Identification of an Entomopathogenic Bacterium, Photorhabdus temperata subsp. temperata, in Korea

Kang, Sangjin,Han, Sangchan,Kim, Yonggyun Korean Society of Applied Entomology 2004 Journal of Asia-Pacific Entomology Vol.7 No.3

Two genera of entomopathogenic nematodes, Heterorhabditis and Steinernema, are mutualistically associated with their symbiotic bacteria. This study reports an identification of the symbiotic bacteria of H. megidis collected in Andong, Korea. The isolated bacteria emitted bioluminescence and showed red color on MacConkey agar medium. Fatty acid composition and carbon utility were analyzed by two microbial identification systems and showed high similarity with Photorhabdus temperata subsp. temperata. This identification was further supported by 16S rDNA sequence with 99.5% identity to that of P. temperata subsp. temperata. The bacteria had potent pathogenicity against the fifth instar larvae of Galleria mellonella and Spodoptera exigua.

Identification of an Entomopathogenic Bacterium, Photorhabdus temperata subsp. temperata, in Korea

Sangjin Kang,Sangchan Han,Yonggyun Kim 한국응용곤충학회 2004 Journal of Asia-Pacific Entomology Vol.7 No.3

Two genera of entomopathogenic nematodes, Heterorhabditis and Steinernema, are mutualistically associated with their symbiotic bacteria. This study reports an identification of the symbiotic bacteria of H. megidis collected in Andong, Korea. The isolated bacteria emitted bioluminescence and showed red color on MacConkey agar medium. Fatty acid composition and carbon utility were analyzed by two microbial identification systems and showed high similarity with Photorhabdus temperata subsp. temperata. This identification was further supported by 16S rDNA sequence with 99.5% identity to that of P. temperata subsp. temperata. The bacteria had potent pathogenicity against the fifth instar larvae of Galleria mellonella and Spodoptera exigua.

Identification and Pathogenic Characteristics of Two Korean Isolates of Heterorhabditis megidis

Sangjin Kang,Sangchan Han,Yonggyun Kim 한국응용곤충학회 2005 Journal of Asia-Pacific Entomology Vol.8 No.4

Heterorhabditis megidis (Rhabditida: Heterorhabditidae) is an entomopathogenic nematode used commercially to manage several insect pests. Despite its occurrence in many other countries, no H. megidis isolate has been reported in Korea. This is the first report of H. megidis indigenous to Korea. The nematodes were identified by morphological characters of infective juveniles and adult males, and the identification was supported by the molecular character. Two conserved primers flanking internal transcribed spacer (ITS) of ribosomal DNA (rDNA) were used to synthesize ca. 1 kb PCR product. The full sequence (1,047 nucleotides in Andong strain and 1,051 nucleotides in Hwasung strain) of the product gave partial 18S, ITS-1, 5.8S, ITS-2, and partial 28S sequences. Of the full sequence, the region (566 bp) including partial 18S, ITS-1, and partial 5.8S showed the highest sequence homology with that of H. megidis among eight Heterorhabditis species. The two Korean isolates were similar in morphological characters and also highly homologous in the total ITS rDNA sequence with only seven nucleotide differences. The identified H. megidis exibited a pathogenic preference with the highest insecticidal activity against the beet armyworm, Spodoptera exigua among five tested lepidopteran species (Galleria mellonella, Plodia interpunctella, Hyphantria cunea, and Bombyx mori). Analysis of the nemaode life stages in the S. exigua showed that the infective juveniles could develop into hermaphrodite adults, which produced amphimictic sexual stages in the following generation. The production of the infective juveniles varied with the host lepidopteran species in terms of developmental time and yield.

Real-Time Detection of the Dynamic Eccentricity in Permanent-Magnet Synchronous Motors by Monitoring Speed and Back EMF Induced in an Additional Winding

Kang, Kyungjin,Song, Jeongyong,Kang, Chiho,Sung, Sangjin,Jang, Gunhee IEEE 2017 IEEE transactions on industrial electronics Vol.64 No.9

<P>We developed a real-time method to detect the dynamic eccentricity of a rotor in a permanent-magnet (PM) motor by monitoring a fault detection signal induced in an additional winding, without performing any further postprocessing, even under a nonstationary rotational speed. After deriving a mathematical equation of the back electromotive force (EMF) induced in a tooth-coil winding, we proposed a fault detection signal, which is the back EMF in an additional winding divided by the rotational speed, when the additional winding is wound around the teeth corresponding to an even number of pole pitches. We used the 2-D finite-element model of a three-phase PM motor with eight poles and 12 slots to verify the proposed method. We also developed an experimental setup which can change the dynamic eccentricity of a PM motor and we performed the experiment for PM motors with dynamic eccentricities of 0%, 25%, and 50% to verify the proposed method. Through the mathematical equation, numerical simulation, and experiment, we confirmed that the fault detection signal proposed in this paper can successfully detect the dynamic eccentricity in a PM motor in real time.</P>

Purification and Characterization of Human Tyrosinase

Sangjin Kang,Jung Do Choi 생화학분자생물학회 1993 BMB Reports Vol.26 No.7

Tyrosinase, a key enzyme for melanin biosynthesis, was purified from cultured human melanoma cells by solubilization, ion-exchange chromatography, Con-A Sepharose chromatography, and hydroxylapatite chromatography. Con-A Sepharose chromatography was effective for human tyrosinase purification. Specific activity was increased 69 times and the activity yield was 40.4%. The molecular weights of purified isozymes were approximately 64,000, 62,000, 58,000, and 57,000 daltons. K_m values of L-dopa and L-tyrosine were 0.4 mM and 0.2 mM, respectively. Human tyrosinase exhibited kinetic properties of lag time, substrate inhibition, and requirement of L-dopa as a cofactor for hydroxylase activity. Phenylthiourea and arbutin showed noncompetitive and competitive inhibition, respectively.

CRF receptor antagonists for the treatment of stress-induced hair loss

Sangjin KANG 한국생물공학회 2015 한국생물공학회 학술대회 Vol.2015 No.4

Cellular and molecular stimulation of adipose-derived stem cells under hypoxia.

Kang, Sangjin,Kim, Soo-Min,Sung, Jong-Hyuk Published for the International Federation for Cel 2014 Cell biology international Vol.38 No.5

<P>Cultivation under hypoxia has beneficial effects on adipose-derived stem cells (ASCs). Despite a history of extensive research on the responses of ASCs to hypoxia, investigations have focused on functional alterations of ASCs. Therefore, we provide novel insight in this review into the cellular and molecular changes that occur in ASCs under hypoxic conditions. Hypoxia increases the proliferation and migration of ASCs by the generation of reactive oxygen species (ROS) and downstream phosphorylation of platelet-derived growth factor receptor-beta, ERK1/2, and Akt. Chronically, activation of these signaling pathways upregulates miR-210 via phosphorylation of NF-κB and Elk1. Protein tyrosine phosphatase, non-receptor type 2 (PTPN2) is a direct miR-210 target, and downregulation of PTPN2 mediates the proliferation and migration of ASCs during hypoxia. In addition, the paracrine effect of ASCs is enhanced under hypoxic conditions, irrespective of whether ROS are generated. Hypoxic preconditioning stabilizes hypoxia inducible factor-1α under hypoxic conditions and increases secretion of vascular endothelial growth factor, thereby improving the regenerative potential of ASCs. Therefore, understanding the cellular and molecular changes that occur during hypoxia is highly relevant for the development of novel ASC therapies.</P>

The Development of Skin Whitening Agents

( Sangjin Kang ) 대한화장품학회 2000 대한화장품학회지 Vol.26 No.2

Tizen 플랫폼 기반의 스마트워치에 대한 디지털포렌식 기법 연구

최상진(Sangjin Choi),김휘강(Huy Kang Kim),이상진(Sangjin Lee) 한국디지털포렌식학회 2021 디지털 포렌식 연구 Vol.15 No.4

최근 건강관리에 대한 사람들의 관심이 늘어나면서 웨어러블 기기의 판매량도 증가하고 있다. 범죄 수사에서도 웨어러블 기기에 저장된 정보의 확보와 분석이 더욱 중요해지고 있다. 하지만 다양한 플랫폼이 탑재된 웨어러블 기기에 대해 아직 많은 연구가 이루어지지 않아 범죄가 발생했을 때 신속한 자료 수집과 분석이 어렵다. 본 논문에서는 웨어러블 기기 중 삼성전자에서 출시한 Tizen 플랫폼이 탑재된 스마트워치에 대한 디지털포렌식 기법을 제안하고자 한다. Tizen 플랫폼이 탑재된 스마트워치에서 획득한 자료를 분석하여 범죄 수사에서 활용할 수 있는 유의미한 자료들이 있는지 살펴본다. 그리고 스마트폰과 클라우드에 연동된 스마트워치의 건강 정보들을 확보하여 분석하고, 스마트폰의 연결 없이 스마트워치를 단독으로 사용할 때 스마트워치 전용 앱에서 확보할 수 있는 정보를 분석한다. 본 연구를 통해 범죄 수사에 있어서 스마트워치 내의 정보를 빠른 시간 내에 정확히 확보하는데 활용할 수 있을 것으로 기대한다. Recently, as people"s interest in health care increases, the sales rate of wearable devices is also increasing. Acquisition and analysis of information stored in wearable devices is becoming more important in criminal investigations. However, as many studies have not yet been conducted on wearable devices equipped with various platforms, it is difficult to quickly collect and analyze data when a crime occurs. In this study, among wearable devices, we propose a digital forensic technique for smartwatch equipped with the Tizen platform launched by Samsung Electronics. We analyze the data obtained from the smartwatch equipped with the Tizen platform to see if there are any meaningful data that can be used in criminal investigations. In addition, it analyzes the health information of the smartwatch linked to the smartphone and the cloud, and analyzes the information that can be obtained from the smartwatch app when the smartwatch is used alone without a smartphone connection. Through this study, it is expected that the information in the smartwatch can be accurately secured in a short time in criminal investigations.

3D 피부세포 배양계를 이용한 피부광노화 연구

강상진 ( Sangjin Kang ) 대한화장품학회 1999 대한화장품학회지 Vol.25 No.2

Skin is continuously exposed to external stimuli including ultraviolet radiation, which is a major cause of skin photoaging. According to recent discoveries, UVA with a lower energy but deep-penetrating properties, compared to UVB, is likely to play a major part in causing skin photoaging. The clinical and histochemical changes of photoaging are well characterized, but the biochemical mechanisms are poorly understood partly due to the lack of suitable experimental systems. In this work, three-dimensional, reconstituted skin culture models were prepared. After certain period of maturation, the equivalent models were shown to be similar in structure and biochemical characteristics to normal skin. Mature dermal and skin equivalent models were exposed to sub-lethal doses of UVA, and the effects of UVA relevant to dermal photoaging were monitored, including the production of elastin, collagen, collagenase(MMP-1), and tissue inhibitor of metalloproteinases-1 (TIMP-1). Interestingly, dermal and skin equivalents reacted differently to acute and chronic exposure to UVA. Elastin production was increased as soon as one week after commencing UVA irradiation by chronic exposure, although a single exposure failed to do so. This early response could be an important advantage of equivalent models in studying elastosis in photoaged skin. Collagenase activity was increased by acute UVA irradiation, but returned to control levels after repeated exposure. On the other hand, collagen biosynthesis, which was increased by a single exposure, decreased slightly during 5 weeks of prolonged UVA exposure. Collagenase has been thought to be responsible for collagen degeneration in dermal photoaging. However, according to the results obtained in this study, elevated collagenase activity is not likely to be responsible for the degeneration of collagen in dermal photoaging, while reduced production of collagen may be the main reason. It can be concluded that reconstituted skin culture models can serve as useful experimental tools for the study of skin photoaging. These culture models are relatively simple to construct, easy to handle, and are reproducible. Moreover, the changes of dermal photoaging can be observed within 1 ~ 4 weeks of exposure to ultraviolet light compared to 4 months to 2 years for human or animal studies. These models will be useful for biochemical and mechanistic studies in a large number of fields including dermatology, toxicology, and pharmacology. The aging of human skin is a complex process in which many factors contribute to the age-related changes. One of these factors relates to UV-radiation, but the exact mechanistic details are not well established. Skin is directly exposed to environmental stresses, particularly ultraviolet(UV) radiation from the sun, which induces various sorts of photodamage. The short-term exposure to UV results in inflammation, skin darkening, and decreased immune function. Beside the acute effects, repeated exposure to the sun for long periods induces deep wrinkles, loss of elasticity, and premature aging, usually referred to as “photoaging’,^1-3. Accumulating evidence suggests that alterations in the dermal extracellular matrix are primarily responsible for the clinical appearance of photodamaged skin^1,4. There is an accumulation of amorphous mass of elastotic material in the papillary dermis5, 6 with degeneration of collagen⁷ and changes in the proteoglycan contents⁸. Within sunlight, UVB is primarily responsible for most biological effects including inflammation, changes in pigmentation, immunosupression and carcinogenesis. However, UVA radiation, once believed harmless to skin, is now recognized as being capable of producing profound damage to most epidermal and dermal components^3,9. It is not only the larger amount of UVA reaching to the skin that makes UVA an important cause of photoaging, but also UVA can penetrate deep into the dermis¹⁰. Solar UVB radiation is known to induce various effects in many cases as a result of the direct absorption of photons by DNA and proteins in mammalian skin^11,12. In contrast, the skin-damaging effects of UVA appear to result from oxygen-mediated photodynamic reactions in which UVA in the presence of certain photosensitizing chromophores(e.g. riboflavin, porphyrins, NADPH etc.) leads to the formation of reactive oxygen species¹³. Because of these differences, UVA and UVB show different biological effects on the skin. The important point with respect to the present work is that the effects of UVA are closely related to the changes occurring on a result of aging process such as free radical formation13, impairment of cutaneous antioxidant defense system¹³, protein crosslinking^14,15, and age-associated changes of dermal protein metabolism, such as increased elastin and collagenase production^16,17. Thus UVA probably plays a more important role in dermal photoaging than UVB. Almost all the studies published to date about photoaging were performed in vitro using monolayer cell culture^18-21 or in vivo on animal and human skin^22-26. Both of these systems have some shortcomings. Cells in monolayer culture, in a situation far removed from that in vivo, show different behavior and respond differently to external stimuli including UV radiation. These cells show rapid proliferation and are actively producing extracellular matrix components and remodeling enzymes. Moreover, skin fibroblasts and keratinocytes can not be maintained long enough to reveal signs of aging without passage, which change may overwhelm or negative the effects of UV exposure. On the other hand, in vivo models are good for endpoint studies of the effects of long-term UV exposure. However, it is difficult to perform controlled experiments on the study of the mechanism and control of photoaging, because these systems are too complicated and it takes long time to see the initial signs of photoaging^22,23. Since reconstituted three-dimensional cultures of skin were developed^27,28, many improvements have been made for equivalent models to produce structure and function similar to those in in vivo state^29,30. In this study, dermal and skin equivalent models were prepared and subjected to repeated exposure to sublethal doses of UVA radiation, to see if these models are suitable for the investigation of dermal photoaging. Dermal equivalents, consisted of normal human skin fibroblasts and type I collagen isolated from rat tail, showed extensive contraction, which ceased at about two weeks after fabrication. During this period, fibroblasts underwent striking morphological changes ; the cells which were stellate in the early stages lost their dendrites and assumed a bipolar morphology(Fig. la, b). Parallel with the contraction, which is believed to be similar to what happens in the wound healing process, the production of elastin, one of the extracellular matrix components, was enhanced and returned to its normal level followed by a transient increase in the level of remodeling enzyme(collagenase) activity (Fig. 2). These results indicate that an initial maturation period was required during which fibroblasts remodel the extracellular matrix and regain their normal physiological state. The rapid proliferation of fibroblasts which occurring during the initial stages also decreased and, after this maturation period, the number of fibroblasts remained approximately constant. To prepare skin equivalent, normal human keratinocytes were seeded on top of the dermal equivalent. About 48 hours after seeding onto derma】 equivalents the keratinocytes were confluent, and the cultures were then raised to the air/liquid interface. Stratum corneum and suprabasal layers were apparent as early as 3 days after air/liquid exposure, which became mature, with 10-15 suprabasal layers and thick stratum corneum, within 3 weeks. The deposition of basement membrane components, type IV collagen and laminin, were visualized by immunohistochemistry. The patches of type IV collagen were recognized one week after air/liquid exposure, and continuous deposition of type IV collagen and laminin were observed at three weeks. In this study, fibroblasts in dermal and skin equivalents, after certain period of maturation, showed relatively normal metabolic features of the dermal extracellular components and have produced a good basement membrane. Therefore, the effects of extrinsic stimuli on 'normal5 cells may be studied in these models, which are simple and in which it is easy to control the experimental conditions compared to the more complex in vivo model systems. To evaluate the effects of single exposure to UVA radiation, monolayer culture of fibroblasts and mature dermal and skin equivalents were exposed to varying doses of UVA(0 to 40 J/ cm²). At least 95% of fibroblasts in dermal equivalents were viable following exposure to 5 J/cm² UVA. Interestingly, as seen in normal human skin, sunburn cells could be observed in skin equivalents, 24 hours after irradiation with 40 J/cm² UVA. Elastin biosynthesis was measured in the conditioned media of cultures irradiated with varying doses of single UVA irradiation (0 to 30 J/cm²). There was no difference in elastin levels/unit cell number in the conditioned media from fibroblasts both in monolayer cultures and in dermal equivalents. Acute UVA seems to have little or no effect on elastin biosynthesis in fibroblasts in monolayer culture and in equivalent models. [³H]-proline incorporation into collagenous protein by fibroblasts in dermal equivalents was increased 3-fold by as little as 5 J/cm² UVA irradiation, and no further increase was observed by higher UVA dosages(Fig. 3■). On the other hand, collagen biosynthesis in sham-irradiated monolayer cultures was similar to that of irradiated dermal equivalents and the level was decreased dose-dependently by UVA irradiation(Fig. 3◆). Collagenolytic activities in conditioned media from dermal and skin equivalent cultures were assayed after UVA irradiation. Little activity was detected in the medium without APMA treatment, indicating that most of the MMP-1 is present in latent form. Although the total activities were not significantly changed by UVA irradiation, the activity per unit cell number showed dose-dependent increase(Fig. 4). The mRNA levels of MMP-1 were dramatically elevated both in dermal and skin equivalents with higher levels in skin equivalents, while TIMP-1 gene expression showed slight increase(Table 1). To evaluate the effects of chronic UV exposure, Dermal and skin equivalents were exposed to sublethal doses of UVA(5 J/cm²) five days a week for up to 5 weeks. Strikingly, dermal and skin equivalent models responded differently to acute and chronic exposure to UVA light. In contrast to the acute effect, elastin concentrations released into the conditioned media from both dermal and skin equivalents were increased by repeated exposure to UVA irradiation within a week and increased further until 3 weeks(Fig. 5a). Similar elevation patterns were observed in both dermal and skin equivalents. The initial elevated levels of collagen synthesis in UVA-irradiated dermal and skin equivalents returned to those of non-irradiated controls within one week, and a slow reduction in collagen biosynthesis was observed showing about 20% reduction after 5 weeks of repeated exposure. This effect was similar in both dermal and skin equivalents except that a higher collagen biosynthesis was observed in skin equivalents(Fig. 5b). Collagenase activities in both dermal and skin equivalent models were increased during the early period of UVA exposure. However, after prolonged exposure, these elevated collagenase activities returned to normal. In dermal equivalents, collagenase activity showed a peak at 5 days after the start of irradiation and returned to the level of non-irradiated controls after 2 weeks(Fig. 6■). The similar but slower response was seen in skin equivalents, showing collagenase activities peaking after 1 ~ 2 weeks and returning to normal after 4 weeks of irradiation (Fig. 6▲). Higher collagenase activities in non-irradiated control were noticed in skin equivalents than dermal equivalents. Also, the return of elevated collagenase activities to normal levels took a longer time in skin equivalents than dermal equivalents. Elevated collagenolytic activity following UV exposure in fibroblasts in monolayer culture as well as in human or animal skin have repeatedly been reported by several groups, suggesting that the reduced collagen content in photoaged skin is a result of increased or accelerated degradation. Most of these data were obtained by single or several exposure to relatively large amount of UV radiation. However, because aging is generally considered as a result of accumulation of minor damage over a long period, it is worth confirming whether the same result is obtained following longterm exposure to low levels UV radiation or whether the damage is produced by different or additional mechanisms. In the study reported here, reconstituted skin cultures were repeatedly irradiated with sublethal doses of UVA and the changes in collagen biosynthesis and collagenolytic activity were monitored. Acute and chronic UVA exposure brought about different results in dermal metabolism in equivalent models. Elastin production was enhanced only after repeated exposure to UVA. Increased collagen biosynthesis was observed after single exposure, but the opposite was seen following repeated exposure. Also, collagenase activity, which was enhanced by a single UVA irradiation, returned to normal after several weeks of chronic UVA exposure. The mechanisms leading to these different responses are not known. Possible explanations could include feedback control by the extracellular concentration and activity of the proteins and enzymes or their degradation products, or a different set of signals triggered by repeated UV exposure leading to different results. Overall one can conclude that the biochemical modifications that follow repeated exposure to UVA are not the result of simple accumulation of the effects brought about by single exposure and therefore it is not appropriate to explain the changes in photoaged skin on the basis of data obtained in experiments in which there is single or short-term UV exposure. For example, the enhanced collagenolytic activities were thought to be responsible for the decreased collagen levels in photoaged skin based on results obtained from acute exposure to ultraviolet in in vivo and in vitro experiments^17,32,33 in contrast, according to the results from the present study, however, decreased collagen biosynthesis might be a more important reason for this change and may help to resolve the confusion originating from different results obtained under varying experimental conditions and in different models. The early signs of skin photoaging, such as increased elastin production and reduced collagen synthesis, could be recognized in equivalent models within a relatively short period compared to in vivo models. These changes could explain the mechanism of solar elastosis and degeneration of collagen in photoaged skin, and agreed well with other Tesults, such as reduced type I and III procollagen levels in photoaged human skin compared with the light-protected skin of the same patients³⁴, elevated elastin and fibrillin gene expression in photoaged skin²⁴, and enhanced elastin promotor activities in transgenic mice³⁵. The different basal levels of collagen and collagenase, and the different responsiveness to chronic UVA in collagenase activities, between dermal and skin equivalents might reflect the role of keratinocytes and epidermal cytokines in producing dermal changes after UVA exposure. The results in this study suggest that reconstituted skin culture model is a useful tool for the study of photoaging. There are some limitations, however, with present techniques skin equivalent models can only be maintained for relatively short periods, say a maximum of 7 to 8 weeks after exposure at the air/liquid interface, and thereafter lose their structure and viability for the reasons that are not clear. More importantly, these models do not contain other types of ceils which are known to play significant roles in UV-induced skin responses, including skin-residing Langerhans5 cells, melanocytes, macrophages, and neutrophils^25,36. Especially cells from blood vessels secret cytokines as well as various matrix-degrading enzymes, such as collagenase, gelatinase, and elastase, in response to the inflammatory signals including UV radiation^37,38. Neutrophil- derived lysozyme and elastase may also participate in producing elastosis^39,40.