Biomedical subjects

G H Ahn

Publications and source records attributed to G H Ahn.

12 recordsLinked to original sources

PubMed2007

Expression of TGF-beta signaling proteins in normal placenta and gestational trophoblastic disease.

The transforming growth factor beta (TGF-beta) is a vital regulator of placental development and functions. TGF-beta exerts several modulatory effects on trophoblast cells, such as inhibition of proliferation and invasiveness, and stimulation of differentiation by inducing multinucleated cell formation. In this study, we determine the expression patterns of TGF-beta signaling molecules in normal trophoblast, various hydatidiform mole types and choriocarcinoma. A total of 132 cases, including 51 normal placenta (20 first trimester, 11 second trimester, and 20 third trimester) and 81 gestational trophoblastic diseases (17 choriocarcinoma, and 64 hydatidiform moles: 39 complete, 6 partial, and 19 invasive) were immunohistochemically analyzed with anti-TGF beta1/2, TGF-beta receptor type I (TbetaRI), TbetaRII, Smad 2/3, and Smad 4 antibodies on paraffin blocks. In the case of normal placenta, maximal levels of all TGF-beta signaling molecules were observed in villous trophoblast in the first trimester, which decreased with gestational age. Expression of all the TGF-beta signaling proteins except Smad2/3, was significantly enhanced in various moles, relative to normal trophoblast. Moreover, TGF-beta signaling molecules were significantly downregulated in choriocarcinoma, compared to moles. In particular, TbetaRI and Smad2/3 levels were lower in choriocarcinoma than normal villous trophoblast (TbetaRI: p<0.025, Smad2/3: p<0.001). In conclusion, the TGF-beta signaling pathway plays an important role in the pathogenesis and progression of gestational trophoblastic disease, and may thus be employed as a potential therapeutic target and a diagnostic biomarker.

Activin Receptors, Type I↗

PubMed2006

Comparison of calculated spectra for the interaction of photons in a liquid scintillator. Example of 54Mn 835 keV emission.

The CIEMAT/NIST and TDCR methods in liquid scintillation counting, initially developed for the activity standardization of pure-beta radionuclides, have been extended to the standardization of electron capture and beta-gamma radionuclides. Both methods require the calculation of the energy spectrum absorbed by the liquid scintillator. For radionuclides emitting X-rays or gamma-rays, when the energy is greater than a few tens of keV the Compton interaction is important and the absorption is not total. In this case, the spectrum absorbed by the scintillator must be calculated using analytical or stochastic models. An illustration of this problem is the standardization of 54Mn, which is a radionuclide decaying by electron capture. The gamma transition, very weakly converted, leads to the emission of an 835 keV photon. The calculation of the detection efficiency of this radionuclide requires the calculation of the energy spectrum transferred to the scintillator after the absorption of the gamma ray and the associated probability of absorption. The validity of the method is thus dependent on the correct calculation of the energy transferred to the scintillator. In order to compare the calculation results obtained using various calculation tools, and to provide the metrology community with some information on the choice of these tools, the LS working group of the ICRM organised a comparison of the calculated absorbed spectra for the 835 keV photon of 54Mn. The result is the spectrum of the energy absorbed by the scintillator per emission of an 835 keV gamma ray. This exercise was proposed for a standard 20 ml LS glass vial and for LS cocktail volumes of 10 and 15 ml. The calculation was done for two different cocktails: toluene and a widely used commercial cocktail, Ultima Gold. The paper describes the results obtained by nine participants using a total of 12 calculation codes.

Algorithms↗

PubMed2001

Immunoexpression of inhibin alpha-subunit in adrenal neoplasms.

Inhibin normally is produced by ovarian granulosa cells and testicular Sertoli cells. Extragonadal inhibin expression also has been detected in the placenta, pituitary gland, and liver. It may be difficult to make a distinction between adrenal cortical tumors, pheochromocytoma, and metastatic carcinomas including renal cell and hepatocellular carcinoma. Immunohistochemical expression of inhibin alpha-subunit was evaluated to determine whether any usefulness of immunostaining could be found for inhibin alpha-subunit in the differential diagnosis of adrenal glandular lesions. The authors performed immunostaining against inhibin alpha-subunit on 5 cases of normal adrenal gland, 1 case of adrenal cortical hyperplasia, 25 cases of adrenal cortical adenoma, 6 cases of adrenal cortical carcinoma, 21 cases of pheochromocytoma, 8 cases of metastatic carcinoma, and 10 cases of primary renal cell carcinoma. Normal adrenal gland showed a strong immunoreactivity against inhibin alpha-subunit, especially in the inner layer of the adrenal cortex, representing the zona reticularis, but adrenal medulla was negative for inhibin alpha-subunit. Adrenal cortical hyperplasia associated with Cushing's syndrome showed a strong, diffuse immunoreactivity for inhibin alpha-subunit. Immunoreactivity against the inhibin alpha-subunit was identified in all cases of adrenal cortical adenoma and carcinoma, especially in the adrenal cortical neoplasm with Cushing's syndrome, which showed a strong reactivity. However, immunoreactivity was absent in two metastatic carcinomas from the liver and colon and most of the pheochromocytomas, except three cases with weak focal positivity for inhibin alpha-subunit. Four cases of metastatic renal cell carcinoma and 10 cases of primary renal cell carcinoma revealed no immunoreactivity. Metastatic adenocarcinoma from the prostate showed a weak immunoreactivity for inhibin alpha-subunit. Metastatic hepatoblastoma was negative against inhibin alpha-subunit with endogenous biotin blocking. Immunoexpression for inhibin alpha-subunit is useful for making distinction between adrenal cortical tumors, pheochromocytoma, and metastatic carcinoma. Inhibin alpha-subunit may be valuable as part of a diagnostic immunohistochemical panel in adrenal glandular lesions.

Adolescent↗

PubMed2001

Erdheim-Chester disease with extensive marrow necrosis: a case report and literature review.

Erdheim-Chester disease is a rare systemic disorder characterized by a fibrosing xanthogranulomatous infiltration of multiple organs. We report a case of Erdheim-Chester disease with diffuse necrosis leading to difficulty in making a prompt diagnosis. Radiologically, osteosclerotic lesions with osteolytic element involved metadiaphyses of both proximal tibia, and retroperitoneal infiltrations encasing both kidneys, both adrenals, and aorta were found. A biopsy of the tibia showed diffuse infiltration of foamy histiocytes, Touton-type giant cells, and fibroblastic cells associated with extensive coagulative necrosis. Immunohistochemically, foamy histiocytes were positive for CD68 and peanut agglutinin and negative for S-100 protein. A few Langerhans' cells, which were difficult to identify in hematoxylin-eosin stain, were highlighted by immunostain for S-100 protein. The patient received supportive therapy and was alive 1 1/2 years after diagnosis, with newly developed bilateral retrobulbar lesions and worsened heart failure.

Bone Diseases↗

PubMed1999

High CD99 expression in memory T and B cells in reactive lymph nodes.

We investigated the expression of CD99 in 35 hyperplastic perigastric lymph nodes, which were resected for gastric carcinoma or chronic peptic ulcer. Essentially, all lymphocytes in lymph nodes expressed CD99, but there were two populations with respect to the intensity of CD99 expression--CD99high and CD99low cells. We showed CD99high cells were distributed in paracortical and medullary cords by immunohistochemical study while germinal center cells were CD99low. Using three-color flow cytometric analysis with CD3, CD4, CD8, CD19, CD23, CD45RA, CD45RO, CD69, CD138, IgM, IgD, and IgG, most of CD99high cells were shown to be activated/memory T cells. CD4+CD45RO+ T cells were the subset revealing the highest intensity of CD99 expression while CD4+CD45RA+ T cells were CD99low. Among B cells, IgG+ B cells revealed a higher level of CD99 molecules than IgM+ B cells. These results suggest that CD99 is one of activation-related molecules which are upregulated in recently activated lymphocytes.

12E7 Antigen↗

PubMed1991

Clear cell carcinoma of the inguinal region arising from endometriosis.

The second and third examples of clear cell carcinoma of the inguinal region arising from endometriosis are reported. In one patient a right inguinal mass was excised along with an inguinal lymph node dissection. The tumor recurred in the retroperitoneum and was removed, and postoperative radiation therapy was administered. The patient died of recurrent tumor after 11 years. The other patient was treated by excision of a left inguinal mass and an inguinal lymph node dissection and was alive without recurrence 4 years and 8 months later.

Abdominal Neoplasms↗

PubMed1989

Clear-cell chondrosarcoma--a case report.

Clear-cell chondrosarcoma, a recently specified entity, is a low-grade malignant tumor and has characteristic clinical, roentgenographic and pathologic findings which separate it from conventional chondrosarcoma and other benign tumors. Therefore, correct diagnosis is important from the viewpoint of both prognosis and therapeutic approach. We report a case of typical recurrent clear-cell chordirosarcoma. Typical round cells with clear cytoplasm, large nuclei, and small nucleoli were wellnoted. The clear cytoplasm was faintly positive in PAS staining. Electronmicroscopic study showed that these cells were of chondroid origin, showing indented nuclei, large dilated endoplasmic reticulum cisternae, bundles of actin-like filaments and a few glycogen particles.

Chondrosarcoma↗

PubMed1988

Serous papillary cystadenoma of borderline malignancy of broad ligament. A report of 25 cases.

The clinical and pathological features of 25 serous papillary cystadenomas of borderline malignancy of the broad ligament were analyzed. The ages of the patients ranged from 19 to 67 (average, 32) years. The clinical presentation was lower abdominal pain, pelvic pain or both in five cases, accompanied by menometrorrhagia or amenorrhea in three cases. One patient was thought to have an acute abdominal disorder. The tumors of the remaining 19 patients were discovered either on routine gynecological examination or during an evaluation of the pregnancy status of the patient. In 14 cases the tumor was located in the left broad ligament and in 11 cases it was on the right side; all the tumors were entirely separated from the ipsilateral ovary. On gross examination the tumors were 1-13 cm in greatest dimension, had smooth outer surfaces, and contained straw-colored, watery fluid. The inner lining bore single or multiple 0.3-2.5 cm excrescences. Microscopic examination revealed that the cyst walls and their excrescences were lined by simple to pseudostratified, cuboidal to columnar, focally ciliated epithelium. Slight nuclear atypism, very rare mitotic activity, and focal psammoma body formation were also found. The stroma resembled ovarian stroma but no primary follicles or follicular derivatives were identified. Twenty-three of the patients were alive and well from 0.5 to 11 years after excision of the tumor, one patient was disease-free for 8.5 years but died of an open-heart surgical procedure; and two patients were lost to follow-up examination.

Adnexa Uteri↗

PubMed1986

Ovarian sex cord tumor with annular tubules.

A pathologic study was done on four cases of ovarian sex cord tumor with annular tubules. All four tumors occurred in young women (11-24 years of age) and were not associated with the Peutz-Jeghers syndrome. Two patients had evidence of hyperestrinism. One patient who had metastasis to the retroperitoneum, left supraclavicular lymph node, and liver confirmed the malignant potential of this tumor. Gross examination revealed tumors that were solid, yellowish, and unilateral, with varying degrees of cystic degeneration. Microscopic examination showed simple or complex annular tubules with prominent basement membranes. Many tumor cells contained lipid in the cytoplasm. Ultrastructural study showed Charcot-Bottcher filaments in all four cases, indicating Sertoli cell differentiation. True lumens and microvilli were identified in one case. The classification of the sex cord tumor with annular tubules as a Sertoli cell tumor, annular tubular type was proposed on the basis of ultrastructural findings.

Adolescent↗

PubMed1985

Malignant lymphomas in Korea.

A retrospective histological study based on biopsy material of 341 cases of malignant lymphoma diagnosed at the Department of Pathology of the Seoul National University from 1976 through 1983 was conducted, to reveal some characteristics of malignant lymphomas occurring in Korea. Malignant lymphoma was the seventh most common malignant tumor (4.03%) among Koreans. Non-Hodgkin's lymphoma predominated over Hodgkin's disease, accounting for 87% of all malignant lymphomas. Follicular lymphoma was rarely seen in Korea (3%), and among types of non-Hodgkin's lymphoma the diffuse histiocytic type (57%) and the poorly differentiated lymphocytic type (26%) of Rappaport were common. Follicular center cell lymphomas (Lukes-Collins) were most commonly seen, whereas T-cell lymphoma was found in approximately 10% of the non-Hodgkin's lymphomas. Not a single case of pleomorphic adult T-cell lymphoma was encountered in this series. Among subtypes of Hodgkin's disease the nodular sclerosis type was particularly rare, comprising only 15% of the Hodgkin's disease cases.

Adolescent↗

PubMed1982

Osteoblastoma: classification and report of 16 patients.

In 16 patients who had osteoblastoma treated within the last eight years, the lesions can be classified as vertebral (four cases), central "benign" (seven cases), "aggressive" (three cases) and periosteal (two cases). The radiographic features were highly variable except for the consistent shell of reactive periosteal bone. None of the lesions resembled osteoid osteoma or osteosarcoma. The histological pattern was typical, showing sheets of osteoblasts forming irregular, poorly ossified bone trabeculae in a fibrovascular stroma. The three "aggressive" lesions had a distinctly more ominous histologic pattern, a more destructive radiographic appearance and recurred promptly following local curettage. Treatment varied, but for the vertebral, benign "central," and periosteal osteoblastomas, curettage or marginal resection was generally curative. Local wide resection was required for individual aggressively growing tumors.

Adolescent↗

PubMedDate not supplied

Relationship between p53-associated proteins and estrogen receptor status in ovarian serous neoplasms.

We studied the immunoexpression of p14ARF, MDM2, and p53, in addition to relationships between those protein expressions and estrogen receptor (ER)alpha in ovarian serous tumors including benign (n= 23), borderline (n= 41), and malignant (n= 94). The aberrant expressions of p14ARF, MDM2, and p53 were observed in 19.6% (31/158), 47.5% (75/158), and 39.9% (63/158) of cases, respectively. The expression of MDM2 was significantly higher in borderline tumors compared to benign (P= 0.04) and malignant (P < 0.01) tumors. p53 expression in borderline tumors was uncommon, and p14ARF expression loss was mainly observed in carcinomas. Altered expression of p14ARF, MDM2, and p53 shows significant relationship with stage. Overexpression of MDM2 (P= 0.01) and loss of p14ARF expression (P= 0.04) were significantly associated with ER expression. Our results suggest that alteration of p14ARF-MDM2-p53 pathway proteins may contribute significantly to the tumorigenesis of ovarian serous neoplasms, and ER is involved in cellular regulation of p14ARF-MDM2-p53 pathway in ovarian serous neoplasms.

Adolescent↗