• The korean journal of orthodontics
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• v.25 no.6 s.53
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• pp.689-696
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• 1995

Effects of several cytokines($IL-1{\beta},\;TNF_{\alpha},\;and\;IFN_{\gamma}$) have been examined on fetal rat osteoblast-like cells. To investigate whether cytokines play direct causal roles in production of lysosomal enzyme, fetal rat osteoblast-like cells were treated with $IL-1{\beta},\;TNF_{\alpha},\;and\;IFN_{\gamma}$, respectively or combined. And acid phosphatase was determined by biochemical method. Alkaline phosphatase was assayed to determine the effects of $IL-1{\beta},\;TNF_{\alpha},\;and\;IFN_{\gamma}$ on the expression of this enzyme. And also experiment of calcified nodule formation was performed to assess the effects of cytokines on the bone-forming activity of osteoblast-like cells in vitro. Acid phosphatase activity was significantly increased by the addition of $IL-1{\beta}\;and\;TNF_{\alpha}$, whereas decreased by $IFN_{\gamma}$. However, no significant change:: in alkaline phosphatase activity was observed when the osteoblast-like cells were treated with $IL-1{\beta}\;and\;TNF_{\alpha}$. Interestingly, $IFN_{\gamma}$ showed stimulatory effect on alkaline phosphatase activity. The number of calcified nodules was decreased by treatment of cultures with 1 ng/ml $IL-1{\beta},\;20\;ng/ml\;TNF_{\alpha}$, and 500 u/ml $IFN_{\gamma}$ continuously for 21 days, while considerable number of calcified nodules were formed in control group of osteoblast-like cell in culture for 21 days. These results seem to suggest that cytokines may play crucial roles in bone remodeling through the direct action on the osteoblast-like cell.

• Clinical and Experimental Pediatrics
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• v.51 no.8
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• pp.874-878
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• 2008

Purpose : This study was undertaken to develop an animal model of periventricular leukomalacia (PVL) induced by in utero clamping of pregnant rat aorta in fetal rats. Methods : A timed pregnanct Sprague-Dawley rat on embryonic day 21 just prior to delivery was sedated and anesthetized, and a Harvard ventilator for small animals was applied. Following laparotomy, the maternal aorta was clamped reversibly for 40 minutes using a surgical clip. The fetal rats were then delivered by Cesarean section, resuscitated if necessary, and reared by a surrogate mother rat until postnatal day 21 to obtain the brain specimen. After systemic perfusion and fixation, $10{\mu}m$ thick serial brain sections were obtained and stained for pathologic examination and assessment of ventriculomegaly. Ventriculomegaly was assessed by the measured ventricle to total brain volume ratio. Results : Eight out of eleven fetal rats (73%) survived in the ischemia group after induction of in utero ischemia by clamping maternal rat aorta, and all ten survived in the control group. Body and brain weights measured at postnatal day 21 were significantly lower in the ischemia group compared to the control group. In pathologic findings, significant ventriculomagaly ($3.67{\pm}1.21%$ vs. $0.23{\pm}0.06%$) was observed in the ischemia group compared to the control group; although cystic lesion was not observed, mild (n=6) and moderate (n=2) rerefaction of the brain tissue was observed. Conclusion : A fetal rat model of PVL induced by in utero clamping of pregnant rat aorta was developed.

• BMB Reports
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• v.34 no.6
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• pp.573-577
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• 2001

The mammalian heart is known to undergo significant mechanical changes during fetal and neonatal development. The objective of this study was to define the ontogeny of the ryanodine receptor/$Ca^{2+}$ release channel and SERCA that play the major roles in excitation-contraction coupling. Whole ventricular homogenates of fetal (F) (19 and 22 days in gestation), postnatal (N) (1 and 7 days postnatal), and adult (A) (5 weeks postnatal) Sprague-Dawley rat hearts were used to study [$^3H$]ryanodine binding and oxalate-supported $^{45}Ca^{2+}$ uptake. For the ryanodine receptor, the major findings were: (1) The ryanodine receptor density, as determined by maximal [$^3H$]ryanodine binding ($B_{max}$), increased 3 fold between the F22 and A periods ($0.26{\pm}0.1$ vs. $0.73{\pm}0.07$ pmoles/mg protein, p<0.01), whereas there was no significant change during the F22 and N1 development phases ($0.26{\pm}0.1$ vs. $0.34{\pm}0.01$). (2) Affinity of the ryanodine receptor to ryanodine did not significantly change, as suggested by the lack of change in the $K_d$ during the development and maturation. For SERCA, changes started early with an increased rate of $Ca^{2+}$ uptake in the fetal periods (F19: $8.1{\pm}1.1$ vs. F22: $19.3{\pm}2.2$ nmoles/g protein/min; p<0.05) and peaked by 7 days (N7) of the postnatal age ($34.9{\pm}2.1$). Thus, we conclude that the quantitative changes occur in the ryanodine receptor during myocardial development. Also, the maturation of the $Ca^{2+}$ uptake appears to start earlier than that of the $Ca^{2+}$ release.

• Korean Journal of Veterinary Research
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• v.43 no.4
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• pp.531-539
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• 2003

Changes in the rat testis interstitium from birth to adulthood were studied using Sprague Dawley rats of 1, 7, 14, 21, 28, 40, 60, and 90 days of age to investigate Leydig cell differentiation. In addition, serum testosterone concentrations and luteinizing hormone stimulated (LH; 100 ng/ml) testosterone secretory capacity per testis in vitro were determined via radioimmunoassay. Fetal Leydig cells were present in rat testes from birth to 21 days, and they were only steroidogenic cells in the testis at days 1 and 7. The average volume of a fetal Leydig cell and the absolute volume of fetal Leydig cell per testis were similar at all ages of experimental groups except at day 21 when lower values were observed for both parameters. The number of fetal Leydig cells per testis remained constant from birth through 21 days. Adult Leydig cells were recognized at day 14 and their absolute volume and number per testis increased linearly from 14 to 90 days. The average volume of an adult Leydig cell increased significantly with age and reached maximum size by 60 days of age where the volume was nearly three times bigger than that of at day 14. Total testosterone production per testis in vitro and serum testosterone concentrations were not significantly different at day 1 compared with 7, 14, and 21 days of age. Significant increases were observed at days 40 and 60. Values at days 60 and 90 were not significantly different.

• Animal cells and systems
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• v.5 no.4
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• pp.327-331
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• 2001

There is a critical developmental period during which brain sexual differentiation proceeds irreversibly under the influence of gonadal hormone. Recently, kinesin superfamily-associated protein 3 (KAP3) gene expressed during the 'critical period' of rat brain differentiation was identified by us (Choi and Lee, 1999). KAP3 functions as a microtubule-based motor that transports membranous organelles anterogradely in cells, including neurons (Yamazaki et al., 1996). mRNA level of KAP3 gene markedly increased before the initiation of puberty. Neonatal treatment of estrogen clearly inhibited the prepubertal increase in KAP3 mRNA level (Choi and Lee, 1999). In the present study, we aimed to investigate the effects of polychlorinated biphenyls (PCBs), as endocrine disruptors (EDs) on the expression of KAP3 gene during the 'critical period' of rat brain development. In our data, PCBs significantly decreased the expression of KAP3 gene in the fetal (day 17) and the neonatal (day 6 after birth in) male and female rat brains. The body weight and the breeding ability were significantly decreased in the PCBs-exposed rats compared with the control. These results showed that PCBs affect the transcriptional level of brain sexual differentiation related gene, KAP3, in the fetal and the neonatal rat brains. The maternal exposure to the PCBs may lead to toxic response in embryonic brain sexual differentiation and breeding ability after sexual maturation. This study indicates that KAP3 gene may be useful as a gene marker to analyze the molecular mechanism of toxic response in the animal brain development and sexual maturation exposed to PCBs.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.342-347
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• 2003

The enzyme $20{\alpha}$-hydroxysteroid dehydrogenase ($20{\alpha}$-HSD) catabolizes progesterone to $20{\alpha}$-dihydroprogesterone ($20{\alpha}$-OHP), and is appeared in rat corpora luteal and placenta. A polled samples of 10-15 placental and ovarian tissues collected from each individual rat were subjected to measurement of $20{\alpha}$-HSD activity. A $20{\alpha}$-HSD activity in the cytosol fraction was based on the generation of NADPH. In this study, it is designed to study cytosolic $20{\alpha}$-HSD activity in rat ovarian and placenta during pregnancy, and its relationship to embryonic mortality. It was found that from days 5 to 18 of pregnancy the $20{\alpha}$-HSD activities steady by decreased but at parturition time rapidly increased in ovary. On the other hand, placental cytosolic $20{\alpha}$-HSD activities were high detected from days 8 to 10 of pregnancy, not detectable from days 11 to 20 of pregnancy, but again very high at the time of parturition. Analysis of DEAE column chromatography revealed that two different types of $20{\alpha}$-HSD (HSD-1 and HSD-2) were found with similar activity in the placental cytosol on day 10 of pregnancy. The number of fetuses on day 10 of pregnancy was 15.4 and decreased significantly to 12.9 on day 12. The results suggested that expression of $20{\alpha}$-HSD in the placental tissues seems to be related the number of fetal survived in the specific time (days 11 and 12) which spontaneous fetal loss occurs.

• Journal of Nutrition and Health
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• v.56 no.6
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• pp.655-666
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• 2023

Purpose: Gestational nutrition has an impact on the growth and development of the fetus. Choline (C) and docosahexaenoic acid (DHA) are important and essential nutrients for humans that play a role in the structural integrity of the membranes as well as signalling. C is used in the synthesis of phosphatidylcholine, and cell membranes are highly enriched with DHA. The dietary intake of C or DHA during pregnancy directly influences fetal development. Currently, there is no evidence to prove the effectiveness of the combined dietary supplementation of both C and DHA during gestation on developmental outcomes in the offspring. Methods: The current study was designed to assess the physical, sensory, and motor development of rat pups born to mothers supplemented with C and/or DHA during the entire gestational period. Pregnant rat dams were divided into the following five groups: Normal control (NC), Saline control (SC), Choline (C), DHA, and Choline+DHA (C+DHA). The NC dams did not receive any supplementation during the entire gestation period. The experimental groups were supplemented with Saline, C, and/or DHA, respectively, during the entire gestation (E0 to delivery). Results: Rat pups (n = 6/group) exposed to combined C and DHA showed significant improvement in birth weight, fur development, eye-opening as well as weight gain on the 7th, 14th, and 21st postnatal day and pinnae detachment (assessed from birth to postnatal day 21) when compared with age-matched NC, SC or C or DHA pups. Further, significant reflex responses were observed in visual placing and bar holding of pups exposed to both C and DHA, whereas the differences in surface righting, negative geotaxis, and grasping reflexes were not significant between the groups. Conclusion: Gestational supplementation of both C and DHA rather than either of them alone is better in enhancing developmental outcomes in rat pups.

• Toxicological Research
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• v.17 no.2
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• pp.83-90
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• 2001

The background control data were compiled from rat developmental toxicity studies con-ducted at Toxicology Research Center, KRICT during the 1993-1999 period. These data were assembled in order to provide background in formation for the maternal and fetal data collected in 13 developmental toxicity studies using Sprague-Dawley rats. A total of 325 mated females were used in these studies during the seven-year period and overall pregnancy rate of these females was 93.8%. The present background control data included body weights, food consumption, hematological values, and organ weights of pregnant females, caesarean section data, and fetal examination data. These data can be used not only as a historical database for the meaningful interpretation of data from reproductive and developmental toxicity studies, but also as a contribution to biological characterization oj Sprague-Dawley rats.

• Applied Microscopy
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• v.15 no.2
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• pp.19-30
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• 1985

Morphogenesis of rat spleen was studied by light and electron microscope from the fetal stage till the newborn or adult stages. The results indicate as follows: at the 14th day of gestation rat spleen, as an early form, consists of intercellular spaces and mesenchymal cells. And at this stage the spleen is in a premature state, then it appears its adult condition in structures after the 7th postnatal day. Erythropoiesis is shown to be an active process in rat spleen beginning about the 18th day of gestation, and once established the process continues at least till the 7th postnatal day. At the 20th day of gestation, there are splenic nodules, trabeculae, venous sinus, and granular leucocytes such as neutrophils and basophils in rat spleen. Lymphocytes appeared to be well differentiated at the 7th postnatal day and were present till the adult stage. While degenerating erythrocytes are phagocytosed by macrophages. In conclusion, rat spleen started to be appeared from the 14th day of gestation and erythropoiesis in rat spleen was carried out for about 10 days between prenatal and postnatal stage. Erythrophagocytosis was accomplished by macrophages and it is suggested that the proper functions of rat spleen set off from the 7 th postnatal day when its structures are similar to the adult's.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.150-156
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• 1999

The induction of proliferation of adult rat islets was investigated under various culture conditions. The islets were isolated from male Sprague-Dawley rats and subsequently embedded in collagen gels, which mimic the in vivo three-dimensional surroundings. During the culture period, the effects of heterologous serum (fetal bovine serum, FBS), epidermal growth factor (EGF), and retinoic acid (RA) on islet growth were examined with respect to the morphological and total DNA content changes. To investigate these changes at the cellular level, whole mount immunocytochemistry using specific antibodies for insulin and glucagon was performed. The results showed that (i) collagen gels as an extracellular matrix can maintain islets in a similar way to that in vivo, (ii) heterologous serum (FBS) had stimulatory effects on islet proliferation in a dose-dependent manner, (iii) RA had inhibitory effects on islet proliferation induced by the serum in a dose-dependent manner, (iv) EGF had weak inhibitory effects on islet proliferation induced by the serum except at the concentration of 10 nM where its effect was not significant, and (v) whole mount immunocytochemistry revealed that newly proliferated islet cells were mainly $\beta$-and $\alpha$-cells.