Dendritic cells (DCs) play a significant role in establishing self-tolerance through their ability to present self-antigens to developing T cells in the thymus. DCs are predominantly localized in the medullary region of thymus and present a broad range of self-antigens, which include tissue-restricted antigens expressed and transferred from medullary thymic epithelial cells, circulating antigens directly captured by thymic DCs through coticomedullary junction blood vessels, and peripheral tissue antigens captured and transported by peripheral tissue DCs homing to the thymus. When antigen-presenting DCs make a high affinity interaction with antigen-specific thymocytes, this interaction drives the interacting thymocytes to death, a process often referred to as negative selection, which fundamentally blocks the self-reactive thymocytes from differentiating into mature T cells. Alternatively, the interacting thymocytes differentiate into the regulatory T (Treg) cells, a distinct T cell subset with potent immune suppressive activities. The specific mechanisms by which thymic DCs differentiate Treg cells have been proposed by several laboratories. Here, we review the literatures that elucidate the contribution of thymic DCs to negative selection and Treg cell differentiation, and discusses its potential mechanisms and future directions.
Autoantigens ; Blood Vessels ; Central Tolerance* ; Clonal Deletion ; Dendritic Cells* ; Epithelial Cells ; T-Lymphocytes ; T-Lymphocytes, Regulatory ; Thymocytes ; Thymus Gland

No abstract available.
Acute Coronary Syndrome ; Aneurysm ; Aorta, Thoracic ; Coronary Vessels

Placental abnormality is the important predisposing cause of intrauterine growth retardation. Massive subchorionic hematoma is defined as a large size of maternal blood clot that separates the chorionic plate from the villous chorion and can result in serious obstetrical complications. We report a case of massive subchorionic hematoma diagnosed prenatally, and propose an additional peculiar finding detectable on both the ultrasound and magnetic resonance images: a large hematoma in the subchorionic region at 17 weeks gestation. At 18 weeks 2 days gestation, the fetus was miscarried. The clinical and pathological findings were compatible with massive subchorionic hematoma. Recurrent massive subchorionic hematoma without thrombophilic finding was observed at the next pregnancy in 17 weeks 5 days by ultrasound. The patient was managed conservatively and had successful outcome at term. So we report the case with the brief review of literatures.
Chorion ; Fetal Growth Retardation ; Fetus ; Hematoma* ; Humans ; Pregnancy ; Ultrasonography

The Philadelphia (Ph) chromosome is a well- known chromosome abnormality in adults with B-lineage ALL, and is associated with a poor prognosis. This study compared the clinical manifestations and prognosis in adult Ph-positive and Ph-negative ALL patients. MATERIALS AND METHODS: We retrospectively analyzed the clinical records of adult patients newly diagnosed as B-lineage ALL, between January 1995 and February 2001. Fifty five patients were included in this study. We divided the patients into Ph-positive and Ph-negative groups. RESULTS: Eighteen of the 55 patients (32.7%) were found to have the Ph chromosome. At initial diagnosis, the Ph-positive patients had higher circulating leukocyte counts, lower platelet counts and had a greater tendency to bleed, than the Ph-negative group. The complete remission rates were 83.3% and 83.8% for the Ph-positive and the Ph-negative groups, respectively. Four of the Ph-positive, and 13 of the Ph-negative, patients underwent allogenic bone marrow transplantation. The median follow-up for the surviving patients was 39.3 months. The three-year survival rates were 10.4% and 51.8% for the Ph-positive and the Ph-negative groups, respectively. The median disease-free survival was 7.7 months for the Ph-positive group, but did not reach the median value in the Ph-negative group. Among the Ph-positive patients, age was the only factor that had an impact on the disease outcome. CONCLUSION: In adult B-lineage ALL, the Ph-positive patients had similar complete remission rates to other patients; however, the remission was of shorter duration, with a higher relapse rate in the Ph-positive patients. More effective treatments are needed to improve the survival of the Ph-positive patients.
Adult* ; Bone Marrow Transplantation ; Chromosome Aberrations ; Diagnosis ; Disease-Free Survival ; Follow-Up Studies ; Humans ; Hydrogen-Ion Concentration ; Leukocyte Count ; Philadelphia Chromosome ; Platelet Count ; Prognosis* ; Recurrence ; Retrospective Studies ; Survival Rate

Villous adenomas of the common bile duct are rare and accordingly it is difficult to render a firm preoperative diagnosis. They are the unusual cause of bile duct obstruction and can mimic malignant extrahepatic biliary tumors or stones. Until recently, only a few cases had been reported in the medical literature. Although some authors advocate open surgical excision, especially with recurrence or carcinomatous change, an endoscopic resection of a distal common bile duct adenoma is a viable alternative for those patients considered poor surgical risks. We present two cases of villous adenoma of the common bile duct diagnosed by an endoscopic biopsy and endoscopically resected, with review of the relevant literature on the subject.
Adenoma ; Adenoma, Villous* ; Biopsy ; Cholestasis ; Common Bile Duct* ; Diagnosis* ; Humans ; Recurrence

BACKGROUND: For acute promyelocytic leukemia (APL), NCI criteria (1990) does not provide reliable information regarding therapeutic response. We studied APL cases in our hospital and evaluated various criteria for their predictability of therapeutic response. METHODS: Group I (GI) included 8 APL cases treated with chemotherapy and group II (GII), 10 cases with ATRA plus chemotherapy. Four treatment response indices were; (1) NCI criteria, (2) the percent sum of myelocyte and metamyelocyte (PSMM), (3) Differentiation Index[ (myelocyte+metamyelocyte+band neutrophil+segmented neutrophil)%/ (myeloblast+promyelocyte)%, DI], and (4) Maturation Index[ (metamyelocyte+band neutrophil+segmented neutrophil)%/ (myeloblast+promyelocyte+myelocyte)%, MI]. RESULTS: Among those achieving complete remission (CR), four of GI and eight of GII showed normocellularity or hypercellularity, two were in partial remission and three in persistence of GI by NCI criteria and one of GII showed persistent Auer rods at D14. Applying NCI criteria, the blast plus leukemic promyelocyte as leukemic cell were correlated well with clinical outcome. PSMM of GII were relatively constant as 20 to 29.7% at D28. DI showed wide variation and MI over 2 (Nakajima, 1996) did not correlate with CR by NCI criteria in 5 cases at D14 and 1 case at D28. CONCLUSION: NCI criteria are the reliable predictor of CR at D28 after chemotherapy if blasts plus leukemic promyelocytes are regarded as leukemic cell while they are inappropriate at D14. The persistence of Auer rods dose not exclude CR. After ATRA plus chemotherapy therapy, PSMM over 20% at D28 may be considered as a marker for CR.
Bone Marrow* ; Drug Therapy ; Granulocyte Precursor Cells ; Leukemia, Promyelocytic, Acute*

BACKGROUND: Three-dimensional (3D) echocardiography has been reported to be valuable for evaluating the geometry of cardiac chambers. We validated the accuracy of 3D transthoracic echocardiography for quantifying aortic root geometry in comparison with cardiac multi-detector computed tomography (MDCT). METHODS: Twenty-three patients who underwent cardiac MDCT and showed normal left ventricular ejection fraction (> 55%), as assessed by 2-dimensional transthoracic echocardiography, were enrolled (12 male, mean 53 +/- 9 years). We defined the aortic root volume as the volume from the aortic annulus to the sinotubular junction. The aortic root volume at end-diastole measured by both cardiac MDCT and 3D echocardiography was assessed. RESULTS: The cross-sectional area of the aortic root was asymmetric. At the annulus level, the cross-sectional area showed asymmetric triangle. From the aortic annulus to the most dilated point of the sinus of Valsalva, the asymmetric triangular shape was maintained. From the most dilated point of the sinus of Valsalva to the sinotubular junction, the cross-sectional shape of the aortic root changed to oval. The average aortic root volumes measured by 3D echocardiography (ARV-3DE) were 13.6 +/- 4.8 mL at end-diastole and 14.1 +/- 5.3 mL at end-systole, respectively. The average aortic root volume measured by MDCT at end-diastole (ARV-CT) was 14.1 +/- 5.7 mL. At end-diastole, the ARV-3DE correlated well with the ARV-CT (R2 = 0.926, difference = 0.5 +/- 1.7 mL), and the two methods were in excellent agreement (the percent difference was 0%). CONCLUSION: Our results demonstrate both the feasibility and accuracy of 3D echocardiography for the clinical assessment of the geometry of the aortic root.
Echocardiography ; Echocardiography, Three-Dimensional ; Humans ; Male ; Sinus of Valsalva ; Stroke Volume

BACKGROUND: Essential thrombocythemia (ET) is a rare chronic myeloproliferative disorder characterized by an extremely high platelet count in the circulating blood and abnormal proliferation of the megakaryocytes in bone marrow, resulting in splenomegaly, thromboembolic or hemorrhagic complications. We studied the presence of nuclear hyperploidy of the megakaryocytes in bone marrow, the presence of abnormal response to the individual reagent on platelet aggregation test, and its clinical implication. METHODS: We analyzed the 43 cases of ET at the Asan Medical Center between January, 1989 and March, 1999. The Polycythemia Vera Study Group criteria were used to diagnose ET. RESULTS: Nuclear hyperploidy was observed at 43 cases (100%). Platelet aggregation test was done at 32 (74.4%) cases, of which 27 (84.4%) cases showed abnormal response to more than one reagent, 16 (50%) cases to more than two reagents. Abnormal response to epinephrine and collagen was most common, but 5 cases showed normal response. By individual reagent, 1 (3%) cases to adenosine diphosphate, 1 (3%) case to ristocetin, 22 (69%) cases to epinephrine, 19 (59%) cases to collagen showed abnormal response. CONCLUSION: We observe that nuclear hyperploidy of the megakaryocyts and abnormal response on platelet aggregation test are frequent in ET in this study.
Adenosine Diphosphate ; Blood Platelets* ; Bone Marrow ; Chungcheongnam-do ; Collagen ; Epinephrine ; Indicators and Reagents ; Megakaryocytes* ; Myeloproliferative Disorders ; Platelet Aggregation* ; Platelet Count ; Polycythemia Vera ; Ristocetin ; Splenomegaly ; Thrombocythemia, Essential*

Treatment-related myelodysplastic syndrome (t-MDS) and acute myelogenous leukemia (t-AML) are now well established as complications of cytotoxic chemotherapy. We experienced a 28-yr-old female patient who developed t-MDS/t-AML with characteristic chromosomal abnormalities including 11q23 chromosomal rearrangement following high-dose chemotherapy with autologous stem cell transplantation (ASCT) for non-Hodgkin's lymphoma. The patient was admitted with bulky abdominal masses of B cell lineage non-Hodgkin's lymphoma. After 2 cycles of systemic chemotherapy of the Vanderbilt regimen, the patient underwent ASCT with high dose chemotherapy of the BEAC regimen. She also received radiation of 48 Gy for the residual periportal lymphadenopathy. The initial cytogenetic analysis of the infused mononuclear cells revealed a normal karyotype. Twenty two months after the ASCT, pancytopenia was noted and her bone marrow aspirate showed dysplastic hemopoiesis with myeloblasts up to 12% of nonerythroid nucleated cells. The patient was diagnosed as t-MDS (refractory anemia with an excess of blasts). Cytogenetic analysis showed complex chromosomal abnormalities including 11q23 rearrangement, which is frequently found in topoisomerase II inhibitor-related hematologic malignancies. Four months later, it was noted that the t-MDS had evolved into an overt t-AML. Cytogenetic analysis showed an evolving pattern with more complex abnormalities. The patient was treated with combination che-motherapy, but her leukemic cells were resistant to the therapy.
Adult ; Antineoplastic Agents, Phytogenic/adverse effects ; Antineoplastic Combined Chemotherapy Protocols/*adverse effects ; B-Lymphocytes/cytology ; Bone Marrow Cells/pathology ; Carmustine/*adverse effects ; Chromosome Aberrations ; Chromosomes, Human, Pair 11 ; Combined Modality Therapy/adverse effects ; Cyclophosphamide/*adverse effects ; Cytarabine/*adverse effects ; Etoposide/*adverse effects ; Female ; Gene Rearrangement ; Hematopoietic Stem Cell Transplantation/*adverse effects ; Humans ; Leukemia, Myeloid, Acute/*etiology/genetics ; Lymphoma, Non-Hodgkin/*therapy ; Myelodysplastic Syndromes/*etiology/genetics ; Neoplasms, Second Primary/*etiology ; Pelvis ; Pregnancy ; Pregnancy Complications, Neoplastic/*therapy ; Transplantation, Autologous