• Title/Summary/Keyword: Drug effects

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Effects of Ibandronate on the Expression of Matrix Metalloproteinases in Human U2OS Osteosarcoma Cells (사람 U2OS 골육종 세포에서 Matrix Metalloproteinase의 발현에 Ibandronate가 미치는 영향)

  • Jung, Sung-Taek;Seo, Hyoung-Yeon;Xin, Zeng-Feng;Kim, Yang-Kyung;Kim, Hyung-Won
    • The Journal of the Korean bone and joint tumor society
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    • v.15 no.2
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    • pp.111-121
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    • 2009
  • Background: Osteosarcoma is one of the most common primary malignant tumors of bone occurring mainly in children and adolescents. Although surgery combined with chemotherapy has markedly improved patient survival during the last years, the use of anticancer drugs is still associated with serious problem, such as the frequent acquisition of drug-resistant phenotypes and occurrence of "secondary malignancies". Several solid tumors display enhanced expression of matrix metalloproteinases (MMPs), and recently clinical trials have been initiated on MMP-inhibitors. On the other hand, bisphosphonates (BPs) are inhibitors of bone resorption, and widely used to treat osteoclast-mediated bone diseases. Also they appear to possess direct antitumor activity. Methods: One osteosarcoma cell line (U2OS) was treated with ibandronate (0, 0.1, 1, $10{\mu}M$) for 48 hours. Cell viabilities were determined using MTT assay, the mRNA levels of MMP-2 and MT1-MMP were detected by reverse-transcription polymerase chain reaction, the amount of MMP-2 and MT1-MMP protein were measured by Westernblot, the activities of MMP-2 were observed by Gelatin zymography, and Matrigel invasion assays were used to investigate the invasive potential of osteosarcoma cell lines before and after ibandronate treatment. Results: The invasiveness of U2OS cell line was reduced dose-dependently following 48 hour treatment of up to $10{\mu}M$ of the ibandronate at which concentration no cytotoxicity occurred. Furthermore, the gelatinolytic activities and protein and mRNA levels of MMP-2 and MT1-MMP were also suppressed by increasing ibandronate concentrations. Conclusion: Given that MMP-2 is instrumental in tumor cell invasion, it is very likely that the reduction in osteosarcoma cell invasion by ibandronate is a consequence, at least in part, of suppressed expression of both MMP-2 and MT1-MMP. Isolation of a molecule (s) responsible for the bisphosphonate inhibition of tumor cell invasion would pave the way for the development of a new generation of metastasis inhibitors.

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Sensitization of TNFα and Agonistic FAS/CD95 Antibody-Induced Apoptosis by INFγ on Neuroblastoma Cells (신경모세포종에서 IFNγ에 의한 TNFα와 길항적 FAS/CD95항체 유도성 세포고사의 감작화)

  • Bang, Ho Il;Kim, Jong Duck;Choi, Du Young
    • Clinical and Experimental Pediatrics
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    • v.46 no.7
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    • pp.702-709
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    • 2003
  • Purpose : $IFN{\gamma}$ sentitizes many tumor cells to $TNF{\alpha}$ and FASL-mediated apoptosis by enhancing the expression of TNF or FAS/CD95 receptor and modulating the activation of caspase and Bcl-2 family. It has been reported that $IFN{\gamma}$ and $TNF{\alpha}$ synergistically caused differentiation and growth inhibition of neuroblastoma cells. Even though some neuroblastoma cell express FASR/FASL on the cell surface, they could not induce apoptosis by ligation of the FAS/CD95 receptor. But the treatment of $IFN{\gamma}$ is reported to induce apoptosis in some neuroblastoma cell lines through the CD95/CD95L autocrine circuit. In this study, we examined whether $IFN{\gamma}$ could affect $TNF{\alpha}$ and agonistic FAS/CD95 antibody(CH-11)-induced apoptosis against neuroblastoma cell lines that had shown diverse drug sensitivity and resistance. Methods : CHLA-15, CHLA-90 and LA-N-2 neuroblastoma cells were cultured in IMDM and treated with recombinant $IFN{\gamma}$, $TNF{\alpha}$ and CH-11 antibody. Cell viability was measured by DIMSCAN with a fluorescent calcein-AM. Apoptosis was analyzed through flow cytometry using Annexin V-PE and 7-ADD staining and confirmed by pancaspase and caspase-8 blocking experiments. The expression of TNF RI and FAS/CD95 receptor was evaluated by flow cytometry using the corresponding antibody and PE-conjugated secondary antibody. Results : $IFN{\gamma}$ or $TNF{\alpha}$ alone had no demonstrable cytotoxic effects, whereas both cytokines in combination induced apoptosis synergistically in CHLA-15 and CHLA-90 cells. Although there was no cytotoxicity with the ligation of CH-11 alone in CHLA-90 cells, pretreatment of $IFN{\gamma}$ increased the sensitivity of CH-11-mediated apoptosis. The expression of TNFRI and FAS/CD95R were non-specifically enhanced after treatment of $IFN{\gamma}$ without relation to sensitivity to $TNF{\alpha}$ and CH-11. This finding suggest up-regulation of both receptors may contribute to sensitization of $TNF{\alpha}$ and CH-11-mediated apoptosis by $IFN{\gamma}$ in only sensitive cell lines. Conclusion : $IFN{\gamma}$ induced sensitization of $TNF{\alpha}$ and agonistic FAS/CD95 antibody-mediated apoptosis on some neuroblastoma cells through up-regulation of TNFRI and FAS/CD95 receptor.

In vitro antioxidant, anti-diabetic, anti-cholinesterase, tyrosinase and nitric oxide inhibitory potential of fruiting bodies of Coprinellus micaceus (갈색먹물버섯 자실체의 메탄올과 열수추출물의 항산화, 항당뇨, 항콜린에스테라아제, 항티로시나아제 및 Nitric oxide의 저해 효과)

  • Nguyen, Trung Kien;Lee, Min Woong;Yoon, Ki Nam;Kim, Hye Young;Jin, Ga-Heon;Choi, Jae-Hyuk;Im, Kyung Hoan;Lee, Tae Soo
    • Journal of Mushroom
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    • v.12 no.4
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    • pp.330-340
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    • 2014
  • Coprinellus micaceus, belongs to family Psathyrellaceae of Agaricales, Basidiomycota, has been used for edible purposes in the world. This study was initiated to evaluate the antioxidant, anti-diabetic, anti-cholinesterase, anti-tyrosinase, and nitric oxide inhibitory activities of fruiting bodies from C. micaceus extracted with methanol and hot water. The HPLC analysis of phenolic compounds from the mushroom extracts identified 4 phenolic compounds including procatechuic acid, chlorogenic acid, (-)-epicatechin, and naringin. In 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging assay, the scavenging activities of methanol and hot water extracts were lower than that of positive control, BHT. The chelating effects of methanol and hot water extracts were significantly higher than that of BHT, the positive control at the all concentrations tested. In the reducing power assay, methanol and hot water extracts exhibited the lower activities compared with positive control at the 0.125-0.2 mg/ml. The methanol and hot water extracts of the mushroom inhibited the ${\alpha}$-glucosidase activity by 62.26% and 67.59%, respectively at the 2.0 mg/ml, while acarbose, the positive control, inhibited the ${\alpha}$-glucosidase activity by 81.81% at the same concentration. In the acetylcholinesterase(AChE) inhibitory activity assay, methanol and hot water extracts of the mushroom inhibited the AChE by 94.64% and 74.19%, respectively at 1.0 mg/ml, whereas the galanthamine, standard drug, inhibited the AChE activity by 97.80% at the same concentration. The tyrosinase inhibitory activities of methanol and hot water extracts were 91.33% and 91.99% at 2.0 mg/ml, while the inhibitory activity of kojic acid, the positive control, was 99.61% at the same concentration. Nitric oxide(NO) production in lipopolysaccahride (LPS) activated RAW 264.7 cells were inhibited by the methanol and hot water extracts in a concentration dependent manner. Therefore, it is concluded that fruiting bodies of C. micaceus contained natural antioxidant, anti-acetylcholinesterase and ${\alpha}$-glucosidase inhibitory, anti-inflammatory, anti-tyrosinase substances which might be used for promoting human health.

Antioxidative Effects of Lycium chinense Miller on Cisplatin-induced Nephrotoxicity in Rats (Cisplatin으로 유도된 급성신부전증에 대한 지골피(地骨皮)의 항산화효과)

  • Jung, Yu-Sun;Park, Chan-Hum;Shin, Hyeon-Cheol
    • The Journal of Internal Korean Medicine
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    • v.35 no.1
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    • pp.92-105
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    • 2014
  • Objectives : Cisplatin is a widely used cancer therapy drug. However, nephrotoxicity resulting in increased oxidative stress is a major side effect of cisplatin chemotherapy, thereby limiting its chemotherapeutic use. Lycium chinense Miller (LCM) has been used as a traditional herbal medicine in various febrile and inflammatory diseases such as night sweat, cough, nosebleed, bronchitis, pulmonary tuberculosis, etc. In this study we investigated the protective and antioxidative potential of LCM against cisplatin-induced nephrotoxicity in rats. Methods : Twenty-four 8-week-old male Wistar rats were divided into four groups: normal untreated; cisplatin treatment only; LCM 10 mg/kg plus cisplatin treatment; and LCM 30 mg/kg plus cisplatin treatment. Twenty-four hours after the last cisplatin injection, all the rats were sacrificed, and serological changes were evaluated. The levels of NF-${\kappa}B$ activity and NOX-4, $p47^{phox}$, $p22^{phox}$, COX-2, iNOS, SOD, catalase expressions were analyzed in Western blot analysis. Results : Cisplatin injection caused an increase in the BUN level, which is a reliable indicator of renal toxicity. The levels of BUN, renal ROS, and renal TBARS were significantly reduced in the LCM groups compared with the cisplatin-only groups. The levels of $p47^{phox}$ and $p22^{phox}$, which are NADPH oxidase subunits, were increased in the cisplatin-only groups, whereas they were decreased in the LCM groups. The levels of renal NF-${\kappa}B$ activity and COX-2, iNOS expressions were increased significantly in the cisplatin-only groups compared with the normal groups, whereas they were decreased in the LCM groups. Compared with the cisplatin-only groups, renal GSH and GSH/GSSG increased in the LCM groups. Also, the administration of LCM increased levels of SOD and catalase as compared with the cisplatin-only groups. Conclusions : These results suggest that LCM protects cisplatin-induced nephrotoxicity via a mechanism that may involves the inhibition of oxidative stress by the activation of antioxidants.

Interrelationship between Dopaminergic Receptors and Catecholamine Secretion from the Rat Adrenal Gland (흰쥐 부신에서 카테콜아민 분비작용과 도파민 수용체간의 상관성)

  • Lim, Dong-Yoon;Yoon, Joong-Keun;Moon, Baek
    • The Korean Journal of Pharmacology
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    • v.30 no.1
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    • pp.87-100
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    • 1994
  • It has been known for some time that dopamine-containing cells are existed in sympathetic ganglia, i.e., small, intensely fluorescent cells. However, its role and mechanism of action as a peripheral neurotransmitter are poorly understood so far. In the present study, an attempt was made to examine the effect of apomorphine, which is known to be a selective agonist of dopaminergic $D_2$. receptor on secretion of catecholamines (CA) from the isolated perfused rat adrenal gland. The perfusion of a low concentration of 10uM apomorphine into an adrenal vein for 20 min produced significant reduction in CA secretion induced by 5.32 mM ACh, 56 mM KCl, 100 uM DMPP and 100 uM McN-A-343. Increasing apomorphine concentration to 30 uM led to more markedly decreased CA secretion as compared to the case of 10 uM apomorphine and also did inhibit clearly CA release by $10^{-5}M$ Bay-K-8644. Furthermore, in adrenal glands preloaded with a higher dose of 100 uM apomorphine, CA releases evoked by ACh, excess $K^+$, DMPP and McN-A-343 were almost abolished by the drug. The perfusion of $3.3{\pm}10^{-5}M$ metoclopramide, which is well-known as a selective dopaminergic $D_2$ antagonist, produced significantly inhibitory effect of CA release by ACh, DMPP and McN-A-343 but did not affect that by excess $K^+$. However, preloading of 30uM apomorphine in the presence of metoclopramide did not modify the CA secretory effect of excess $K+$ and DMPP. These experimental results demonstrate that apomorphine causes dose-dependent inhibition of CA secretion by cholinergic receptor stimulation and also by membrane depolarization from the isolated perfused rat adrenal gland, suggesting that these effects appear to be exerted by inhibiting influx of extracellular calcium into the rat adrenal medullary chromaffin cells through activation of inhibitory dopaminergic receptors.

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Effect of Glucose Control, SDSCA and Quality of Life of D-chiro-inositol(DCI) in patients with type 2 diabetes: A Path Analysis (제2형 당뇨병 환자의 D-chiro-inositol의 혈당강하 효과와 당뇨 자가관리 및 삶의 질: 경로분석)

  • Kang, Young Mi;Kim, Hyun Jin;Lee, Tae-Yong;Ku, Bon-Jeong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.10
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    • pp.243-253
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    • 2018
  • This study aimed to investigate the effects of DCI on glucose control, quality of life(SF-36 Version 2.0, Korean) and SDSCA(Summary of Diabetes Self-Care Activities) in patients with type 2 diabetes mellitus. A randomized, double-blind, placebo-controlled study was performed on 46 patients with HbA1c 7.0% taking triple anti-diabetic drug regimen who visited the department of Endocrinology and Metabolism in Chungnam National University Hospital between March 2015 and May 2016. As a result, DCI treatment in the intervention group resulted in significantly reduced HbA1c levels $8.75{\pm}0.79%$(baseline), $8.36{\pm}1.03%$(after 12weeks), and $8.65{\pm}0.81%$(after 24weeks). However, patients in the control group did not show any significant change. Interestingly, both DCI treatment group and the control group significantly showed improvements in SDSCA. Participants in the intervention group showed a small yet significant improvement in their only fasting blood glucose test in SDSCA and revealed significant increase in the quantitative levels of quality of life, from $73.05{\pm}16.85$ to $82.74{\pm}10.68$. By using pathway analysis, improvement of SDSCA scores(${\beta}=-0.505$, t=-2.743) was the most influential factor to the fasting blood glucose. The quality of life of patients with type 2 diabetes mellitus was affected by changes of SDSCA scores(${\beta}=0.411$, t=2.024) and fasting c-peptide(${\beta}=-0.445$, t=-2.668) in DCI treatment group. In conclusion, treatment of DCI effectively improved glucose control in patients with type 2 DM(HbA1c level>7.0%) after 12 weeks of treatment, although it had no impact on glucose control after 24 weeks of treatment. Improved glucose control may encourage diabetic patients to conduct self-care activities and improve the quality of life. Based on the present study, we suggest that diabetes self-management, as well as consideration of comprehensive laboratory findings, may be important factor in regulating the quality of life in type 2 DM patients.

The Relationship between the Refractive Power and Nutrient Intake of the Growth Period in Accordance with the Income (소득에 따른 성장기 영양소 섭취와 굴절력과의 관계)

  • Ye, Ki-Hun;Lee, Wan-Seok
    • Journal of Korean Ophthalmic Optics Society
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    • v.18 no.2
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    • pp.213-229
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    • 2013
  • Purpose: The Nutrient intake during the growth period is a critical factor for the development of the vision. In this study, we have analyzed the nutrient that has a correlation with the decrease of induced visual impairment. In addition, we investigated visual acuity and correlation of the nutrient in the higher-income youth and low-income youth. Methods: We used the Korean National Health and Nutrition Examination Survey 2010 document. The Korean National Health and Nutrition Examination Survey didn't show the clear standard of carbohydrates and fats, so we used the data from the Ministry of Food and Drug Safety standards with each 330 g, 51 g. In order to compare the correlation of nutrients and refraction, Nutrients has been classified macronutrients(energy, dietary fiber, protein, carbohydrate, fat), fat-soluble vitamins (vitamin A), water-soluble vitamins (vitamin C, riboflavin, niacin), trace minerals (iron), minerals (calcium, phosphorus, sodium, potassium) and water. Results: We investigated the correlation between refraction and nutrients on average about 328 subjects belonging to the high-income group. The fat intake was $54.21{\pm}32.60$ g, and it was about 2~10 times less than the recommended daily intake (112-540 g). Refractive power and fat intake showed a statistically significant correlation (O.D:p=0.033, O.S:p=0.029). We investigated the correlation between refraction and nutrients on average about 309 subjects belonging to the lowincome group. The phosphorus showed higher ingested by the $1118.75{\pm}501.98$ mg, and the sodium showed intake more than three times recommended intake by the $3705.24{\pm}2089.42$ mg. In addition, unlike other macro mineral it showed that was a correlation on the refraction by the 0.031. Conclusions: A broad variety of taking nutrition and good eating habits at the time of growth seems to have an effects to the good growth and vision and the senescence inhibition of vision.ave an effect to the good growth, the good vision and the senescence inhibition of vision.

Studies on the Fracture Healing in the Alloxan treated Rabbits (Alloxan 투여 가토(家兎)에 대한 골절치유 실험)

  • Kim, Sung-Joon
    • The Korean Journal of Pharmacology
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    • v.7 no.1
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    • pp.53-65
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    • 1971
  • It is well known that diabetes mellitus is associated with metabolic derangements, such as hyper-glycemia, ketosis, glycosuria, and also widespread alterations in the blood vessels, kidneys, eyes, peripheral nerves and heart. It is also recognized that healing of skin wound is delayed in diabetics. In bone, according to Aegerter, osteopenia develops in diabetes mellitus and it is chiefly ascribed to overutilization of protein. Shim claims that total blood flow to the entire skeletal system is approximately 4 to 8 percent of resting cardiac output and blood supply to the skeletal system would be decreased on account of secondary arteriosclerotic changes in the diabetics. An adequate blood supply is an essential factor in the healing process of fracture, and disturbed blood flow, either local or systemic, will invariably delay union of the fragments or the fragments from being fused. As the author has encountered several cases of diabetics in whom healing of fracture was delayed or incomplete, this experimental study was undertaken to elucidate the effects of hyperglycemia and diabetes mellitus on the healing process of fracture. In this experiment adult albino rabbits, weighing about 2 kg. were used and divided into 6 groups. The femur of each animal was fractured surgically, and then the healing process of fracture was periodically checked by radiography at an interval of one week for a period of 6 weeks. Thereafter, all the rabbits were killed to obtain tissue preparation of the femur. The experimental groups were as follows; 1) Control group: Six rabbits sustained a surgical fracture to the femur, without being given any other treatment or drug. 2) Alloxan-treated group: For inducing diabetes, alloxan was given intravenously to 17 rabbits in various dose as follows; to 7 of them 40 mg/kg, to 6 rabbits 80 mg/kg and to 4 rabbits 120 mg/kg of body weight, respectively. 3) Insulin-treated group: Protamine-zinc insulin was injected subcutaneously to each of 6 rabbits in a daily dose of 1 unit per kilogram of body weight. 4) Group treated with insulin after alloxan: Four rabbits were given 80 mg of alloxan once and than 1 unit of insulin per kilogram of body weight daily. Another 5 rabbits were injected 1 unit of insulin per kg of body weight daily following administration of alloxan in a dose of 120 mg/kg. 5) Homotransplantation group: Following intravenous injection of alloxan in a dose of 120 mg/kg, 10 rabbits underwent homotransplantation of a short bone segment to the femur. Five of them were subsequently given 1 unit/kg of insulin daily. 6) Sugar-treated group: six rabbits were fed $15{\sim}20$ gm of sugar daily throughout the period of experiment. The results obtained are summarized as follows; 1. Blood sugar level and damage to the pancreatic islet increased proportionately when alloxan was given to the rabbits in various doses. No appreciable change could be observed in the islets when the blood sugar level was altered by either oral administration of sugar or subcutaneous injection of insulin. 2. Comparing with the control group, healing of fracture was delayed in the alloxan-treated group, while callus formation and periosteal reaction were shown to be more prominent in this group and subsequently, the ultimate osseous tissue formed at the fracture site was significantly smaller in amount and less compact. These findings were more marked as the amount of alloxan increased. 3. Administration of insulin prevented the delay in healing process of fracture in the rabbits with alloxan-induced hyperglycemia. In this case, the course and progression of fracture healing were almost similar to those of control group. 4. Union between the host bone and the fragment transplanted from other rabbit of the same species was more delayed in the group treated with alloxan alone than in the group to which insulin was administered after development of alloxan-induced diabetes. In both groups periosteal new bone developed from the ends of the host bone, above and below the transplanted fragment, and directly fused with failure of periosteal callus to bridge the adjacent ends of the host bone and the transplanted fragment. 5. The healing process of fracture was not inhibited by alteration in blood sugar level when the blood sugar was abnormally increased by excessive sugar intake or lowered by administration of insulin alone. The healing of fracture in these groups progressed similarly as in the control group. In brief summary, it appears that the healing process of fracture would be definitely disturbed in diabetic state brought about by damage to the pancreatic islet. As such an inhibition could be overcome with insulin, it seems that insulin plays an important role in healing of fracture, but alteration in blood sugar level alone does not modify healing process of fracture to significant degree.

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The effect of local rifampicin instillation on the treatment of suppurative BCG lymphadenitis (BCG 접종에 따른 화농성 림프절염의 rifampicin 국소투여 효과)

  • Kim, Min Son;Jo, Dae Sun;Kang, Mi Kyung;Kim, Sang Jae;Kim, Jung Soo
    • Clinical and Experimental Pediatrics
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    • v.49 no.1
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    • pp.40-45
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    • 2006
  • Purpose : The purpose of this study was to evaluate the types of lymphadenitis after BCG vaccination and the effect of local rifampicin instillation on the treatment of suppurative BCG lymphadenitis. Methods : A total of 32 otherwise healthy infants with suppurative BCG lymphadenitis, who visited the Department of Pediatrics of Chonbuk National University Hospital, from March 2002 through June 2004, were enrolled in this study. They were treated with needle aspiration and local rifampicin instillation. We investigated the time the lymphadenitis took to be suppurative, accompanying clinical manifestations, and the treatment effects. Results : Of the 32 infants, 19 were male and 13 were female. They were full term babies and one preterm baby with a gestational age of 30 weeks. They received intradermal administration, with the BCG vaccine of $Pasteur^{(R)}$(French) strain mostly on the left deltoid area(96.9 percent). Regional lymphadenitis occurred in 1 to 11 months after BCG vaccination, mostly 1-5 months after vaccination (78.1 percent). Among the infants, 87.5 percent had unilocular lesion but 12.5 percent had more than one enlarged lymph node cares. Most of the lymphadenitis presented in the left axillary area(77.8 percent), and the left supuraclavicular area(11.1 percent). After one to three times of needle aspiration with rifampin instillation, all infants recovered completely without surgical excision or severe complication. Conclusion : The regional lymphadenitis is the most common complication in infants who receive intradermal BCG vaccination. This study supports that in suppurative BCG lymphadenitis the needle aspiration and local rifampicin instillation is very effective and can be a more economical treatment modality.

Comparison of Paraquat Actions on Oxygen Radical Generation and Lipid Peroxidation between Submitochondrial Particle and Microsome of Mouse Liver (Paraquat에 의한 산소 Radical 생성 및 지질과산화 작용의 Mouse 간 Submitochondria Particle과 Microsome에서의 비교)

  • Choi, Jung-Hwan;Kim, Yong-Sik;Park, Jong-Hwan;Chung, Myung-Hee;Yunn, Chong-Ku
    • The Korean Journal of Pharmacology
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    • v.27 no.2
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    • pp.155-166
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    • 1991
  • In order to evaluate a potential role of mitochondria in the mediation of toxicity of paraquat (PQ), submitochondrial particle and microsome of mouse liver were compared by oxygen radical generation and lipid peroxidation. With NADH in submitochondrial particle and NADPH in microsome as electron donors, PQ stimulated production of superoxide anion and $H_2O_2$ in both fractions. Under the same conditions, PQ enhanced the generation of ethylene from methional suggestiong stimulation of OH production by PQ. But these effects by PQ were somewhat lower in submitochondrial particle than in microsome. In addition, lipid peroxidation(measured as MDA production) was stimulated by PQ in both fractions. The stimulation of lipid peroxidation in both fractions seemed to occur by the same mechanism probably through perferryl ion. This was supported by the following findings: i) The lipid peroxidation in both fractions was partially inhibited by SOD and completely inhibited by DETAPAC(an iron chelator) but not by catalase or OH scavenger. ii) Addition of $ADP-Fe^{3+}$ further increased PQ-induced lipid peroxidation but decreased ethylene production from methional suggesting no correlation between OH production and lipid peroxidation. The redox-cycling of PQ in mitochondria appeared to be linked to NADH dehydrogenase, not to CoQ since all of the observed stimulations by PQ in submitochondrial particle were inhibited by p-hydroxymercuribenzoate(a NADH dehydrogenase inhibitor) but not affected by other respiratory chain blockers. The above results demonstrate that redox-cycling properties of PQ leading to oxygen radical generation and lipid peroxidation can also occur in mitochondria in the same manner as in microsome. Therefore, the observed actions of PQ in mitochondria suggest that mitochondria may also contribute to toxicity of this drug in vivo.

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