• Title/Summary/Keyword: U&I

Search Result 3,502, Processing Time 0.034 seconds

Therapeutic Effects of Binsosan(檳蘇散) on Adjuvant-induced Rheumatoid Rats (Freund's complete adjuvant로 유발시킨 rat 류마티스성 관절염에 대한 빈소산의 치료 효과)

  • An, Keun-Sang;Woo, Chang-Hoon;Kwon, O-Gon;An, Hee-Duk
    • Herbal Formula Science
    • /
    • v.16 no.2
    • /
    • pp.115-131
    • /
    • 2008
  • 실험목적 : 빈소산은 11가지 생약으로 구성된 복합 한약 처방으로 관절염을 포함한 다양한 염증성 질환의 치료제로 사용되어 왔으나, 관절염에 대한 직접적인 효력평가는 찾아 보기 힘들다. 따라서 본 실험에서는 빈소산 추출물이 Freund's complete adjuvant (FCA)로 유발된 rat 류마티스성 관절염에 미치는 치료 효과를 dexamethasone (15mg/kg, 복강 투여) 의 효과와 비교 평가하였다. 실험방법 : 류마티스성 관절염은 FCA (10mg in 1ml paraffin oil 0.1ml/rats)를 좌측 후지에 피내 투여하여 유발하였다. 실험동물은 Wistar 랫트를 사용하였고, FCA 투여 14일 후 유사한 무릎관절 둘레를 나타내는 류마티스성 관절염 유발 rat와 정상 rat 및 실험군을 그룹당 9마리씩 나누었다. 실험동물은 100 또는 200mg/kg의 빈소산 추출물을 FCA 투여 14일 후부터 14일간 경구 투여하였으며, dexamethasone은 15mg/kg 농도로 복강 투여한 다음, 희생하여, 체중, 연골내 collagen 함량 및 chondroitin sulphate, heparin sulphate 및 hyaluronic acid와 같은 뼈내 glycosaminoglycan 함량의 변화를 각각 관찰하였다. 실험결과는 항염 효과가 이미 입증되어 있는 dexamethasone 15mg/kg 복강 투여군과 비교하였다. 결과 : FCA 투여는 현저한 체중, 연골내 collagen 함량 및 chondroitin sulphate, heparin sulphate 및 hyaluronic acid와 같은 뼈내 glycosaminoglycan 함량의 감소와 함께 유발 관절 둘레 및 조직내 prostaglandin $E_2$의 증가와 같은 전형적인 류마티스성 염증을 초래하였으나, 이러한 류마티스성 관절염 소견은 dexamethasone 및 모든 용량의 빈소산 추출물 투여에 의해 현저히 억제되었으며, 특히 빈소산 투여군에서는 투여 용량 의존적인 감소가 인정되었다. 결론 : 이상에서 빈소산 추출물은 투여 용량 의존적인 prostaglandin $E_2$ 억제를 매개하여 FCA 유발 류마티스성 관절염에 대한 치료 효과를 나타내는 것으로 관찰되었다. 따라서 새로운 관절염에 대한 치료제로서 개발 가능성이 있을 것으로 판단된다. 한편 빈소산 추출물은 주로 prostaglandin $E_2$ 억제작용에 의해 항염 효과를 나타내는 것으로 관찰되었으나, 금후 다른 작용기전에 대한 연구와 빈소산의 구성성분 중 유효 성분 규명을 위한 실험이 수행되어야 할 것으로 판단된다.

  • PDF

Studies on the Larvae and Juveniles of Flying Fish, Prognichthys agoo (Temminck and Schlegel) (Pisces, Exocoetidae) I. Development of Eggs, Larvae and Juveniles (날치의 자치어에 관한 연구 1. 난발생과 자치어의 발육)

  • PARK Yang Sung;KIM Yong Uk
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.20 no.4
    • /
    • pp.308-316
    • /
    • 1987
  • The flying fish, Prognichthys agoo, is widely distributed in the coastal waters of south-eastern Korea. On July 14, 1986, mature adults of flying fish were captured from U-do, Cheju-do. The eggs were stripped and fertilized by the wet method on the ship. The mature eggs are demersal and adhesive with 30-40 filaments. The egg diameter varied from 1.42 to 1.58 mm. The water temperature throughout incubation ranged from 23.70 to $27.82^{\circ}C$, and salinity was maintained at $30.75-33.76\%_{\circ}$. The hatching took place in 174 hours after fertilization. The newly hatched larvae measured 4.75-5.25 mm in total length possessing yolk sac and about 45-46 myotomes. The larvae cultured for ten days after hatching reached 11.45-12.60 mm in total length and entered the juvenile period of life. Twenty days after hatching, the juveniles measured 20.01 mm in mean total length, and the scales were formed behind the pectoral fin.

  • PDF

The Effect of Self-help Group Program on Adaptation and Quality of Life of Mastectomy Patients (자조집단 프로그램이 유방절제술 환자의 적응과 삶의 질에 미치는 효과)

  • Park, Young-Shin;Lim, Nan-Young
    • The Korean Journal of Rehabilitation Nursing
    • /
    • v.2 no.1
    • /
    • pp.61-71
    • /
    • 1999
  • This quasi-experimental study was intended to test the effect of self-help group program, which is one of the way to enhance adaptation and quality of life to mastectomy patients. Data was collected from July 14, 1998 to Oct. 31, 1998 at two Medical Center in Seoul. The subjects for this study were the patients who had undergone mastectomy and were follow-up ; 14 in experimental group and 14 in control group matched with age and treatment. The instruments for this study were adaptation in Lee(1994)'s physical symptom questionnaire, Zung's Self-rating Depression Scale(SDS, 1965), and Self-rating Anxiety Scale(SAS, 1970), quality of life in Spranger(1996)'s and No(1988)'s Quality of Life Questionnaire. The self-help group program for mastectomy patients was developed based on literature review and pilot study by the investigator. The subjects of experimental group were participated in 6 weeks self-help group program and were received arm and shoulder exercise, informational support, and interpersonal support by group members. The control group were received no intervention, Both group answered questionnaires prior to intervention and 6 weeks later. The data analyzed by frequency, $X^2$-test, Mann-Whitney U test. Wilcoxon Signed Rank test, Pearson's Correlation Coefficient and Stepwise Multiple Regression using SPSS WIN. The results are as follows ; Hypothesis 1. "The experimental group with the self-help group program will have a higher score on adaptation state than control group." was not supported. But the post test score of anxiety and depression in experimental group were declined and the depression score was reduced relatively. Hypothesis 2. "The experimental group with the self-help group program will have a higher score on quality of life than control group." was not supported. But the posttest score of quality of life in experimental group was reduced relatively. Hypothesis 3. "The higher adaptation state of mastectomy patients, the higher quality, of life." was supported(r=,80, p<.001). Additionally, the lower physical symptom, depression and anxiety, the higher quality of life And depression, which was the main predictor of quality of life, accounted for 59.5%, depression and anxiety accounted for 65.5% of the variance in quality of life. In conclusion, when the self-help group program was intervened to mastectomy patients, it was tended to increase quality of life and to reduce depression and anxiety. So self-help group program can be considered useful nursing inter vention effect on adaptation and quality of life of mastectomy patients. With discussion, I suggest repeated further re search on self-help group with appropriate sample size and longitudinal study. Also during adjuvant therapy, it is needed to develop convenient method to be supported from peer group and family, such as computer mediated support group.

  • PDF

Comparative Study of Gingival Changes in Cyclosporine-Induced Nephrotoxicity with Normal and Low Salt Diet (저염식으로 유도한 Cyclosporine 신독성 백서에서의 치은 변화)

  • Lim, Jae-Gye;Kim, Yong-Jin;Park, Yong-Hoon
    • Journal of Periodontal and Implant Science
    • /
    • v.30 no.2
    • /
    • pp.359-374
    • /
    • 2000
  • Cyclosporine A(CsA) is a widely used immunosuppressant for transplant patients and is also used for the treatment of a wide variety of systemic diseases with immunologic disorders. However, its use is frequently limited because of complications such as nephrotoxicity or gingival hyperplasia. Although several hypotheses have been postulated for CsA-induced gingival hyperplasia, i.e. various cytokine effects of inflammatory cells, existence of plaque or CsA itself, but its pathogenesis is still unclear. For experimental chronic CsA toxicity, salt depletion has been shown to increased susceptibility of rodents to the effects of CsA, and this maneuver facilitates production of arteriolopathy and interstitial fibrosis in kidney that mimic the changes found in human. The purpose of this study was to evaluate pathogenesis of CsA-induced gingival hyperplasia by comparing changes between CsA administration groups of normal standard diet and those of low salt diet group. Specific pathogen-free, 20 to 25 days old(120 to 150 g), male Fisher-344 rats(KIST, Korea), 120 to 150g of body weight, were assigned to four groups of six animals each after one week of adaptation period for powder food. Group 1 received olive oil($300{\mu}l/g\;of\;diet$) with normal standard diet(0.4% of sodium)(NSD). Group 2 received CsA(Cypol-N, Jonggundang, Korea; $300{\mu}g/g\;of\;diet$) with normal standard diet(NSD+CsA). Group 3 received same amount of olive oil with low salt diet(0.05 % of sodium, Teklad Premier, U.S.A.)(LSD). Group 4 received same dose of CsA with low salt diet(LSD+CsA). Rats were pair fed and were sacrificed after six weeks. Renal histologic lesions associated with CsA, consisted of cortical interstitial fibrosis, tubular atrophy and hyalinization of arterioles and the impairment of renal function including increase of serum creatinine and decrease of glomerular filtration rate was more severe in low salt diet group. These were proved as the results of activated of renin-angiotensin system in the kidney by low salt condition. Meanwhile the degree of gingival hyperplasia at incisor and molar tooth was less severe in low salt diet group compared with normal sodium diet group. Hyperplastic gingiva showed mild epithelial hyperplasia and expanded underlyng stroma which consisted of matrix increasement, capillary proliferation and dilatation. While the number and the activation of fibroblasts were increased, inflammatory cells were rare in the stroma. The immunohistochemistry for TGF-${\beta}_1$ in the kidney and gingiva revealed stronger positive in LSD+CsA in kidney but in gingiva of NSD+CsA. These results suggested followings; Gingival hyperplasia can be developed without inflammatory cells infiltration and seemed not induced by CsA by itself. The major role for gingival hyperplasia by CsA would be the secondary effect of TGF-${\beta}$, which maybe upregulated by CsA administration. Low salt diet can attenuate this hyperplasia perhaps by decreasing the activation of $TGF-{\beta}$.

  • PDF

Lactation Performance of German Fawn Goat in Relation to Feeding Level and Dietary Protein Protection

  • Chowdhury, S.A.;Rexroth, H.;Kijora, C.;Peters, K.J.
    • Asian-Australasian Journal of Animal Sciences
    • /
    • v.15 no.2
    • /
    • pp.222-237
    • /
    • 2002
  • Effects of high and low levels of feeding with or without protected protein on the performance of lactating goats were studied. Twenty four German Fawn goats either from 1st ($43.37{\pm}3.937$ kg and 2 year old) or 3rd $62.64{\pm}6.783$ kg and 4-5 year old) parity were used for the trial. Feeding levels were 7.2 (I) and 5.2 (II) MJ ME/litre of milk of 3.5% fat in addition to that of the maintenance allowance. At each feeding level, diet had either unprotected (U) or formaldehyde protected (P) soya-meal. Thus, four diets were IU, IP, IIU and IIP, having six animals in each. The diets were composed of hay and pellet (10:4:1 of beet pulp : barley : soya-meal). Effect of feeding level, protein protection, parity, health status and kid number on intake, milk yield, milk composition, growth rate of goats were recorded across the 21 weeks of study. High feeding level resulted increase (p<0.001) in estimated metabolizable energy (ME) and metabolizable protein (MP) availability. Dietary inclusion of protected soya-meal increased (p<0.001) the estimated MP but not the ME availability. Animals in 1st parity ate more (p<0.001) DM (111 vs. 102 g/kg $W^{0.75}$/d) than those in 3rd parity. Animals with twin kids (110 g/kg $W^{0.75}$/d) had higher (p<0.001) DM intake than those with single kid (102 g/kg $W^{0.75}$/d). Fat (4%) corrected milk (FCM) yield was not effected by high (1,924 g/d) or low (1,927 g/d) feeding level but increased (p<0.001) with protected (2,166 g/d) compared with unprotected (1,703 g/d) soya-meal. FCM yield for four dietary combinations were 1,806, 2,078, 1,600 and 2,254 g/d for diets IU, IP, IIU and IIP, respectively. For unit increase (g) in estimated MP availability relative to ME (MJ) intake, FCM yield increased ($1,418{\pm}275.6$) g daily ($r^2$=0.58; p<0.001). Milk fat (3.14 vs. 3.54%; p<0.001) and protein (2.94 vs. 3.04% p<0.05) contents were lower at high than the low feeding level. Protected protein increased (p<0.001) the fat, lactose and net energy (NE) content of milk. Milk urea concentration of 175, 183, 192 and 204 mg/l for diets IU, IP, IIU and IIP, respectively indicated lower RDP content of these diets. The RDP contents were 6.97, 6.70, 7.30 and 6.83 g/MJ of ME for diets IU, IP, IIU and IIP, respectively. Live weight change over the experimental period were 41, 6, 17 and 19 g/d. Absence of any positive response of high feeding was probably due to inefficient rumen fermentation resulting from inadequate RDP supply. Protected protein improved production performance apparently by increasing MP:ME ratio in the absorbed nutrient.

Phytoextraction of Heavy Metals Induced by Bioaugmentation of a Phosphate Solubilizing Bacterium

  • Arunakumara, K.K.I.U.;Walpola, Buddhi Charana;Song, Jun-Seob;Shin, Min-Jung;Lee, Chan-Jung;Yoon, Min-Ho
    • Korean Journal of Environmental Agriculture
    • /
    • v.33 no.3
    • /
    • pp.220-230
    • /
    • 2014
  • BACKGROUND: Excessive metals in the soil have become one of the most significant environmental problems. Phytoremediation has received considerable attention as a method for restoring the contaminated soils. The microbes having remarkable metal tolerance and plant growth-promoting abilities could also play a significant role in remediation of metal-contaminated soils, because bioaugmentation with such microbes could promote phytoextraction of metals. Therefore, the present study was focused on evaluating the phytoextraction of heavy metals (Co, Pb and Zn) in Helianthus annuus (sunflower) induced by bioaugmentation of a phosphate solubilizing bacterium. METHODS AND RESULTS: A phosphate solubilizing bacterium was isolated from metal-contaminated soils based on the greater halo size (>3 mm) with solid NBRIP agar medium containing 10 g glucose, 5 g $Ca_3(PO_4)_2$, 5 g $MgCl_2{\cdot}6H_2O$, 0.25 g $MgSO_4.7H_2O$, 0.2 g KCl, 0.1 g $(NH_4)_2SO_4$ in 1 L distilled water. Isolated bacterial strain was assessed for their resistance to heavy metals; $CoCl_2.6H_2O$, $2PbCO_3.Pb(OH)_2$, and $ZnCl_2$ at various concentrations ranging from $100-400{\mu}g/mL$ (Co, Pb and Zn) using the agar dilution method. A pot experiment was conducted with aqueous solutions of different heavy metals (Co, Pb and Zn) to assess the effect of bacterial strain on growth and metal uptake by Helianthus annuus (sunflower). The impact of bacterial inoculation on the mobility of metals in soil was investigated under laboratory conditions with 50 mL scaled polypropylene centrifuge tubes. The metal contents in the filtrate of plant extracts were determined using an atomic absorption spectrophotometer (Perkinelmer, Aanalyst 800, USA). CONCLUSION: Inoculation with Enterobacter ludwigii PSB 28 resulted in increased shoot and root biomass and enhanced accumulation of Co, Pb and Zn in Helianthus annuus plants. The strain was found to be capable of promoting metal translocation from the roots to the shoots of H. annuus. Therefore, Enterobacter ludwigii PSB 28 could be identified as an effective promoter of phytoextraction of Co, Pb and Zn from metal-contaminated soils.

Effects of Gonadotrophins on In Vitro Growth and Maturation of Mouse Preantral Follicles (생쥐 Preantral Follicles의 체외성장 및 성숙에 있어서 Gonadotrophins의 역할)

  • 김동훈;지희준;강희규;한성원;이훈택;정길생;이호준
    • Korean Journal of Animal Reproduction
    • /
    • v.23 no.1
    • /
    • pp.53-61
    • /
    • 1999
  • The present study was designed to investigate the effects of gonadotrophins on in vitro growth and maturation in mouse preantral follicles. Ovaries were removed from 12-day-old ICR mice. Follicles were dissociated enzymetically in Leibovitz L-15 medium containing 1 mg/$m\ell$ collagenase and 0.2 mg/$m\ell$ DNase I. The follicles were cultured on Transwell-COL membrane inserts in six well cluster dishes for 10 days. The culture medium was $\alpha$MEM medium supplemented with 5% fetal bovine serum and FSH or HMG. After 10 days of growth in vitro, follicles were allowed to mature for 18~20 hr in medium supplemented with 1.5 IU/$m\ell$ hCG. The oocytes were then denuded of their cumulus cells and assessed maturation status. Concentrations of oestradiol and progesterone were measured with a radioimmunoassay. Oocyte diameter was determined with an ocular micrometer. The survival and Metaphase II rates of oocytes were significantly higher in FSH treatment groups than in control group (P<0.001), but there were no differences among the groups of treated FSH concentration. The survival and Metaphase II rates of oocytes in HMG treatment group (60.9 and 40.6%) were higher than in FSH treatment group (76.6 and 48.2%) and control group (49.2 and 7.1%). The survival and Metaphase II rates of oocytes on both FSH and LH treatment groups were no differences among the ratios of FSH and LH. Diameter of oocyte was no differences among the treatment groups, but smaller than compared to in vivo grown oocyte. Through the entire culture period, secretions of oestradiol and progesterone were significantly less in control group than in HMG and FSH treatment groups. These results suggest that gonadotrophins playa key role in in vitro culture of mouse preantral follicles. Especially, addition of FSH and LH should be more effective than FSH alone.

  • PDF

Effect of Baekryunchihyo-tang(白蓮治哮湯) on Expression of Chemokines in Human Mast Cell Line (HMC-I) (사람 Mast cell에서의 케모카인에 대한 백연치효탕(白蓮治哮湯)의 효과(效果))

  • Jung, Hee-Jae;Rhee, Hyung-Koo;Jung, Sung-Ki;Lee, Hyung-Chul
    • The Journal of Internal Korean Medicine
    • /
    • v.25 no.4
    • /
    • pp.289-299
    • /
    • 2004
  • Background : Although the pathophysiology of asthma has been reported, its mechanism has not been fully elucidated. The mast cell is an effector cells in allergic inflammation and secretes a number of chemokines. Chemokines are important for the recruitment of leukocytes to sites of infection, which is essential in host defense. Chemokines also contribute to the pathogenesis of several disorders such as asthma, chronic bronchitis, atopic dermatitis, allergic rhinitis, and rheumatoid arthritis. Objective : In this study, the aim was to identify the effect of Baekryunchihyo-tang(白蓮治哮湯) on expression of chemokines. This was examined by RT-PCR using the human mast cell line (HMC-l) Materials and Methods : HMC-l cells were used, which is known to secrete and express chemokines. In order to investigate the protective effect of Baekryunchihyo-tang(白蓮治哮湯), HMC-l cells were incubated with pretreatment of Baekryunchihyo-tang(白蓮治哮湯) for 24 hrs. RT-PCR analyses of chemokine genes of cells pretreated with Baekryunchihyo-tang(白蓮治哮湯) showed that expressions of IL-8, $MIP-l{\beta}$, and RANTES genes in these cells were lower and $MIP-l{\alpha}$ showed a similar pattern compared to the calcium ionophore-treated group. In addition, cell cytotoxicity concentration measurements were performed by MTT assay method. Results : After stimulation with 1 uM calcium ionophore A23178 for 2 hrs, IL-8, major one of CXC chemokines, was highly expressed, and expression of $MIP-l{\beta}$ and RANTES (CC chemokines) increased, while expression of $MIP-l{\alpha}$ did not change. The cell cytotoxicity of Baekryunchihyo-tang(白蓮治哮湯) with treatments at various concentrations and times was not observed, respectively. Conclusion : This study suggests that Baekryunchihyo-tang(白蓮治哮湯) has dose-dependent effects on mRNA expression of IL-8(CXC chemokines), $MIP-l{\beta}$ and RANTES(CC chemokines) in human mast cellline(HMC-l). So these herbal medicines may inhibit the inflammatory process of asthma. Advanced studies are required to investigate the mechanism of inhibition by herbal medicine in the asthma model. This study provides basic data on the possibility of the clinical treatment of Baekryunchihyo-tang(白蓮治哮湯) for allergic disorders.

  • PDF

Immunostimulation of C6 Glioma Cells Induces Nitric Oxide-Dependent Cell Death in Serum-Free, Glucose-Deprived Condition

  • Shin, Chan-Young;Choi, Ji-Woong;Ryu, Jae-Ryun;Ryu, Jong-Hoon;Kim, Won-Ki;Kim, Hyong-Chun;Ko, Kwang-Ho
    • Biomolecules & Therapeutics
    • /
    • v.8 no.2
    • /
    • pp.140-146
    • /
    • 2000
  • Recently, we reported that immunostimulation of primary rat cortical astrocyte caused stimulation of glucose deprivation induced apoptotic cell death. To enhance the understanding of the mechanism of the potentiated cell death of clucose-deprived astrocyte by immunostimulation, we investigated the effect of immunostimulation on the glucose deprivation induced cell death of rat C6 glioma cells. Co-treatment of C6 glioma cells with lipopolysaccharide (LPS, $1\;{\mu}\textrm{g}/ml$) and interferon ${\gamma}(IFN{\gamma},\;100U/ml)$ is serum free condition caused marked elevationo f nitric oxide production ($>50\;{\mu}M$). In this condition, glucose deprivation caused significant release of lactate dehdrogenase (LDH) from C6 glioma cells while control cells did not show LDH release. To investigate whether elevated level of nitric oxide is responsible for the enhanced LDH release in glucose-deprived condition, C6 glioma cells were treated with 3-morphorinosydnonimine (SIN-1) and it was observed that SIN-1 caused increase in LDH release from glucose-deprived C6 glioma cells. Treatment of C6 glioma cells with $25\;{\mu}M$ of pyrrolidinedithiocarbamate (PDTC) which inhibit Nuclear factor kB (NF-kB) activation, caused complete inhibition of nitric oxide production. Treatment of C6 glioma cells with NO synthase inhibitors, $N^{G}$-nitro-L-arginine (NNA) or L-$N{\omega}$-nitro-L-arginine methyl ester (L-NAME), caused inhibition of nitric oxide production and also glucose deprivation induced cell death of cytokine-stimulated C6 glioma cells. In addition, diaminohydroxypyrimidine (DAHP, 5 mM) which inhibits the synthesis of tetrahydrobiopterine (BH4), one of essential cofactors for iNOS activity, caused complete inhibition of NO production from immunostimulated C6 glioma cells. The results from the present study suggest that immunostimulation causes potentiation of glucose deprivation induced death of C6 glioma cells which is mediated at least in part by the increased production of nitric oxide. The vulnerability of immunostimulated C6 glioma cells to hypoglycemic insults may implicate that the elevated level of cytokines in various ischemic and neurodegenerative diseases may play a role in their pathogenesis.

  • PDF

Optimal Strategy of Hybrid Marketing Channel in Electronic Commerce (전자상거래하에서의 하이브리드 마케팅 채널의 믹스 전략에 관한 연구)

  • Chun, Se-Hak;Kim, Jae-Cheol
    • Asia pacific journal of information systems
    • /
    • v.17 no.2
    • /
    • pp.83-95
    • /
    • 2007
  • We are motivated by how offline and online firms compete. The Internet made many conventional offline firms build a dynamic online business as another sales channel using their advantages such as brand equity, an existing customer base with comprehensive purchasing data, integrated marketing, economies of scale, and longtime experience with the logistics of order fulfillment and customer service. Even though the hybrid selling using both offline and online channel seems to have advantages over a pure online retailer, all the conventional offline firms are not seen to create an online business. Many conventional offline firms began to launch online business since the Internet era, however, just being online business is not likely to guarantee success. According to Bizate.com's report whether the hybrid channel strategy is successful is still under investigation. For example, consider the classic case of Barnes and Noble versus Amazon.com, Barnes and Noble was already the largest chain of bookstores in the U,S., when Amazon.com was established in 1995, BarnesandNoble.com followed suit in 1997, After suffering losses in its initial years, Amazon finally turned profitable in 2003. In 2004, Amazon's net income was $588 million on revenues of $6.92 billion, while Barnes and Noble earned $143 million on revenues of $4.87 billion, which included BarnesandNoble.com's loss of $21 million on revenues of $420 million. While these examples serve to motivate our thinking, it does not explain when offline firms should venture online. It also does not provide an analytical framework that can generalized to other competitive online-offline situations. We attempt to do this in this paper and analyze a hybrid channel model where a conventional offline firm competes against online firms using its own direct online channels. We are particularly interested in an optimal channel strategy when a conventional offline firm sells its products through its own direct online channel to compete with other rival online firms. We consider two situations where its direct online channel and other online firms are symmetric and asymmetric in the brand effect. The analysis of this paper presents several findings. In the symmetric model where a hybrid firm's online channel is not differentiated from a pure online firm, (i) a conventional offline firm will not launch its online business. In the asymmetric model where a hybrid firm's online channel is differentiated from a pure online firm, (ii) a conventional offline firm can launch its online business if its brand effect is greater than a certain threshold. (iii) there is a positive relationship between its brand effect and online customer costs showing that a conventional offline firm needs more brand effect in order to launch online business as online customer costs decrease. (iv) there is a negative relationship between its brand effect and the number of customers with access to the Internet showing that a conventional offline firm tends to launch its online business when customers with access to the Internet increases.