités plus grandes de hormone ont ete trouvées dans l'urine des chiens plus âgés du groupe dysplastique, après l'injection d'estradiol— 17β. Les résultats indiquent que les chiens avec dysplasie héréditaire de la hanche ont une capacité moindre que la mornale de métaboliser l'estradiol biologiquement active. Zusammenfassung— —Oestradiol-17β im Urin wurde mittels Gas-Chromotagraphie in 22 normalen odcr dysplastischen Hunden gemessen, die intramuskulaere Injektionen von Oestradiol erhalten hatten. Messbare Mengen von Oestradiol-17β wurden im Urin dieser Hundc vor der Verabreichung des exogenen Hormons nicht gefunden. Der Oestradiol-17β-Spiegel im Urin war in normalen Hunden niedriger als in dysplastischen Hunden nach der Hormon-Injektion. Groessere Hormonmengen kamen im Urin von aelteren Hunden von dysplastischer Abstammung nach Oestradiol-17β-Injektion vor. Diese Resultate zeigen, dass Hunde mit hereditaerer Hueften-Dysplasie eine niedriger als normale Faehigkeit haben, biologisch aktives Oestradiol zu metabolisieren.     

Syneresis of vitreous by carbon dioxide laser radiation

In carbon dioxide laser surgery of the vitreous a process of vaporization has been advocated. In this report syneresis, a thermal liquefaction of gel, is shown to be over ten times more efficient on an energy basis than vaporization. Syneresis of vitreous is experimentally shown to be a first-order kinetic process with an activation energy of 41 +/- 0.5 kilocalories per mole. A theory of laser surgery in which this figure is used agrees closely with results from laser experiments on human eye-bank vitreous. The syneresis of vitreous by carbon dioxide laser radiation could lead to a more delicate form of ocular microsurgery, and application to other biological systems may be possible.     

T-cell tumor elimination as a result of T-cell receptor-mediated activation

It has recently been shown that activation of murine T-cell hybridomas with antigen inhibits their growth in vitro. The "suicide" of these neoplastic T cells upon stimulation with antigen suggested the possibility that activation via the antigen-specific receptor could also inhibit the growth of neoplastic T cells in vivo. To test this, mice were subcutaneously inoculated with antigen-specific T-cell hybridomas and then treated intraperitoneally with antigen. Administration of the appropriate antigen immediately after inoculation with the T-cell hybridoma abrogated tumor formation; antigen administered after tumors had become established decreased the tumor burden and, in a substantial fraction of animals, led to long-term survival. The efficacy of antigen therapy was due to both a direct inhibitory effect on tumor growth and the induction of host immunity. These studies demonstrate the utility of cellular activation as a means of inhibiting neoplastic T-cell growth in vivo and provide a rationale for studying the use of less selective reagents that can mimic the activating properties of antigen, such as monoclonal antibodies, in the treatment of T-cell neoplasms of unknown antigen specificity.