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Biomedical subjects

S H Feng

Publications and source records attributed to S H Feng.

12 recordsLinked to original sources
PubMed1999

Lipid extract of Mycoplasma penetrans proteinase K-digested lipid-associated membrane proteins rapidly activates NF-kappaB and activator protein 1.

Lipid-associated membrane proteins (LAMPs) of Mycoplasma penetrans rapidly induced macrophages to produce proinflammatory cytokines such as tumor necrosis factor alpha (TNF-alpha). Our analysis showed that the macrophage-stimulating activity of TNF-alpha production was mainly attributable to a lipid extractable component(s) in the LAMP preparation. Since induction of gene expression is normally preceded by activation of transcriptional factors that bind to their specific recognition elements located in the upstream promoter region, we examined the activity of transcriptional factors, namely, NF-kappaB and activator protein 1 (AP-1), in thioglycolate exudate peritoneal (TEP) macrophages treated with M. penetrans lipid extract of proteinase K (PK)-digested LAMPs. Initially, in the nuclei of unstimulated TEP cells, there was only a low basal level of active AP-1, and the active form of NF-kappaB could not be detected. M. penetrans lipid extract of PK-digested LAMPs activated both NF-kappaB and AP-1 in TEP macrophages within 15 min. The markedly increased activities of both factors gradually declined and dissipated after 2 h. Parallel to the rapid increase of NF-kappaB and AP-1, the TNF-alpha transcript also increased significantly 15 min after the stimulation. The high-level expression of TNF-alpha persisted over 2 h. Dexamethasone blocked the activation of both NF-kappaB and AP-1 and suppressed the production of TNF-alpha in TEP macrophages stimulated by M. penetrans lipid extract of PK-digested LAMPs. Our study demonstrates that the M. penetrans lipid extract of PK-digested LAMP is a potent activator for NF-kappaB and AP-1 in murine TEP macrophages. Our results also suggest that high-level expression of TNF-alpha in cells induced by M. penetrans lipid extract of PK-digested LAMPs is associated with rapid activation of transcriptional factors NF-kappaB and AP-1.

Animals↗
PubMed1999

Mycoplasmal infections prevent apoptosis and induce malignant transformation of interleukin-3-dependent 32D hematopoietic cells.

32D cells, a murine myeloid cell line, rapidly undergo apoptosis upon withdrawal of interleukin-3 (IL-3) supplement in culture. We found that 32D cells, if infected by several species of human mycoplasmas that rapidly activated NF-kappaB, would live and continue to grow in IL-3-depleted culture. Mycoplasma-infected cells showed no evidence of autocrine production of IL-3. Pyrrolidine dithiocarbamate (PDTC) blocked activation of NF-kappaB and led to prominent cell death. Heat-killed mycoplasmas or mycoplasmal membrane preparations alone could support continued growth of 32D cells in culture without IL-3 supplement for a substantial period of time. However, upon removal of heat-inactivated mycoplasmas, 32D cells quickly became apoptotic. In comparison, live Mycoplasma fermentans or M. penetrans infection for 4 to 5 weeks induced malignant transformation of 32D cells. Transformed 32D cells grew autonomously and no longer required support of growth-stimulating factors including IL-3 and mycoplasmas. The transformed 32D cells quickly formed tumors when injected into nude mice. Karyotyping showed that development of chromosomal changes and trisomy 19 was often associated with malignant transformation and tumorigenicity of 32D cells. Mycoplasmal infections apparently affected the fidelity of genomic transmission in cell division as well as checkpoints coordinating the progression of cell cycle events.

Animals↗
PubMed1994

Induced mouse spleen B-cell proliferation and secretion of immunoglobulin by lipid-associated membrane proteins of Mycoplasma fermentans incognitus and Mycoplasma penetrans.

Mycoplasmas have been implicated as a possible cofactor in AIDS pathogenesis. Mycoplasma fermentans and M. penetrans infect human immunodeficiency virus-positive patients at a significantly higher frequency than non-human immunodeficiency virus-infected control subjects. Various mycoplasmal membrane preparations are known to affect the functions of immune cells both in vitro and in vivo. A group of lipid-associated membrane proteins (LAMPs) extracted by Triton X-114 from mycoplasmas are major antigenic targets of human host antibody responses. In this study, LAMPs prepared from both M. fermentans and M. penetrans nonspecifically stimulated spleen cells of CBA/CaH mice to proliferate. LAMPs were also stimulatory to spleen cells from athymic mice. On the other hand, enriched splenic T cells from CBA/CaH mice with or without accessory cells responded poorly. Thus, the mitogenic effect of mycoplasmal LAMPs appeared mainly on B cells. High levels of immunoglobulin (Ig) M and low but detectable amounts of IgG were found in the supernatant of LAMP-treated splenic cell culture. M. penetrans LAMPs had a much more potent effect on murine spleen cells than did M. fermentans incognitus LAMPs in inducing both B-cell proliferation and Ig secretion. In conclusion, the mycoplasmal LAMPs contained an active component(s) with T-independent B-cell mitogenic effect.

Animals↗
PubMed1993

[Changes in serum lipid peroxide concentration in open heart surgery].

During open heart surgery, the release of oxygen free radicals as a result of ischemia and reperfusion often induces post-operative low cardiac output, arrhythmias or cardiac re-performance failure. Changes in serum lipid peroxide (LPO) concentrations were studied in 72 patients undergoing open heart surgery, to quantitate the rhythm of changes, and to seek for proper measures in myocardial protection. Blood samples were drawn before induction of anesthesia, just before aortic cross-clamping, 5 min after the release of aortic cross-clamping, immediately after rewarming to 35 degrees C, 30 min after cardiac performance, and at the end of the procedure. Fluorescent spectrophotometric method was used to detect the variation of LPO concentrations. The results showed that intraoperative serum LPO concentrations were significantly lower than pre-induction serum LPO concentrations (P < 0.01). It seems probable that methods of myocardial protection, hypothermia and hemodilution may induce lower concentrations of LPO. Serum LPO concentrations at the end of the procedure were smaller than those of the pre-induction concentrations (P > 0.05). This phenomena was caused by numerous factors that reduce serum LPO concentration.

Adolescent↗
PubMed1991

VH gene family expression in mice with the xid defect.

Preferential use of particular VH gene families in the response to specific antigens has been demonstrated in several systems. The lack of responses to certain types of antigens, therefore, could be the result of deletion of or failure to express some VH genes. Because CBA/N mice, which carry the X-linked immunodeficiency (xid) gene defect, have been shown to be unresponsive to thymus-independent polysaccharide antigens, it was of interest to examine if this unresponsiveness could be accounted for by abnormal expression of particular VH gene families. Using in situ hybridization on B cell colonies, we determined the expression of nine VH gene families in CBA/CaHN females (genotypically normal), CBA/N males (xid) and females (xid), and (CBA/N x CBA/CaHN)F1 males (xid) and females (phenotypically normal). Our results indicate that VH gene family expression, including the S107 family, in CBA/N males and F1 males, is similar to that of CBA/CaHN and F1 females with predominant expression of J558, the largest gene family, in all individuals. Interestingly, CBA/N female mice, which carry two defective X chromosomes, as a group expressed significantly reduced levels of the J558 gene family, and as individuals showed variation in which family was predominantly expressed. We conclude that the unresponsiveness of mice with the xid defect to polysaccharide antigens can not attributed to a failure to express the nine VH gene families that we examined. Our findings do not support previous studies (Primi, D., and P.-A. Cazenave 1986. J. Exp. Med. 165:357), which found an absence of expression of the S107 family in xid mice.

Animals↗
PubMed1991

A simple method for coating native polysaccharides onto nitrocellulose.

A method for coating native, non-derivatized, polysaccharide (PS) onto nitrocellulose (NC) for identifying PS-specific antibodies has been developed. The new feature of this method is that PS molecules are vacuum filtered onto NC in their native state by devices that can accommodate NC of different sizes and shapes. PS-coated NC disks were used to localize antibody secreting hybridoma cells cultured on filter paper disks. These were analyzed by blotting with size-matched PS-coated NC disks and specific antibodies secreted by individual colonies were detected by enzyme-linked immunoblot. In another application of this method, immune sera were separated by isoelectric focusing and the gels were blotted with PS-coated NC sheets. The spectrotype and isotype of antibodies that bound to the NC were examined using isotype specific enzyme-linked antibody. These immunoblots showed high resolution and specificity. The advantages of this method are that the PS used for coating does not need to be derivatized in order to bind the NC, and that smaller quantities of PS may be utilized by this coating method when compared to other techniques. This provides a useful tool to ask many questions regarding the immune response to PS.

Animals↗
PubMed1989

[Effects of shengmaiyin and danshen-chuanxiong decoction on preventing cardiopulmonary changes in adults caused by a high-altitude environment].

Compared with the cardiopulmonary function of the healthy adults on the plateau at an altitude of 4475 m and of 2500 m, the HR was faster, LVET was shorter, PEP/LVET rate was larger (P less than 0.05 or P less than 0.01) in the former. Besides the FEV1% and FEF25%, the FVC, FEV1.0, MMF, PEFR, FEF75% and FEF50% were all elevated (P less than 0.05 or P less than 0.01). After the villagers at the altitude of 2500 m area entered the area at the altitude of 4475 m, their LVETI became shorter, PEPI became longer, and PEP/LVET rate was increased (P less than 0.05 or P less than 0.01). Besides FEV1% and PEFR, other values of pulmonary function were increased obviously (P less than 0.05 or P less than 0.01). The Shengmaiyin could efficiently protect the villagers from the plateau reaction described above, while the Danshen-Chuanxiong decoction was not satisfactory.

Adolescent↗
PubMed1988

Expression of Thy-1 and effect of phosphatidylinositol-specific phospholipase C on primate and murine cell lines.

BALC/c mice were immunized with isolated human brain Thy-1. The antisera at an appropriate dilution only reacted with a doublet of an apparent molecular weight (MW) around 25,000 among all the glycoproteins of brain tissue isolated by lentil lectin affinity chromatography when tested by enzyme-linked immunosorbent assay and immunoblotting. When the antisera were used to test a number of human cell lines and a marmoset T-cell line (70N2) by flow cytometry, an astrocytoma cell line (U-373), a T-lymphoblastoid cell line (MOLT-3), and two cutaneous T-lymphoma cell lines (HUT-78 and HUT-102) as well as the 70N2 cells were stained. However, a B-lymphoma cell line (Raji), a plasmacytoma cell line (HMy2), and normal peripheral blood lymphocytes were negative. When the positive cells were treated with phosphatidylinositol-specific phospholipase C, a significant decrease in both stain intensity and percentage of positive cells was demonstrated by immunofluorescence. Although Thy-1 expression in human lymphoid system is currently thought to be confined in early T- and B-lymphocyte development, our data suggest that well-differentiated T cells with mature phenotypes such as HUT-78 and HUT-102 which may be considered as tumor counterparts are also capable of expressing Thy-1, presumably after certain stimulation.

Animals↗
PubMed1988

Expression of the Thy-1 gene in human T lymphoid cell lines.

We have previously shown that three human T cell lines (MOLT-3, HUT-78 and HUT-102) were able to react with anti-human brain Thy-1 sera by cell surface immunofluorescence. However, the possibility that the antisera might cross-react with molecules other than Thy-1 could not be entirely excluded. In this report, mRNA prepared from these three T cell lines as well as from a murine T cell line (EL4) and a human B cell line (Raji) was subjected to Northern blot analysis and probed with a murine Thy-1.2 gene fragment. The result confirms our cell surface immunofluorescence data and indicates that HUT-78 and HUT-102 cells have approximately 20-fold more of the Thy-1 mRNA than MOLT-3 cells do. The Thy-1 mRNA was not detectable in the human B cell line Raji. This work is the first demonstration that the Thy-1 gene is expressed in human T cell lines. The finding is helpful in clarifying the current confusion regarding the expression of Thy-1 in human lymphoid cells and it also provides a possible model system for exploring the function of Thy-1 in cultured human T lymphocytes.

Antigens, Surface↗
PubMed1988

Detection of Thy-1 on cell surface of human T lymphoid cell lines by a monoclonal antibody.

A mouse IgG2b(kappa) monoclonal antibody (MAb) HB-2S-1 against human brain Thy-1 was secreted by a hybridoma clone after fusion of mouse myeloma cells with spleen cells from a mouse that went through a prolonged immunization procedure before fusion. When tested against isolated human Thy-1 by the enzyme-linked immunosorbent assay (ELISA), MAb HB-2S-1 in culture supernatant showed a titer of over 100,000, and a titer of over 10 million in ascites of a mouse injected with the hybrid clone. By immunoblotting, this antibody was found to bind a doublet of protein bands of approximately 25,000 daltons among all proteins solubilized by deoxycholate (DOC) from membrane of human brain cells. When tested on human lymphoid cell lines by immunofluorescence, MAb HB-2S-1 strongly stained four T lymphoma cell lines, C91-Pl, HUT-102, HUT-78, and C5-MJ; and weakly two leukemia cell lines, MOLT-3 and Jurkat(clone E6-1). It did not stain a third T leukemia cell line, CCRF-CEM; a human B cell line, Raji; a plasmacytoma cell line, HMy2; or a myelomonocytic cell line, HL-60. Peripheral blood lymphocytes from ten normal human adults and the viable T cells isolated from another normal individual were also negative.

Animals↗
PubMed1985

The genetic polymorphism of alpha 2-HS glycoprotein: study by ultrathin-layer isoelectric focusing and immunoblot.

The genetic polymorphism of human alpha 2-HS glycoprotein was studied by ultrathin-layer isoelectric focusing in a pH range 4.2-4.9 followed by immunoblotting using antisera specific for the protein. Three common phenotypes, HSGA1-1, HSGA2-2, and HSGA1-2, were easily recognized using this technique. Each homozygous phenotype was constituted by five major bands with different pI's, and the heterozygous phenotype represented an exact combination of each of them. After removal of sialic acid, each homozygous pattern was resumed in a single band, which differed in charge between HSGA1 and HSGA2. Asialo-heterozygous HSG1-2 combined the two bands characteristic of each allele product. Family studies are in agreement with an autosomal codominant transmission of the two alleles. Population studies indicate that the frequency of the HSGA1 and 2 alleles are .65 and .35, respectively.

Blood Proteins↗