Biomedical subjects

H G Song

Publications and source records attributed to H G Song.

At least 19 recordsLinked to original sources

PubMed2001

Changes in orofacial muscle activity in response to changes in respiratory resistance.

Increased resistance in the upper airway is known to be a contributing factor to deviant facial growth patterns. These patterns are the result of a prolonged presence of unbalanced oropharyngeal muscle activity. We hypothesized that mechanically increasing airway resistance would enhance the activity of the muscles facilitating respiration, and we attempted to demonstrate that the increased muscle activity is modulated by mechanoreceptors in the pharyngeal airway. The response of oropharyngeal muscles to increased airway resistance during spontaneous breathing was observed in 11 rabbits. Electromyographic signals from the ala nasi, orbicularis oris superior, genioglossus, mylohyoid muscles, and the diaphragm were recorded by fine-wire electrodes. Pressure changes were monitored by pressure transducers at the side branch of the cannule close to openings for the nose and the trachea. The study consisted of 2 experimental sessions. First, to evoke the response of muscles to the inspiratory resistance, increasing stepwise polyethylene tubes of various diameters were attached to the nasal and tracheal opening and the diameter of the tubes was gradually reduced. Muscle activity changes in response to the increased resistance were recorded during spontaneous nasal or tracheal breathing. Second, to examine muscle responses to negative pressure to the pharyngeal airway, irrespective of breathing activity, the pharynx was isolated as a closed circuit by a stoma constructed at a more caudal side in the trachea. Muscle responses to the negative pressure generated by a syringe in the pharyngeal segment were measured. Nasal breathing induced a greater muscle activity than did tracheal breathing, in general, at P <.05. When resistance was gradually increased, nasal breathing resulted in a greater increase in muscle activity than did tracheal breathing (P <.05), except in the diaphragm. Application of negative pressure to the isolated pharyngeal airway segment increased the muscle activity significantly (P <.05). We conclude that an increased airway resistance may facilitate oropharyngeal muscle activity through mechanoreceptors in the oropharyngeal airway.

Airway Obstruction↗

PubMed2000

Differential activation of MAP kinase family members triggered by CD99 engagement.

The molecular basis for the modulatory properties of CD99 is not well understood. Treatment of human Jurkat T lymphocytes with anti-CD99 antibody led to activation of three mitogen-activated protein kinase (MAPK) members, ERK, JNK, and p38 MAPK, along with homotypic aggregation. While phosphorylation of ERK and JNK was inhibited by the pretreatment of a PKC inhibitor, bisindolylmaleimide I, activation of p38 MAPK was upregulated by the same pretreatment. The signaling pathways to MAPKs by CD99 engagement were independent of PI-3 kinase, distinguishing from those by CD3 engagement. Among MAPKs, ERK pathway was essential for homotypic aggregation together with intracytoplasmic Ca(2+).

Antibodies, Monoclonal↗

PubMed2000

Comparison of 2,4,6-trinitrotoluene degradation by seven strains of white rot fungi.

The degradation of 2,4,6-trinitrotoluene (TNT) by seven strains of white rot fungi was examined in two different media containing 50 mg L(-1) of TNT. When TNT was added into a nutrient-rich YMG medium at the beginning of the incubation, four of the fungal strains completely removed TNT during several days of incubation and showed higher removal rates than those of Phanerochaete chrysosporium. TNT added into YMG medium after a 5-day preincubation period completely disappeared within 12 hours, and the removal rates were higher than those in N-limited minimal medium. Isomers of hydroxylamino-dinitrotoluene were identified as the first detectable metabolites of TNT. These were transformed to amino-dinitrotoluenes, which also disappeared during further incubation from cultures of Irpex lacteus. During the initial phase of TNT degradation by I. lacteus, dinitrotoluenes were also detected after the transient formation of a hydride-Meisenheimer complex, indicating that I. lacteus used two different pathways of TNT degradation simultaneously.

Biodegradation, Environmental↗

PubMed1999

Development of new adherent mutant from human myeloma-derived cell line: in vitro model of anaplastic transformation of myeloma.

Anaplastic myeloma is a rare but distinct, biologically aggressive variant of myeloma which usually results from dedifferentiation or anaplastic transformation of the myeloma cells. The molecular mechanisms that determine the biologic behavior of anaplastic myeloma and effective treatment modalities have not been well known due to lack of in vitro models. In the present study, we have developed an anaplastically transformed mutant from a human myeloma-derived cell line. In the process of long-term culture of the myeloma-derived IM-9 cell line in low serum and nutrient conditions, an adherent mutant line was developed and named IM-9/AD. This mutant cell line displayed several characteristics resembling anaplastic myeloma such as: 1, large cells with large vesicular nucleus and prominent nucleolus, multinuclearity and high mitotic figures; 2, loss of leukocyte-associated antigens; and 3, higher tumorigenecity in scid mice than its parental cell line. This newly developed mutant cell line may serve as a readily available in vitro model to investigate the biology of anaplastic myeloma.

Animals↗

PubMed1999

LFA-1- and ICAM-1-dependent homotypic aggregation of human thymocytes induced by JL1 engagement.

Cell-cell adhesion is essential for the appropriate immune response, differentiation, and migration of lymphocytes. This important physiological event is reflected in vitro by homotypic cell aggregation. We have previously reported that a 120 kDa cell surface glycoprotein, JL1, is a unique protein specifically expressed by immature double positive (DP) human thymocytes which are in the process of positive and negative selections through the interaction between thymocyte and antigen-presenting cells (APCs). The function of the JL1 molecule, however, is yet to be identified. We show here that anti-JL1 monoclonal antibody (mAb) induced the homotypic aggregation of human thymocytes in a temperature- and Mg2+-dependent manner. It required an intact cytoskeleton and the interaction between leucocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) since it was blocked by cytochalasin B and D, and mAb against LFA-1 and ICAM-1 which are known to be involved in the aggregation of thymocytes. Translocation of phosphatidylserine (PtdSer) through the cell membrane was not detected, implying that the molecular mechanism of JL-1-induced homotypic aggregation is different from that of CD99-induced homotypic aggregation. In summary, JL1 is a cell surface molecule that induces homotypic adhesion mediated by the LFA-1 and ICAM-1 interaction and cytoskeletal reorganization. These findings suggest that JL1 may be an important regulator of thymocyte development and thymocyte-APC interaction.

Antibodies, Monoclonal↗

PubMed1999

Reduced expression of CD99 and functional disturbance in anencephalic cortical thymocytes.

In a significant proportion of cases, anencephaly is associated with thymic enlargement, suggesting a possibility that anencephalic fetuses have a functional disturbance in thymocyte differentiation and development. In this report, we demonstrated that CD99 expression was consistently reduced in cortical thymocytes of all anencephalic fetuses. In addition, the CD99-dependent aggregation of immature cortical thymocytes was almost completely impaired and apoptosis of thymocytes was markedly reduced in several cases. These results are in agreement with previous findings that CD99 regulates the aggregation and apoptosis of various types of cells. These data strongly suggest that functional disturbance of thymocytes and thymic hyperplasia are related to the reduced expression of CD99 molecule in anencephalic fetuses.

12E7 Antigen↗

PubMed1999

Phakomatous choristoma of the eyelid.

This article describes the first report of phakomatous choristoma of the eyelid in Korea. A six-month-old boy underwent excision of a congenital inferonasal orbital mass arising from the left lower lid. A dermoid cyst was suspected, however a diagnosis of phakomatous choristoma was made following conventional histology. An immunohistochemical study of this rare benign congenital tumor was conducted. The cuboidal epithelial cells comprising this choristoma showed strongly positive cytoplasmic staining with S-100 protein and vimentin. They also showed focally positive staining with a neuron-specific enolase, while they showed no immunoreactivity to cytokeratin or epithelial membrane antigen. The results of the immunohistochemical study support the conclusion that this tumor is of lenticular anlage origin.

Biomarkers↗

PubMed1998

ILK (beta1-integrin-linked protein kinase): a novel immunohistochemical marker for Ewing's sarcoma and primitive neuroectodermal tumour.

ILK (beta1-integrin-linked protein kinase) is a recently identified 59-kDa serine/threonine protein kinase that interacts with the cytoplasmic domain of the beta1-integrin containing four ankyrin-like repeats. We have developed a polyclonal antibody against ILK and explored the ILK immunoreactivity in normal human cells and tissues. ILK was mainly expressed in cardiac muscle and skeletal muscles. Surprisingly, ILK expression was observed in Ewing's sarcoma (ES; 100%), primitive neuroectodermal tumour (PNET; 100%), medulloblastoma (100%), and neuroblastoma (33.3%), whereas other small round cell sarcomas were not stained by the anti-ILK antibody. These results suggest that ILK could be a novel marker for tumours with primitive neural differentiation. Our findings support the notion that ES is a tumour that is closely related to PNET and that both originate from the neuroectoderm. ILK may be a sensitive and specific immunohistochemical marker and useful for the positive identification of ES and PNET in formalin-fixed, paraffin-embedded tissue sections.

Adolescent↗

PubMed1997

Thymocytes positively select thymocytes in human system.

We previously demonstrated the expression of MHC class II molecules in a significant percentage of human fetal and postnatal thymocytes. These results, at that time, raised the question as to whether the MHC class II molecules on immature thymocytes could actively be involved in the selection of immature T cells. We have developed a human reaggregate culture system to address this issue. Surprisingly, despite the fact that thymic epithelial cells (TECs) have been shown to be a major selecting cell type of positive selection, we were clearly able to see the involvement of MHC class II+ thymocytes during selection process through T-T interaction. In addition, maturation to single positive (SP) cells occurred only in the presence of MHC class II molecules and immature thymocytes were found to be arrested at the double positive (DP) stage of differentiation by blocking of TCR recognition of MHC class II molecules. All these results strongly suggest that human MHC class II+ thymocytes actively participate in the selection of the TCR repertoire, for which TCR recognition of peptide/MHC class II may be an initial determining step.

Cell Aggregation↗

PubMed1997

Calcifying fibrous pseudotumor of mediastinum--a case report.

This report presents a case of calcifying fibrous pseudotumor arising in the posterior mediastinum of a 54-year-old woman. The histopathologic features of this case were identical to that of calcifying fibrous pseudotumor first designated in 1993. It is a distinctive benign fibrous lesion characterized by the presence of characteristics psammomatous or dystrophic calcification, abundant hyalinized collagen and lymphoplasmacytic cell infiltrate. Immunohistochemically most of the scattered fibroblasts were positive for vimentin, but not for CD-34 and cytokeratins, distinguishing it from solitary fibrous tumor of pleura and desmoplastic mesothelioma. The unusual site of the posterior mediastinum and the old age characterize this case.

Age Factors↗

PubMed1996

DN4: a novel cell surface molecule on cortical epithelial cells of the human thymus.

A novel cell surface molecule, DN4, defined by an mAb raised against human thymic epithelial cells, showed a specificity for epithelial cells of the thymic cortex. This antigen was not expressed at detectable levels on any other types of tissues in the human body except for the thymus and bone marrow. Immunohistochemical analysis revealed that the reactivity of anti-DN4 mAb was restricted to the thymic cortex, and the antigen-expressing cells were arranged in a reticular network with long processes between thymocytes. The cellular nature of DN4-positive cells was identified as cortical epithelial cells, as DN4 was expressed in a subpopulation of freshly prepared thymic stromal cells which contain a large amount of keratin and expression of DN4 was strictly confined to the cortical area within the thymus on immunohistochemical analysis of frozen tissues. Immunofluorescence and flow cytometric analysis revealed that a subpopulation of bone marrow cells was also positive for DN4 (20%). The large blasts of normal bone marrow cells were clearly labeled with anti-DN4 mAb, in contrast to small-sized bone marrow cells. This finding suggests that DN4 seems to be transiently expressed in certain blastic stages during the differentiation of bone marrow cells. Immunoprecipitation of 125I-labeled cell lysates from THP-1 and U937 cell lines with anti-DN4 mAb yielded a single chain glycoprotein with an approximate size of 80-85 kd. There was a reduction in apparent molecular weight of approximately 40 kd in the immunoprecipitation of cell lysates after endoglycosidase F treatment. Thus, DN4 seemed to have a considerable amount of carbohydrate group. DN4 appears to be a novel cortical epithelial cell antigen of the human thymus, and although the role of this molecule has not been well established experimentally, the possibility can be suggested that the DN4 molecule might be involved in the positive selection of thymocytes which occurs predominantly in the thymic cortical area.

Antibodies, Monoclonal↗

PubMed1995

A novel T-cell differentiation antigen expressed in immature human thymocytes and neuroglial cells.

We report a novel human thymocyte differentiation antigen ICT-1 with a molecular weight of 49 kDa that is noncovalently associated with another 12-kDa protein. The ICT-1 antigen is expressed in 50-70% of total thymocytes, but not in resting or PHA-activated peripheral blood T-cells and bone marrow cells. The thymocytes expressing ICT-1 antigen appear after the 18th week of gestation during fetal development. Since the distribution pattern of the ICT-1 antigen within thymus partly overlaps with that of the CD1 antigens, we investigated whether ICT-1 was one of the CD1 antigen family. However, the failure of anti-ICT-1 antibody to react with mouse L cells transfected with cDNA of CD1a, -b, and -c and the different histologic distribution patterns from that of CD1d strongly suggest that the anti-ICT-1 antibody recognizes an antigen distinct from CD1. Furthermore, ICT-1 is also expressed in human neuroglial cells such as oligodendroglioma, glioblastoma multiforme, Ewing's sarcoma, and cerebellar astrocyte. Hence we believe that the ICT-1 antigen may be a novel thymus-leukemia (TL) antigen or a nonclassical MHC class I antigen.

Animals↗

PubMed1994

A monoclonal antibody to cell surface antigen of human thymic epithelial cell.

The cell surface molecule identified by a monoclonal antibody(TE-1) to human thymic epithelial cell showed the specificity for thymic epithelial cells of both the cortex and medulla. TE-1 reacted with the epithelial cells of normal thymus and thymoma in fresh frozen tissues. The antigen recognized by TE-1 was mostly confined to the cell surface membrane and arranged in reticular network with long processes between thymocytes. On immunohistochemical analysis, TE-1 did not recognize normal epithelial cells of the uterine cervix, skin and stomach, and neoplastic cells of squamous cell carcinoma and gastric adenocarcinoma, all of which were stained with anti-cytokeratin monoclonal antibody. Among the tumor cell lines tested with flow cytometry, most of epithelial and all of hematopoietic cell origin were not labeled with TE-1. In summary, TE-1 appears to be a monoclonal antibody against a surface antigen of human thymic epithelial cell that is immunohistologically different from known epithelial cell surface antigens reported so far.

Animals↗

PubMed1993

A case of juvenile form Pompe's disease manifested as chronic alveolar hypoventilation.

We describe a case of the juvenile form of Pompe's disease that presented as primary alveolar hypoventilation due to respiratory muscle involvement. This 17-year-old girl had been asymptomatic until this admission, although she had a delayed puberty. Arterial blood gas analysis, pulmonary function test as well as physical findings were compatible with chronic alveolar hypoventilation syndrome. Since she had lower extremity muscle weakness and pseudomyotonic discharge on electromyography a muscle biopsy was done, which revealed glycogen storage disease. The patient was managed successfully with nasal intermittent positive pressure ventilation.

Adolescent↗

PubMed1993

Detection of chromosome aberrations in interphase nuclei using fluorescence in situ hybridization technique.

We report here several experiences of interphase cytogenetics, using fluorescence in situ hybridization (FISH) technique, for the detection of chromosome aberrations. FISH, using alpha satellite specific probes of 18, X, Y chromosomes, was done in interphase nuclei from peripheral blood of patients with Edwards' syndrome, Klinefelter's syndrome and Turner's syndrome with healthy male and female controls, respectively. The distributions of fluorescent signals in 100 interphase nuclei were well correlated with metaphase findings. Nowadays FISH plays an increasingly important role in a variety of research areas, including cytogenetics, prenatal diagnosis, tumor biology, gene amplification and gene mapping.

Adolescent↗

PubMed1991

A monoclonal antibody to human leukocyte common antigen, SHL-1, and its use for formalin-fixed, paraffin-embedded tissues.

The authors describe a newly characterized murine monoclonal antibody to the human leukocyte surface antigen, SHL-1. The antigen belongs to the leukocyte common antigen (LCA) family, and its molecular weight is about 180,000 daltons, which is similar to that of some previously characterized LCAs. The SHL-1 antigen is resistant to conventional tissue-fixation and embedding procedures. This antibody can therefore be used in the immunohistochemical staining of paraffin-embedded tissue sections. Wide screening with a sufficient number of both fresh and routinely processed paraffin-embedded tissues was done with indirect immunoperoxidase technique. With this procedure, SHL-1 labeled the majority of normal leukocytes and hematopoietic malignancies. Some B-cell malignancies were not stained with this antibody. The non-hematologic malignancies posing diagnostic problems of differentiation from lymphomas or leukemias were completely negative to SHL-1. The immunoreactivity to SHL-1 of samples from 24 leukemic patients and 15 human tumor cell lines was determined by the immunofluorescence method. Of 24 leukemic preparations, 23 were strongly reactive to this antibody. One case of B-cell leukemia did not react with SHL-1. No immunoreactivity was demonstrated in non-hematopoietic tumor cell lines. The overall reaction pattern of SHL-1 proved its usefulness in both diagnostic and research practice in hematological disorders. This antibody detected cell surface antigens of the T cell series more effectively than those of the B-cell series in terms of the positive number of cells and mean fluorescence intensity.

Antibodies, Monoclonal↗

PubMed1991

Requirements for in vitro growth of human thymocytes.

Since it is difficult to study human thymocyte maturation in vitro, we have developed an in vitro thymocyte culture system which has allowed us to select the optimal growth conditions for thymocyte subpopulations. Three thymocyte subpopulations (CD3-CD1-, CD1+CD3-, and CD3+CD1-) were isolated by a single step percoll density gradient centrifugation and indirect panning procedure using anti-CD1 and anti-CD3 monoclonal antibodies, and their purity was checked by flow cytometry. The combination of concanavalin A (Con A), tetradecanoylphorbol acetate (TPA), and IL-2 was shown to be the most reliable stimulus for the proliferation of CD3-CD1- thymocytes for up to 15 days in a culture system in vitro. Flow cytometric analysis for the phenotypic change of CD3-CD1- thymocytes revealed a steady increase of CD3 antigen after a 3-day cultivation, whereas there was no change in CD1 antigen intensity. A combination of Con A and IL-2 was both sufficient and necessary to induce growth of CD3+CD1- thymocytes. The major population of immature cortical thymocytes (CD3-CD1+ or CD3+CD1+), which are considered to be the most unresponsive dead-end cells, could not be maintained or stimulated with any combination used in this experiment, even in the presence of thymic accessory cells.

Antigens, CD↗

PubMed1990

Effects of jet fuel spills on the microbial community of soil.

Hydrocarbon residues, microbial numbers, and microbial activity were measured and correlated in loam soil contaminated by jet fuel spills resulting in 50 and 135 mg of hydrocarbon g of soil. Contaminated soil was incubated at 27 degrees C either as well-aerated surface soil or as poorly aerated subsurface soil. In the former case, the effects of bioremediation treatment on residues, microbial numbers, and microbial activity were also assessed. Hydrocarbon residues were measured by quantitative gas chromatography. Enumerations included direct counts of metabolically active bacteria, measurement of mycelial length, plate counts of aerobic heterotrophs, and most probable numbers of hydrocarbon degraders. Activity was assessed by fluorescein diacetate (FDA) hydrolysis. Jet fuel disappeared much more rapidly from surface soil than it did from subsurface soil. In surface soil, microbial numbers and mycelial length were increased by 2 to 2.5 orders of magnitude as a result of jet fuel contamination alone and by 3 to 4 orders of magnitude as a result of the combination of jet fuel contamination and bioremediation. FDA hydrolysis was stimulated by jet fuel and bioremediation, but was inhibited by jet fuel alone. The latter was traced to an inhibition of the FDA assay by jet fuel biodegradation products. In subsurface soil, oxygen limitation strongly attenuated microbial responses to jet fuel. An increase in the most probable numbers of hydrocarbon degraders was accompanied by a decline in other aerobic heterotrophs, so that total plate counts changed little. The correlations between hydrocarbon residues, microbial numbers, and microbial activity help in elucidating microbial contributions to jet fuel elimination from soil.

Journal Article↗