• Title/Summary/Keyword: inhibitory mechanism

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Skin Regeneration, Anti-wrinkle, Whitening and Moisturizing Effects of Cheongsangbangpung-tang Aqueous Extracts with Cytotoxicity (청상방풍탕 열수 추출물의 피부재생, 주름개선, 미백, 보습 효과 및 세포독성 평가)

  • Woo, Chang-Yoon;Kim, Dong-Chul
    • The Journal of Korean Obstetrics and Gynecology
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    • v.30 no.2
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    • pp.49-70
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    • 2017
  • Objectives: The present study is to observe the skin-regeneration, anti-wrinkle, whitening and skin moisturizing effects of Cheongsangbangpung-tang (CSBPT) with cytotoxicity. Methods: In the present study, cytotoxicity of CSBPT lyophilized aqueous extracts (yield=18.71%) was experimented against human normal fibroblast cells and B16F10 murine melanoma cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium Bromide (MTT) assay, and skin regeneration and anti-wrinkle effects were also showed through the assay of collagen type I synthesis by an enzyme immunoassay (EIA) kit as comparing with transforming growth factor (TGF)-${\beta}1$, hyaluronidase, collagenase and matrix metalloproteinase (MMP)-1 inhibitory assays as comparing with oleanolic acid (OA), and elastase inhibitory effects as comparing with phosphoramidon disodium salt (PP). In addition, whitening effects of CSBPT were observed by tyrosinase inhibitory assay and melanin formation test in B16/F10 melanoma cells as comparing with arbutin, and skin moisturizing effects were measured through mouse skin water contents test, respectively. Results: No CSBPT treatment related cytotoxic effects were demonstrated against human normal fibroblast cells and B16/F10 murine melanoma cells. CSBPT concentration-dependent increased collagen type I synthesis at human normal fibroblast cells. It also effectively suspreessed hyaluronidase, collagenase, elastase and MMP-1 activities, which were enzymes that related to declining of ECM and formation of wrinkle. CSBPT supressed B16/F10 melanoma cells's melanin productions with tyrosinase activity, which was an enzyme connected with melanin formation, and dose-dependent and significant increases of skin water contents were detected in CSBPT treated mouse skin as compared with vehicle control skins. Conclusions: CSBPT showed favorable and enough skin regeneration, anti-wrinkle, whitening and skin moisturizing effects at least in a condition of this experiment. However, more detail mechanism and in vivo skin protective efficacy studies should be conducted in future with the screening of the biological active compounds in individual herbs of Cheongsangbangpung-tang.

Inhibitory Effects of Extracts from Arabis glabra on Lipopolysaccharide Induced Nitric Oxide and Prostaglandin E2 Production in RAW264.7 Macrophages (RAW264.7 대식세포에서 장대나물 추출물의 Nitric oxide 및 Prostaglandin E2생성 저해효과)

  • Nam, Jung-Hwan;Seo, Jong-Taek;Kim, Yul-Ho;Kim, Ki-Deog;Yoo, Dong-Lim;Lee, Jong-Nam;Hong, Su-Young;Kim, Su-Jeong;Sohn, Hwang-Bae;Kim, Hyun-Sam;Kim, Bo-Sung;Shin, Ji-Sun;Lee, Kyung-Tea;Park, Hee-Jhun
    • Korean Journal of Plant Resources
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    • v.28 no.5
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    • pp.568-573
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    • 2015
  • Arabis glabra is a localized common rhizomatous flowering plant, This plant is often used in Korean traditional systems of medicine as a remedy for blood cleaning, detoxification, abscess, gastrospasm, arthritis, contraction and diarrhea. Generally drugs that are used for arthritis have antinociceptive and anti-inflammatory properties. However, validity of the anti-inflammatory activity has not been scientifically investigated so far. Therefore, the aim of this study was to investigate the anti-inflammatory potential of A. glabra using the ethanolic extract and its sub-fractions. To evaluate the anti-inflammatory effects, we examined the inflammatory mediators such as nitric oxide (NO) and prostaglandin E2 (PGE2) on RAW 264.7macrophages. Our results indicated that hexane and chloroform fraction significantly inhibited the LPS-induced NO and PGE2 production in the cells. The hexane fraction inhibitory activity for NO tests with IC50 values showed in 21.0 ㎍/㎖. The chloroform fraction inhibitory activity for PGE2 tests with IC50 values showed in 18.0 ㎍/㎖. These efficacy are expected to be able to present the potential for the development of health functional food for the prevention inflammatory diseases because it has sufficient preventive medical possibilities. Further, it is determined that it is necessary to further study the mechanism of cytokine and protein expression associated with inflammation.

Anti-inflammatory Metabolites of Agrimonia pilosa Ledeb. and Their Mechanism

  • Park, Mi Jin;Ryu, Da Hye;Cho, Jwa Yeoung;Kang, Young-Hwa
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2018.04a
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    • pp.13-13
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    • 2018
  • The anti-inflammatory (INF) compounds (1-15) were isolated from Agrimonia pilosa Ledeb. (APL) by activity-guided isolation technique. The isolated compounds (1-15) were identified as quercetin-7-O-rhanmoside (1), apigenin-7-O-glycoside (2), kaempferol-7-O-glycoside (3), apigenin-7-O-[6"-(butyl)-glycoside] (4), querceitn (5), kaempferol (6), apigenin (7), apigenin-7-O-[6"-(pentyl)-glycoside] (8), agrimonolide (9), agrimonolide-6-O-glucoside (10), desmethylagrimonolide (11), desmethylagrimonolide-6-O-glucoside (12), luteolin (13), vitexin (14) and isovitexin (15). Flavonoids, compound 2, 3, 11, and 14-15 have been found in APL for the first time. Furthermore, two novel flavone derivatives, compound 4 and 8, have been isolated inceptively in plant. In the no cytotoxicity concentration ranges of $0-20{\mu}M$, nitric oxide (NO) production level of 1-15 was estimated in LPS-treated Raw 264.7 macrophage cells. The flavone aglycones, 7 (apigenin, $IC_{50}=3.69{\pm}0.34{\mu}M$), 13 (luteolin, $IC_{50}=4.62{\pm}0.43{\mu}M$), 6 (kaempferol, $IC_{50}=14.43{\pm}0.23{\mu}M$) and 5 (quercetin, $IC_{50}=19.50{\pm}1.71{\mu}M$), exhibited excellent NO inhibitory (NOI) activity in dose-dependent manner. In the structure activity relationship (SAR) study of apigenin-derivatives (APD), apigenin; Api, apigenin-7-O-glucoside; Api-G, apignenin-7-O-[6"-(butyl)-glycoside]; Api-BG and apignenin-7-O-[6"-(pentyl)-glycoside]; Api-P, from APL on INF activity was investigated. The INF mediators level such as NO, INF-cytokines, NF-KB proteins, iNOS and COX-2 were sharply increased in Raw 264.7 cells by LPS. When pretreatment with APD in INF induced macrophages, NOI activity of Api was most effective than other APD with $IC_{50}$ values of $3.69{\pm}0.77{\mu}M$. And the NOI activity was declined in the following order: Api-BG ($IC_{50}=8.91{\pm}1.18{\mu}M$), Api-PG ($IC_{50}=13.52{\pm}0.85{\mu}M$) and API-G ($IC_{50}=17.30{\pm}0.66{\mu}M$). The NOI activity of two novel compounds, Api-PG and Api-BG were lower than their aglycone; Api, but more effective than Api-G (NOI: Api-PG and Api-BG). And their suppression ability on INF cytokines such as $TNF-{\alpha}$, $IL-1{\beta}$ and IL-6 mRNA showed the similar tendency. Therefore, the anti-INF mechanism study of Api-PG and Api-BG on nuclear factor-kappa B ($NF-{\kappa}B$) pathway, representative INF mechanism, was investigated and Api was used as positive control. Api-BF was more effectively prevent the than phosphorylation of $pI{\kappa}B$ kinase (p-IKK) and p65 than Api-PG in Raw 264.7 cells. In contrast, Api-PG and Api-BG were not reduced the phosphorylation of inhibitor of kappa B alpha ($I{\kappa}B{\alpha}$). Moreover, pretreatment with Api-PG and Api-BG, dose-dependently inhibited LPS-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNAs and proteins in macrophage cells, and their expression were correlated with their NOI activity. Therefore, APL can be utilized to health promote agent associated with their AIN metabolites.

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Studies on the Functional Interrelation between the Vestibular Canals and the Extraocular Muscles (미로반규관(迷路半規管)과 외안근(外眼筋)의 기능적(機能的) 관계(關係)에 관(關)한 연구(硏究))

  • Kim, Jeh-Hyub
    • The Korean Journal of Physiology
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    • v.8 no.2
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    • pp.1-17
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    • 1974
  • This experiment was designed to explore the specific functional interrelations between the vestibular semicircular canals and the extraocular muscles which may disclose the neural organization, connecting the vestibular canals and each ocular motor nuclei in the brain system, for vestibuloocular reflex mechanism. In urethane anesthetized rabbits, a fine wire insulated except the cut cross section of its tip was inserted into the canals closely to the ampullary receptor organs through the minute holes provided on the osseous canal wall for monopolar stimulation of each canal nerve. All extraocular muscles of both eyes were ligated and cut at their insertio, and the isometric tension and EMG responses of the extraocular muscles to the vestibular canal nerve stimulation were recorded by means of a physiographic recorder. Upon stimulation of the semicircular canal nerve, direction if the eye movement was also observed. The experimental results were as follows. 1) Single canal nerve stimulation with high frequency square waves (240 cps, 0. 1 msec) caused excitation of three extraocular muscles and inhibition of remaining three muscles in the bilateral eyes; stimulation of any canal nerve of a unilateral labyrinth caused excitation (contraction) of the superior rectus, superior oblique and medial rectus muscles and inhibition (relaxation) of the inferior rectus, inferior oblique and lateral rectos muscles in the ipsilateral eye, and it caused the opposite events in the contralateral eye. 2) By the overlapped stimulation of triple canal nerves of a unilateral labyrinth, unidirectional (excitatory or inhibitory) summation of the individual canal effects on a given extraocular muscles was demonstrated, and this indicates that three different canals of a unilateral vestibular system exert similar effect on a given extraocular muscles. 3) Based on the above experimental evidences, a simple rule by which one can define the vestibular excitatory and inhibitory input sources to all the extraocular muscles is proposed; the superior rectus, superior oblique and medial rectus muscles receive excitatory impulses from the ipsilateral vestibular canals, and the inferior rectus, inferior oblique and lateral rectus muscles from the contralateral canals; the opposite relationship applies for vestibular inhibitory impulses to the extraocular muscles. 4) According to the specific direction of the eye movements induced by the individual canal nerve stimulation, an extraocutar muscle exerting major role (a muscle of primary contraction) and two muscles of synergistic contraction could be differentiated in both eyes. 5) When these experimental results were compared to the well known observations of Cohen et al. (1964) made in the cats, extraocular muscles of primary contraction were the same but those of synergistic contraction were partially different. Moreover, the oblique muscle responses to each canal nerve excitation appeared to be all identical. However, the responnes of horizontal (medial and lateral) and vertical (superior and inferior) rectus muscles showed considerable differences. By critical analysis of these data, the author was able to locate theoretical contradictions in the observations of Cohen et al. but not in the author's results. 6) An attempt was also made to compare the functional observation of this experiment to the morphological findings of Carpenter and his associates obtained by degeneration experiments in the monkeys, and it was able to find some significant coincidence between there two works of different approach. In summary, the author has demonstrated that the well known observations of Cohen et al. on the vestibulo-ocular interrelation contain important experimental errors which can he proved by theoretical evaluation and substantiated by a series of experiments. Based on such experimental evidences, a new rule is proposed to define the interrelation between the vestibular canals and the extraocular muscles.

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Effect of Solvent Fractions from Doenjang on Antimutagenicity, Growth of Tumor Cells and Production of Interleukin-2 (된장 분획물의 항돌연변이 및 암세포 증식 억제효과와 interleukin-2 생성에 미치는 영향)

  • Kim, Kwang-Hyuk;Park, Kun-Young;Lee, Sook-Hee;Lim, Sun-Young
    • Journal of Life Science
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    • v.17 no.6 s.86
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    • pp.791-797
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    • 2007
  • We studied the inhibitory effect of solvent fractions from doenjang on mutagenicity using Salmonella typhimurium TA100 in Ames test. We also investigated the effect of solvent fractions from doenjang on the growth of tumor cells and the production of interleukin-2 (IL-2). The treatment of dichlorormethane and ethylacetate fractions (2.5 mg/assay) from doenjang to Ames test system inhibited aflatoxin B$_1$ (AFB$_1$) induced mutagenicity by 96% and 97%, respectively, and showed a higher antimutagenic effect than other solvent fractions. In case of N-methyl-N'-nitro-N-nitrosoguamidine (MNNG) induced mutagenicity, the ethylacetate fraction showed the highest inhibitory effect (by 75%) among the other sol-vent fractions, although the inhibitory effect was not stronger compared to AFB$_1$ induced mutagenicity. The treatment of dichloromethane and ethylacetate fractions markedly inhibited the growth of Yac-1 (by 80% and 94%, respectively) and sacroma-180 cancer cells (by 60% and 96%, respectively) after 4 days of incubation at 37${\circ}$C. To elucidate the immunological mechanism of antitumor activity of doenjang, spleen cells of Balb/c mouse were exposed to the dichloromethane and ethyl-acetate fractions for 24 hours at 37${\circ}$C . The culture supernatants following the treatment of djchloromethane and ethylacetate factions to spleen cells increased the production of IL-2. These results indicated that the anticarcinogenic effect of doenjang was mediated by the production of IL-2.

The Effects of Cudrania tricupidata Tea Leaves on the Blood Glucose and Serum Lipids Profiles of Streptozotocin-Induced Hyperglycemic Rats (꾸지뽕잎차 첨가 식이가 Streptozotocin으로 유발한 고혈당 흰쥐의 혈당 및 혈청지질 함량에 미치는 영향)

  • Park, Bum-Ho;Shin, Jong-Wook;Lee, Sang-Il;Kim, Soon-Dong
    • Journal of the East Asian Society of Dietary Life
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    • v.18 no.4
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    • pp.516-523
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    • 2008
  • The effects of pan-fired (PM) and fermented (FM) Cudrania tricupidata tea leaves on $\alpha$-glucosidase inhibitory activity, oral glucose tolerance, blood glucose levels and serum lipids profiles in streptozotocin (STZ)-induced hyperglycemic rats were investigated. The $\alpha$-glucosidase inhibitory activity of FM ethanol extracts (20 mg/mL) was higher (92.5%) than that of raw dried leaves (RM) (69.1%) and PM (54.6%). In addition, the results of a glucose tolerance test revealed that the glucose levels of hyperglycemic rats that were fed PM and FM ethanol extracts and then orally administered glucose began to decrease after 60 minutes, but recovered after 120 minutes. However, the blood glucose levels in the hyperglycemic control group did not begin to decrease for 360 minutes. Additionally, the results of animal experiments that were conducted over five weeks to compare the dietary effects of PM and FM following hyperglycemic induction to the effects on the hyperglycemic control group (DM) were as follows: The body weight gain and FER of the treated rats were $12.9{\sim}16.9%$ higher than those of the DM group, whereas the amounts of feed and water intake by the treated rats were $6.8{\sim}10.1%$ lower. Additionally, the levels of blood glucose and serum fructosamine decreased by $27.3{\sim}39.8%$ and $6.7{\sim}20.0%$, respectively, in the treated rats. Moreover, the serum triglyceride, total cholesterol and LDL-cholesterol concentrations in the treated rats were $24.9{\sim}27.1%$, $15.9{\sim}17.4%$ and $33.8{\sim}38.4%$ lower, respectively. Finally, the HDL-cholesterol contents were $20.5{\sim}24.8%$ higher in the treated rats than in the control group. The above results suggest that PM and FM exerts an anti-hyperglycemic effect that occurs due to the inhibition of $\alpha$-glucosidase activity as well as via prevention and/or inhibition of changes in the serum lipid profile. In addition, the results of this study revealed that the synthetic anti-hyperglycemic effect of FM was greater than that of PM. However, further detailed studies are needed to confirm these results.

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A Co-inhibitory Molecule, B7-H4, Synergistically Potentiates Oral Tolerance by Inducing CD4+CD25+FoxP3+ T Cells

  • Wen, Lanying;Yang, Sung-Yeun;Choi, Jae-Kyoung;Kim, Young-Hee;Kwon, Eun-Hee;Lee, Hyun-Ji;Jeoung, Hae-Young;Hwang, Du-Hyeon;Hwang, Dong-Jin;Choi, In-Hak
    • IMMUNE NETWORK
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    • v.8 no.1
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    • pp.21-28
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    • 2008
  • Background: A co-inhibitory molecule, B7-H4, is believed to negatively regulate T cell immunity by suppressing T cell proliferation and inhibiting cytokine production. However, the mechanism behind B7-H4-mediated tolerance remains unclear. Methods: Balb/c $(H-2^d)$ mice were fed with dendritic cell line, DC2.4 $(H-2^d)$ every day for 10 days. Meantime, mice were hydrodynamically injected with recombinant plasmid expressing B7-H4 fusion protein (B7-H4.hFc) or hFc via tail vein. One day after last feeding, mice were immunized with allogeneic B6 spleen cells. 14 days following immunization, mice were challenged with B6 spleen cells to ear back and the ear swelling was determined the next day. Subsequently, a mixed lymphocyte reaction (MLR) was also performed and cytokines profiles from the reaction were examined by sandwich ELISA. Frequency of immunosuppressive cell population was assayed with flow cytometry and mRNA for FoxP3 was determined by RT-PCR. Results: Tolerant mice given plasmid expressing B7-H4.hFc showed a significant reduction in ear swelling compared to control mice. In addition, T cells from mice given B7-H4.hFc plasmid revealed a significant hyporesponsiveness of T cells against allogeneic spleen cells and showed a significant decrease in Th1 and Th2 cytokines such as IFN-${\gamma}$, IL-5, and TNF-${\alpha}$. Interestingly, flow cytometric analysis showed that the frequency of CD4+CD25+FoxP3+ Tregs in spleen was increased in tolerant mice given recombinant B7-H4.hFc plasmid compared to control group. Conclusion: Our results demonstrate that B7-H4 synergistically potentiates oral tolerance induced by allogeneic cells by increasing the frequency of FoxP3+ CD4+CD25+ Treg and reducing Th1 and Th2 cytokine production.

Inhibitory Effects of Functional Sujeonggwa Drinks on Hepatic Lipid Accumulation in Hypercholesterolemic ApoE Knockout Mice (고콜레스테롤혈증 ApoE Knockout Mice에서 기능성 수정과의 간지질 축적 억제 효과)

  • Baek, Aran;Kim, Mijeong;Jung, Koeun;Kim, Seulki;Lee, Jeehyun;Song, Yeong Ok
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.43 no.11
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    • pp.1648-1657
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    • 2014
  • In this study, the hepatic lipid-lowering effects and related mechanism of action of sujeonggwa were examined in hypercholesterolemia-induced apoprotein E knockout (apo E ko) mice. Sujeonggwa drink was prepared with cinnamon, ginger, and sugar by modifying the traditional recipe of sujeonggwa. Sugar was partially substituted with either stevia or short chain fructooligosaccharide (scFOS) in order to reduce the calorie content of sujeonggwa, which was measured by descriptive analysis. Apo E ko mice (n=42) were induced to have hypercholesterolemia (plasma total cholesterol concentration >1,000 mg/dL) by administration of a high cholesterol diet for 4 weeks, followed by division into six groups. Experimental groups were orally administered water as a vehicle (normal group), sugar solution (control group), commercially available 'V' sujeonggwa drink (positive control group), or three different types of sujeonggwa drinks (S-sugar, S-stevia, and S-scFOS group) for 6 weeks while high cholesterol diet was provided to all animals. Compared to the control group, concentrations of hepatic triglycerides, total cholesterol, thiobarbituric acid reactive substances, and reactive oxygen species in S-sugar, S-stevia, S-scFOS were significantly reduced (P<0.05), indicating that sujeonggwa had inhibitory effects on hepatic lipid accumulation. Protein expression levels of fatty acid synthase (FAS) and its transcription factor, sterol regulatory element-binding protein (SREBP)-1 responsible for triglyceride synthesis, as well as 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) and its transcription factor, SREBP-2 responsible for cholesterol synthesis, were also reduced in S-sugar, S-stevia, and S-scFOS groups (P<0.05). These benefits of sujeonggwa were even greater in S-stevia and S-scFOS compared to S-sugar. The beneficial effects of S-stevia on regulation of hepatic lipid metabolism were slightly greater than those of S-scFOS although the differences were not significant. In conclusion, sujeonggwa drinks, especially functional sujeonggwa drinks in which sugar was partially substituted with stevia or scFOS, inhibited hepatic lipid accumulation via suppressing FAS and HMGCR protein expression through down-regulation of SREBP-1 and 2.

Change of both Palmar Temperature During Thoracoscopic Sympathicotomy for Palmar Hyperhidrosis (다한증환자의 흉부교감신경절단술시 양측 손바닥의 온도변화)

  • Lee, Hyeon-Jae;Kim, Dae-Sik;Moon, Seung-Cheol;Koo, Won-Mo;Yang, Jin-Young;Lee, Gun;Lim, Chang-Young;Park, Chung-Hyun
    • Journal of Chest Surgery
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    • v.32 no.5
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    • pp.461-464
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    • 1999
  • Background: Thoracoscopic T2 sympathicotomy is an effective method for the treatment of palmar hyperhidrosis. Not only are the symptoms of hyperhidrosis abolished but also the temperature of the ipsilateral palm is elevated due to the sympatholytic vasodilation after the completion of the sympathicotomy on the first side. However little is known about the temperature changes in the contralateral palm. This study was performed to evaluate the changes in both palmar temperatures during the thoracoscopic T2 sympathicotomy for palmar hyperhidrosis. Material and Method: Thoracoscopic T2 sympathicotomy was performed in 15 patients with primary palmar hyperhidrosis. Surface temperatures of both palms were monitored continuously and were recorded simultaneously during the 7 different stages of the operation. Result: When T2 sympathicotomy was performed on the first(left) side, an ipsilateral increase with a contralateral decrease of temperature was observed. The difference in the temperature of both palms was greatest just before the sympathicotomy on the contralateral(right) side(Lt. 34.6$\pm$0.9$^{\circ}C$ vs. Rt. 31.6$\pm$1.3$^{\circ}C$, P<0.0001). After the sympathicotomy on the second(right) side, temperature of the right palm was elevated. The difference in the temperature of both palms was abolished at the end of the operation(Lt.34.7$\pm$0.9$^{\circ}C$ vs. Rt.34.4$\pm$1.$0^{\circ}C$, P=0.415). Conclusion: When T2 sympathicotomy was performed on the first side, an ipsilateral palmar temperature increased due to the sympatholytic vasodilation. However contralateral palmar temperature decreased due to a vasoconstriction. Although the mechanism of vasoconstriction is still unknown, it is postulated that there may be a cross- inhibitory effect by the post-ganglionic neurons innervating blood vessels of the palm.

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Extracellular $K^+$ Effects on the Mouse Aortic Endothelial Cell Contractility (쥐 대동맥 혈관 내피세포에서 세포 외 $K^+$에 의한 혈관 수축선 조절 기전)

  • 안재호;유지영
    • Journal of Chest Surgery
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    • v.36 no.12
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    • pp.887-893
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    • 2003
  • External stimuli increases intracellular (IC) $Ca^{2+}$, which increases extracellular (EC) $K^{+}$. To verify $K^{+}$ effects on the vascular contraction, we performed an experiment using mouse aortic endothelial cell. Meterial and Method: We examined the mouse aortic contractility changes as we measured the IC $Ca^{2+}$ change and ionic current by using the voltage clamp technique under different conditions such as: increasing EC $K^{+}$, removing endothelial cell, giving L-NAME (N-nitro-L-arginine methyl ester) which suppress nitric oxide formation, Ouabain which control N $a^{+}$ - $K^{+}$ pump and N $i^{2+}$ which repress N $a^{+}$-C $a^{2+}$ exchanger Result: When we increased EC $K^{+}$ from 6 to 12 mM, there was no change in aortic contractility. Aorta contracted with more than 12 mM of EC $K^{+}$. Ace-tylcholine (ACh) induced relaxation was inhibited with EC $K^{+}$ from 6 to 12 mM, but was not found after de-endothelialization or L-NAME treatment. ATP or ACh increased IC $Ca^{2+}$ in cultured endothelium. After maximal increase of IC $Ca^{2+}$, increasing EC $K^{+}$ from 6 to 12 mM made IC $Ca^{2+}$ decrease and re-decreasing EC $K^{+}$ to 6 mM made IC $Ca^{2+}$ increase. Ouabain and N $i^{2+}$ masked the inhibitory effect of endothelium dependent relaxation by increased EC $K^{+}$. Conclusion: These data indicate that increase in EC $K^{+}$ relaxes vascular smooth muscle and reduces $Ca^{2+}$ in the endothelial cells which inhibit endothelium dependent relaxation. This inhibitory mechanism may be due to the activation of N $a^{+}$- $K^{+}$ pump and N $a^{+}$-C $a^{2+}$ exchanger. $a^{+}$-C $a^{2+}$ exchanger.r.