• 한국수정란이식학회지
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• 제25권4호
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• pp.259-262
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• 2010

Optimization of the preimplantation mammalian embryo culture condition was widely focused on refining medium composition under the name of chemically defined media. However, recent research revealed that the alteration of physical environment can be a crucial factor to a successful embryo development. In this study, under the same embryo density, a novel culture device named oil-free micro tube culture (MTC) system was evaluated using porcine parthenogenetic embryos. The activated oocytes were placed into the 0.2 ml thin-wall flat cap PCR tube and cultured to the blastocyst stage. As a preliminary step, embryo density and culture medium volume were optimized under a standard drop culture system. The optimal embryo density range for in vitro culture was 0.5 embryos per ${\mu}l$ in $20\;{\mu}l$ drop (20.5%) and 1.0 embryos per ${\mu}l$ in $10\;{\mu}l$ drop (20.6%). Based on these results, we compared drop culture system and 'MTC' system in terms of the developmental rate to the blastocyst stage. In $20\;{\mu}l$ medium volume, the 'MTC' system showed similar blastocyst formation rate when compared with drop culture system (20.2% versus 20.5%, respectively) while the 'MTC' system showed lower blastocyst formation rate than drop culture system in $10\;{\mu}l$ one (12.7% versus 20.0%, respectively). Therefore the $20\;{\mu}l$ MTC system may be an alternative incubation system for short-distance embryo transport without carrying the $CO_2$ incubator and this provides novel embryo culture device to clinical veterinary embryologists.

• 대한치과교정학회지
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• 제21권2호
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• pp.341-351
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• 1991

Dental maturity is one of the index of physiological maturity indicators. To investigate the relationship between dental maturity and chronological age, the author took the orthopantomograms of 984 students, aged 7 through 17 years, having normal occlusion. The orthopantomograms were examined and calcification degree of each tooth on the left side was rated according to the method described by Demirjian. On the basis of findings of this study, the following results were obtained. 1. The root completion periods of mandibular permanent teeth were as follows; Central Incisor M $8.32{\pm}1.03\;years$ F $7.96{\pm}1.04\;years$ Lateral Incisor M $9.40{\pm}1.30\;years$ F $9.01{\pm}0.90\;years$ Canine M $12.81{\pm}1.24\;years$ F $11.42{\pm}0.94\;years$ 1st Premolar M $12.76{\pm}1.74\;years$ F $12.19{\pm}1.33\;years$ 2nd Premolar M $13.31{\pm}1.88\;years$ F $12.88{\pm}1.49\;years$ 1st Molar M $9.60{\pm}1.69\;years$ F $9.30{\pm}1.16\;years$ 2nd Molar M $14.38{\pm}1.73\;years$ F $13.96{\pm}1.63\;years$ 2. Sexual differences in same age group at given calcification stage were not significant statistically. 3. The developmental order in mandibular permanent teeth was as follows; a) central incisor, b) lateral incisor, c) 1st molar, d) canine and 1st premolar, e) 2nd premolar, f) 2nd molar.

• Reproductive and Developmental Biology
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• 제29권3호
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• pp.145-147
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• 2005

Autocrine or paracrine mediators released by the early embryo are implicated in the support of embryonic development. Their mechanisms and optimal embryo density in the medium, however, are uncertain. This study was conducted to establish the optimal embryo density and culture medium volume in mouse parthenogenetic embryo culture. In experiment 1, culture of parthenogenetirally activated oocytes at a concentration of $2{\~}4$ embryos/${\mu}L$ significantly improved development to the blastoryst stage ($72{\%}{\leq}$) compared with culture at the lower ($0.2{\~}1$e mbryos/${\mu}L,\;0\~37.5\%$) and the higher ($5{\~}6$ embryos/${\mu}L,\;30\~53\%$) concentration for 120 h when the oocytes were cultured in a 5 ${\mu}L$ drop under mineral oil In experiment 2, the embryos cultured at a concentration of $2{\~}4$ embryos/${\mu}L$ in a 10 ${\mu}L$ drop ($81.1{\%}$) showed significantly higher blastocyst rates than those in a 5 ${\mu}L$ drop ($68.5{\%}$). This study optimizes in vitro culture condition by modifying embryo density and the volume of culture medium It may give appropriate level of autocrine and/or paracrine factors to enhance viability and subsequent normal development of mouse parthenogenetic embryos in vitro.

• Reproductive and Developmental Biology
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• 제29권2호
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• pp.117-120
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• 2005

This study was conducted to establish the optimal temperature condition before oocyte activation in B6m F1 mouse. In experiment 1, two embryo culture media (CZB vs KSOM) were evaluated for the development of activated mouse oocytes. Parthenogenetic embryos cultured in KSOM showed better blastocyst development than ones cultured in CZB $(56.2\%\;vs\;81.0\%\;p<0.01)$. Two-hour of pre-incubation before activation significantly reduced the number of hatched blastocysts in KSOM $(22.0\%\;versus\;8.8\%\;p<0.05)$. In experiment 2, recovered oocytes were pre-incubated at different temperature conditions before activation. The experimental groups were divided by 5 as follows. Group A: pre-incubation for 120 min at $37^{\circ}C$, Group B: pre-incubation at $37^{\circ}C$ for 90 min then at $25^{\circ}C$ for 30 min, Group C: pre-incubation at $37^{\circ}C$ for 60 min then at $25^{\circ}C$for 60 min, Group D: pre-incubation at $37^{\circ}C$ for 30 min then at $25^{\circ}C$ for 90 min, and Group E: pre-incubation at $25^{\circ}C$ for 120 min before activation. Group A $(67.6\%)$ and B $(66.7\%)$ showed better development to the blastocyst stage than other groups $(Group\;C:\;50.0\%\;Group \;D:\;49.2\%\;Group\;E:\;33.3\%,\;p<0.05)$. The present study indicates that the temperature before activation affects the development of B6D2 F1 mouse parthenogenetic oocytes and exposure to room temperature should be limited to 30-min when the oocytes are left in HEPES-buffered medium for micromanipulation.

• 한국수정란이식학회지
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• 제24권2호
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• pp.105-108
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• 2009

This study was designed to investigate the effect of kinetin on in vitro development of parthenogenetic porcine oocytes exposed to demecolcine prior to activation. In vitro matured metaphase II stage oocytes were incubated in 0 or 2 ${\mu}$g/ml demecolcine supplemented defined culture medium for 3 h and the oocytes were activated electrically. The parthenogenetic porcine embryos were then cultured in 0 or 200 ${\mu}$M kinetin supplemented defined culture medium for 7 days. Regardless of demecolcine treatment, kinetin supplementation increased blastocyst rates significantly (7.0% versus 12.1% and 4.9% versus 8.5%; Control versus Kinetin and Demecolcine versus Kinetin + Demecolcine, respectively, p<0.05). Demecolcine treatment before activation tended to decrease blastocyst rates regardless of kinetin supplementation although it is not statistically significant. Total cell numbers in the blastocysts also tended to be elevated in embryos when supplemented with kinetin, however only the result between Kinetin and Demecolcine groups is statistically significant (37.6 ${\times}$ 7.2 versus 28.1 ${\times}$ 9.5, respectively, p<0.05). In conclusion, the present report shows that kinetin enhances developmental competence of parthenogenetic porcine embryo regardless of demecolcine pre-treatment before parthenogenetic activation when they were developed in defined culture condition.

• 대한소아치과학회지
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• 제48권4호
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• pp.414-424
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• 2021

이 후향적 연구의 목적은 한국 성장기 아동의 수직적인 안모 형태와 성별에 따라 골격적 성숙도와 치아의 성숙도를 평가하는 것이다. 총 184명의 8 - 14세 소아∙청소년을 대상으로 진행하였다. 하악평면각을 기준으로 3개의 군으로 나누었으며 성별 간 비교를 위해 3개의 군을 각각 남아와 여아의 하위 군으로 나누었다. 골격적 성숙도와 치아 성숙도는 측모두부 방사선 사진, 수완부 방사선 사진, 파노라마 방사선 사진으로 평가하였다. 수직적 성장군은 수평적 성장군보다 경추골 및 수완부 골의 높은 성숙도를 보였다. 치아 성숙도는 수직적 성장군에서 가장 높았다. 남아보다 여아에서 골격적 성숙도가 더 높았으며 치아 성숙도는 성별 간 유의한 차이는 관찰되지 않았다. 환자의 수직적 안모 형태 분석은 교정치료 시작 시기 결정에 도움이 되는 보조지표를 제공할 수 있으며, 수직적 안모 형태를 보이는 환자의 경우 교정치료를 조기에 시작하는 것을 고려할 수 있다.

• Molecules and Cells
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• 제43권6호
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• pp.581-589
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• 2020

Neurons have multiple dendrites and single axon. This neuronal polarity is gradually established during early processes of neuronal differentiation: generation of multiple neurites (stages 1-2); differentiation (stage 3) and maturation (stages 4-5) of an axon and dendrites. In this study, we demonstrated that the neuron-specific n-glycosylated protein NELL2 is important for neuronal polarization and axon growth using cultured rat embryonic hippocampal neurons. Endogenous NELL2 expression was gradually increased in parallel with the progression of developmental stages of hippocampal neurons, and overexpression of NELL2 stimulated neuronal polarization and axon growth. In line with these results, knockdown of NELL2 expression resulted in deterioration of neuronal development, including inhibition of neuronal development progression, decreased axon growth and increased axon branching. Inhibitor against extracellular signal-regulated kinase (ERK) dramatically inhibited NELL2-induced progression of neuronal development and axon growth. These results suggest that NELL2 is an important regulator for the morphological development for neuronal polarization and axon growth.

• 한국융합학회논문지
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• 제12권6호
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• pp.39-47
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• 2021

이 연구는 치아발육단계에서 성장호르몬 결핍의 영향을 알아보기 위해서 성장호르몬 결핍이나 특발성 저신장 소아와 정상 소아 간의 차이를 분석하는 것을 목적으로 한다. 영남대학교 의과대학 부속병원 소아청소년과에서 저신장으로 진단받은 소아들을 성장호르몬 결핍인 대상자와 특발성 저신장 소아로 분류하였다. 구강 파노라마와 신체지수를 계측하여 치아발육과의 관계를 분석하였다. 성장호르몬 결핍성 저신장 소아와 특발성 저신장 소아 간의 유의한 차이는 측절치에서만 나타났다. 성장호르몬 결핍성 저신장 소아와 정상 소아 간에는 모든 치아에서 성장호르몬 결핍성 저신장 소아의 발육이 유의하게 늦은 것으로 나타났다. 결론적으로 저신장 소아에서 성장호르몬 결핍성 저신장 소아나 특발성 저신장 소아 모두 신장뿐만 아니라 치아 발육 역시 영향을 받은 것으로 나타났다. 이 연구는 향후 저신장 소아의 교정치료 프로토콜의 기초자료를 제시할 수 있을 것으로 기대한다.

• 대한소아치과학회지
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• 제24권4호
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• pp.795-804
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• 1997

Developmental dental morphological anomalies are fusion, gemination, twinning, concrescence and etc. They may cause many problems in conservative, periodontal and esthetic aspects. Fusion is a condition where two separate tooth buds unite at some stage in their development to form a bifid crown. If tooth contact occurs early, at least before the start of calcification, the two teeth may be completely unites to form a single large tooth. If tooth contact occurs after the time when a portion of the tooth crown has completed its formation, there may be union of the roots only. In fusion the dentin is always confluent. Fusion teeth is more common in the deciduous than in the permanent dentition. Fused teeth are relatively rare, and are mostly mandibular anterior teeth. Fusion of normal and supernumerary teeth or between normal teeth may occurs. The exact etiology factor of fusion is unknown, but genetic and environmental factors seems to be related. A variety of complications and subsequent treatments have been suggested on this teeth. Periodontal conditions may arise due to a groove formed at the line of fusion of the two teeth. Crowding or Protrusion with potential for malocclusion or delayed eruption of adjacent teeth. Fusion teeth appear in the anterior region, they usually cause esthetic problems. Treatments vary depending on the problem, the location, and the extent of fusion. Treatment of fused teeth has been reported from endodontic, orthodontic, periodontic, surgical and multidisciplinary. This report presents the esthetic improvements by separation of two clinical crowns. Bone reduction or endodontic treatments are not required.

• 부모자녀건강학회지
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• 제4권2호
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• pp.56-72
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• 2002

Web sites on the internet are getting major resources to gain information related to child care. Though the numerous web sites deliver child care information, they have never been evaluated with criteria before. The purpose of this study is to identify existence and organization of child care portal sites and to analysis their contents, therefore to suggest guidelines for parents. The survey was conducted from Sep. 1. to Oct. 30., 2001. by means of Lycos Korea and Daum search engine and finally 45 portal sites related to child care were selected eliminating the commercial and personal homepages. The results were as follows: 1. Most of the sites(95.6%) were operated by corporations without registration(82.2%). Consultants were mostly professional (71.1%). 2. The contents were analyzed 4 categories including 19 themes. 3. Diet & Nutrition category include weaning food, breast feeding, bottle feeding and snack. The recipe and type of weaning food on months were topped(64.44%). 4. Infant Care category include bathing, sleeping, clothes, skin care and cord care. bathing method and heat of bathing water were topped(44.44%). 5. Growth & Development category was consisted of developmental characteristics, dental growth, play & exercise and learning & guidance. Developmental stage and motor development were topped (62.22%). 6. Health maintenance & promotion category was consisted of emergency care, prevention of accidents, vaccination, common pediatric disease and parental role. Care of diarrhea, constipation and fever, and precautions for vaccination were topped(48.89%).