• Applied Microscopy
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• v.27 no.1
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• pp.13-30
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• 1997

The experiment was performed to study the morphological responses of the thymus of the mice, to antitumour agents (5-Fluorouracil or mitomycin C). Healthy adult mice weighing 25 gm each were divided into normal and experimental groups. 5-Fluorouracil (60 mg/kg) or Mitomycin-C $(400{\mu}g/kg)$ were injected subcutaneously to the animals every other day. Animals were sacrificed at 4 days and 7 days following the first injection. Pieces of the tissue taken from the thymus were prefixed with 2.5% paraformaldehyde-l.5% glutaraldehyde, followed by post-fixation with 1% osmium tetroxide. Ultrathin sections stained with uranyl acetate and lead citrate were observed with a JEM 100 CX-II electron microscope. The observed results were as follow: 1. Apoptoses of T-lymphocytes were observed more frequently in the thymus of the experimental groups than in those of a normal group. 2. In the experimental group, the plasma cells with distended cisternae of the granular endoplasmic reticulum and the eosinophile leukocytes were observed frequently. 3. In the experimental group, newly forming Hassall's corpurscles were observed frequently. 4. In the mitomycin-treated group, the epithelial reticular cells containing distended perinuclear cisternae, distended the granular endoplasmic reticula and pyknotic nuclei were observed in the cortico-medullary junctional area. 5. In the mitomycin-treated group, nuclear bodies with medium electron dense materials were often observed in the T lymphocyte. 6. In the 5-fluorouracil-treated groups, fused and dissolved tonofilament bundles and apoptotic bodies were observed in the some epithelial reticular cells in the medullary area. 7. In the 5-fluorouracil-treated groups, some elongated and bar-shaped lysosomes with electron lucent gap were often observed in the macrophages. 8. In the 5-fluorouracil-treated group, membrane complex of the smooth endoplasmic reticulum were ofen observed in the macrophage. From the above results, it was suggested that 5-fluorouracil or mitomycin could induce rapid involution of the thymus, and disturb maturation and differentiation of T lymphocytes, and, in turn, supress immunity.

• Applied Microscopy
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• v.12 no.2
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• pp.69-79
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• 1982

In order to define the morphological changes of the secreting cells of prothoracic gland during larva-pupal molt, ultrastructural observations were carried out using Bombyx mori L. as the experimental material. At first stage of present experiment, 4 day old 5th instar larva, the polyhedral secreting cells were centrally located in the prothoracic gland surrounded by the connective sheath. The secreting cells were attached to the neighboring cells by the prominent desmosomes, and the plasma membrane contacted with connective sheath were highly infolded. In cytoplasm, the most of the cell organelles, such as rod-like mitochondria, rough surfaced endoplasmic reticulum, ribosome were developed. As the stages advance from larva to pupa, general feature of the secreting cells were retained, but structural changes of the various cytoplasmic organelles-ribosome, rough surfaced endoplasmic reticulum, mitochondria, Golgi apparatus, lamellar body, and vesicle-were noted. In the perinuclear cytoplasm of the secreting cells at the stage of 6 day old 5th instar larva, it is peculiar that only a large amount of ribosomes were distributed and the other organelles were retreated from the juxtanuclear region. Just before and after spining cocoon, these features were more remarkable. Rough surfaced endoplasmic reticulum were gradually increased from the stage just before spining cocoon to the pharate pupa. Rod-like mitochondria with irregular cristae and the matrix showing low density were distributed throughout the cytoplasm in the secreting cells of the 4 day old 5th instar larva. Sometimes, longitudinally distended and curved mitochondria were observed. At the stage of pharate pupa, most of mitochondria were deformed. The rod-like mitochondria of the secreting cells of pupal prothoracic gland were narrower than those of 4 day old 5th instar larva, and the electron density of the mitochondrial matrix is increased in pupa. Golgi apparatus were a few in number in both stages, last instar larva and spining cocoon. In stages of the pharate pupa, the Golgi apparatus were frequently observed. Cytoplasmic vesicles were observed for the first time in the secreting cells of one day after spining cocoon, and the number and the size of cytoplasmic vesicles were distinctly increased inpharate pupa and just after pupation. In the secretory cells of the PG, it in concluded that the RER was closely related to syntheting the enzymes seem to produce the ecdysone.

• Journal of Life Science
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• v.17 no.2 s.82
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• pp.185-191
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• 2007

Akt/PKB plays pivotal roles in many physiological responses such as proliferation, differentiation, apoptosis, and angiogenesis. Here we show that tyrosine phosphorylation of Akt/PKB is essential for the subsequent phosphorylation at $Thr^{\308}$. Tyrosine phosphorylation of Akt/PKB was induced by stimulation of COS-7 cells with epidermal growth factor receptor (EGF) and its phosphorylation was significantly enhanced by constitutive targeting of Akt/PKB to the plasma membrane by myristoylation. Interestingly, incubation of affinity purified Myc-tagged Akt/PKB with purified EGF receptor resulted in tyrosine phosphorylation as well as $Ser^{\473}$ phosphorylation of Akt/PKB. In addition, tyrosine-phosphorylated Akt/PKB could directly associate with activated EGF receptor in vitro. Finally, alanine mutation at putative tyrosine phosphorylation site $(Tyr^{\326})$ abolished EGF induced $Thr^{\308}$ phosphorylation of wild type as well as constitutively active form of Akt/PKB. Given these results we suggest here that direct tyrosine phosphorylation of Akt/PKB by EGF receptor could be another mechanism of EGF-induced control of many physiological responses.

• Polymer(Korea)
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• v.35 no.1
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• pp.35-39
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• 2011

In this work, mesoporous carbons (CMK-3) were prepared by a conventional templating method using mesoporous silica (SBA-15) for using catalyst supports in polymer electrolyte membrane fuel cells (PEMFCs). The CMK-3 were chemically activated to obtain high surface area and small pore diameter with different potassium hydroxide (KOH) amounts, i.e., 0, 1, 3, and 4 g as an activating agent. And then Pt-Ru was deposited onto activated CMK-3 (K-CMK-3) by a chemical reduction method. The characteristics of Pt-Ru catalysts deposited onto K-CMK-3 were determined by surface area and pore size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and inductive coupled plasma-mass spectrometry (ICP-MS). The electrochemical properties of Pt-Ru/K-CMK-3 catalysts were also analyzed by cyclic voltammetry (CV). From the results, the K3g-CMK-3 carbon supports activated with 3 g KOH showed the highest specific surface areas. In addition, the K3g-CMK-3 led to uniform dispersion of Pt-Ru onto K-CMK-3, resulted in the enhancement of elelctro-catalystic activity of Pt-Ru catalysts.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.4 s.59
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• pp.209-217
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• 2006

Emulsion is a dispersion system among liquids which are not miscible together. There are numerous cosmetic raw materials which have different physicochemical properties. Therefore, emulsion technology is very useful in cosmetics. With the development of emulsifier, several emulsification technologies have been developed. Since HLB method by Griffin in 1950's, PIT method, gel method, and D-phase methods, etc, have been developed. Recently, the application of natural emulsifier and polymeric emulsifier increases in cosmetics in order to achieve enhanced safety and biocompatibility. Besides nano-emulsion, multiple-emulsion, liquid crystal emulsion, and Pickering emulsion have been developed and applied as means of differentiating appearance and texture of products and achieving enhanced delivery of active ingredients. Meanwhile, the application studies of nano-dispersed structural system such as liposome or cubosome are on progress. Liposome is a bi- or multi-lamella layer dispersion system composed of amhiphilic molecules - phospholipids which are main components of plasma membrane. Cubosome also is a nano-sized dispersion system composed of a specific molecule like glyceryl monoloeate derived from natural products. And it has a cubic bicontinuous structure in water due to its unique molecular structure. Incorporating compounds (active materials) into such nano-particles can increase biocompatibility and delivery efficiency of target compounds. Manufacturing process and application of cosmetic emulsions and nano-particles are briefly introduced in this paper.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.56-63
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• 2007

Insulin stimulates the fusion of intracellular vesicles containing glucose transporter 4 (GLUT4) with plasma membrane in adipocytes and muscle cells. Here we show that adipocyte differentiation results in enhanced insulin sensitivity of glucose uptake. On the other hand, glucose uptake in response to platelet-derived growth factor (PDGF) stimulation was markedly reduced by adipocyte differentiation. Expression level of insulin receptor and caveolin-1 was dramatically increased during adipocyte differentiation. Adipocyte differentiation caused :ilightly enhanced activation of acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt) by insulin stimulation. However, activation of Akt by PDGF stimulation was largely reduced. Activation of ERK was not detected in both fibroblasts and adipocytes after stimulation with insulin. PDGF-dependent activation of ERK was reduced by adipocyte differentiation. Insulin-dependent glucose uptake was abrogated by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, in both fibroblasts and adipocytes. Also disassembly of caveolae structure by $methyl-\beta-cyclodextrin$ caused impairment of Akt activation and glucose uptake. Finally, insulin receptor, Akt, SH2-domain-containing inositol 5-phosphatase 2 (SHIP2), and regulatory subunit of PI3K are localized at lipid raft domain and the translocation was facilitated upon insulin stimulation. Given these results, we suggest that lipid raft provide proper site for insulin action for glucose uptake.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.97-104
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• 2007

Present study aims to investigate the effect of muddy water on gill and kidney tissues and blood components of Opsariichthys uncirostris amurensis in Imha reservoir. As a result of observing the gill tissues in muddy water with light and scanning electron microscopes, the edema, the exfoliation of epithelial cells and fusion of the secondary lamellae were observed. The space between gill lamellae was irregular, and a lots of muddy debris around the secondary lamellae were observed. In case of kidney tissues, the size of glomerulus was smaller and thickness of basal membrane was broader and the empty space in Bowman's capsule was wider than those of the control. The blood cells of O. uncirostris amurensis in muddy water were increased in number. Of the white blood cells, acidophilic granulocytes were highly distributed, and the shapes were irregular. Among the plasma components, the concentration of TP, ALB, A/G ratio, TG, CHOL, and AST were low, whereas that of the inorganic materials was high. Based on the above results, it is considered that muddy water possibly involves in the decrease of respiratory and excretory rates, giving rise to secondary lesion of tissues.

• Journal of Life Science
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• v.25 no.6
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• pp.715-723
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• 2015

Insects represent the largest class within the animal kingdom in terms of species number. Humans had been utilized insect in the broad area, including food, agriculture, industry, pharmaceuticals and so on. At present, insects are emerging as a leading group for identifying and extracting novel bioactive substances due to enormous number and a high nutritional value. Insects rely on a suite of systemic response to resist infection such as immune cells, hemocytes, activation of enzymes cascades, and antimicrobial peptide/protein. Among the substances, antimicrobial peptides (AMPs) are main components of potent antimircrobial innate defense system into the insect hemolymph. AMPs raise influential candidate as avenue to resolve the development of antibiotic-resistant microbial organism. Insect AMPs are classified into four main classes: cecropins, insect defensins, glycine/proline-rich peptides. Insect AMPs have been purified, over 150. In this review, AMPs derived from several insects were summarized including honey bee, dung beetle, butterfly and longicorn beetle. These peptides almost exhibited potent antimicrobial activities against human microbial pathogens without causing remarkable hemolysis to erythrocytes excluding melittin, and their mode of action(s) are based on disruption of the plasma membrane or fungal apoptosis. Therefore, study of insect AMPs is expected to be useful for designing novel therapeutic antimicrobial applications.

• Journal of Life Science
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• v.25 no.7
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• pp.748-756
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• 2015

The report explores the possibility that the single extract of natural substances and the mixture of single extracts of natural substances create a synergy effect to increase the antimicrobial activity. It also compares the previous researches to find out if the natural medicinal herbs’ extract has antimicrobial activity on dandruff causative organism, Malassezia furfur. For the experiment on the mixture of single extracts of natural substances, the results are like following: 1. Staphylococcus aures’s antibacterial activity is resistant to mixture of three natural substances. 2. Escherichia coil’s antibacterial activity is resistant to mixture with Coptidis rhizoma. 3. Candida albicans’ antifungal activity is resistant to mixture with Chinese galls, which means the different results may be expected when tested with each germ. 4. On the other hand, Malassezia furfur has no antifungal activity on the single extract of natural substances and shows weak antifungal activity, whose diameter is 3.20 mm when tested with the mixture of 50% of Coptidis rhizoma and 50% of Phytoncide. The result is totally different from the one on the same eumycetes, C. albicans. That is because M. furfur has more lipophilic chemicaled cell walls than C. albicans does and it also consists of lamella layer, inner plasma membrane and intermediate multiple layers.

• Journal of Life Science
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• v.26 no.6
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• pp.721-726
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• 2016

It has already been reported that short neuropeptide F (sNPF) stimulates feeding behaviors in a wide variety of insect species. In the present study, we cloned cDNA, encoding a sNPF receptor homologue from a silkworm, Bombyx mori, named BsNPF-R. The amino acid sequence of BsNPF-R was compared with those of sNPF-R thus far reported, which is shared with humans (36%), mice (34%), zebrafish (35%), and fruit flies (51%), respectively. A BsNPF-R protein’s mass was theoretically estimated to be 42,731 Da and it is a putative plasma membrane-penetrating protein. The mRNA expression of BsNPF-R was tested; the results showed that a strong expression was detected at the midgut, post-silk gland, Malpighian, and testis; however, a weak expression was at the fat body, hemocyte, and ovary. In addition, the synthesized sNPF of a silkworm regulated the BsNPF-R mRNA expression through the cell-based functional analysis.