• Applied Microscopy
• /
• 제21권2호
• /
• pp.1-13
• /
• 1991

In order to investigate the factors of the control mechanism of somitogenesis, early chick embryos (H-H stage $8{\sim}13$) were treated with heat shock, ${\alpha}$-amanitin and cycloheximide and morphological changes of somite were examined by light microscopy, transmission and scanning electron microscopy. In normal chick embryo, somites were formed from the somitomere which preexisted in segmental plate. Somites were wrapped with extracellular collagen fibrils and connected with neural tube, notochord and ectoderm. And then, somites were differentiated to sclerotome, dermatome and myotome by the interaction of nervous tissue. Abnormal somites were observed after formation of six or seven so mites in heat shock treated group. Amounts of collagen fibrils were obviously decreased in this group. In cycloheximide treated group, most so mites were smaller and neural tube formation was incomplete. Chromatins were condenced and formed several heterochromatins in the nucleus of somite cells. Lipid like cytoplasmic dense mass and lipid droplets were also observed. Segmentation of somites seemed to be normal progress in ${\alpha}$-amanitin treated group. Center of somite, however, hollowed in longitudinal sectioned samples. These results suggested that so mites were already existed in the segmental plate as the form of somitomere. Segmented somites were contacted with neural tube or notochord and the somites were tightly connected with each other by the extracellular collagen fibrils which were secreted from neuroepithelium and somite cells. Somites are thought to differentiate into sclerotome, dermatome and myotome by these interactions.

• Annals of Coloproctology
• /
• 제34권6호
• /
• pp.317-321
• /
• 2018

Purpose: We evaluate the role of transanal tube drainage (TD) as a conservative treatment for patients with anastomotic leakage (AL). Methods: Patients treated for AL who had undergone a low or an ultralow anterior resection with colorectal or coloanal anastomosis for the treatment of rectal cancer between January 2013 and January 2017 were enrolled in this study. The data were collected prospectively and analyzed retrospectively. The primary outcomes were the diagnosis and the management of AL. Results: Two hundred thirteen consecutive patients, 122 males and 91 females, were included. The mean age was $66.91{\pm}11.15years$, and the median body mass index was $24kg/m^2$ (range, $20-35kg/m^2$). The median tumor distance from the anal verge was 8 cm (range, 4-12 cm). Ninety-three patients (44%) received neoadjuvant therapy for nodal disease and/or locally advanced rectal cancer. Only 13 patients (6%) developed AL. Six patients developed subclinical AL as they had a defunctioning ileostomy at the time of the initial procedure. They were treated conservatively with TD under endoscopic guidance in the endoscopy unit and received intravenous antibiotics. Six weeks after discharge, these 6 patients underwent follow-up flexible sigmoidoscopy which showed a completely healed anastomotic defect with no residual stenosis. Seven patients developed a clinically significant AL and required reoperation with pelvic abscess drainage and Hartmann colostomy formation. Conclusion: These results suggest that TD for management of patients with AL is safe, cheap, and effective. Salvaging the anastomosis will help decrease the need for Hartmann colostomy formation. Proper patient selection is important.

• Toxicological Research
• /
• 제11권2호
• /
• pp.169-173
• /
• 1995

The effects of tumor necrosis factor alpha $(TNF-{\alpha})$ on growth and tubular formation of bovine aortic endothelial cells were examined using an in vitro angiogenesis model system. The growth of endothelial cells was enhanced in a dose-dependent manner when the cells were cultured with $TNF-{\alpha}$ for 3 days, but $TNF-{\alpha}$, at the concentration of 1 nM or higher, produced a growth inhibition of endothelial cells when the cells were cultured for 8 days. The endothelial cells incubated with $TNF-{\alpha}$ for 48-h exhibited a typical morphologic change. Then, they showed a fibroblastoid organization of overlapping, elongated, and spindle-shaped cells. $TNF-{\alpha}$, at the concentration of O. 1 nM or higher, inhibited the tubular formation of vascular endothelial cells in an in vitro anglogenesis model using a 3-dimensional culture system.

• 한국세라믹학회지
• /
• 제37권4호
• /
• pp.332-337
• /
• 2000

Forming mechanism of fibrous TiC during self-propagating high temperature synthetic reaction was analyzed and suggested. It was revealed that critical temperature for the stable fiber formation was not the melting point of TiC, but the eutectic reaction temperature of TiC and C. Minimum amount of TiC diluent addition required to form fibers was calculated to be 25.6%, which was consistent with the experimental result. Synthesized fibers were found hollow tube-like. The morphology was explained by the diffusion rates of C and Ti in TiC, and by the molar volume chnage of C during the reaction. Expanding shell model was suggested for the hollow fiber formation mechanism.

• Restorative Dentistry and Endodontics
• /
• 제7권1호
• /
• pp.71-75
• /
• 1981

Five different labelled composite resin, Hypol (Korea), Glass-Ionomer (Japan), Simulate (U.S.A.), Durafil (U.S.A.) and Microfil (U.S.A.) were collected to employ for this experimental study. The purpose of the study is to determine the effect of finger pressure technic and traditional filling by means of plastic instruments on porosity formation in composite materials. Each material with pressure and non-pressure cases were carefully examined under electron microscope. Following were the results obtained through the study. 1. Pressured cases showed smaller number of porosity and the size of porosity was significantly smaller than non-pressured cases in each mateial. 2. Glass-Ionomer with pressure cases were seen as tube-like appearance because of pressured small porosities communicate in a certain direction. 3. Durafil cases both pressured and non pressured, appeared the least porosity formation. among the materiats. 4. Border line between the outmost periphery of the porosity and matrix of the resin in both pressured or non-pressured eases were found characteristically clear in Mierofil cases.

• 대한미생물학회지
• /
• 제3권1호
• /
• pp.43-49
• /
• 1968

Japanese encephalitis(JE) shows its explosive epidemicity in the temperate zone of Asia but little is known on the overwintering mechanism. One of the hypotheses on the overwintering mechanism is that the virus overwinters in the hibernating animals. There has been no report on the proliferation of JE virus(JEV) or antibody formation in the snakes. The purpose of this experiment is to explore the mutual relationship between JEV and snake and to clarify whether JEV proliferates and induce antibody formation in snakes. Three species of non-poisonous common snakes were employed. Precipitation test was carried out after injecting calf serum and, HI and neutralization tests were done by injecting JEV into the snakes. The gamma globulin fraction of pre- and post-injection serum were compared by paper chromatography. According to the results, precipitating antibody reaction to calf serum could be observed only at $4^{\circ}C$. It was failed to demonstrate HI antibody formation but neutralizing antibody could be detected in one of the 9 snakes. Although antibody could not be detected in test-tube, tile result of paper chromatography shows the remarkable increase of gamma globulin fraction after the injection. Above results are strongly indicating the antibody formation in the snakes.

• 대한본초학회지
• /
• 제26권3호
• /
• pp.83-90
• /
• 2011

Objectives : This study was performed to investigate the influence of black ginseng radix extracts (BG) and ginsenoside Rg3, Rg5 on basic fibroblast growth factor (bFGF) induced proliferation, migration and capillary tubule-like formation of human umbilical vein endothelial cells (HUVECs). Methods : HUVECs were cultured with BG and ginsenoside Rg3, Rg5 at different concentrations (60, 125, 250, 500, $1,000{\mu}g/m\ell$) for 2 day In the presence of bFGF, respectively. XTT was used to detect the proliferation. Migration and tube formations were examined to detect the antiangiogenesis. Also, the chick embryo chorioallantoic membrane (CAM) assay was performed to detect the antiangiogenesis. Results : BG and ginsenoside Rg3, Rg5 significantly inhibited bFGF-induced endothelial cell proliferation and migration in a dose-dependent manner. Tube formation in bFGF-induced HUVECs were suppressed by BG and ginsenoside Rg3, Rg5. Moreover, BG and ginsenoside Rg3, Rg5 (30-$50{\mu}g$/egg) inhibited new blood vessel formation on the growing CAM. Conclusions:Based on the present results, it can be suggested that BG has a potential chemopreventive agent via antiangiogenesis.

• 한국결정성장학회지
• /
• 제4권2호
• /
• pp.178-189
• /
• 1994

$BaTiO_3$ 미분말은 여러종류의 0.05 M 출발용액으로부터 초음파 분무 열분해법으로 합성하였다. 이때, 유속은 0.5 cm/sec, 저온로는 $300^{\circ}C$, 고온로는$700^{\circ}C$로 고정하였다. 입자의 형성과정은 반응 단계별로 포집된 분말을 SEM으로 직접 관찰하였고 또한, 반응기내에서의 입자의 거동을 이론적으올 고찰하고자 하였다. 순수한 $BaTiO_3$ 미분말은 출발용액이 nitrate aqueous solution인 경우에 합성이 가능하였다. 합성된 미분말은 19.1 nm의 일차입자들로 구성된 porous한 약 $0.42 {mu}m$크기의 구형의 이차임자였다. 형성과정은 건조단계에서 입자의 크기가 감소한 후 열분해 초기단계에서 증가하고 반응이 진행됨에 따라 점차 다시 감소하여 최종 $0.42 {mu}m$의 고화된 입자로 되었고 입도분포는 반응이 진행됨에 따라 점차 넓어졌다. 또한, 반응기내에서 입자들의 이론적 거동은 반응기 중심쪽으로 향하여 진행된다.

• 한국추진공학회지
• /
• 제25권3호
• /
• pp.56-61
• /
• 2021

본 연구에서는 극초음속 비행체의 냉각제로 사용되는 액체탄화수소 연료와 흡열 촉매의 안정적 사용을 위해 Al₂O₃와 H-ZSM-5를 stainless steel tube 내벽에 코팅하는 연구를 수행하였다. 액체탄화수소 연료의 흡열분해 반응에서 coke 생성이 불가피하며, stainless steel tube reactor를 냉각채널로 사용하게 됨에 따라 Fe, Ni 금속이 filamentous coke 생성을 유발한다. 이에 따라 stainless steel에 H-ZSM-5를 코팅함으로써, Fe과 Ni 금속이 액체탄화수소 연료에 직접 노출되는 것을 방지하고 filamentous coke 생성을 억제하고자 하였다. 또한 stainless steel과 H-ZSM-5 사이에는 Al₂O₃을 코팅하여, 부착 강도를 증진 시키고자 하였다.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제39권
• /
• pp.8.1-8.8
• /
• 2017

Background: For an effective bone graft for reconstruction of the maxillofacial region, an adequate vascular network will be required to supply blood, osteoprogenitor cells, and growth factors. We previously reported that the secretomes of bone marrow-derived mesenchymal stem cells (MSC-CM) contain numerous growth factors such as insulin-like growth factor (IGF)-1, transforming growth factor $(TGF)-{\beta}1$, and vascular endothelial growth factor (VEGF), which can affect the cellular characteristics and behavior of regenerating bone cells. We hypothesized that angiogenesis is an important step for bone regeneration, and VEGF is one of the crucial factors in MSC-CM that would enhance its osteogenic potential. In the present study, we focused on VEGF in MSC-CM and evaluated the angiogenic and osteogenic potentials of MSC-CM for bone regeneration. Methods: Cytokines in MSC-CM were measured by enzyme-linked immunosorbent assay (ELISA). Human umbilical vein endothelial cells (HUVECs) were cultured with MSC-CM or MSC-CM with anti-VEGF antibody (MSC-CM + anti-VEGF) for neutralization, and tube formation was evaluated. For the evaluation of bone and blood vessel formation with micro-computed tomography (micro-CT) and for the histological and immunohistochemical analyses, a rat calvarial bone defect model was used. Results: The concentrations of IGF-1, VEGF, and $TGF-{\beta}1$ in MSC-CM were $1515.6{\pm}211.8pg/mL$, $465.8{\pm}108.8pg/mL$, and $339.8{\pm}14.4pg/mL$, respectively. Tube formation of HUVECs, bone formation, and blood vessel formation were increased in the MSC-CM group but decreased in the MSC-CM + anti-VEGF group. Histological findings suggested that new bone formation in the entire defect was observed in the MSC-CM group although it was decreased in the MSC-CM + anti-VEGF group. Immunohistochemistry indicated that angiogenesis and migration of endogenous stem cells were much more abundant in the MSC-CM group than in the MSC-CM + anti-VEGF group. Conclusions: VEGF is considered a crucial factor in MSC-CM, and MSC-CM is proposed to be an adequate therapeutic agent for bone regeneration with angiogenesis.