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Biomedical subjects

C C Chou

Publications and source records attributed to C C Chou.

At least 91 records · Page 5Linked to original sources
PubMed1996

Dose-dependent effects of berberine on cell cycle pause and apoptosis in Balb/c 3T3 cells.

In determining the morphological appearance of Balb/c 3T3 cells from berberine-treated (100 and 200 micrograms/ml) cultures by light microscopy demonstrated that the high berberine concentration (200 micrograms/ml) treatment was associated with the accumulation of numerous apoptotic cells, as identified by condensed nuclei and decrease in cell size. On the other hand, accumulation of cells in G2/M phase instead of induction of apoptosis was observed after 48-72 h of 100 micrograms/ml berberine treatment. Berberine was found mainly in cytoplasm during berberine-induced (100 micrograms/ml) cell cycle G2/M arrest, while it was highly concentrated in nuclei in the induction of apoptosis under high dose of berberine (200 micrograms/ml) treatment. Further addition of berberine (100-200 micrograms/ml) had little effect on the induction of apoptosis in the cells that had already been exposed to 100 micrograms/ml of berberine for 48 h. Our results suggest that there may exist in Balb/c 3T3 cells an important threshold for regulation of cell cycle pause and induction of apoptosis, that is dose-dependent.

3T3 Cells↗
PubMed1996

Immunotherapy suppresses the production of monocyte chemotactic and activating factor and augments the production of IL-8 in children with asthma.

BACKGROUND: Histamine-releasing factor consists of a group of cytokines that can cause basophils or mast cells to release histamine. However, the composition of histamine-releasing factor remains undefined. OBJECTIVE: This study was done to measure the concentrations, in plasma and mononuclear cell culture supernatants from children with asthma, of chemokines that are known to contribute to histamine-releasing factor activity. RESULTS: Plasma and mononuclear cell culture supernatants were obtained from 25 children newly diagnosed with asthma, 25 good responders to immunotherapy, 23 poor responders, 25 patients with acute attacks, and 13 normal subjects. All the patient groups produced, spontaneously and after stimulation with phytohemagglutinin and mite allergen, greater amounts of monocyte chemotactic and activating factor, macrophage inflammatory protein-1 alpha, and RANTES (beta chemokines) and IL-8 and growth-related gene alpha (alpha chemokines) than did normal subjects. Successful immunotherapy resulted in decreased production, especially the spontaneous type, of beta chemokines that cause histamine release and in increased production of a chemokines that inhibit histamine release. CONCLUSION: Abnormal chemokine production may contribute to the pathogenesis of bronchial asthma, and restoration of normal chemokine production may be used to explain, in part, the clinical efficacy of immunotherapy.

Adjuvants, Immunologic↗
PubMed1996

Structure and humanization of a rat monoclonal Fab to human interleukin-5.

The X-ray crystal structure of a rat monoclonal Fab JES1-39D10, raised against recombinant human interleukin-5, has been determined with the use of molecular replacement techniques and refined at 2.7 A resolution by simulated annealing. The overall structure is similar to a murine Fab HyHEL-10 that is specific for hen egg white lysozyme. An interesting feature of the structure is the presence of leucine residues to support the H1 complementarity-determining region (CDR) loop. To our knowledge this is the first Fab crystal structure containing this unusual H1 loop support pattern. The activity of three humanized versions of 39D10 is explained by analysis of Fv interface residues and H1 support patterns of 39D10 and the human template HIL.

Amino Acid Sequence↗
PubMed1996

Isolation of type 1 and type 2 cloned mite allergen-specific T cells from an asthmatic child.

Allergen-specific T cells have been thought to play a central role in the pathogenesis of asthma. It has been well documented that allergen-specific T cells derived from atopic patients are predominantly of type 2 T helper cell pattern. However, allergen-specific T cells derived in nonatopic normals are of type 1 in contrast to atopic patients. The purpose of the study was to develop and characterize both mite allergen-specific TH1 and TH2 clones from the same asthmatic child. With exogenous supplemental cytokine, both TH1 and TH2 clones from the same patient have been developed and maintained in this laboratory for more than one year. All these T cell clones showed dose dependent allergen-specific proliferative response and expressed with CD4+, CD45RA- markers. Elucidation of the origin and interaction between these two different types of T helper cells might shed light on understanding the pathogenesis of atopic diseases and the mechanisms of hyposensitization in atopic patients.

Allergens↗
PubMed1996

Different kinds of antigen-presenting cells exert different effects on T-helper cells development.

It has been well documented that environmental factors such as antigen-presenting cells and related cytokines can affect the development of T-helper cells. The purpose of this study was to investigate the role of different antigen-presenting cells on T-cell development. Ovalbumin (OVA) combined with complete Freud's adjuvant (CFA) was used to sensitize mice subcutaneously or intraperitoneally, and then to follow-up production of IgG and IgE anti-OVA antibodies. In addition, semiquantitative PCR was used to determine the level of cytokine mRNA of different antigen-presenting cells. Resulting data showed that antigen-presenting cells expressed with different characteristics: (1) IgG2a anti-OVA antibody was higher in mice sensitized subcutaneously compared to those sensitized intraperitoneally. (2) The levels of cytokine mRNA were higher in antigen-stimulated spleen cells of mice immunized subcutaneously compared to those of mice immunized intraperitoneally. (3) Langerhans cells expressed a high level of IL-12; in contrast, peritoneal B cells expressed a high level of IL-10, but not IL-12. In summary, cytokine levels such as IL-10 and IL-12 were different among different kinds of APC, and their role in production of different isotypes of antibodies needs further elucidation.

Animals↗
PubMed1996

Decreased production of IFN gamma and increased production of IL-6 by cord blood mononuclear cells of newborns with a high risk of allergy.

BACKGROUND: The underlying mechanisms of elevated IgE level in atopic patients are still obscure, however, extensive efforts have been tried to identify an immunological parameter as a predictor of atopy. OBJECTIVE: This study compared the difference in cytokine production by cord blood mononuclear cells between new borns with high-risk of allergy (family allergy score, FAS > or = 3) and those with low-risk (FAS = 0). METHODS: Following stimulation with PHA (100 micrograms/mL) and PMA (1 ng/mL), the cytokines produced by cord blood CD4+ T cells in the presence of monocytes were measured by ELISA kits and the mRNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) technique. RESULTS: Our results showed: CD4+ T cells in the presence of monocytes and isolated monocytes from the high-risk group produced a much greater amount of IL-6, either spontaneously or after stimulation, than did those of the low-risk group; CD4+ T cells of low-risk group produced a significantly greater amount of interferon gamma (IFN gamma) than did those from the high-risk group; IL-4 cannot be detected by ELISA kit, and only a trace amount of IL-4 mRNA was detected by RT-PCR technique; cord blood basophils stimulated with PHA and PMA could produce a significant amount of IL-4; there was an inverse correlation between the production of IFN gamma and cord blood IgE level (high-risk group, r = 0.647, n = 17) and the number of natural killer (NK) cells (CD3- CD16+ CD56+) was significantly lower in high-risk group than for low-risk group. CONCLUSION: Our data suggested increased production of IL-6 and decreased production of IFN gamma of cord blood mononuclear cells appear to be the hallmark of newborns from the high-risk population.

Basophils↗
PubMed1996

Putative normal counterparts of leukaemic cells from CD7-positive acute myeloid leukaemia can be demonstrated in human haemopoietic tissues.

CD7-positive acute myeloid leukaemias (CD7+AML) represent a distinct biological and clinical subtype of AML. The results of previous studies suggested that CD7 expression on myeloid leukaemic blasts might result from leukaemic transformation and maturation arrest of haemopoietic precursors at the stage of early myeloid differentiation when CD7 was transiently expressed. However, CD7+ myeloid progenitors have not yet been directly documented in normal human haemopoietic tissues. In this study, haemopoietic cells from 16 human fetal livers with a gestational age of 16-28 weeks were studied. Double myeloperoxidase (MPO) and CD7-positive cells could be demonstrated on 0-4% (mean 1.8%) of total fetal liver mononuclear cells (FLMC) by double cytochemical reaction of MPO and immunocytochemical staining of CD7. Simultaneous expression of CD7 and myeloid antigens (CD13 and/or CD33) could also be detected on 2.2-15.6% (mean 9.3%) of FLMC by dual-colour immunofluorescence flow cytometry analyses. CD13 and/or CD33 positive (CD13/33+) myeloid cells were positively selected by immunomagnetic bead separation system to a purity of 86.5-99.1% (mean 96.0%) of which < or = 3.3% were CD3+ cells and < or = 1.2% were CD19+ cells. Coexpression of CD7 was detected on 8.7-34.5% (mean 17.3%) of this CD 13/33+ cell population, but it was induced to decrease significantly after short-term in vitro culture with the differentiation-inducing agent phorbol ester (TPA). Coexpression of CD7 and CD13/33 could also be shown on a minor population of adult bone marrow and cord blood mononuclear cells (mean 3.9% and 1% respectively). In conclusion, the normal putative counterparts of blasts from CD7+ AML could be demonstrated in human haemopoietic tissues. The fact that CD7 expression tended to be lost after TPA stimulation suggested that CD7 was transiently expressed in early myeloid differentiation.

Acute Disease↗
PubMed1996

Color Doppler sonogrphy in differentiation between testicular torsion and epididymoorchitis: report of three cases.

Clinical assessment of the testicular torsion and epididymoorchitis is inherently difficult. Inadequate clinical information may prevent differentiation testicular torsion from non-surgical condition. We reported 3 cases with symptoms of acute scrotal condition who had received color Doppler sonography. One man had epididymoorchitis and color Doppler sonography showed profusely increased blood flow in the region of epididymis and testis. Symptoms subsided with one week of medical treatment. Sonography correctly detected absence of testicular perfusion in 2 boys who had sugical exploration of the scrotum. Testicular torsions were confirmed by surgical findings. Absence or markedly decreased testicular blood flow which indicated testicular ischemia or infarction was easily identified. Conversely, hyperemia of the testis and/or epididymis is usually associated with inflammation However, incomplete torsion or detorsion may demonstrate normal testicular flow on color Doppler sonography. Color Doppler sonography provides early diagnosis of acute testicular torsion, and prevents unnecessary scrotal exploration.

Adolescent↗
PubMed1996

Successful bone marrow transplantation in a Chinese boy with Wiskott-Aldrich syndrome.

We describe the successful use of HLA-compatible sibling bone marrow transplantation (BMT) in a 17-month-old Chinese boy in whom Wiskott-Aldrich syndrome (WAS) was diagnosed on the basis of eczema, thrombocytopenia, recurrent otitis media and abnormal immunological tests. The conditioning chemotherapy included 2 days' oral busulfan, 40 mg/m2/6 hours, and 2 days' intravenous cyclophosphamide, 60 mg/kg/day (BU2CY2). Complete hematological chimerism was achieved 3 weeks after transplantation. Eight months after his BMT the eczema has resolved, platelet count is normal, and he no longer has frequent infections. BU2CY2 as a preconditioning regimen gave complete lymphohematopoietic engraftment in this WAS patient with no evidence of graft-versus-host disease. The excellent clinical response of this patient and the inevitable fatal outcome of WAS support the opinion that where a histocompatible donor is available, BMT at the earliest opportunity is the best option. We believe this is the first case of successful BMT in a Chinese patient with WAS.

Asian People↗
PubMed1995

Intracellular ATP is required for actinomycin D-induced apoptotic cell death in HeLa cells.

In the present report, we demonstrate that reduction of cellular ATP content with antimycin A blocks actinomycin D-induced apoptotic cell death in HeLa cells. Compared to cells (approximately 80%) treated with actinomycin D (1 microgram/ml; 48 h) alone in glucose-containing medium, a much smaller percentage of cells (approximately 20%) treated with actinomycin D in the presence of antimycin A in glucose-free medium shows morphological characteristic of apoptosis. ATP-depleted cells with or without actinomycin D treatment, on the other hand, die necrotically. In cells under actinomycin D short exposure treatment (1 microgram/ml; 1 h), apoptosis occurs when cellular ATP content is rapidly recovered after the removal of antimycin A and resupplementation of glucose-containing medium. In the incubation of isolated Triton-permeabilized cells with ATP ( > 0.5 mM), apoptotic nuclei become abundant 4 h after ATP treatment. These results implicate the requirement of ATP for the induction of apoptosis.

Adenosine Triphosphate↗
PubMed1995

Berberine complexes with DNA in the berberine-induced apoptosis in human leukemic HL-60 cells.

Berberine, an alkaloid initially isolated from Chinese herbal medicine exhibited the ability to induce morphological changes and internucleosomal DNA fragmentation, characteristic of apoptosis in promyelocytic leukemia HL-60 cells. Cell cycle studies showed that only about 20% of the cells underwent apoptosis at the early time (6 h) of berberine (25 micrograms/ml) treatment; these appeared to be cells in S phase at the time of berberine treatment. At extended time (6-48 h), cells were cell cycle arrested, the number of cells of each phase, particularly the cells of S phase decreased and much more (> 50%) of the cells appeared with DNA content less than G1. Attempts were also made to isolate possible berberine-DNA complexes from cell cultures treated with berberine (25 micrograms/ml; 2-24 h). Shifts of absorption maxima of berberine in the direction of longer wavelengths were observed in the isolated berberine-DNA complexes. Palmatine, an analog of berberine, which was not able to induce apoptosis, also complexed with DNA in cells treated with palmatine (25 micrograms/ml; 2-24 h). Our results suggest that some important cellular processes other than the intracellular DNA-interacting action of berberine may be involved in the berberine-induced apoptosis in HL-60 cells.

Apoptosis↗
PubMed1995

The functional characterization of interleukin-10 receptor expression on human natural killer cells.

Human natural killer (NK) cells are large granular lymphocytes that constitutively express functional forms of the interleukin-2 receptor (IL-2R) and lyse tumor and virally infected cells without prior sensitization. NK cells with high density expression of CD56 (CD56bright) express the high affinity IL-2R and proliferate in response to low (picomolar) concentrations of IL-2. CD56dim NK cells express the intermediate affinity IL-2R and demonstrate enhanced cytotoxic activity without proliferation in response to high (nanomolar) concentrations of IL-2. In the present study, we characterized IL-10R expression on human NK cells and the functional consequences of IL-10 binding directly to highly purified subsets of CD56bright and CD56dim NK cells. Binding studies using 125I-IL-10 indicated that resting human NK cells constitutively express the IL-10 receptor protein at a surface density of approximately 90 receptor sites per cell, with a kd of approximately 1 nmol/L. Alone, IL-10 did not induce proliferation of CD56bright or CD56dim NK cell subsets. However, at low concentrations (0.5 to 5 ng/mL), IL-10 significantly augmented IL-2-induced proliferation of the CD56bright NK cell subset mediated via the high-affinity IL-2R. In the absence of IL-2, IL-10 was able to induce significant NK cytotoxic activity against NK-resistant tumor cell targets in both subsets of NK cells in a dose-dependent fashion. Furthermore, the combination of IL-10 and IL-2 had an additive effect on NK cytotoxic activity, whereas that of IL-10 and IL-12 did not. Production of interferon-gamma, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor by IL-2-activated NK cells was also significantly enhanced by IL-10. Neither resting nor activated human NK cells appear to produce human IL-10 protein. In summary, NK cells constitutively express the IL-10R protein in low density, and the functional consequences of IL-10 binding directly to human NK cell subsets appear to be stimulatory and dose-dependent. In contrast to its direct effects on human T cells and monocytes/macrophages, IL-10 potentiates cytokine production by human NK cells.

Antigens, CD↗
PubMed1995

Characterization of recombinant extracellular domain of human interleukin-10 receptor.

The extracellular region of the human interleukin-10 (hIL-10) receptor was expressed using a myeloma cell line and was purified to homogeneity by ligand-affinity chromatography. SDS-polyacrylamide gel electrophoresis analysis indicated that the soluble receptor is glycosylated and has an apparent molecular mass of 35,000-45,000. Under native conditions, soluble hIL-10 receptor was determined by gel filtration to be a monomeric protein. Soluble hIL-10 receptor was able to inhibit the binding of 125I-hIL-10 to the full-length receptor and was able to antagonize the effect of human IL-10 in cell proliferation and cytokine synthesis inhibition. The apparent dissociation constant (Kd) of soluble hIL-10 receptor was determined to be 563 +/- 59 pM, approximately 2- to 10-fold higher than that found on intact cells (Tan, J. C., Indelicato, S. R., Narula, S. K., Zavodny, P. J., and Chou, C.-C. (1993) J. Biol. Chem. 268, 21053-21059; Liu, Y., Wei, S. H.-Y., Ho, A. S.-Y., de Waal Malefyt, R., and Moore, K. W. (1994) J. Immunol. 152, 1821-1829). When hIL-10 binds soluble hIL-10 receptor in solution, a single complex was detected by gel filtration, and the complex was found to consist of two hIL-10 dimers and four soluble receptor monomers, suggesting that hIL-10 may induce a novel mode of oligomerization of the receptor upon binding.

Amino Acid Sequence↗
PubMed1995

Lymphomagenesis in the SCID-hu mouse involves abundant production of human interleukin-10.

Both human (hu) and viral (v) interleukin-10 (IL-10) appear to be important cofactors in the survival and growth of lymphoblastoid cell lines infected with Epstein-Barr virus (EBV). When mice with severe combined immune deficiency (SCID) are injected with human peripheral blood lymphocytes (PBL) from normal individuals who are seropositive for EBV, the majority of hu-PBL-SCID mice will develop an EBV-associated lymphoproliferative disease (EBV-LPD) of human B-cell origin, not unlike some cases of EBV-LPD that are seen in immunocompromised individuals. The role of huIL-10 or vIL-10 in this chimeric mouse model of EBV-LPD is unknown. In the present study, we show that hu-PBL-SCID mice that develop EBV-LPD have significant elevation of serum huIL-10 levels compared with mice that do not develop EBV-LPD (P = .005). vIL-10 was undetectable in all animals. The EBV+ tumor samples express transcript for huIL-10 and huIL-10 receptor, express huIL-10 protein by immunohistochemical staining, and show specific binding of recombinant (r) huIL-10. In vitro analysis of the functional consequences of rhuIL-10 binding to IL-10 receptors on fresh EBV+ tumor cells shows that rhuIL-10 can prevent programmed cell death as well as promote proliferation and can do so at concentrations of huIL-10 found in vivo. Thus, huIL-10 production by EBV+ tumor cells may contribute directly to their malignant outgrowth in the hu-PBL-SCID mouse by two autocrine mechanisms: prevention of programmed cell death and proliferation. The implications of such findings with regard to EBV-LPD in humans is discussed.

Animals↗
PubMed1995

Growth inhibition of malignant CD5+B (B-1) cells by antisense IL-10 oligonucleotide.

Malignant B-1 cells derived from NZB mice, a murine model of chronic lymphocytic leukemia, produce significantly higher levels of IL-10 mRNA than normal B-1 or B cells. IL-10 may act as an autocrine growth factor for malignant B-1 cells. By addition of antisense oligodeoxynucleotides specific for IL-10 mRNA, we were able to dramatically inhibit the growth of leukemic B-1 cells in a time and dose dependent manner. Control cell lines which do not depend on IL-10 for growth were not affected. Antisense therapy targeted at the 5' region of the IL-10 mRNA not only resulted in inhibition of malignant B-1 cell proliferation but also inhibited IL-10 production by malignant B-1 cells. Because endogenous IL-10 gene activation is critical for B-1 cell expansion, inactivation of the endogenous IL-10 gene by IL-10 antisense rather than extracellular regulation of the IL-10 gene product should be successful in controlling the malignant growth.

Animals↗
PubMed1995

Establishment of human IgE system in severe combined immunodeficient mice with peripheral blood mononuclear cells from asthmatic children.

The frequency of allergic diseases, such as asthma, has increased rapidly during the past decade; however, the exact mechanisms have not been established. In this study we tried to establish an in vivo system to investigate immune regulation of allergic diseases by using severe combined immunodeficient (SCID) mice. Peripheral blood mononuclear cells isolated from asthmatic children or normal adults were injected into peritoneal cavities of SCID mice. Human IgG, IgA, IgM, and IgE could be detected in SCID mice reconstituted with human PBMCs (SCID-PBL-hu mice) 3 weeks later. Moreover, the mice injected with peripheral blood mononuclear cells from asthmatic children had much higher IgE levels than mice reconstituted with cells from normal adults. Phenotypic analysis of spleen cells and peritoneal exudate cells from SCID-PBL-hu mice demonstrated that human lymphocytes could survive in the peritoneal cavity and spleen for several months. After intraperitoneal immunization, mite-specific IgE antibodies could also be detected in SCID-PBL-hu mice. This study indicates that the human IgE system can be established in SCID mice and that this model can be used to study the regulation of IgE production and the immunopathogenesis of human allergic disease.

Animals↗
PubMed1995

Dysregulation of T helper cell cytokines in autoimmune prone NZB x NZW F1 mice.

Multifactorial involvement in the pathogenesis of autoimmune NZB/W F1 mice has been well documented. To further elucidate the role of cytokines in the disease development of murine lupus, single spleen cells isolated from NZB/W F1 and non-autoimmune C57BL/6 mice were stimulated with T cell mitogens or anti-CD3 antibody at pre-determined optimal concentration. Supernatants were collected and assayed for production of cytokines including IL-2, gamma-IFN, IL-3, IL-4, IL-5 and IL-10. In both young and old mice, cytokine profiles by mitogen-stimulated T cells showed higher TH2 (type 2 T helper) cell-related cytokine production in NZB/W F1 mice compared to those in non-autoimmune C57BL/6 mice. In contrast, cytokines produced by TH1 (type 1 T helper) cells, such as gamma-IFN and IL-2, were lower in NZB/W F1 mice by stimulation with either mitogen or anti-CD3 antibody. In addition, cytokine production at different time points also demonstrated decreased gamma-IFN and increased IL-4 levels by anti-CD3 stimulated splenic cells in autoimmune NZB/W F1 mice. Furthermore, the IL-10 levels produced by lipopolysaccharide (LPS)-stimulated splenic and peritoneal exudate cells were higher in young NZB/W F1 mice compared to those in C57BL/6 mice. Our data suggest that dysregulation between TH1 and TH2 cells may play an important role in the pathogenesis of autoimmunity in NZB/W F1 mice.

Age Factors↗