Biomedical subjects

J Ni

Publications and source records attributed to J Ni.

At least 109 records · Page 6Linked to original sources

PubMed1999

Identification of a novel activation-inducible protein of the tumor necrosis factor receptor superfamily and its ligand.

Among members of the tumor necrosis factor receptor (TNFR) superfamily, 4-1BB, CD27, and glucocorticoid-induced tumor necrosis factor receptor family-related gene (GITR) share a striking homology in the cytoplasmic domain. Here we report the identification of a new member, activation-inducible TNFR family member (AITR), which belongs to this subfamily, and its ligand. The receptor is expressed in lymph node and peripheral blood leukocytes, and its expression is up-regulated in human peripheral mononuclear cells mainly after stimulation with anti-CD3/CD28 monoclonal antibodies or phorbol 12-myristate 13-acetate/ionomycin. AITR associates with TRAF1 (TNF receptor-associated factor 1), TRAF2, and TRAF3, and induces nuclear factor (NF)-kappaB activation via TRAF2. The ligand for AITR (AITRL) was found to be an undescribed member of the TNF family, which is expressed in endothelial cells. Thus, AITR and AITRL seem to be important for interactions between activated T lymphocytes and endothelial cells.

Amino Acid Sequence↗

PubMed1999

Cloning and characterization of a novel beta integrin-related cDNA coding for the protein TIED ("ten beta integrin EGF-like repeat domains") that maps to chromosome band 13q33: A divergent stand-alone integrin stalk structure.

Herein we describe the cDNA sequence of a novel human gene, ITGBL1, encoding a beta integrin-related protein termed TIED [for ten beta integrin epidermal growth factor (EGF)-like repeat domains]. Overlapping cDNA clones from fetal lung, HUVEC, and osteoblast cDNA libraries encode a sequence comprising a typical signal peptide, followed by a hydrophilic 471-amino-acid domain containing 10 tandem EGF-like repeats strikingly similar to those found in the cysteine-rich "stalk-like" structure of integrin beta subunits. The EGF-like repeats of TIED and beta integrins are unique in that they alternate in homology and possess two additional cysteines (eight in total) whose positions differ from those in the other eight-cysteine EGF-like domains of laminin, fibrillin, and the latent TGF-beta binding proteins. TIED mRNA transcripts of 2.8 kb were detected in aorta, thymus, and osteogenic sarcoma cells. The ITGBL1 gene was mapped to human chromosome 13, band 13q33. We suggest that ITGBL1 may be linked in some way with the evolution of the integrin beta subunits.

3' Untranslated Regions↗

PubMed1999

LYVE-1, a new homologue of the CD44 glycoprotein, is a lymph-specific receptor for hyaluronan.

The extracellular matrix glycosaminoglycan hyaluronan (HA) is an abundant component of skin and mesenchymal tissues where it facilitates cell migration during wound healing, inflammation, and embryonic morphogenesis. Both during normal tissue homeostasis and particularly after tissue injury, HA is mobilized from these sites through lymphatic vessels to the lymph nodes where it is degraded before entering the circulation for rapid uptake by the liver. Currently, however, the identities of HA binding molecules which control this pathway are unknown. Here we describe the first such molecule, LYVE-1, which we have identified as a major receptor for HA on the lymph vessel wall. The deduced amino acid sequence of LYVE-1 predicts a 322-residue type I integral membrane polypeptide 41% similar to the CD44 HA receptor with a 212-residue extracellular domain containing a single Link module the prototypic HA binding domain of the Link protein superfamily. Like CD44, the LYVE-1 molecule binds both soluble and immobilized HA. However, unlike CD44, the LYVE-1 molecule colocalizes with HA on the luminal face of the lymph vessel wall and is completely absent from blood vessels. Hence, LYVE-1 is the first lymph-specific HA receptor to be characterized and is a uniquely powerful marker for lymph vessels themselves.

Amino Acid Sequence↗

PubMed1999

Receptor activator of NF-kappaB recruits multiple TRAF family adaptors and activates c-Jun N-terminal kinase.

Receptor activator of NF-kappaB (RANK) is a recently cloned member of the tumor necrosis factor receptor (TNFR) superfamily, and its function has been implicated in osteoclast differentiation and dendritic cell survival. Many of the TNFR family receptors recruit various members of the TNF receptor-associated factor (TRAF) family for transduction of their signals to NF-kappaB and c-Jun N-terminal kinase. In this study, the involvement of TRAF family members and the activation of the JNK pathway in signal transduction by RANK were investigated. TRAF1, 2, 3, 5, and 6 were found to bind RANK in vitro. Association of RANK with each of these TRAF proteins was also detected in vivo. Expression of RANK in cultured cells also induced the activation of JNK, which was blocked by a dominant-negative form of JNK. Furthermore, by employing various C-terminal deletion mutants of RANK, the regions responsible for TRAF interaction and JNK activation were identified. TRAF5 was determined to bind to the C-terminal 11 amino acids and the other TRAF members to a region N-terminal to the TRAF5 binding site. The domain responsible for JNK activation was localized to the same region where TRAF1, 2, 3, and 6 bound, which suggests that these TRAF molecules might mediate the RANK-induced JNK activation.

Amino Acid Sequence↗

PubMed1999

TL1, a novel tumor necrosis factor-like cytokine, induces apoptosis in endothelial cells. Involvement of activation of stress protein kinases (stress-activated protein kinase and p38 mitogen-activated protein kinase) and caspase-3-like protease.

TL1 is a recently discovered novel member of the tumor necrosis factor (TNF) cytokine family. TL1 is abundantly expressed in endothelial cells, but its function is not known. The present study was undertaken to explore whether TL1 induces apoptosis in endothelial cells and, if so, to explore its mechanism of action. Cultured bovine pulmonary artery endothelial cells (BPAEC) exposed to TL1 showed morphological (including ultrastructural) and biochemical features characteristic of apoptosis. TL1-induced apoptosis in BPAEC was a time- and concentration-dependent process (EC50 = 72 ng/ml). The effect of TL1 was not inhibited by soluble TNF receptors 1 or 2. TL1 up-regulated Fas expression in BPAEC at 8 and 24 h after treatment, and significantly activated stress-activated protein kinase (SAPK) and p38 mitogen-activated protein kinase (p38 MAPK). The peak activities of SAPK and p38 MAPK in TL1-treated BPAEC were increased by 9- and 4-fold, respectively. TL1-induced apoptosis in the BPAEC was reduced by expression of a dominant-interfering mutant of c-Jun (62.8%, p < 0.05) or by a specific p38 inhibitor, SB203580 (1-10 microM) dose-dependently. TL1 also activated caspases in BPAEC, and TL1-induced apoptosis in BPAEC was significantly attenuated by the caspase inhibitor, ZVAD-fluromethyl-ketone. The major component activated by TL1 in BPAEC was caspase-3, which was based on substrate specificity and immunocytochemical analysis. These findings suggest that TL1 may act as an autocrine factor to induce apoptosis in endothelial cells via activation of multiple signaling pathways, including stress protein kinases as well as certain caspases.

Animals↗

PubMed1999

Membrane supports as the stationary phase in high-performance immunoaffinity chromatography.

The membrane with a composite of cellulose grafted with acrylic polymers formed by polymerizing a glycidyl methacrylate in the presence of dispersed cellulose fiber was prepared as the stationary phase; the column (40 x 4 mm i.d.) which was compatible with the HPLC instrument was packed with pieces of the cut membrane. Protein A and human IgG were immobilized on the membrane stationary phase. The column based on the membrane support provided us good reproducibility, high efficiency, and low back pressure. High-performance immunoaffinity chromatographic analysis of human IgG in serum and polyclonal antibody to human IgG raised in goat was performed within 2.5 min. The fast-speed immunoaffinity analysis was developed by increasing the flow rate of the mobile phase and decreasing the duration time for the switch of the mobile phase; an operation for immunoaffinity analysis of human IgG could be finished within 30 s.

Cellulose↗

PubMed1999

Study of physically absorbed stationary phases for open tubullar capillary electrochromatography.

A novel method based on the adsorption of positively charged compounds on the wall of a fused-silica capillary was applied to prepare stationary phases for open tubular capillary electrochromatography (OTCEC). The positively charged substances including cationic surfactant such as cetyltrimethylammonium bromide (CTAB) and basic chiral selectors such as protein, peptide and amino acid were physically adsorbed onto the capillary wall under specially selected conditions. The adsorbed stationary phase of CTAB was used to separate neutral compounds, while the others were used for chiral separations. The run-to-run reproducibility of retention time was rather good with relative standard deviation (RSD) values of less than 2.3%. The separation efficiency was excellent with the highest theoretical plate number of up to 590000/m and the average one above 250000/m. Stored at 2-8 degrees C in the refrigerator, the adsorbed stationary phase can last at least one month. It was observed that the UV spectra for the enantiomers are significantly different due to the diastereomeric interactions of enantiomers with the chiral stationary phase in the detection window. With the use of the same capillary, the same instrument, and the same mobile phase, the superiority of OTCEC over open tubular liquid chromatography (OTLC) and capillary zone electrophoresis (CZE) was illustrated.

Animals↗

PubMed1999

Effects of organic modifiers on solute retention and electrokinetic migrations in micellar electrokinetic capillary chromatography.

Influences of seven organic modifiers, including urea, methanol (MeOH), dioxane (DIO), tetrahydrofuran (THF), acetonitrile (ACN), 1-propanol (1-PrOH) and 2-propanol (2-PrOH), on the solute retention and the electrokinetic migrations in micellar electrokinetic capillary chromatography (MEKC) are investigated with sodium dodecyl sulfate (SDS) micelle as pseudostationary phase. It is observed that in the limited concentration ranges used in the MEKC systems the effect of organic modifier concentration on the retention can be described by the equation logk1=logk1w-SC for most binary aqueous-organic buffer, but deviations from this retention equation are observed at ACN and particularly THF as organic modifiers. With parameter S as a measure of the elutropic strength, the elutropic strength of the organic modifiers is found to follow a general order urea <MeOH<ACN<2-PrOH<DIO, while THF is found to be the most abundant modifier in selectivity among the organic modifiers studied. The electroosmotic mobility decreases linearly with increasing modifier concentrations. The strength of modifiers to suppress the electroosmotic mobility follows the order urea < MeOH, ACN < DIO, THF, 1-PrOH, 2-PrOH. The addition of ACN affects the electrophoretic mobility of the SDS micelle in different patterns depending on the buffer composition used, while the addition of the other modifiers leads to a rough linear decrease of the electrophoretic mobility of the SDS micelle. The suppressing strength of THF on the electrophoretic mobility of the SDS micelle is strongly related to the buffer composition, whereas the suppressing strength for the other modifiers follows the sequence urea < MeOH < DIO, 1-PrOH, 2-PrOH. The migration time window is expanded by the use of organic modifiers. Urea and MeOH have the least expanding strength while ACN, DIO, THF, 1-PrOH and 2-PrOH have the highest expanding strength on the migration time window.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed1999

The detection of viral genomes by polymerase chain reaction in the myocardium of pediatric patients with advanced HIV disease.

OBJECTIVES: The aim of this study was to investigate the frequency of viral nucleic acid detection in the myocardium of human immunodeficiency virus (HIV)-infected children to determine whether an association exists with the development of heart disease. BACKGROUND: As improved medical interventions increase the life expectancy of HIV-infected patients, increased incidences of myocarditis and dilated cardiomyopathy (DCM) are becoming more apparent, even in patients without clinical symptoms. METHODS: Myocardial samples were obtained from the postmortem hearts of 32 HIV-infected children and from 32 age-matched controls consisting of patients with structural congenital heart disease and no myocardial inflammation and no cardiac or systemic viral infection. The hearts were examined histologically and analyzed for the presence of viral sequences by polymerase chain reaction (PCR) or reverse transcription-PCR. RESULTS: Myocarditis was detected histologically in 11 of the 32 HIV-infected patients, and borderline myocarditis was diagnosed in another 13 cases. Infiltrates were confined to the epicardium in two additional hearts. Virus sequences were detected by PCR in 11 of these 26 cases (42.3%); adenovirus in 6, CMV in 3 and both adenovirus and CMV in 2. Two cases without infiltrates were also positive for adenovirus: one had congestive heart failure (CHF) and the other adenoviral pneumonia. No other viruses were detected by PCR, including HIV proviral DNA. All control samples were negative for all viruses tested. CONCLUSIONS: These data suggest that the presence of viral nucleic acid in the myocardium is common in HIV-infected children, and may relate to the development of myocarditis, DCM or CHF and may contribute to the rapid progression of HIV disease.

Base Sequence↗

PubMed1999

Detection and quantification of 1,N(6)-ethenoadenine in human placental DNA by mass spectrometry.

Exocyclic DNA adducts have been reported to derive from various exogenous as well as endogenous sources, such as lipid peroxidation. Among them, 1,N(6)-ethenoadenine (epsilonAde) has previously been detected in tissue DNA of untreated rodents and humans by an immunoaffinity/(32)P-postlabeling method. This study reports detection and quantification of the endogenous epsilonAde adduct in the same human placental DNA by three independent assays, namely, GC/MS, LC/MS, and HPLC/fluorescence. Using a recently reported gas chromatography/negative ion chemical ionization/mass spectrometry (GC/NICI/MS) method [Chen, H.-J. C., et al. (1998) Chem. Res. Toxicol. 11, 1474], the level of epsilonAde in human placental DNA from a commercial source was found to be 2.3 adducts per 10(6) Ade bases. To confirm these findings, a liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI/MS/MS) method was developed for epsilondAdo. With this LC/MS assay, epsilondAdo was detected at the level of 2.5 adducts per 10(6) dAdo nucleosides in the same human placental DNA. The stable isotopes of epsilonAde and epsilondAdo were added as internal standards in both GC/MS and LC/ESI/MS/MS assays, respectively, and thus provided high specificity, reproducibility, and accurate quantification. The relatively high levels of epsilonAde in this human placental DNA detected by mass spectrometry were further verified by HPLC/fluorescence analysis. The GC/MS method was validated by the HPLC/fluorescence assay using calf thymus DNA treated with chloroacetaldehyde or by the LC/MS method with 2, 3-epoxy-4-hydroxynonanal-modified calf thymus DNA. The epsilonAde level in human placental DNA freshly isolated in the presence of an antioxidant was similar to that in DNA from the commercial source. Since epsilonAde is a potential mutagenic lesion, analysis of epsilonAde by the specific and sensitive GC/NICI/MS method may provide a useful biomarker in cancer risk assessment.

Adenine↗

PubMed1999

Structure of the arginine repressor from Bacillus stearothermophilus.

The arginine repressor (ArgR) is a hexameric DNA-binding protein that plays a multifunctional role in the bacterial cell. Here, we present the 2.5 A structure of apo-ArgR from Bacillus stearothermophilus and the 2.2 A structure of the hexameric ArgR oligomerization domain with bound arginine. This first view of intact ArgR reveals an approximately 32-symmetric hexamer of identical subunits, with six DNA-binding domains surrounding a central oligomeric core. The difference in quaternary organization of subunits in the arginine-bound and apo forms provides a possible explanation for poor operator binding by apo-ArgR and for high affinity binding in the presence of arginine.

Amino Acid Sequence↗

PubMed1999

VEGI, a novel cytokine of the tumor necrosis factor family, is an angiogenesis inhibitor that suppresses the growth of colon carcinomas in vivo.

A novel member of the tumor necrosis factor (TNF) family has been identified from the human umbilical vein endothelial cell cDNA library, named vascular endothelial growth inhibitor (VEGI). The VEGI gene was mapped to human chromosome 9q32. The cDNA for VEGI encodes a protein of 174 amino acid residues with the characteristics of a type II transmembrane protein. Its amino acid sequence is 20-30% identical to other members of the TNF family. Unlike other members of the TNF family, VEGI is expressed predominantly in endothelial cells. Local production of a secreted form of VEGI via gene transfer caused complete suppression of the growth of MC-38 murine colon cancers in syngeneic C57BL/6 mice. Histological examination showed marked reduction of vascularization in MC-38 tumors that expressed soluble but not membrane-bound VEGI or were transfected with control vector. The conditioned media from soluble VEGI-expressing cells showed marked inhibitory effect on in vitro proliferation of adult bovine aortic endothelial cells. Our data suggest that VEGI is a novel angiogenesis inhibitor of the TNF family and functions in part by directly inhibiting endothelial cell proliferation. The results further suggest that VEGI maybe highly valuable toward angiogenesis-based cancer therapy.

Amino Acid Sequence↗

PubMed1999

The integrin alpha10 subunit: expression pattern, partial gene structure, and chromosomal localization.

Herein we report the cloning of cDNAs and incompletely processed hnRNAs from endothelia and heart that encode the alpha10 subunit forming part of the novel collagen type II-binding integrin alpha10beta1 of chondrocytes. Analysis of hnRNA clones and reported expressed sequence tags revealed the positions of 17 putative intron-exon splice junctions shared with those of the p150,95 (ITGAX) gene. Human alpha10 transcripts of 5.4 and 1.8 kb were not restricted to chondrocytes but, instead, were widely expressed in a panel of 24 tissue types, where the highest expression was found in muscle and heart. The human alpha10 subunit gene (ITGA10) was localized to band q21 of chromosome 1.

Amino Acid Sequence↗

PubMed1999

[Effect of human inhibin alpha-fragment 1-32-Tyr(P33) on apoptosis of cultured rat corpus luteal cells].

Recently, increasing evidence suggests that alpha inhibin or related proteins may be a functional regulator in the ovary, which is independent of hetero-dimer inhibin. In our previous study, it was demonstrated that human inhibin alpha-N-terminal fragment Tyr-1-32 (P(33)) significantly inhibited progesterone production by rat corpus luteal cells in vitro, and stimulated luteal functional regression and apoptosis in vivo. In the present work, the action of P(33) on apoptosis was further studied in vitro in cultured rat CL cells. Gel electrophoretic analysis for detection of oligonucleosomal DNA fragmentation, AO-EB or PI assays and flow cytometry were used to observe the action of P(33) on the occurrence of spontaneous apoptosis by collagenase-DNase dispersed CL cells, obtained from PMSG-hCG induced pseudopregnant rats. The results showed that P(33) (1 microg/ml) stimulated spontaneous apoptosis of CL cells. The inhibitor of tyrosine protein kinase, genistein (50 microg/ml),inhibited P(33) enhanced spontaneous apoptosis. RNA and protein synthesis inhibitors cycloheximide (Cyx,50 microg/ml) and actinomycin D(Act D,50 microg/ml) did not protect the cells from apoptosis stimulated by P(33). The results suggest that P(33) stimulates spontaneous apoptosis in cultured rat CL cells with the involvement of tyrosine specific protein kinase system. This work provides further evidence for the hypothesis that alpha inhibin or related protein might be a functional regulator in the ovary.

Animals↗

PubMed1999

[Focal adhesion kinase].

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Focal Adhesion Protein-Tyrosine Kinases↗

PubMed1999

Method development of adsorbed stationary phase open tubular capillary electrochromatography.

The adsorption effect of capillary wall, which was usually considered as a troublesome factor, has been used as driving force for preparing stationary phase for open tubular capillary electrochromatography (OTCEC). A number of compounds have been applied as stationary phase materials, which include cationic surfactants such as cetyltrimethylammonium bromide (CTAB), basic proteins such as lysozyme and cytochrome C, basic peptides such as Lys-Tyr and Lys-Ser-Tyr, and basic amino acid L-lysine. The adsorbed CTAB phase is used for separation of neutral compounds while other adsorbed stationary phases are used for chiral separation. The run-to-run reproducibility of retention time is rather good with RSD values less than 2.3%. The separation efficiency is excellent with the highest theoretical plate number of up to 590,000/m and the average plate number of more than 250,000/m. Being stored at 2-8 degrees C in refrigerator, the adsorbed stationary phase can last at least one month.

Adsorption↗

PubMed1999

[The application of artificial neural network in QSAR research of PCDD].

The study of QSAR between molecular structure and retention behavior of solutes is an important topic of chromatographic basic theory. PCDD (polychlorinated dioxin) is a kind of important environmental toxin. The basic skeleton of PCDD is [symbol: see text]. PCDDs are all chlorine substituted, so they are only different from each other in the number and position of chlorine substitutents on the skeleton. There are 76 kinds of homologues (1 to 8 chlorine substituent) for 3, 4, 5 and 6 chlorine substituted compounds including more than ten kinds of isomerides. In this paper, the description of molecular structure and feature selection have been investigated. Artificial neural network (ANN) is used to relate the molecular structure and retention time of PCDD. The predicted results of 49 PCDDs retention time by ANN are listed. It was shown that as to the relative error more than 95% data was less than 10% and more than 80% data was less than 5%.

Chromatography↗

PubMed1999

[Screening and analysis of biologically active components in traditional Chinese medicine by molecular biochromatography].

Screening of biologically active components from Chinese medicines by molecular biochromatography has been first proposed by authors. This paper summarizes their recent progresses on screening and analysis of Chinese medicines by molecular chromatography, including the comparison of the chromatograpic pattern for a number of herbal medicines, and the same kind of medicines but different sources, method development for screening and quality control of Chinese medicines, and the study on the interactions between the biologically active compounds in Chinese medicines and protein. The prospect of molecular biochromatography on study of Chinese medicines has also been highlighted.

4-Butyrolactone↗