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Biomedical subjects

H R Park

Publications and source records attributed to H R Park.

At least 37 records · Page 2Linked to original sources
PubMed1996

Papillary ependymoma: its differential diagnosis from choroid plexus papilloma.

Papillary ependymoma is a rare variant of ependymoma and often gives rise to confusion with choroid plexus papilloma because of topographic, light microscopic and ultrastructural similarities. Here, we report two cases of papillary ependymomas regarding their unique clinicopathologic features and differential points from choroid plexus papilloma. Brain MRI revealed a large mass in the left lateral ventricle in one case and a 3cm sized mass in the pineal area and the 3rd ventricle in the other. Microscopically, the tumor was characterized by papillary and tubular structures. Immunohistochemically, the tumor cells in both cases expressed cytokeratins(CK22 and CAM 5.2) but did not express glial fibrillary acidic protein(GFAP), vimentin, epithelial membrane antigen, and S100 protein. This is a very unusual immunohistochemical feature for papillary ependymoma. Ultrastructurally, the tumor showed a mosaic pattern of tumor cells with frequent intercellular microrosettes having a few stubby microvilli, a few cilia and zonulae adherentes. The cytoplasmic processes were markedly reduced compared to conventional ependymoma. The cytoplasm did not contain intermediate filaments. Interestingly, the mitochondria showed abnormal features with a pleomorphic shape and abnormal cristae in both cases. These ultrastructural features enabled differentiation between papillary ependymoma and choroid plexus papilloma in addition to the light microscopic findings.

Adult↗
PubMed1995

Chondromyxoid fibroma of the femur: a case report with intra-cortical location.

Chondromyxoid fibroma (CMF) is the least common benign cartilaginous tumor, comprising less than 0.5 to 1% of all skeletal neoplasms. This subject was a 16-year-old female with a three-year history of pain involving the distal femoral metaphysis. This case showed an unusual feature: it was intracortical in location. Radiologic differential diagnosis included metaphyseal fibrous defect, periosteal chondroma, simple or aneurysmal bone cyst, and cortical abscess. On operation, the lesion filled the intracortical defect with whitish myxoid soft tissue, bulging into the adjacent soft tissue. Microscopically, it showed typical features of chondromyxoid fibroma composed of mainly myxoid nodules and peripheral fibrous elements with focal chondroid differentiation.

Adolescent↗
PubMed1995

Osteocalcin expression in primary bone tumors--in situ hybridization and immunohistochemical study.

Osteocalcin is one of the most abundant noncollagenous proteins found in adult bone. It is a highly conserved gamma-carboxyglutamic acid-containing protein that is believed to be produced exclusively by osteoblasts. In this study, intracellular and extracellular localization of osteocalcin in osteosarcoma was examined with anti-osteocalcin antibody and in situ hybridization using a synthetic oligonucleotide. Immunohistochemically, osteoblastic osteosarcomas were all positive for osteocalcin. The chondroblastic osteosarcomas were positive on the neoplastic chondrocytes. The five fibroblastic osteosarcomas out of seven were positive for osteocalcin immunostaining over the neoplastic spindle cells. Five cases of osteoblastic osteosarcomas out of seven were positive for osteocalcin in situ hybridization. Two cases of chondroblastic osteosarcomas and three cases of fibroblastic osteosarcomas were positive for in situ demonstration of osteocalcin. The malignant tumor giant cells were positive for osteocalcin immunostaining 83%. They were also positive for in situ hybridization. The benign giant cells in five giant cell tumors and five aneurysmal bone cysts were negative for osteocalcin immunostaining. The benign giant cells in three chondroblastoma and three Paget's disease were positive for osteocalcin. In this study, the osteocalcin in situ hybridization and immunostaining has very important meaning for making differential diagnoses of, especially giant cell rich bone forming tumors.

Base Sequence↗
PubMed1995

Expression of p53 protein, PCNA, and Ki-67 in osteosarcomas of bone.

Expressions of p53 protein, a product of the tumor suppressor gene were studied in osteosarcomas relating to various prognostic factors. Thirty-four osteosarcomas were investigated immunohistochemically with a monoclonal antibody clone PAb240, which recognizes a common conformational epitope of mutant p53 proteins and another clone PAb1801, which reacts with both wild- and mutant-type p53 proteins. The results were compared with expressions of proliferating cell nuclear antigen (PCNA) and Ki-67 providing a simple method for the assessment of growth fractions of tumors. PAb240 stained nuclei and cytoplasm of tumor cells in 8 of 34 osteosarcomas (23.5%), whereas PAb1801 reacted in all 34 osteosarcomas (100%). Fifteen tumors (44.1%) showed positivity for PAb1801 in more than half of the tumor cells. Twelve patients were alive and thirteen were dead. Tumors from 9 patients (75%) who survived revealed only focal positive immunoreactions with PAb1801 and tumors from 6 patients (46.1%) who died revealed diffuse reactions. Twelve cases (35.3%) showed a high PCNA index (> 40%) and fibroblastic osteosarcomas revealed the highest PCNA positivity. Twenty-two cases (64.7%) revealed a very low Ki-67 index (less than 10%) and Ki-67 index showed a good correlation with PCNA positivity (r = 0.6247). Expressions of both wild-and mutant-type p53 protein, PCNA, and Ki-67 were not correlated with other clinical or pathological parameters.

Adolescent↗
PubMed1995

Assessment of diagnostic utility of anti-CD34 in soft tissue tumors.

We have performed this study to define the usefulness of an anti-human progenitor cell antigen-1(anti-CD34) to distinguish some kinds of soft tissue tumors in formalin-fixed, paraffin-embedded tissues. Sixty three cases of vascular, fibrohistiocytic, neural and other tumors were immunostained for CD34 using the streptavidin-biotin immunoperoxidase method. All of the vascular tumors including hemangiomas, epithelioid hemangioendotheliomas, hemangiopericytomas, and lymphangiomas revealed strong CD34 positivity along the cytoplasmic membranes. Among the fibrohistiocytic lesions, all of five examples of dermatofibrosarcoma protuberans showed diffuse, strong, and linear staining along the cytoplasmic processes. In contrast, none of the benign fibrous histiocytomas and malignant fibrous histiocytomas expressed CD34. CD34-positive cells with delicate dendritic processes could be identified within the normal nerves, neuromas, neurofibromas, and Antoni B areas of neurilemomas. However, all of the malignant peripheral nerve sheath tumors were uniformly negative. In addition, an epithelioid sarcoma and four cases of leiomyosarcoma revealed focal, weak positivity with anti-CD34. In conclusion, this study demonstrated variable anti-CD34 staining pattern of certain fibrohistiocytic, muscle, and neural tumors and confirmed the potential usefulness of anti-CD34 in differentiating fibrous histiocytoma from dermatofibrosarcoma protuberans. It's also helpful to diagnose epithelioid hemangioendothelioma from other epithelioid-type tumors.

Antibodies, Monoclonal↗
PubMed1994

High level expression of hepatitis B virus preS1 peptide in Escherichia coli.

PreS1 region gene fragment encoding the N-terminal 56 amino acid (aa) of hepatitis B virus (HBV, adr subtype), which encodes B- and T-cell epitopes and an hepatocyte receptor binding site, was synthesized by PCR and fused to the 3'-end of MalE gene encoding maltose-binding protein (MBP) to yield expression plasmid pMalpreS1-56. The plasmid was introduced into Escherichia coli DH5 alpha and expressed at 37 degrees C under the control of inducible tac promoter. The resulting fusion protein was highly expressed in a soluble form, about 40% of total cellular proteins, but it bound only partially to an amylose column. Therefore, the soluble preS1 fusion protein was purified to near homogeneity by two passages of anion-exchange chromatography followed by gel filtration. The yield of the fusion protein was 70 mg per 1 culture that had been induced by IPTG for 6 h. The purified fusion protein was specifically cleaved by a Factor Xa digestion to release the preS1 peptide, which was then purified by gel filtration to homogeneity. The purity, integrity, antigenicity and immunogenicity of the purified preS1 peptide was confirmed by glycerol-SDS-PAGE, Western analysis, N-terminal amino acid sequencing and an indirect ELISA.

ATP-Binding Cassette Transporters↗
PubMed1993

Endodermal sinus tumour associated with benign teratoma of the common bile duct.

We report a 5-year-old boy with endodermal sinus tumour associated with benign cystic teratoma of the common bile duct (CBD). To our knowledge, there has been one case of teratoma of the CBD in the English literature with no morphological or radiological description. Our case presented a lobulated polypoid mass obstructing the distal CBD on sonography and computed tomography, which resembled the botryoid masses of rhabdomyosarcoma.

Child, Preschool↗
PubMed1992

Primary non-Hodgkin's malignant lymphoma of the vulva--a case report.

A case of primary non-Hodgkin's malignant lymphoma of the vulva which occurred in a 68-year-old woman is presented. Non-Hodgkin's malignant lymphoma is infrequently involved in the female genital tract. Moreover, primary vulvar involvement of this tumor is very rare. To date only 6 cases have been reported in the literature. To our knowledge this is the first reported case of a non-Hodgkin's malignant lymphoma of the vulva in Korea.

Aged↗
PubMed1992

Spinal meningeal melanocytoma.

A case of spinal meningeal melanocytoma is reported along with clinicopathologic, immunohistochemical and ultrastructural studies. This patient presented clinically with paraparesis, tingling sensation and numbness of both lower extremities of 4 months duration. No mucocutaneous pigmented nevi were found. On operation, scattered coal-black pigmented lesions were found in the meninges between T3 and T4-5 interspace level. Nearly total removal was carried out. The tumor was composed of spindle and epithelioid cells with heavy brown-black pigmentation. There was no pleomorphism, mitosis, hemorrhage, necrosis or invasion to the underlying cord tissue. In Korea, this case appears to be the first example of this disease. Neurologic deficit improved after surgical excision.

Adult↗
PubMed1991

A case of retroperitoneal teratoma with nephroblastoma.

We present a case of retroperitoneal teratoma in a 4-year-old girl in which a Wilms' tumor-like element was predominant, unlike the usual pattern of the immature or malignant teratoma. Mature elements were composed of adipose tissue, neural plexus and ganglia, cartilage, smooth and skeletal muscles, and glandular epithelium of the respiratory and gastrointestinal types. Three months after complete excision of the mass, a recurrent tumor developed. It consisted of only nephroblastomatous elements without teratomatous components. Theories for the histogenesis of this rare tumor are discussed.

Child, Preschool↗
PubMed1991

A case of anisakiasis causing intestinal obstruction.

A 31-year old salesman living in Seoul developed suddenly abdominal pain due to intestinal obstruction. Exploratory laparotomy exhibited segmental jejunal cellulitis caused by penetrating Anisakis larva. The patient had eaten raw fish. The typical history of intestinal anisakiasis was presented with a short review of Korean patients of anisakiasis.

Adult↗
PubMed1990

In vivo N-glycosylation and fate of Asn-X-Ser/Thr tripeptides.

The minimum primary structural requirement for a tripeptide to serve as a substrate for oligosaccharyl transferase is the sequence -Asn-X-Ser/Thr-. In the present study the activities of three structurally different tripeptides containing acceptor sequences for oligosaccharyl transferase were compared in three systems: Xenopus oocytes, in which they were introduced into the cytoplasm by microinjection, cultured mammalian cells, and isolated rat liver microsomes. In the last two systems, the peptides were added exogenously to the culture or to the incubation medium, respectively. On the basis of lectin column and paper chromatographic analysis it was established that the microinjected acceptor tripeptides were glycosylated in Xenopus oocytes. However, lectin column analysis and retention of sensitivity to endoglycosidase H revealed that none of the three glycopeptides was processed to complex oligosaccharide chains and none was subsequently secreted. Rather, over a 24-h period the glycopeptides were degraded. Chloroquine was found to block this degradation process, but even under these conditions, the glycopeptides were not secreted into the medium. In the isolated microsomes the glycosylation of the acceptor tripeptides was time-dependent and the tripeptide with an iodotyrosine residue in the X position was found to be a poor substrate. When added to cultured mammalian cells, all three of the tripeptides were taken up, glycosylated, and subsequently secreted. These results are discussed in the context of the wide differences in glycosylation of the three peptides and their lack of secretion after glycosylation in Xenopus oocytes.

Amino Acid Sequence↗
PubMed1989

Inhibitors of metalloendoproteases block spiculogenesis in sea urchin primary mesenchyme cells.

Metalloendoproteases have been implicated in a variety of fusion processes including plasma membrane fusion and exocytosis. As a prerequisite to skeleton formation in the sea urchin embryo, primary mesenchyme cells undergo fusion via filopodia to form syncytia. The spicule is formed within the syncytial cable by matrix and mineral deposition. To investigate the potential involvement of a metalloendoprotease in spiculogenesis, the effect of inhibitors of this enzyme on skeleton formation was studied. Experiments with primary mesenchyme cells in vitro and in normal embryos revealed that skeleton formation was blocked by these inhibitors. These findings implicate a metalloendoprotease in spiculogenesis; such an enzyme has been demonstrated in homogenates of primary mesenchyme cells. The most likely site of action of the metalloendoprotease is at the cell membrane fusion stage and/or at subsequent events requiring membrane fusion.

Animals↗
PubMed1989

A calcium-binding, asparagine-linked oligosaccharide is involved in skeleton formation in the sea urchin embryo.

We have previously identified a 130-kD cell surface protein that is involved in calcium uptake and skeleton formation by gastrula stage embryos of the sea urchin Strongylocentrotus purpuratus (Carson et al., 1985. Cell. 41:639-648). A monoclonal antibody designated mAb 1223 specifically recognizes the 130-kD protein and inhibits Ca+2 uptake and growth of the CaCO3 spicules produced by embryonic primary mesenchyme cells cultured in vitro. In this report, we demonstrate that the epitope recognized by mAb 1223 is located on an anionic, asparagine-linked oligosaccharide chain on the 130-kD protein. Combined enzymatic and chemical treatments indicate that the 1223 oligosaccharide contains fucose and sialic acid that is likely to be O-acetylated. Moreover, we show that the oligosaccharide chain containing the 1223 epitope specifically binds divalent cations, including Ca+2. We propose that one function of this negatively charged oligosaccharide moiety on the surfaces of primary mesenchyme cells is to facilitate binding and sequestration of Ca+2 ions from the blastocoelic fluid before internalization and subsequent deposition into the growing CaCO3 skeleton.

Animals↗
PubMed1987

Developmental expression of a cell-surface protein involved in calcium uptake and skeleton formation in sea urchin embryos.

The developmental expression of a cell-surface protein involved in Ca2+ accumulation and skeleton formation in sea urchin embryos has been studied. In Strongylocentrotus purpuratus, this protein is present in the egg and in all cell types of the early embryo. After gastrulation, its synthesis and expression are restricted to the skeleton-forming primary mesenchyme cells. In Lytechinus pictus, the protein cannot be detected in eggs or in embryos until the mesenchyme blastula stage. Hybrid embryos demonstrate a pattern of expression indistinguishable from that of the species contributing the maternal genome, which suggests that early expression of the protein in S. purpuratus embryos is due to utilization of maternal transcripts from the egg. Later expression of this protein in primary mesenchyme cells is the result of cell-type-specific synthesis, likely encoded by embryonic transcripts. This cell-type-specific expression in primary mesenchyme cells correlates temporally with Ca2+ accumulation during skeleton formation in the embryo.

Animals↗
PubMed1985

Active site-directed photoaffinity labeling and partial characterization of oligosaccharyltransferase.

Oligosaccharyltransferase, the enzyme that catalyzes the transfer of the oligosaccharide chain of dolichol-P-P-GlcNAc2Man9Glc3 to asparagine residues in -Asn-X-Thr/Ser- sites within polypeptides, has been radiolabeled using a photoactivatable azido tripeptide acceptor, N alpha-[3H]Ac-Asn-Lys(N epsilon-p-azidobenzoyl)-Thr-NH2. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the molecular mass of the oligosaccharyltransferase polypeptide from hen oviduct microsomes is 60 kDa. Radiolabeling of the 60-kDa polypeptide was completely dependent upon photolysis of hen oviduct endoplasmic reticulum preparations in the presence of the azido peptide and Mn2+, which is required for enzymatic activity. Labeling of the enzyme was not inhibited in the presence of a 10-fold excess of the nonacceptor peptides, unacetylated Asn-Lys(N epsilon-p-azidobenzoyl)-Thr-NH2 or unacetylated Asn-Leu-Thr-NH2, whereas it was completely abolished by the presence of a 10-fold excess of the competing acceptor peptide, N alpha-Bz-Asn-Leu-Thr-NH2. Thermal inactivation of oligosaccharyltransferase was achieved by heating endoplasmic reticulum preparations to 60 degrees C. This loss of enzyme activity at 60 degrees C paralleled a comparable decrease in radiolabeling of the 60-kDa polypeptide, whereas temperatures of 50 degrees C and lower had no effect on either process. Oligosaccharyltransferase itself may be an N-linked glycoprotein, because the 60-kDa radiolabeled polypeptide binds to concanavalin A-agarose and is susceptible to digestion by beta-endohexosaminidase H.

Affinity Labels↗