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E Wang

Publications and source records attributed to E Wang.

At least 271 records · Page 15Linked to original sources
PubMed1994

IgG autoantibodies to "switch peptide" determinants of TCR alpha/beta in human pregnancy.

The fetus is a natural allograft that is protected from immunologic rejection by a complex set of structural and regulatory mechanisms. We determined whether healthy pregnant women differed significantly from healthy non-pregnant controls in their capacity to produce autoantibodies to defined antigenic determinants of the alpha/beta T-cell receptor. Although controls and pregnant women expressed comparable levels of autoantibodies against an intact recombinant T-cell receptor containing the complete V alpha/V beta structures, analysis of comparative reactivity against individual peptide segments of the molecules, indicated enhanced reactivity to regions corresponding to the CDR1 of the alpha chain and to the Fr3 of the variable region of the beta chain. A major difference was noted by increased reactivity of IgG autoantibodies of pregnant women to peptides corresponding to the "switch" region joining the variable and constant domains. This was noted with both the Tcr alpha and beta chains and was directed against highly conserved determinants within these molecules. Antibodies to this region are lacking in the non-pregnant controls. It is possible that autoantibodies directed against conserved regions of the T-cell receptor might function in the suppression of T-cell reactivity of fetal determinants.

Amino Acid Sequence↗
PubMed1994

Commitment to cell death is signaled by the appearance of a terminin protein of 30 kDa.

Programmed cell death appears to be regulated by a specific molecular program, often dependent upon the activation of unique genes. We have identified terminin in the 60-kDa form as the unique subspecies present only in senescent human diploid fibroblasts. In this report, the biochemical properties of terminin during the process of induced cell death in Swiss 3T3 cells is investigated by total removal of serum, which subsequently activates apoptosis as determined by DNA degradation. Evidence presented here indicates that a specific proteolytic cleavage of terminin proteins occurs during apoptosis, leading to the appearance of a protein species with a molecular mass of 30 kDa (Tp-30) in serum-deprived mouse 3T3 cells. The appearance of Tp-30 can be modulated up to 24 h after serum deprivation by pretreatment with cycloheximide or returning to serum-containing conditions. These studies thus define the association of apoptosis-specific proteolysis of terminin and the appearance of Tp-30 with cell death in mouse 3T3 fibroblasts and can serve as a marker for cells on their way to apoptosis.

3T3 Cells↗
PubMed1994

Proliferative activity at colonic anastomoses as determined by statin. A nonproliferation-specific nuclear protein.

PURPOSE: One theory of anastomotic recurrence in large bowel carcinoma is that epithelial hyperplasia at the suture line causes metachronous carcinoma. METHODS: S44, a monoclonal antibody directed against statin, a nuclear protein expressed in quiescent cells, was used to determine whether the anastomosis represents an area with a high proliferation rate. During follow-up colonoscopic examination of patients who had undergone previous resection for colorectal carcinoma, biopsies were taken from the anastomotic site and from the mucosa 10 to 15 cm from the anastomosis. One side of 10 well-oriented crypts was counted for each patient with the number of nuclei positive for statin being determined by the presence of dark brown reaction product. RESULTS: The average percentages of statin-positive cells varied between 19.4 and 44.4 (average, 31.3 +/- 6.5) for the normal mucosa and 22.8 to 35.1 (average, 29.98 +/- 3.67) for the anastomotic mucosa. The differences were not significant. There were no differences between those patients in whom the postoperative time elapsed was two years or less and those greater than two years. CONCLUSION: This study is unique in that the proliferative activity at the site of colonic anastomosis was determined in a clinical setting, and patients in which the anastomoses were created anywhere from 1 to 14 years earlier were included. Using S44 as a marker, this study does not support the theory that suture line recurrence is a result of an enhanced proliferation rate.

Adult↗
PubMed1994

Statin--a novel marker of nonproliferation. Expression in nonneoplastic lymphoid tissues and follicular lymphomas.

Statin is a 57 kDa nuclear protein exclusively found in noncycling cells. Its expression in hematolymphoid cells had not been examined previously. The authors studied statin immunoreactivity in nonneoplastic lymphoid tissues from 26 lymph nodes, 3 tonsils, and 2 spleens. Statin was detected primarily in small lymphoid cells and histiocytes, along with such accessory elements as fibroblasts and endothelial cells. The distribution of positive cells showed an inverse correlation with the proliferative activity of the various lymphoid compartments. Statin labeling was also quantified in 15 follicular lymphomas and compared with that in hyperplastic follicles. Although reactivity in benign germinal centers was less than that in neoplastic follicles, this difference did not prove statistically significant. Statin provides an alternative to proliferation-associated parameters, such as Ki-67 and proliferating cell nuclear antigen, in the analysis of hematolymphoid processes and may be helpful in the dissection of their kinetic heterogeneity.

Cell Cycle Proteins↗
PubMed1994

Dietary fumonisin B1 induces disruption of sphingolipid metabolism in Sprague-Dawley rats: a new mechanism of nephrotoxicity.

Fumonisins are potent inhibitors of sphingolipid biosynthesis produced by several Fusarium species. Consumption of corn or corn products infected with F. moniliforme, or high levels of fumonisins, is associated with several animal diseases. In a 4-wk feeding study, the concentration of fumonisin B1 that caused nephrotoxicity in Sprague-Dawley rats was much less than that required to cause hepatotoxicity. This retrospective study shows a close correlation between the extent and severity of ultrastructural lesions and the degree of disruption of sphingolipid metabolism. The kidney was more sensitive to fumonisin B1-induced disruption of sphingolipid metabolism than liver with significant elevation of free sphingosine, free sphinganine, and the free sphinganine:free sphingosine ratio in rats fed 15, 50 and 150 micrograms/g fumonisin B1. Accumulation of free sphinganine and elevation of the free sphinganine:free sphingosine ratio in urine closely reflected the changes that occurred in kidney. The accumulated sphinganine and elevation of the free sphinganine:free sphingosine ratio was associated with accumulation of cells in urine. Thus, urine rather than serum is the fluid of choice for detecting elevated free sphingoid bases generated as a consequence of fumonisin-induced kidney damage.

Animals↗
PubMed1994

High-frequency S-layer protein variation in Campylobacter fetus revealed by sapA mutagenesis.

Campylobacter fetus utilizes paracrystalline surface (S-) layer proteins that confer complement resistance and that undergo antigenic variation to facilitate persistent mucosal colonization in ungulates. C. fetus possesses multiple homologues of sapA, each of which encode full-length S-layer proteins. Disruption of sapA by a gene targeting method (insertion of kanamycin (km) resistance) caused the loss of C. fetus cells bearing full-length S-layer proteins and their replacement by cells bearing a 50 kDa truncated protein that was not exported to the cell surface. After incubation of the mutants with serum, the survival rate was approximately 2 x 10(-2). Immunoblots of survivors showed that phenotypic reversion involving high-level production of full-length (98, 127 or 149 kDa) S-layer proteins had occurred. Revertants were serum resistant but caused approximately 10-fold less bacteraemia in orally challenged mice than did the wild-type strain. Southern hybridizations of the revertants showed rearrangement of sapA homologues and retention of the km marker. These results indicate that there exists high-frequency generation of C. fetus sapA antigenic variants, and that intracellular mechanisms acting at the level of DNA reciprocal recombination play key roles in this phenomenon.

Animals↗
PubMed1994

Persistence of Campylobacter fetus bacteremia associated with absence of opsonizing antibodies.

Campylobacter fetus causes systemic infections in immunocompromised hosts. We describe a case in which C. fetus bacteremia apparently relapsed after 7 years in a patient with hypogammaglobulinemia and characterize the serum resistance of the patient's C. fetus strain and the inability of the patient's serum, with and without commercial intravenous immunoglobulin, to opsonize this and another C. fetus strain effectively. The probable presence of a sequestered site of infection in bone, the intrinsic serum resistance of the C. fetus strain, and the absence of specific antibody may account for the persistent infection in this patient. These studies suggest that intravenous immunoglobulin treatment is not useful in eradicating C. fetus bacteremia.

Agammaglobulinemia↗
PubMed1994

Interleukin 12 at the site of disease in tuberculosis.

Interleukin 12 (IL-12), a heterodimeric cytokine composed of p40 and p35 chains, has potent immunologic effects in vitro. We used tuberculous pleuritis as a model to study the immunoregulatory potential of IL-12 in vivo at the site of human infectious disease. Messenger RNAs for p40 and p35 were detected in pleural fluid from six of six patients by reverse-transcription polymerase chain reaction. By using an ELISA that detected both free p40 and heterodimeric IL-12, we found that mean concentrations were 585 +/- 89 pg/ml in pleural fluid of patients with tuberculous pleuritis, which were significantly higher than those in serum of the same patients (54 +/- 36 pg/ml), or in malignant pleural effusions (123 +/- 35 pg/ml). By using an ELISA specific for heterodimeric IL-12, we found that mean concentrations in pleural fluid of patients with tuberculous pleuritis were 165 +/- 28 pg/ml and undetectable in serum of the same patients, or in malignant pleural effusions. Bioactive IL-12 was detectable in five of five supernatants of pleural fluid cells stimulated with Mycobacterium tuberculosis. Addition of anti-IL-12 antibodies suppressed proliferative responses of pleural fluid cells to M. tuberculosis by 36 +/- 7%. These data indicate that IL-12 may play a role in the human immune response to infectious agents in vivo. We hypothesize that IL-12 contributes to the antimycobacterial immune response by enhancing production of interferon-gamma, facilitating development of Th1 cells and augmenting cytotoxicity of antigen-specific T cells and natural killer cells.

Base Sequence↗
PubMed1994

Sexual dimorphism of urine angiotensinogen excretion in the rat.

To determine the source of angiotensinogen excreted in urine, urine angiotensinogen was measured in male and female rats during growth. Angiotensinogen in 24-hr urine, measured by direct radioimmunoassay with antibody against rat angiotensinogen, increased fourfold in males between the ages of 5 and 7 weeks, whereas no significant changes were observed in females or castrated males. Plasma levels of angiotensinogen, in contrast, showed no significant differences between these groups at any age. Castration of adult males caused a significant reduction of urinary angiotensinogen after 4 weeks. Consecutive s.c. administration of 17 alpha-methyltestosterone for 3 weeks in castrated males resulted in a threefold increase in the urinary excretion of angiotensinogen, as well as a twofold increase in the renal expression of angiotensinogen messenger RNA (mRNA). Renal levels of angiotensinogen mRNA in intact adult males were about threefold higher than those in females and castrated males, whereas there were no significant differences in hepatic angiotensinogen mRNA between these animals. These results suggest that the sexual differences in the urinary excretion of angiotensinogen are primarily due to the androgen-dependent dimorphic expression of angiotensinogen mRNA in the kidney; thus, levels of angiotensinogen in urine might reflect intrarenal production.

Age Factors↗
PubMed1994

Synthetic autoantigens of immunoglobulins and T-cell receptors: their recognition in aging, infection, and autoimmunity.

Immunoglobulins and their close relatives, the antigen-specific T-cell receptors, are recognition proteins that express structures which readily serve as self-immunogens. Healthy humans can produce antibodies against variable region-defined recognition structures termed idiotypes, as well as against constant region structures, and the levels of these can increase markedly in autoimmune disease; e.g., rheumatoid factors are autoantibodies directed against a conformational determinant of the gamma heavy chain. More recent analyses employing synthetic peptide technologies and construction of recombinant T-cell receptors document that autoantibodies directed against both variable and constant region markers of the alpha/beta T-cell receptor occur in healthy individuals. Alterations in levels of antibody, usage of IgM or IgG isotypes, and specificity for particular peptide-defined regions vary with natural physiological processes (aging, pregnancy), with artificial allografting, with retroviral infection, and with the inception and progression of autoimmune disease (e.g., rheumatoid arthritis, systemic lupus erythematosus). Two of the major autoimmunogeneic regions of the Tcr alpha/beta are "constitutive" markers inasmuch as all individuals tested produce antibodies against these regions. The most frequently observed autoantibodies are against Tcr V beta CDR1 and Fr3 markers. It is hypothesized that these are normally involved in immunoregulation. Autoantibodies usually are not detected against CDR2 region determinants, or the "private idiotypes" defined by the CDR3 region, or the highly conserved FR4 segment specified by the joining gene segment. However, autoantibodies against the CDR2 of the Tcr alpha chain occur in some SLE patients, and healthy pregnant women produce antibodies against the common peptide determinant expressed by the joining gene and the beginning of the C alpha or C beta domain. Although the precise role of the naturally occurring autoantibodies in immunoregulation remains to be determined, modification of the course of autoimmune diseases in experimental rodent models (experimental allergic encephalomyelitis) has been successfully carried out by immunization with synthetic peptides corresponding to the CDR2 and Fr3/CDR3 segments, and immunization of humans with synthetic V beta CDR2 segments may prove helpful in multiple sclerosis. Moreover, infusion of intravenous immunoglobulins has been successful in the treatment of many autoimmune diseases, including examples where levels of T cells bearing particular V beta gene subsets were elevated. The recent knowledge gained from T-cell receptor structural analysis and antigenic modeling holds promise for determining the roles of particular variable domain structures in antigen recognition MHC-restriction and immunoregulation, and in the development of synthetic and recombinant reagents for modulation of autoimmune and infectious diseases.

Aging↗
PubMed1993

Fumonisin B1 inhibits sphingosine (sphinganine) N-acyltransferase and de novo sphingolipid biosynthesis in cultured neurons in situ.

Fumonisins, mycotoxins produced by Fusarium moniliforme and a number of other fungi, cause neuronal degeneration, liver and renal toxicity, cancer, and other injury to animals. Recent work with rat hepatocytes (Wang, E., Norred, W. P., Bacon, C. W., Riley, R. T., and Merrill, A. H., Jr. (1991) J. Biol. Chem. 266, 14486-14490) found that fumonisins block sphingosine biosynthesis by inhibiting the conversion of sphinganine to dihydroceramides, which precedes introduction of the 4,5-trans-double bond of sphingosine. The current study utilized mouse cerebellar neurons in culture to evaluate how this affects the distribution of newly synthesized ceramides among different complex sphingolipids. Fumonisin B1 inhibited ceramide synthase in mouse brain microsomes with a competitive-like kinetic behavior with respect to both sphinganine and stearoyl-CoA. Fumonisin B1 inhibited sphingolipid biosynthesis in cultured cerebellar neurons in situ as reflected by accumulation of free sphinganine, a reduction in the mass of total sphingolipids, reductions in the incorporation of [14C]serine into glucosylceramide, lactosylceramide, sphingomyelin, and gangliosides (GM1, GD3, GD1a, GD1b, GT1b, and GQ1b), and inhibition of the incorporation of [14C]galactose and [3H]sphinganine into complex sphingolipids. Dose-response studies revealed that the labeling of sphingomyelin (IC50 of 0.7 microM) was more sensitive to inhibition by fumonisin B1 than was glycolipid formation (IC50 of approximately 7 microM) in these cells. A similar effect was seen when beta-fluoroalanine was added to inhibit the activity of serine palmitoyltransferase, the first enzyme of the pathway. The inhibition of complex sphingolipid synthesis was reversible, and nearly normal labeling profiles were obtained 48 h after removing the mycotoxin. These studies establish that fumonisin B1 inhibits de novo sphingolipid biosynthesis by neuronal cells and, moreover, that limiting ceramide synthesis differentially affects the formation of sphingomyelin versus glycosphingolipids.

Acyltransferases↗
PubMed1993

Heparin therapy during cardiopulmonary bypass in children requires ongoing quality control.

Heparin therapy for children undergoing cardiopulmonary bypass (CPB) is monitored in the operating room by automated whole blood activated clotting times (ACT). For many years our institution used Hemochron (HC) ACT machines but changed to HemoTec (HT) ACT machines because they required a smaller blood sample and provided results in duplicate. When HemoTec ACT machines were introduced at our institution, the surgical team was concerned that increased amounts of heparin were being administered to our patients during CPB. This study was conducted to investigate the potential mechanisms responsible for these clinical observations. First, we compared ACT values on ex vivo blood samples from 20 consecutive pediatric patients (6 samples each) during CPB. The HC ACT values were significantly and systematically increased over HT ACT values (HC: 750 +/- 40 vs HT: 418 +/- 26, Mean +/- SEM, p < 0.01). 94% of all HC ACT values were above 450 s compared to only 27% of HT ACT values. If HT ACT values had been used for patient monitoring, all patients would have received more heparin to achieve ACT values above 450 s. The two machines reported similar ACT values when heparin was added in vitro to whole blood (0.1-5.0 units/ml), (HC: Y = 98X + 104, r2 = 0.93 HT: Y = 82X + 109, r2 = 0.94). Heparin concentrations in our patients following a bolus of 300 U/kg of heparin, but prior to CPB were 3.2 +/- 0.07 units/ml. Following the initiation of CPB, heparin concentrations decreased to 1.3 +/- 0.05, reflecting, in part hemodilution by the pump prime (1 U of heparin/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Cell cycle kinetic effects of tamoxifen on human breast cancer cells. Flow cytometric analyses of DNA content, BrdU labeling, Ki-67, PCNA, and statin expression.

Tamoxifen is known to inhibit the growth of some human mammary carcinoma cells; this effect is accompanied by a decrease in the proportion of cells synthesizing DNA. In this work, flow cytometry of DNA and of bromodeoxyuridine labeling and the evaluation of the cell cycle-related antigens Ki-67, PCNA, and statin were used to investigate the changes in the proliferation kinetics of MCF-7 cells before and after treatment with 10(-7) M TAM. The treatment with TAM induced a significant decrease in the fraction of S-phase cells and an increase in those with a DNA content typical of G0/1 phase. The TAM-induced block in G0/1 is paralleled by a decrease in the frequency of cells expressing Ki-67 and PCNA, and by an increase in statin-positive (G0) cells. These results confirmed that the TAM-induced inhibition of cell growth is associated with major changes in the cell cycle parameters of MCF-7 cells, and provide the first experimental evidence that two main mechanisms are operating: the accumulation of cells in G1, before the onset of S-phase, and the exit of some cells from the cycling compartment.

Biomarkers, Tumor↗
PubMed1993

Differential expression of S1 and elongation factor-1 alpha during rat development.

Elongation factor-1 alpha (EF-1 alpha) is a highly conserved protein functioning in peptide elongation during translation. A cDNA, S1, was isolated; its deduced amino acid sequence shares high similarity with mammalian EF-1 alpha s (92%). While EF-1 alpha is present in all tissues, S1 mRNA can only be detected in brain, heart, and muscle. We report here that the retropseudogene phenomenon is attributable to EF-1 alpha and not S1, the latter being represented by a single copy in the rat genome. The S1 steady-state mRNA levels are consistently higher than EF-1 alpha in S1-positive tissues. S1 mRNA can only be detected late during brain, heart, and muscle development in vivo and increases to a plateau in early postnatal life. In a cultured muscle system, S1 expression is dependent upon the formation of myotubes, although the accumulation of S1 mRNA is significantly lower than that observed in adult skeletal muscle. EF-1 alpha mRNA levels are down-regulated during brain, heart, and muscle development, but stay relatively steady in liver. We show here that EF-1 alpha and S1 are differentially expressed during rat development and that the activation of S1 gene expression is subsequent to the terminal differentiation process in brain, heart, and muscle.

Amino Acid Sequence↗
PubMed1993

Expression of an EF-1 alpha-like rat cDNA, S1, in E. coli and production of a rabbit polyclonal antiserum to the recombinant protein.

A previously identified rat cDNA (S1) that shares 78% nucleotide homology and a predicted 92% amino acid homology with human EF-1 alpha was constructed into PGEX-2T and inducibly expressed in E. coli as a fusion protein. The purified recombinant S1 protein (rpS1) was used to raise rabbit antiserum which recognized rpS1 but not EF-1 alpha on immunoblots. A polyclonal antiserum to EF-1 alpha failed to react with the rpS1. Our results indicate that rpS1 protein can be used to produce antibodies which distinguish pS1 from EF-1 alpha despite their extensive amino acid sequence homology.

Amino Acid Sequence↗
PubMed1993

Electrochemical detection of cobalt in hair following on-column derivatization with 1-(2-pyridylazo)-2-naphthol-6-sulphonic acid and reversed-phase liquid chromatography.

A method for the specific determination of cobalt based on reversed-phase liquid chromatography with amperometric detection via on-column complex formation has been developed. A water-soluble chelating agent, 1-(2-pyridylazo)-2-naphthol-6-sulphonic acid (PAN-6S), is added to the mobile phase and aqueous cobalt solutions are injected directly into the column to form in situ the cobalt-PAN-6S chelate, which is then separated from other metal PAN-6S chelates and subjected to reductive amperometric detection at a moderate potential of -0.3 V. Because the procedure eliminates the interference of oxygen and depresses the electrochemical reduction of the mobile phase-containing ligand PAN-6S, by virtue of the quasi-reversible electrode process of the cobalt-PAN-6S complex, a low detection limit of 0.06 ng can be readily obtained. Interference effects were examined for sixteen common metal species, and at a 5- to 8000-fold excess by mass no obvious interference was observed. The feasibility of the method as an approach to the specific analysis of cobalt in a hair sample has been demonstrated.

Chromatography, Liquid↗