PURPOSE: Porous hydroxyapatite is resorbable and osteoconductive, so it is slowly replaced by ingrowing new bone. Optimal pore geometry for osteoconduction, however, has not been determined yet. The objective of this investigation was to assess both the histological response and the reinforcing effects of bone ingrowth within the porous hydroxyapatite implants depending on pore size. MATERIALS AND METHODS: Four kinds of cylindrical types (50, 100, 300, 500 micrometer) of porous hydrox-yapatite were prepared. Fifty-six white rabbits were divided into 4 groups and porous hydroxyapatite block was inserted through the medial cortical window of a proximal tibia. Histomorphological changes were examined using light microscopy and scanning electron microscopy. Biomechanical compression test was performed using a material test machine. RESULTS: Hydroxyapatite implants appeared to have no early adverse effects, such as inflammation and foreign body reaction. Osteoconduction through the pores was found in all four implants and new bone was found on the surface of pores with no histologically demonstrable intervening nonosseous tissue. At four weeks after implantation, new bone was arranged in a concentric pattern around the vessel, similar to osteon. New bone formation through pores was most evident at 300 micrometer-sized type. At 8 weeks, active osteoconduction was also found at 50 micrometer-sized type. Evidence of bone marrow formation within porous hydroxyapatite was found. In a biomechanical study, ultimate compression strength significantly increased in the 300 micrometer-sized type, after 8 weeks implantation compared to preimplantation. CONCLUSIONS: Porous hydroxyapatite implanted into rabbit tibia showed biological fixation and osteointegration. A pore size of 300 micrometer was most effective for bone ingrowth. Osteoconduction also took place in 50 micrometer-sized cylindrical pores.
Bone Marrow ; Bone Regeneration* ; Durapatite* ; Foreign-Body Reaction ; Haversian System ; Inflammation ; Microscopy ; Microscopy, Electron, Scanning ; Osteogenesis ; Rabbits ; Tibia

The change of conditions of hydroxyapatite synthesis can affect not oniy the material properties, but also the body reaction to the hydroxyapatite implants. To find out conditions for preparing more biocompatible hydroxyapatite implants as bone graft substitute. we evaluated the biologic response to the dense synthetic hydroxyapatite implants, made with various synthetic conditions, placed in corticocancellous defects of rabbits' long bone. The hydroxyapatites were synthesized with coprecipitation technique using Ca(NO3) 4H2O and (NH4)2HPO4, made with various Ca/P ratio and aging temperatures. Four kinds of hydroxyapatites were selected to use as implants(HA I: Ca/P ratio 1.5, aging temperature 90degrees C; HA V :1.5 , 30degrees C; HA VI: 1.83, 30degrees C; and HA lX: 1.67, 30degrees C). These hydroxyapatites were pressed and sintered at l300degrees C to fabricate dense plates. Biomechanical test and rnorphological examination were performed using Instron, light microscope and electron microscope. The characteristics of hydroxyapatite powder and sintered body were more significantly affected by siarting Ca/P ratios. The bonding strength of HA IX(1.67, 30degrees C) with bone was grcatest at 4 or 8 weeks after implantation with statistically significant difference(p<0.05). Bonding behavior betweeb HA IX and bone was most excellent in terms of new bone formation and new bone ingrowth into resorbed surface of hydroxyapatite plate.
Aging ; Durapatite* ; Hydroxyapatites ; Osteogenesis ; Transplants

The human colorectal carcinoma-associated GA733 antigen epithelial cell adhesion molecule (EpCAM) was initially described as a cell surface protein selectively expressed in some myeloid cancers. Gangliosides are sialic acid-containing glycosphingolipids involved in inflammation and oncogenesis. We have demonstrated that treatment with anti-EpCAM mAb and RAW264.7 cells significant inhibited the cell growth in SW620 cancer cells, but neither anti-EpCAM mAb nor RAW264.7 cells alone induced cytotoxicity. The relationship between ganglioside expression and the anti-cancer effects of anti-EpCAM mAb and RAW264.7 was investigated by high-performance thin-layer chromatography. The results demonstrated that expression of GM1 and GD1a significantly increased in the ability of anti-EpCAM to inhibit cell growth in SW620 cells. Anti-EpCAM mAb treatment increased the expression of anti-apoptotic proteins such as Bcl-2, but the expression of pro-apoptotic proteins Bax, TNF-alpha, caspase-3, cleaved caspase-3, and cleaved caspase-8 were unaltered. We observed that anti-EpCAM mAb significantly inhibited the growth of colon tumors, as determined by a decrease in tumor volume and weight. The expression of anti-apoptotic protein was inhibited by treatment with anti-EpCAM mAb, whereas the expression of pro-apoptotic proteins was increased. These results suggest that GD1a and GM1 were closely related to anticancer effects of anti-EpCAM mAb. In light of these results, further clinical investigation should be conducted on anti-EpCAM mAb to determine its possible chemopreventive and/or therapeutic efficacy against human colon cancer.
Animals ; Antibodies, Monoclonal/*immunology/*therapeutic use ; Antigens, Neoplasm/*immunology ; Apoptosis/drug effects ; Cell Adhesion Molecules/*immunology ; Cell Line ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Colon/drug effects/immunology/metabolism/pathology ; Colonic Neoplasms/*drug therapy/genetics/*immunology/pathology ; Gangliosides/genetics/*immunology ; Gene Expression Regulation, Neoplastic/drug effects ; Humans ; Male ; Mice ; Mice, Inbred BALB C

No abstract available.

BACKGROUND: Acquired idiopathic sideroblastic anemia (AISA) is a heterogeneous condition. Most instances, involving only the erythroid line, are benign disease with a longer survival and a low propensity for evolution into acute leukemia. A subset of patients have severe clinical course and evidence of other cell line involvement at presentation, may develop the emergence of blast cells and evolution into acute leukemia. In an attempt to identify the natural history and the risk factors for the development of acute leukemia, the clinical, hematological and outcome data were studied in the patients with AISA. METHODS: We reviewed retrospectively the medical records of 15 patients of AISA treated at the Catholic University of Taegu-Hyosung and Kyungpook National University Hospital from March 1989 to December 1995. RESULTS: The median age at diagnosis was 41 years and the male to female ratio was 8 : 7. On bone marrow examination, erythroid abnormalities were prominent in all cases, 5 patients also showed involvement of the granulocytic and/or megakaryocytic cell lines (AISA with myelodysplastic features, AISA-M). The median follow-up duration was 32 months. Transfusion dependence occurred in 11 of 16 cases. Progression towards refractory anemia with excess of blasts or acute leukemia (M2) was observed in two patients with AISA-M after follow-up period of 16 months and 24 months, respectively. Infections and hemorrhages were causes of death in 3 patients with AISA-M but not in patients with dyserythropoiesis only (AISA-erythroid, AISA-E). CONCLUSIONS: Most patients with AISA have a relatively benign course with prolonged survival after the onset of anemia. Patients with features of dysgranulopoiesis and/or dysmegakaryopoiesis in addition to dyserythropoiesis at presentation were increased risk of transformation to refractory anemia with excess of blasts or acute leukemia and shorter surtival. But further study of larger numbers of patients and longer follow-up may be warranted.
Anemia ; Anemia, Refractory, with Excess of Blasts ; Anemia, Sideroblastic* ; Bone Marrow Examination ; Cause of Death ; Cell Line ; Diagnosis ; Female ; Follow-Up Studies ; Gyeongsangbuk-do ; Hemorrhage ; Humans ; Leukemia ; Male ; Medical Records ; Natural History ; Retrospective Studies ; Risk Factors

Gangliosides are ubiquitous components of the membranes of mammalian cells that are thought to play important roles in various cell functions such as cell-cell interaction, cell adhesion, cell differentiation, growth control, and signaling. However, the role that gangliosides play in the immune rejection response after xenotransplantation is not yet clearly understood. In this study, the regulatory effects of human leukocytes on ganglioside expression in primary cultured micro-pig aortic endothelial cells (PAECs) were investigated. To determine the impact of human leukocytes on the expression of gangliosides in PAECs, we performed high-performance thin layer chromatography (HPTLC) in PAECs incubated with FBS, FBS containing human leukocytes, human serum containing human leukocytes, and FBS containing TNF-alpha. Both HPTLC and immunohistochemistry analyses revealed that PAECs incubated with FBS predominantly express the gangliosides GM3, GM1, and GD3. However, the expression of GM1 significantly decreased in PAECs incubated for 5 h with TNF-alpha (10 ng/mL), 10% human serum containing human leukocytes, and 10% FBS containing human leukocytes. Taken together, these results suggest that human leukocytes induced changes in the expression profile of ganglioside GM1 similar to those seen upon treatment of PAECs with TNF-alpha. This finding may be relevant for designing future therapeutic strategies intended to prolong xenograft survival.
Cell Adhesion ; Cell Communication ; Chromatography, Thin Layer ; Endothelial Cells ; Gangliosides ; Humans ; Immunohistochemistry ; Leukocytes ; Membranes ; Rejection (Psychology) ; Transplantation, Heterologous ; Tumor Necrosis Factor-alpha