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Lee D.-M.,Yeungnam University | Min T.,Yeungnam University | Min T.,National Research Foundation of Korea NRF | Choi I.,Yeungnam University | And 8 more authors.
Asian-Australasian Journal of Animal Sciences | Year: 2010

Nandrolone, 19-nortestosterone, is a synthetic androgenic-anabolic steroid promoting muscle growth. Nandrolone is also present in pig meat and sera at non-negligible levels. A number of scientific reports have suggested a positive relationship between incidence of infertility and increased meat consumption in humans. The present study was designed to determine out the effect of feeding nandrolone on the testis of the male reproductive tract. Mixtures of food and nandrolone at different concentrations (0.005 ppm and 0.5 ppm) were supplied to pubertal male rats for 6 weeks. Body weight was recorded every week during the entire experimental period. At the end of the treatment, the testis, epididymis, and epididymal fat were collected and weighted. Sperm numbers in the caudal epididymis were counted. Differential gene or protein expression of steroidogenic enzymes in the testes among experimental groups was determined by semi-quantitative real-time PCR or western blotting analysis, respectively. Histological changes of the testis induced by nandrolone treatment were examined by hematoxylin and eosin staining. Immunohistochemical analysis was employed to detect changes in the localization of steroidogenic enzymes in the testes among experimental animals. There were no significant changes on body, testis, epididymis, and epididymal fat weights among experimental groups. A significant increase of caudal sperm number was found in the 0.5 ppm nandrolone-treated group. Histological examination of the testes noted a high frequency of germ cell sloughing in seminiferous tubules of 0.5 ppm nandrolone-treated rats. Even though transcript levels of 3β-hydroxysteroid dehydrogenase (HSD) I, 17β-HSD4, and 17α-hydroxylase were influenced by nandrolone treatments, protein levels of all molecules examined in the present study were not significantly affected. Immunohistochemical analysis showed no visible changes in the localization of steroidogenic enzymes in the testes among experimental groups. The current study showed that oral intake of nandrolone in male rats for 6 weeks did not cause significant damage to the testis. It is considered that a feeding effect of nandrolone on male fertility would not be remarkable. Source


Bae J.-Y.,Pukyong National University | Ok I.-H.,Pukyong National University | Lee S.,Pukyong National University | Hung S.S.O.,Pukyong National University | And 4 more authors.
Asian-Australasian Journal of Animal Sciences | Year: 2011

This study was designed to re-evaluate the dietary methionine requirement by means of the plasma methionine and ammonia concentrations in surgically modified rainbow trout, Oncorhynchus mykiss. A total of 35 rainbow trout averaging 505±6.5 g (initial body weight, mean±SD) were randomly distributed into seven groups with five fish in each group. After 48 h of feed deprivation, each group of fish was fed one of seven L-amino acid based diets containing 0.5% cystine and graded levels of methionine (0.25, 0.40, 0.50, 0.60, 0.70, 0.80 or 0.95% of diet, dry matter bases) by intubation at 1% body weight on dry matter basis. Blood samples were taken at 0, 5 and 24 h after intubation. Post-prandial plasma free methionine concentrations (PPmet, 5 h after intubation) and postabsorptive plasma free methionine concentrations (PAmet, 24 h after intubation) of fish fed diets containing 0.60% or higher methionine were significantly (p<0.05) higher than those of fish fed diets containing 0.50% or lower methionine. PPmet and PAmet in fish fed diets containing 0.60% or higher methionine were not significantly different except PPmet of fish fed diet containing 0.95% methionine. Postprandial plasma ammonia concentrations (PPA, 5 h after intubation) of fish fed diets containing 0.70% or higher methionine were significantly higher than those of fish fed diets containing 0.60% or lower methionine, and PPA of fish fed diets containing 0.25 and up to 0.60% methionine were not significantly different from each other. Broken-line model analyses on PPmet, PAmet, and PPA indicated that the dietary methionine requirement of rainbow trout was between 0.59 (1.69) and 0.67 (1.91) % of diets (% dietary protein bases) when the diets contained 0.5% cystine. Source


Bae J.-Y.,Pukyong National University | Ok I.-H.,Pukyong National University | Lee S.,Pukyong National University | Hung S.S.O.,University of California at Davis | And 2 more authors.
Journal of Applied Ichthyology | Year: 2011

This study aimed to reevaluate the dietary methionine requirement by means of the plasma methionine and ammonia concentrations in surgically modified rainbow trout, Oncorhynchus mykiss. A total of 35 rainbow trout averaging 505±6.5g (initial body weight, mean±SD) were randomly distributed into seven groups with five fish in each group. After 48h of food deprivation, each group was fed one of seven L-amino acid-based diets containing graded levels of methionine (0.25, 0.40, 0.50, 0.60, 0.70, 0.80 or 0.95% of diet, dry matter bases) by intubation at 1% bodyweight. Blood samples were taken at 0, 5 and 24h after intubation. Post-prandial plasma free methionine concentrations (PPmet, 5h after intubation) and post-absorptive plasma free methionine concentrations (PAmet, 24h after intubation) of fish fed diets containing 0.60% or more methionine were significantly (P<0.05) higher than those of fish fed diets containing 0.50% or less methionine. PPmet and PAmet in fish fed diets containing 0.60% or higher methionine were not significantly different except the PPmet of fish fed a diet containing 0.95% methionine. Post-prandial plasma ammonia concentrations (PPA, 5h after intubation) of fish fed diets containing 0.70% or more methionine were significantly higher than those of fish fed diets containing 0.60% or less methionine, and PPA of fish fed diets containing 0.25% and up to 0.60% methionine were not significantly different from each other. Broken-line model analyses on PPmet, PAmet, and PPA indicated that the dietary methionine requirement of rainbow trout was between 0.59% (1.69) and 0.67% (1.91) of diets (% dietary protein bases) when the diets contained 0.5% cystine. © 2010 Blackwell Verlag, Berlin. Source


Lee J.,Korea Institute of Science and Technology | Lim H.,Ajou University | Kim H.-C.,National Research Foundation of Korea NRF | Jeong S.-K.,Korea Institute of SandT Evaluation and Planning KISTEP
2010 10th IEEE Conference on Nanotechnology, NANO 2010 | Year: 2010

Motivations, benefits and challenges in international scientific collaboration for nanotechnology are reviewed through literature and in particular discussions at OECD workshop held in Baraga 2009. Also introduced is the experience of Korea in international research collaboration and a policy recommendation for Korea in international collaboration for nanotechnology, which can be applied to other countries. ©2010 IEEE. Source


Min T.,National Research Foundation of Korea NRF | Lee K.-H.,Eulji University
Asian-Australasian Journal of Animal Sciences | Year: 2010

Male reproduction is influenced by a number of intrinsic and extrinsic factors, including environmental endocrine disruptors. Testosterone is a well recognized intrinsic regulator for development and function of the male reproductive tract, and thus malefertility. The testis and semen of many mammalians contain an unusually high concentration ofestrogen. Testosterone is converted into estrogen by the enzymatic action of cytochrome P450 aromatase complex (Cyp19a1). Of the male reproductive tract, the efferent ductules (EDs) possess exceptionally elevated levels of estrogen receptors (ERs), ERαand ERβ, indicating that estrogen, in addition to testosterone, would have a functional role in regulation of male reproduction. First, this review has focused on description and summary of what is currently known for functions of estrogen in the EDs. The biosynthetic pathway of estrogen occurring in the testis is briefly covered, following by detailed explanation of the morphology and physiology of EDs. In the next section, the sources and targets of estrogen in the male reproductive tract are highlighted, and possible functional roles of estrogen in the EDs are justified from the aspect of physiology, molecular biology, and morphology in adult animal models. Also, this section covers the importance of estrogen and ERs in maintaining normal function and morphology of the EDs duringpostnatal development. In the last part of this review, the effects of extrinsic factors, especially environmental endocrine-disruptors, on the EDs is summarized. The intent ofthis review is to emphasize the importance of estrogen for regulation of physiologicalfunction of the EDs, and thus male fertility. Source

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