Sung Hyun Park

Sungkyunkwan University, Seoul, Seoul, South Korea

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Publications (9)7.89 Total impact

  • Article: Cannabinoid receptor type 1 protects nigrostriatal dopaminergic neurons against MPTP neurotoxicity by inhibiting microglial activation.
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    ABSTRACT: This study examined whether the cannabinoid receptor type 1 (CB(1)) receptor contributes to the survival of nigrostriatal dopaminergic (DA) neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. MPTP induced significant loss of nigrostriatal DA neurons and microglial activation in the substantia nigra (SN), visualized with tyrosine hydroxylase or macrophage Ag complex-1 immunohistochemistry. Real-time PCR, ELISA, Western blotting, and immunohistochemistry disclosed upregulation of proinflammatory cytokines, activation of microglial NADPH oxidase, and subsequent reactive oxygen species production and oxidative damage of DNA and proteins in MPTP-treated SN, resulting in degeneration of DA neurons. Conversely, treatment with nonselective cannabinoid receptor agonists (WIN55,212-2 and HU210) led to increased survival of DA neurons in the SN, their fibers and dopamine levels in the striatum, and improved motor function. This neuroprotection by cannabinoids was accompanied by suppression of NADPH oxidase reactive oxygen species production and reduced expression of proinflammatory cytokines from activated microglia. Interestingly, cannabinoids protected DA neurons against 1-methyl-4-phenyl-pyridinium neurotoxicity in cocultures of mesencephalic neurons and microglia, but not in neuron-enriched mesencephalic cultures devoid of microglia. The observed neuroprotection and inhibition of microglial activation were reversed upon treatment with CB(1) receptor selective antagonists AM251 and/or SR14,716A, confirming the involvement of the CB(1) receptor. The present in vivo and in vitro findings clearly indicate that the CB(1) receptor possesses anti-inflammatory properties and inhibits microglia-mediated oxidative stress. Our results collectively suggest that the cannabinoid system is beneficial for the treatment of Parkinson's disease and other disorders associated with neuroinflammation and microglia-derived oxidative damage.
    The Journal of Immunology 11/2011; 187(12):6508-17. · 5.79 Impact Factor
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    Article: [A case of inferior vena cava thrombosis and acute pancreatitis in a patient with ulcerative colitis].
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    ABSTRACT: A 21-year-old man admitted complaining of sudden severe epigastric pain for 1 day. He had been diagnosed as ulcerative colitis (UC) and taking mesalazine for two months. UC was in nearly complete remission at admission. He never drank an alcohol, and serum amylase was 377 IU/L. CT scan showed inferior vena cava (IVC) thrombosis in addition to mild acute pancreatitis. To evaluate the cause of acute pancreatitis and IVC thrombosis, magnetic resonance cholangiopancreatogram (MRCP), endoscopic ultrasonogram (EUS), lower extremity Doppler ultrasonogram (US) and blood test of hypercoagulability including factor V, cardiolipin Ab, protein C, protein S1, antithrombin III, and anti phospholipids antibody were performed. There was no abnormality except mild acute pancreatitis and IVC thrombosis in all the tests. He was recommended to stop taking mesalazine and start having anticoagulation therapy. After all symptoms disappeared and amylase returned normal, rechallenge test with mesalazine was done. Flare-up of abdominal pain occurred and the elevation of serum amylase was observed. Ulcerative colitis came to complete remission with short-term steroid monotherapy. Acute pancreatitis and IVC thrombosis were completely resolved after 3-month anticoagulation therapy with no more mesalazine. We postulated that IVC thrombosis occurred due to hypercoagulable status of UC and intra-abdominal inflammation caused by mesalazine-induced pancreatitis.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 10/2010; 56(4):255-9.
  • Article: Adenoma incidence after resection of sporadic colorectal cancer with microsatellite instability.
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    ABSTRACT: Microsatellite instability (MSI) tumors that develop via the mismatch repair (MMR) gene pathway show rapid growth. It is unknown if patients with sporadic colorectal cancer (CRC) with MSI would benefit from a shorter interval between colonoscopies. The purpose of this study is to determine if there is a difference in adenoma incidence based on the presence of MSI in patients with sporadic CRC. We retrospectively reviewed the incidence of a recurring adenoma at the 1- and 3-year surveillance colonoscopies in 426 patients who had sporadic CRC after surgery The number of high MSI (MSI-H), low MSI (MSI-L), and microsatellite stable (MSS) tumors were 38 (9%), 27 (6%), and 361 (85%), respectively. After 1 year, the incidence of adenoma (13% vs. 16% for MSI-L + MSS vs. MSI-H, P = 0.61) or advanced adenoma (3% vs. 8% for MSI-L + MSS vs. MSI-H, P = 0.14) did not differ based on MSI status. The incidence of adenoma or advanced adenoma also did not differ based on MSI status at the 3-year surveillance colonoscopy. Our study does not show recommendations for a shorter interval for subsequent colonoscopies in patients with sporadic CRC with MSI-H. Further studies on a large scale are needed.
    Journal of Surgical Oncology 06/2010; 101(7):577-81. · 2.10 Impact Factor
  • Article: [An evaluation of web-based information about Barrett's esophagus in Korea].
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    ABSTRACT: Internet has become an important source of medical information not only for doctors but also patients. However, information available in the Internet may provide wrong or even harmful knowledge to the public. The aim of this study was to evaluate the quality of Internet-based medical information about Barrett's esophagus in Korea. The first 50 Internet links were retrieved from the Google using the key word Barrett's esophagus. The quality of information from a total of 49 websites was evaluated using a checklist. Among total 49 sites related to Barrett's esophagus, only 4 sites (8.2%) were made by hospitals or clinics, and 11 sites (22.4%) were for patients. Of the 49 sites, only one web site (2.0%) had all HON CODE principles (authority, complementarity, confidentiality, attribution, justifiability, transparency of authorship, transparency of sponsorship, honesty in advertising and editorial policy). Sixteen Internet links (32.0%) had fair contents for the definition, and 24 links (48.0%) for the diagnosis, and 15 links (30.0%) for the treatment. Information about Barrett's esophagus was incomplete in the majority of medical web sites. It will bring about confusion in patients who want to get information about Barrett's esophagus from the Internet. There is a need for better evidence-based information about Barrett's esophagus on the web.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 06/2009; 53(5):292-6.
  • Article: [A patient diagnosed as autoimmune pancreatitis 6 years after onset of jaundice].
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    ABSTRACT: The clinical manifestations of autoimmune pancreatitis (AIP) are diffuse pancreatic swelling, diffuse irregular narrowing of the main pancreatic duct, and increased serum IgG or positive serum autoantibody. Clinically, AIP can be improved dramatically with oral steroid therapy. In this report, we describe a 62-year-old woman diagnosed as autoimmune pancreatitis six years after onset of jaundice, who presented with uncontrolled blood glucose levels. The laboratory tests revealed obstructive jaundice, and the computed tomography of the pancreas showed pancreatic swelling. After six years of onset, she was diagnosed with AIP and successfully treated with steroid treatment.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 05/2009; 53(4):257-60.
  • Article: [Virologic response to adefovir dipivoxil monotherapy is not durable in HBeAg-positive, lamivudine-resistant chronic hepatitis B patients].
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    ABSTRACT: It has been shown that adefovir dipivoxil is an effective antiviral agent in the treatment of chronic hepatitis B (CHB), not only in wild-type hepatitis B virus (HBV) infection, but also in lamivudine-resistant (LAMV-R) cases. However, little is known about the durability of the virologic response to adefovir in LAMV-R CHB patients. Fifteen HBV e-antigen (HBeAg)-positive, LAMV-R CHB patients showed a virologic response to adefovir monotherapy. These patients received additional adefovir for at least a further 12 months. The virologic relapse rate after discontinuation of adefovir was evaluated. In addition, predictive factors associated with virologic relapse were investigated. The median level of serum HBV DNA before adefovir administration was 7,457,840 IU/mL (range 107,920-99,524,960 IU/mL). The median duration of adefovir treatment was 30 months (range 14-46 months). During a median follow-up period of 14 months after discontinuation of adefovir, the 1-, 2-, 3-, 6-, and 12-month cumulative relapse rates were 26.7%, 53.3%, 73.3%, 80%, and 80%, respectively. High pretreatment HBV DNA levels were found to be the only factor that was predictive of off-therapy relapse. Our data suggest that the adefovir-monotherapy-induced virologic response is not durable in most patients with LAMV-R HBeAg-positive CHB, especially in those with a high pretreatment HBV DNA level.
    The Korean Journal of Hepatology 04/2009; 15(1):52-8.
  • Article: [A case of carcinosarcoma in the liver].
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    ABSTRACT: Primary hepatic carcinosarcoma which has comprised of a mixture of both carcinomatous and sarcomatous elements is very rare. This tumor has been variously called as carcinosarcoma, pleomorphic large cell carcinoma, giant cell carcinoma, or undifferentiated carcinoma. Only less than 20 cases of carcinosarcoma of the liver have been reported sporadically up to now worldwide. Herein, we present a case of carcinosarcoma of the liver along with a review of the literatures.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 03/2009; 53(3):198-201.
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    Article: Postsplenectomy recurrence of thrombocytopenia with an accessory spleen.
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    ABSTRACT: Autoimmune thrombocytopenic purpura (AITP) is an autoimmune disorder that results from antiplatelet autoantibodies; these autoantibodies cause platelet destruction in the reticluoendothelial system. Oral corticosteroid therapy is the first line treatment. Splenectomy is the major treatment modality after the failure of more conservative medical therapy. Approximately 15% of the patients will relapse either soon after splenectomy or, as is less common, many years later. The presence of an accessory spleen should be sought. We experienced a patient with a known diagnosis of autoimmune thrombocytopenic purpura who had a worsening thrombocytopenia 11 years after splenectomy. This patient was diagnosed with an accessory spleen. Accessory splenectomy was performed with only a transient elevation of the platelets. We report here on this case with a review of the literature.
    The Korean Journal of Internal Medicine 10/2004; 19(3):199-201.
  • Article: [Incidence of gallbladder stones in renal transplant recipients].
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    ABSTRACT: Gallbladder stone is one of the major cause of morbidity in adults. Renal transplantation has been found to increase the risk of gallbladder stone formation. The real incidence of gallbladder stones in renal transplant recipients is not exactly known. We performed this study to identify the risk factors for cholecystolithiasis. We compared the prevalence of gallbladder stone in 222 renal transplantation patients with that in 222 age and sex matched controls. Patients who had chronic liver disease, renal disease, and diabetes were excluded from the control group. In our study, the incidence of gallbladder stones is 8.6% (19/222 patients) in renal transplantation patients, which was significantly higher than 3.60% (8/222 control) in the control group (p=0.029). In the most of our renal transplantation patients, cholecystolithiasis was asymptomatic. We did not find a difference in age, sex, duration after transplantation, causes of renal failure, resistance index between patients with and without gallbladder stones in renal transplantation patients. Our results suggest that the incidence of gallbladder stones is higher in renal transplant recipients than non-transplant population in Korea. Further studies will be needed to focus the factors contributing to the gallbladder stone formation after renal transplantation, especially in regard to immunosuppressive drugs.
    The Korean journal of gastroenterology = Taehan Sohwagi Hakhoe chi 08/2004; 44(1):42-6.