• Korean Journal of Poultry Science
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• v.27 no.2
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• pp.115-132
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• 2000

Eggshell strength and eggshell pigmentation are described in this paper since these are needed for quality egg production. A strong eggshell is determined by the components of the shell (cuticle, true shell and membranes) as well as the proper function of the gastrointestinal tract, the shell gland, the Kidneys and the endocrine system. When the puller reaches sexual maturity, the medullary bone must be ready for the laying hen at the peak egg shell formation. The amount of calcium in the layer diet, sources of calcium feed, the ratio of calcium and phosphorus in the layer diet, adequate levels of vitamin D and the dietary mineral (electrolyte) balance in the body fluid are important factors along with the levels of other nutrients. Biological, environmental and managerial factors such as the age of laying flock, temperature and humidity of the hen house, bird strain, disease, egg collection through transportation and others and influence the shell breakage at various stages of movement of the eggs from the producer to the consumer. The pigments present in eggshells are protoporphyrin-Ⅸ, biliverdin-Ⅸ and its zinc chelate and occasional traces of coproporphyrin-Ⅲ. However, there are several causes of changes in eggshell pigmentation such as the age of hen, disease, drugs and surface defects due to abnormal post-cuticular deposits.

• Korean Journal of Veterinary Research
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• v.45 no.4
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• pp.545-552
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• 2005

The major protocol features of the rodent uterotrophic assay have been evaluated using a range of reference chemicals. The protocol variables considered include the selection of the test species and route of chemical administration, the age of the test animals, the maintenance diet used, and the specificity of the assay for estrogens. The rodents were ovariectomized under general anesthesia via bilateral flank incisions and randomly assigned to groups of 5 animals. Chemicals were DEHP, DBP, BPA and NP, were injected sc once daily with combinations of chemicals treatments for 3 days. In the results, the reported estrogenic chemicals DEHP and DBP were both negative in the single dose treatments. But, in the combinations of chemicals treatments, DEHP and DBP increased in bud number of mammary gland. Treatment of ovariectomized mice with combinations of other chemicals resulted in uterine and vaginal hyperplasia. The additive estrogenic effects were seen with the combinations of $17{\beta}$-Bestradiol and DBP treatment. the competitive estrogenic effects were seen with the combinations of $17{\beta}$-Bestradiol and nonylphenol, $17{\beta}$-Bestradiol and bisphenol-A treatments. These results offers a sysmatic and mechanistically informative approach to assessing estrogenicity. it provides a useful profile of activity using a reasonable amount of resources and is compatible with the study of individual chemicals as well as the investigation of interactions among combinations of chemicals. The results described illustrate the intrinsic complexity of evaluating chemicals for estrogenic activities and conform the need for rigorous attention to experimental design and criteria for assessing estrogenic activity.

• Animal cells and systems
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• v.10 no.4
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• pp.211-217
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• 2006

Heavy metals are well known as important environmental pollutants and also considered as endocrine disrupters. This study was performed to evaluate the direct effects of heavy metals such as cadmium (Cd), zinc (Zn), mercury (Hg), lead (Pb), cobalt (Co), and arsenic (As) on the various steroidogenic enzymes in frog ovarian follicles. Ovarian follicles from Rana catesbeiana were isolated and cultured for 18 hours in the presence of frog pituitary homogenate (FPH, 0.05 gland/ml) or various steroid precursors with or without heavy metals (0.01-100 ${\mu}M$), and steroid levels in the follicle or culture medium were measured by radioimmunoassay (RIA). Thus, the steroidogenic enzyme activities were indirectly evaluated by measuring the converted steroid levels from the added precursor steroid. Among heavy metals, Hg, Cd and Zn significantly inhibited FPH-induced pregnenolone ($P_5$) production by the follicles ($EC_{50},\;4.0{\mu}M,\;25.6{\mu}M\;and\;5.7{\mu}M$, respectively ), and also suppressed the conversion of testosterone (T) to estradiol $17{beta}\;(E_2)\;(EC_{50},\;4.2{\mu}M,\;7.5{\mu}M\;and\;80.0{\mu}M) while Pb, Co and As are not or less effective in the inhibition. Other enzymes such as $C_{17-20}$ lyase and $17{\beta}$-hydroxysteroid dehydrogenase ($17{\beta}$-HSD) were suppressed only in the high concentration of Hg, Cd and Zn. Taken together, these data demonstrate that cytochrome P450 side chain cleavage (P450scc) and aromatase are much more sensitive to heavy metals than other steroidogenic enzymes and Hg, Cd and Zn show stronger toxicity to follicles than other heavy metals examined.

• Development and Reproduction
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• v.5 no.2
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• pp.175-180
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• 2001

The ectopic expression of gonadotropin releasing hormone(GnRH and luteinizing hormone(LH) in several tissues is a quite intriguing phenomenon. Recently, the presence of GnRH and its receptor has been clearly demonstrated in rodents and human mammary gland. In this context, one can postulate that the presence of local circuit composed of GnRH and LH in the gland. The present study was undertaken to elucidate whether there is a correlation between the LH expression in rat mammary gland and physiological status during the process of mammary differentiation. LH contents in mammary gland from cycling to weaning rats were measured by radioimmunoassay(RIA). In cycling rats, changes of the LH level in both serum and mammary gland showed similar pattern as the highest level in proestrus and the lowest level in diestrus II stage. While the serum LH levels were fluctuated from pregnant through involution stage, a sharp decline of mammary LH contents was observed in the lactating rats. This decrement was recovered in involuting rats to the level of proestrus stage. Reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot analyses demonstrated that the transcriptional activities of the mammary LH and GnRH were increased from diestrus I stage to estrus stage, and the increased levels were maintained in pregnant, lactation and involution stages. To test the hypothesis that the alteration in mammary LH expression might be steroid-dependant, ovariectomy(OVX) and steroid supplement model was employed. As expected, supplement of estradiol(E$_2$) after OVX remarkably decreased serum LH level compared to that in serum from vehicle-only treated rats. Likewise, administration of E$_2$ significantly reduced the mammary LH content. The present study demonstrated that (i) the LH expression in mammary gland could be altered by some physiological parameters such as estrous cycle, pregnancy, lactation and involution, and (ii) ovarian steroid especially estrogen seems to be one of major endocrine factors which are responsible for regulation of mammary LH expression.

• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.707-718
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• 1997

The present study was designed to investigate the morphological developments of the stomach in the prenatal and postnatal rats. The gastric fundus of 16- to 22-day-old fetuses, neonates, 7-day-old, 14-day-old, 21-day-old, and adult rats were observed by transmission electron microscopy. 1. In the 19-day-old fetuses, the gastric pits and the parietal cells were the primitive state, but the parietal cells contained numerous microvilli and mitochondria. 2. In the 20-day-old fetuses, the intracellular canaliculus appeared in the parietal cells, and glycogen granules were localized mainly in the basal part of the epithelial cells and parietal cells. 3. In the 20-day-old fetuses, the mucous granules and zonular occludens appeared in the gastric glandular cells adjacent to the parietal cells. 4. In the 21-day-old fetuses, the chief cells were identified in the lamina propria and these cells contained granular endoplasmic reticulum and zymogen granules. 5. In the 20- to 22-day-old fetuses, the definitive parietal cells were firstly appeared in pairs or groups within the lamina propria. These cells tended to be placed near the basement membrane and blood capillary, and frequently tended to be extruded into lumen of gland. 6. The endocrine cells were appeared at the basal areas of the gastric gland after the 14-day-old.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.237-245
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• 2000

The regional distribution and relative frequency of somatostatin-immunoreactive cells in the gastrointestinal tract were studied during the postnatal development(1 day old, 1 month old, 6-month-old and adult) of the Korean native goat by immunohistochemical methods. Somatostatin-immunoreactive cells were found in the entire gastrointestinal tract and were most predominant in the fundic gland region except for the pyloric gland region of the 1 day old. The number of these cells was observed to decrease along the gastrointestinal tract and to decrease according to the increase with age in all postnatal stages. In this study, immunoreactive cells revealed the differences of regional distribution and the relative frequency in the gastrointestinal tract during postnatal development. These results suggest that although the functional significance of fetal endocrine cells remains unknown, this was caused by changing of feeding habits and physiological conditions during different ages.

• International Journal of Oral Biology
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• v.43 no.1
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• pp.5-11
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• 2018

Recent findings indicate that Type 2 taste receptors (T2Rs) are expressed outside the gustatory system, including in the gastrointestinal tracts and the exocrine glands, such as the submandibular (SM), parotid (P), lacrimal (L) glands and pancreas (PC). Specifically, T2Rs are found in some of the gastrointestinal endocrine cells, and these cells secreted peptide hormones in response to stimulation by bitter-tasting compounds. The results show that T2Rs may have significant physiological roles besides bitter taste reception. The functions of the T2Rs in the exocrine glands remain poorly understood. An expression levels analysis of T2Rs will help to determine those functions in the exocrine glands. The expression levels of the T2Rs in the exocrine glands were discovered via the qPCR. C57BL/6J mice of 42~60-day-old were used. Messenger RNAs were extracted from S, P, L and PC. Cloned DNAs were synthesized by reverse transcription. Quantitative PCRs were performed using the SYBR Green method. The expression levels of the T2Rs were calculated as relative expression levels to that of the GAPDH. The statistical significance among the observed exocrine glands was tested using the variance analysis (ANOVA test). Tas2r108, out of murine 35 T2Rs, was the most highly expressed in every observed exocrine gland. This finding was similar to previous results from tongue papillae, but the expression levels were lower than those of the tongue papillae. Tas2r137 of SM, P, L and PC were expressed a little lower than that of tongue papillae. The T2Rs in the exocrine glands may play slightly different roles from those in the tongue. We suggest that physiological studies such as a patch clamp and functional $Ca^{2+}$ imaging of acinar cells are necessary for understanding the Tas2r108 functions.

• Journal of Genetic Medicine
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• v.7 no.1
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• pp.9-15
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• 2010

Congenital hypothyroidism (CH) is detected at a rate of 1 in 3,000 to 4,000 live births, making it the most common congenital endocrine disorder worldwide. CH is most commonly caused by defects in thyroid development leading to thyroid dysgenesis or dyshormonogenesis. Congenital hypothyroidism is usually sporadic, but up to 2% of cases of thyroid dysgenesis are familial, and CH caused by organification defects is often inherited in a recessive manner. The candidate genes associated with this genetically heterogeneous disorder fall into two main groups: those causing thyroid gland dysgenesis and those causing dyshormonogenesis. Genes associated with thyroid gland dysgenesis include the TSHR gene in nonsyndromic CH, and Gsa and the thyroid transcription factor (TTF-1, TTF-2, and Pax-8) genes, which are associated with different complex syndromes that include CH. Among genes associated with dyshormonogenesis, the TPO and TG genes were initially described, and more recently PDS, NIS, and THOX2 gene defects. There is some evidence for a third group of CH conditions associated with iodothyronine transporter defects that are, in turn, associated with severe neurological sequelae.

• The Journal of Internal Korean Medicine
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• v.18 no.2
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• pp.305-331
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• 1997

So far we oriental medical doctors have referred to Shin(腎) as endocrine system, especially suprarenal gland, sexual gland and autonomic nervous system, thyroid etc. as well as kidney. But the sight on thyroid is weak and the relationship with Shin(腎) hasn't been suggested clearly. The purpose of this study is to find out the relationship between Shin(腎) with thyroid. The following are the results. 1. Ki Gi(氣機) of Shin(腎) is similar to the fuction of thyroid in that they are the base of human metabolism, influencing all the metabolism of human tissue. 2. Shin Yang(腎陽) and thyroid hormone are almost identical in that they are the base of Yang Gi(陽氣), the former as source of heat energy, the latter as energy hormone. 3. Shin(腎) and thyroid hormone are almost the same in that they activate growth of human body. 4. Ki Gi(氣機) of Shin(腎) such as Ju Gol(主骨), Saeng Su(生髓), Tong uh Noi(通於腦) is similar to the effects of thyroid hormone on bones, central nervous system and hair 5. The symptoms of deficiency of Shin Eum(腎陰虛) are almost identical with those of hyperthyroidism, so the process of Yang Hwa Gi(陽化氣) caused by exuberance of Yang due to deficiency of Shin Eum(腎陰虛陽亢) is similar to excessive metabolism caused by hyperthyroidism. 6. The process of Eum Seong Hyung(陰成形) caused by preponderance of Eum due to deficiency of Shin Yang(腎陽虛陰盛) is similar to the lowering of metabolism caused by hypothyroidism. 7. Deficiency of Shin Eum(腎陰虛) is similar to hyperthyroidism, deficiency of Shin Yang(腎陽虛) to hypothyroidism. But there are major difference in edema and the fuction of intestine. To conclude, Ki Gi(氣機) of Shin is similar to the function of throid in many respects. I hope that there will be further studies on the relationship beteen thyroid malfuction with deficiency of Shin Yang(腎陽虛) or of Shin Eum(腎陰虛) in the future.

• Medical Lasers
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• v.10 no.1
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• pp.37-44
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• 2021

Background and Objectives Hypothyroidism is the most common endocrine disease. On the other hand, there is no treatment that can improve the thyroid function. Low-level laser therapy (LLLT) can improve the cellular activity. The effect of hypothyroidism is not obvious. This study examined the effects of LLLT on the thyroid gland function of a propylthiouracil (PTU)-induced hypothyroidism mouse model. Materials and Methods Twenty-five male ICR mice were distributed into five groups of five animals each: Negative control (none PTU animal) and positive control (PTU animal) of unirradiated animals, and three experimental groups with LLLT (3J, 6J, and 12J). Each mouse was exposed to a distinct dose of a 632-nm laser once a week for three rounds. The positive control group and three LLLT groups were induced into a hypothyroidism state by PTU administration. The animals' thyroid-stimulating hormone and thyroxine levels were measured using an ELISA kit, and their thyroid tissue was harvested and analyzed after sacrifice at the end of the experiment. The hormone level and morphological changes in the tissue of the five groups were compared. Results The thyroid hormone levels in the control group and LLLT groups were similar. On the other hand, the thyroid tissue of the LLLT groups showed some morphological changes that were similar to those of iodine deficiency thyroid. Conclusion LLLT did not affect the thyroid gland function in PTU-induced hypothyroidism mice.