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J Ni

Publications and source records attributed to J Ni.

At least 181 records · Page 10Linked to original sources
PubMed1996

Signal transduction by DR3, a death domain-containing receptor related to TNFR-1 and CD95.

Tumor necrosis factor receptor-1 (TNFR-1) and CD95 (also called Fas or APO-1) are cytokine receptors that engage the apoptosis pathway through a region of intracellular homology, designated the "death domain." Another death domain-containing member of the TNFR family, death receptor 3 (DR3), was identified and was shown to induce both apoptosis and activation of nuclear factor kappaB. Expression of DR3 appears to be restricted to tissues enriched in lymphocytes. DR3 signal transduction is mediated by a complex of intracellular signaling molecules including TRADD, TRAF2, FADD, and FLICE. Thus, DR3 likely plays a role in regulating lymphocyte homeostasis.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Interpretation of oligonucleotide mass spectra for determination of sequence using electrospray ionization and tandem mass spectrometry.

Procedures are described for interpretation of mass spectra from collision-induced dissociation of polycharged oligonucleotides produced by electrospray ionization. The method is intended for rapid sequencing of oligonucleotides of completely unknown structure at approximately the 15-mer level and below, from DNA or RNA. Identification of sequence-relevant ions that are produced from extensive fragmentation in the quadrupole collision cell are based primarily on (1) recognition of 3'- and 5'- terminal residues as initial steps in mass ladder propagation, (2) alignment of overlapping nucleotide chains that have been constructed independently from each terminus, and (3) use of experimentally measured molecular mass in rejection of incorrect sequence candidates. Algorithms for sequence derivation are embodied in a computer program that requires < 2s for execution. The interpretation procedures are demonstrated for sequence location of simple forms of modification in the base and sugar. The potential for direct sequencing of components of mixtures is shown using an unresolved fraction of unknown oligonucleotides from ribosomal RNA.

Algorithms↗
PubMed1996

FLICE, a novel FADD-homologous ICE/CED-3-like protease, is recruited to the CD95 (Fas/APO-1) death--inducing signaling complex.

To identify CAP3 and CAP4, components of the CD95 (Fas/APO-1) death-inducing signaling complex, we utilized nano-electrospray tandem mass spectrometry, a recently developed technique to sequence femtomole quantities of polyacrylamide gel-separated proteins. Interestingly, CAP4 encodes a novel 55 kDa protein, designated FLICE, which has homology to both FADD and the ICE/CED-3 family of cysteine proteases. FLICE binds to the death effector domain of FADD and upon overexpression induces apoptosis that is blocked by the ICE family inhibitors, CrmA and z-VAD-fmk. CAP3 was identified as the FLICE prodomain which likely remains bound to the receptor after proteolytic activation. Taken together, this is unique biochemical evidence to link a death receptor physically to the proapoptotic proteases of the ICE/CED-3 family.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Grap is a novel SH3-SH2-SH3 adaptor protein that couples tyrosine kinases to the Ras pathway.

A human cytoplasmic signaling protein has been cloned that possesses the same structural arrangement of SH3-SH2-SH3 domains as Grb2. This protein is designated Grap for Grb2-related adaptor protein. The single 2.3-kilobase (kb) grap transcript was expressed predominantly in thymus and spleen, while the ubiquitously expressed grb2 gene produced two mRNA species of 3.8 and 1.5 kb. Grap and Grb2 consist of 217 amino acids and share 59% amino acid sequence identity, with highest homology in the N-terminal SH3 domain. The GrapSH2 domain interacts with ligand-activated receptors for stem cell factor (c-kit) and erythropoietin (EpoR). Grap also forms a stable complex with the Bcr-Abl oncoprotein via its SH2 domain in K562 cells. Furthermore, Grap is associated with a Ras guanine nucleotide exchange factor mSos1, primarily through its N-terminal SH3 domain. These results show that a family of Grb2-like proteins exist and couple signals from receptor and cytoplasmic tyrosine kinases to the Ras signaling pathway.

Adaptor Proteins, Signal Transducing↗
PubMed1996

Immunological abnormality in C3H/HeJ mice with heritable inflammatory bowel disease.

To explore the immunological abnormality of a heritable inflammatory bowel disease developed in a new substrain of C3H/HeJ mice, we examined the expression of integrins beta7 and other cell adhesion molecules on normal and disease mice lymphocytes by flow cytometry. We also examined the cytotoxicity of small intestinal intraepithelial lymphocytes to epithelial cells and the proliferation and aggregation of intestinal lymphocytes. There are several significant changes in the expression levels of alpha4 and alphaM290beta7 integrins, CD11a, ICAM-1, CD45RB, CD4, CD44, and CD45 in different lymphocyte populations. The cytotoxicity of small intestinal intraepithelial lymphocytes from disease mice was higher than that from normal mice and could be stimulated by PHA and inhibited by mAb to alphaM290beta7. The proliferation of both normal and disease small intestinal intraepithelial lymphocytes was enhanced by costimulation by mAb to CD2 or CD3 and ProNectin. In comparison to disease mice, normal small intestinal intraepithelial lymphocytes proliferated at a significantly higher rate in response to sheep RBC and mAb to CD2 or CD3 and ProNectin costimulation. Homotypic aggregation of small intestinal intraepithelial lymphocytes isolated from disease mice was greater than in those from normal mice. The abnormality of expression of integrin beta7 and other cell adhesion molecules and cytotoxic, proliferative, and aggregative responses of lymphocytes from disease mice may play important roles in the pathogenesis of this heritable inflammatory bowel disease.

Animals↗
PubMed1996

Applications of the MTT assay to functional studies of mouse intestinal intraepithelial lymphocytes.

The MTT [3(4,5-dimethyl-thiazoyl-2-yl)2,5 diphenyl-tetrazolium bromide] and other related colorimetric assays were compared, and applied to functional studies of mouse intestinal intraepithelial lymphocytes and their hybridomas. Functional studies of intestinal lymphocytes included cell adhesion, cytotoxicity, growth inhibition, and proliferation. Our data demonstrate that MTT and related assays are time, labor, and cost saving alternatives to standard radiolabeling assays. The novel application of the MTT method to measure cell-to-cell adhesion and cell-mediated cytotoxicity greatly speed and simplify the determination. The new application of the MTT methods provides a reliable, reproducible, and rapid alternative for the study of intestinal immune cell functions.

Animals↗
PubMed1996

PCR diagnosis of viral pneumonitis from fixed-lung tissue in children.

Viral infection in children commonly causes acute lung disease leading to respiratory decompensation requiring intensive supportive therapy. Definitive diagnosis of the causative virus may be difficult, relying on serologic data since viral cultures are frequently negative; lung biopsy may be necessary to increase the diagnostic yield. The objective of this study was to develop a rapid and sensitive diagnostic method using the polymerase chain reaction (PCR). Analyzing Formalin-fixed lung tissue from autopsies of 32 patients with pneumonitis in whom cultures, serology, and histopathology results were blinded to the investigators, and 10 negative control samples, PCR was performed for cytomegalovirus, adenovirus, enteroviruses, herpes simplex virus, and Epstein-Barr virus. Among the 32 affected specimens, 7 were culture-positive for a specific virus in the lung; 6/7 of these were PCR-positive for the identical virus. In the culture-positive specimen not PCR amplified, influenza B was the cultured agent, but this virus was not evaluated by PCR. In the remaining 25 samples which were culture-negative, 11 were PCR-positive. All 10 negative controls were negative by PCR. Three specimens with CMV inclusions but culture-negative were also negative by PCR. We conclude that PCR is sensitive and accurate in the evaluation of lung tissue for viral pneumonitis.

Adolescent↗
PubMed1996

Markedly decreased expression of TAP1 and LMP2 genes in HLA class I-deficient human tumor cell lines.

HLA class I antigens of the human major histocompatibility complex play an important role in immune response. These molecules present foreign antigenic peptides to cytotoxic T lymphocytes and thereby play a role in the immune surveillance of cells infected with virus or other intracellular pathogens or altered by malignant transformation. A marked deficiency or lack of expression of these antigens has been reported in a variety of human neoplasms. In the present study, we examined the expression of class I alpha chain, beta 2-microglobulin, TAP (TAP1 and TAP2) and LMP (LMP2 and LMP7) genes in a number of human tumor cell lines including small-cell lung carcinoma, hepatocellular carcinoma, colon adenocarcinoma and basophilic leukaemia. These cell lines were deficient in expression of both class I alpha chain and beta 2-microglobulin gene products. In addition, these cell lines lacked the products of MHC-encoded proteasome subunit LMP2 as well as the putative peptide transporter TAP1 genes. In contrast, TAP2 and LMP7 genes were expressed in these cell lines. Treatment of cells with gamma-IFN markedly enhanced the expression of class I alpha chain, beta 2-microglobulin, TAP1 and LMP2 genes with a concomitant increase in cell-surface expression of class I molecules. The upregulation of TAP1 and LMP2 expression is associated with increased class I expression, suggesting that endogenous antigens, e.g. tumor antigens, could be presented by class I molecules following treatment of tumor cells with gamma-IFN.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

A mass spectrometric investigation of the reaction between 4,4'-vinylenedipyridine bis[2,2':6',2"-terpyridine platinum(II)] and the self-complementary oligonucleotide d(CpGpTpApCpG).

4,4'-Vinylenedipyridine bis[2,2':6',2"-terpyridine platinum(II)], a potential intermolecular bis-intercalator of DNA, reacts slowly at PtII, the linker being displaced by nucleobases. Crystallization of 4,4'-vinylenedipyridine bis[2,2':6',2"-terpyridine platinum(II)] in the presence of the self-complementary oligonucleotide d(CpGpTpApCpG) gave a product which was analyzed by electrospray ionization mass spectrometry. Molecular mass measurements demonstrated ligation of one terpyridine PtII, which was shown by liquid chromatography-mass spectrometry to reside exclusively on deoxyguanosine. The terpyridine PtII was shown by tandem mass spectrometry to be attached to the 3'-terminal deoxyguanosine, consistent with N-7 substitution.

2,2'-Dipyridyl↗
PubMed1996

Cloning of the mucosal addressin MAdCAM-1 from human brain: identification of novel alternatively spliced transcripts.

The mucosal addressin cell adhesion molecule-1 (MAdCAM-1), expressed selectively on high endothelial venules (HEV) and lamina propria venules, directs lymphocyte traffic by binding the lymphocyte Peyer's patch adhesion molecule-1 (LPAM-1, alpha 4 beta 7). Full-length DNA encoding human MAdCAM-1 was obtained by combining sequences from an expressed sequence tag (EST) identified in an early stage human brain cDNA library, a polymerase chain reaction-derived clone, and a MAdCAM-1 genomic clone. The deduced amino acid sequence revealed an 18 amino acid signal peptide, two N-terminal immunoglobulin (Ig)-like domains conserved (59-65%) in sequence with those of the mouse homologue, an 86 amino acid mucin-like region rich in serine-threonine residues, a 20 amino acid transmembrane domain and a 43 amino acid charged cytoplasmic domain. No counterpart to the third IgA-like domain of mouse MAdCAM-1 was present; however, the serine-threonine-rich mucin domain was extended as two distinguishable major and minor mucin regions unrelated to the mouse domain. The major domain is formed from six tandem repeats of an eight amino acid sequence having the MUC-2-related consensus DTTSPEP/SP. Human MAdCAM-1 mRNA transcripts were restricted to small intestine, colon, spleen, pancreas and brain. Alternatively spliced MAdCAM-1 variants were identified that lack parts of the second Ig domain and all or part of the major mucin domain, indicating that the function of this vascular addressin is regulated by extensive modifications to its multi-domain structure.

Alternative Splicing↗
PubMed1996

Effects of dextran sulphate sodium on intestinal epithelial cells and intestinal lymphocytes.

BACKGROUND AND AIMS: The effects of dextran sulphate sodium (DSS) on mouse intestinal epithelial cells and intraepithelial lymphocytes were analysed to investigate the mechanism by which DSS induces colitis and tumours in mice. Cytotoxicity of DSS towards intestinal epithelial cells and intestinal intraepithelial lymphocyte hybridomas or fresh intestinal intraepithelial lymphocytes seems to have concentration, time, and cell type dependency with increasing concentrations and time causing increased cytotoxicity. RESULTS: Integrin alpha 4 expression was marginally down regulated by 0.5% of DSS, while alpha M290 expression was up regulated. DSS inhibits the binding of 9.1 gamma delta cells to both extracellular matrix (ECM) and epithelial cells. Conversely at high concentrations it increases binding to all ECM except poly-L-lysine. Various cytokines including TGF beta, interleukin 2, and tumour necrosis factor alpha as well as prostaglandin alter the expression of the integrin alpha 4 and M290 subunits at the cell surface, and also alter the adhesion of 9.1 gamma delta cells to epithelial monolayers. The expression of a large number of cell adhesion molecules expressed on intraepithelial lymphocytes is affected by a combination of the abundant gut cytokine TGF beta and DSS, suggesting that DSS induced colitis may ultimately arise from a combination of gut cytokine and DSS. DSS also triggers intraepithelial lymphocyte aggregation on all ECM coated plate tested. CONCLUSIONS: These data suggest that the potential roles of DSS induced colitis may be: (a) direct cytotoxicity; (b) interference with the normal interaction between intestinal lymphocytes, epithelial cells, and ECMs; (c) aberrant modulation of the expression of the integrin beta 7 receptors, other cell receptors, and their functions.

Animals↗
PubMed1996

Diagnosis, surveillance, and epidemiologic evaluation of viral infections in pediatric cardiac transplant recipients with the use of the polymerase chain reaction.

BACKGROUND: Viral infections, particularly those caused by cytomegalovirus, are a major cause of postoperative morbidity and mortality in heart transplant recipients. These infections have classically been diagnosed by history, physical examination, peripheral viral cultures, and serologic studies. These methods are often time-consuming and lack sensitivity. Positive viral cultures from the heart are rarely obtained, and viral myocarditis and acute cellular rejection are unable to be differentiated histologically. We have therefore used the polymerse chain reaction to diagnose possible viral infection in pediatric heart transplant recipients with findings consistent with acute unexplained rejection. METHODS: Polymerase chain reaction was used as an aid to diagnose cytomegalovirus infection of cardiac tissue obtained by right ventricular endomyocardial biopsy and follow its long-term course. In addition, polymerase chain reaction was used to diagnose infection of the heart by other viruses in patients with clinical and histologic evidence of rejection, especially those with unexplained late rejection or chronic rejection. Polymerase chain reaction primers were designed to amplify nucleic acid sequences from cytomegalovirus, parvovirus, adenovirus, herpes simplex virus, Epstein-Barr virus, and the RNA viruses of the Enterovirus family. RESULTS: Forty patients underwent serial right ventricular endomyocardial biopsy (129 samples) for rejection surveillance with positive results obtained in 41 samples (32%) from 21 patients. Viral genome amplified included cytomegalovirus in 16 samples, adenovirus in 14, enterovirus in 6, parvovirus in 3, and herpes simplex virus in 2. In 13 of the 21 patients positive for viral genome (62%), endomyocardial biopsy histologic scores were consistent with multifocal moderate to severe rejection (Internal Society for Heart and Lung Transplantation scores of 3A or greater). CONCLUSIONS: Polymerase chain reactions may be used as a rapid and sensitive method to evaluate postoperative viral infections in heart transplant recipients, especially in those with late-onset rejection or chronic rejection. Polymerase chain reaction may also be useful in the serial analysis of cytomegalovirus status in transplant recipients. The use of multiple viral primers improves the diagnostic evaluation of these patients and may lead to a better understanding of the epidemiologic characteristics of posttransplantation viral infections and the cause of late or chronic rejection.

Adenoviruses, Human↗
PubMed1996

[Effect of IGF-II on progesterone production by cultured rat luteal cells in vitro].

It has been reported recently that IGF-II plays an important role in the regulation of ovarian function. The aim of this study is to investigate whether IGF-II can affect progesterone production by cultured rat luteal cells. The results showed that IGF-II could significantly stimulate basal progesterone production in a dose-dependent manner without altering the cAMP content. IGF-II could enhance 3H-leu incorporation into protein and 3H-TdR incorporation into DNA of the luteal cells, but these effects could be inhibited by CYX and Act D. The above results suggest that stimulating effect of IGF-II on progesterone production by rat luteal cells may be related to enhanced protein and DNA synthesis.

Animals↗
PubMed1996

[Effect of human inhibin alpha-fragments and monoaminergic neurotransmitters on progesterone(P4) production by corpus luteum(CL) of rat in vitro].

The effects of exogenenous monoaminergic neurotransmitters (norepinephrine, NE; epinephrine, E; dopamine, DA and 5-HT) and inhibin alpha N-terminal fragments P32 (1-32), P32-Tyr on P4 production by incubated rat CL cells were studied. The results demonstrated that: (1) alpha fragments caused significant inhibition on P4 production. (2) 0.1 mmol/L NE (or E) and 10 mumol/L DA produced a marked increase in both basal and hCG induced P4 production by CL cells (P < 0.001). The rank orders of potency of the catecholamines in stimulating P4 production were different, for basal P4 production, NE > E > DA; but for hCG induced P4 production, DA > E > NE, i.e. the order just reversed. Addition of P32-Tyr significantly neutrolized the stimulatory action of E, but only slightly increased the action of NE. (3) alpha receptor blocker phentolamine and beta receptor blocker propranolol were effective in decreasing basal and hCG-induced P4 production, the latter being more effective than the former. It was further shown that both blockers augmented the inhibitory effect of alpha-fragments on P4 production. (4) Unlike NE, E, and DA, 5-HT at 0.5 mumol/L exerted inhibitory effect on the basal and hCG-induced P4 production, but profoundly supressed the inhibitory effect of alpha-fragments on P4 production. The above results suggested: (1) Adrenergic, DA and 5-HT receptors are present in rat CL, where catecholamine might exert a stimulating effect on basal and hCG-induced P4 production via different pathways. (2) The inhibitory effect of P32, P32-Tyr on P4 production might be related to their inhibition by partial blocking alpha/beta receptors, which were antagnized by 5-HT. (3) The action of P32, P32-TYr on P4 production is brought on the participation of neurotransmitters NE, E, DA and 5-HT.

Adrenergic alpha-Agonists↗
PubMed1995

Beta 7 integrins and other cell adhesion molecules are differentially expressed and modulated by TNF beta in different lymphocyte populations.

To explore the role of beta 7 integrins subfamily and TNF beta in intestinal mucosal immunity and disease, we have examined the expression and modulation by TNF beta of beta 7 integrins and other cell adhesion molecules on mouse intestinal lymphocytes. Most of the small intestine intraepithelial lymphocytes (SIEL) and lamina propria lymphocytes (LPL) were M293 (beta 7) and M290 (alpha M290 beta 7) positive, whereas only 10-20% of SIEL and approximately 50% of LPL were R1-2 (alpha 4 beta 1/alpha 4 beta 7) positive. Only the expression of the R1-2 integrin was downregulated by TNF beta on SIEL. In contrast, expression of R1-2 was unaffected and expression of M290 was partially down-regulated by TNF beta on LPL. About 2-3% of spleen lymphocytes (SL) were M293, M290, and R1-2 positive, and on these cells expression of M290 (and M293) was strongly induced by TNF beta. CD45 expression was partially downregulated by TNF beta on SIEL, LPL, and SL, whereas the expression of ICAM-1 and CD45RB was upregulated by TNF beta only on SIEL. TNF beta strongly downregulated CD44 expression on SIEL, upregulated CD44 expression on LPL, and had no effect on CD44 on SL. These phenotypic differences and different responses to TNF beta modulation between SIEL, LPL, and SL may reflect differences in the microenvironments in which these cells reside and imply that SIEL and LPL may play different roles in intestinal immunity. Further, TNF beta may play an important role in regulating the function of beta 7 integrins and other cell adhesion molecules.

Animals↗
PubMed1995

Expression of beta 7 integrins and other cell adhesion molecules on mouse lymphocytes and their modulation by a new cytokine, IL-2 receptor-inducing factor.

We explored the role of a new cytokine, IL-2 receptor-inducing factor (IL-2RIF), in intestinal mucosal immunity and in the regulation of integrin beta 7 receptors on intestinal lymphocytes. Most SIEL (small intestine intraepithelial lymphocytes) were M290 (alpha M290 beta 7) positive, while only 10 to 15% of SIEL were R1-2 (alpha 4) positive. The expression of alpha 4 (R1-2) and beta 7 (M293) but not alpha M290 beta 7 integrin on SIEL was up-regulated by IL-2RIF. Incubating SIEL with IL-2RIF resulted in the up-regulation of CD45RB and down-regulation of CD44. About 50% of LPL (lamina propria lymphocytes) were alpha M290 beta 7 positive, while only 20% of LPL were alpha 4 positive. The expression of alpha M290 beta 7 integrin on LPL was down-regulated and alpha 4 and beta 7 integrin was up-regulated by IL-2RIF. Incubating LPL with IL-2RIF resulted in the up-regulation of CD44 and no significant change of CD11a, CD45, CD45RB, and ICAM-1. These results suggested that SIEL and LPL may play a different role in intestinal mucosal immunity and that IL-2RIF may play an important role in regulating the functions of integrins beta 7 on IEL and LPL.

Adjuvants, Immunologic↗