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W Jiang

Publications and source records attributed to W Jiang.

At least 181 records · Page 10Linked to original sources
PubMed1998

Histone H2A.F/Z subfamily: the smallest member and the signature sequence.

The nucleotide sequence of a 700 basepair cDNA obtained from rabbit bladder was determined. It encodes a 123 amino acid protein, which is the smallest member of histone H2A.F/Z subfamily. The known H2A.F/Z variants are highly conserved in their central core regions of about 100 amino acids but more divergent in their N- and C-terminal ends. In addition to the seven amino acid signature sequence previously known for the H2A proteins, all the cloned H2A.F/Z variants contain an identical peptide sequence, L-E-Y-L-T-A-E-V-L-E-L-A-G-N-A. This 15 amino acid motif is proposed here as the signature sequence to identify new members of the H2A.F/Z subfamily.

Amino Acid Sequence↗
PubMed1998

Interaction of mant-adenosine nucleotides and magnesium with kinesin.

Displacement of the fluorescent substrate analogue methylanthraniloyl ADP (mant-ADP) from kinesin by excess ATP results in a biphasic fluorescent transient. The pH and microtubule dependence of the rates and amplitudes indicates that the two phases are produced by release of bound mant-ADP, with an excess of the 3'-isomer, followed by the subsequent relaxation of the free 2'- and 3'-isomers to their equilibrium distribution. The first phase for release of mant-ADP is accelerated by microtubules and occurs at the same rate as ADP release measured using [32P]ADP. The second phase is subject to base catalysis and occurs at the same rate as the isomerization of isolated 2'- or 3'-mant-ATP over a 100-fold range of rates. The bound mant-ADP isomers undergo isomerization rapidly when bound to kinesin at pH 8.2, whereas mant-ADP isomers interconvert only slowly when bound to myosin. No fluorescence resonance energy transfer occurs between the single tryptophan in the kinesin neck domain and bound mant-ADP, but efficient energy transfer does occur from protein tyrosine groups. The rate of mant-ADP release in the absence of microtubules is minimal (0.005 s-1) at pH 7-8, 2 mM Mg2+, and 25 mM KCl but is accelerated at lower pH (0.04 s-1 at pH 5.5) and either lower or higher [KCl] (0.01 and 0. 06 s-1 at 0 and 800 mM KCl, respectively). The microtubule-stimulated rate of ADP release is accelerated at low pH and inhibited by high concentrations of monovalent salts. Reduction of the free Mg2+ by addition of excess EDTA increases the release of mant-ADP from E.MgADP to 0.03 s-1. This acceleration at low Mg2+ likely represents sequential release of Mg2+ at 0.03 s-1 followed by rapid release of ADP, as the rate of ADP release from Mg-free E.ADP is fast (>0.5 s-1). At high Mg2+, rebinding of Mg2+ to E.ADP forces release of ADP from the E.MgADP complex at 0.005 s-1.

Adenosine Diphosphate↗
PubMed1998

Bovine submaxillary mucin contains multiple domains and tandemly repeated non-identical sequences.

A number of cDNA fragments coding for bovine submaxillary mucin (BSM) were cloned, and the nucleotide sequence of the largest clone, BSM421, was determined. Two peptide sequences determined from the purified apoBSM were found near the N-terminus of the mucin-coding region of BSM421. This clone does not contain a start or stop codon, but its 3' end overlaps with the 5' end of a previously isolated clone, lambdaBSM10. The composite sequence of 1589 amino acid residues consists of five distinct protein domains, which are numbered from the C-terminus. The cysteine-rich domain I can be further divided into a von Willebrand factor type C repeat and a cystine knot. Domains III and V consist of similar repeated peptide sequences with an average of 47 residues. Domains II and IV do not contain such sequences but are similar to domains III and V in being rich in serine and threonine, many of which are predicted to be potential O-glycosylation sites. Domain III also contains two sequences that match the ATP/GTP-binding site motif A (P-loop). Only beta-strands and no alpha-helices are predicted for the partial deduced amino acid sequence. Northern analysis of submaxillary gland RNA with the BSM421 probe detected multiple messages of BSM with sizes from 1.1 to over 10 kb. The tandemly repeated, non-identical peptide sequences of approx. 47 residues in domains III and V of BSM differ from the tandemly repeated, identical 81-residue sequences of pig submaxillary mucin (PSM), although both BSM and PSM contain similar C-terminal domains. In contrast, two peptide sequences of ovine submaxillary mucin are highly similar (86% and 65% identical respectively) to the corresponding sequences in domain V of BSM.

Amino Acid Sequence↗
PubMed1998

Modification of yeast Cdc53p by the ubiquitin-related protein rub1p affects function of the SCFCdc4 complex.

The RUB1/NEDD-8 family of ubiquitin-related genes is widely represented among eukaryotes. Here we report that Cdc53p in Saccharomyces cerevisiae, a member of the Cullin family of proteins, is stably modified by the covalent attachment of a single Rub1p molecule. Two genes have been identified that are required for Rub1p conjugation to Cdc53p. The first gene, designated ENR2, encodes a protein with sequence similarity to the amino-terminal half of the ubiquitin-activating enzyme. By analogy with Aos1p, we infer that Enr2p functions in a bipartite Rub1p-activating enzyme. The second gene is SKP1, shown previously to be required for some ubiquitin-conjugation events. A deletion allele of ENR2 is lethal with temperature-sensitive alleles of cdc34 and enhances the phenotypes of cdc4, cdc53, and skp1, strongly implying that Rub1p conjugation to Cdc53p is required for optimal assembly or function of the E3 complex SCFCdc4. Consistent with this model, both enr2delta and an allele of Cdc53p that is not Rub1p modified, render cells sensitive to alterations in the levels of Cdc4p, Cdc34p, and Cdc53p.

Amino Acid Sequence↗
PubMed1998

Protein selectivity with immobilized metal ion-tacn sorbents: chromatographic studies with human serum proteins and several other globular proteins.

The chromatographic selectivity of the immobilized chelate system, 1,4,7-triazocyclononane (tacn), complexed with the borderline metal ions Cu2+, Cr3+, Mn2+, Co2+, Zn2+, and Ni2+ has been investigated with hen egg white lysozyme, horse heart cytochrome c, and horse skeletal muscle myoglobin, as well as proteins present in partially fractionated preparations of human plasma. The effects of ionic strength and pH of the loading and elution buffers on protein selectivities of these new immobilized metal ion affinity chromatographic (IMAC) systems have been examined. The results confirm that immobilized Mn;pl-tacn sorbents exhibit a novel type of IMAC behavior with proteins. In particular, the chromatographic properties of these immobilized M(n+)-tacn ligand systems were significantly different compared to the IMAC behavior observed with other types of immobilized tri- and tetradentate chelating ligands, such as iminodiacetic acid, O-phosphoserine, or nitrilotriacetic acid, when complexed with borderline metal ions. The experimental results have consequently been evaluated in terms of the additional contributions to the interactive processes mediated by effects other than solely the conventional lone pair Lewis soft acid-Lewis soft base coordination interactions, typically found for the IMAC of proteins with borderline and soft metal ions, such as Cu2+ or Ni2+.

Animals↗
PubMed1998

Autocrine TGFalpha expression in the regulation of initiation of human colon carcinoma growth.

Previously, we reported that unaggressive, growth factor-dependent FET human colon carcinoma cells downregulated their transforming growth factor alpha (TGFalpha) expression in a quiescent state (G0/G1) induced by growth factor and nutrient deprivation (Mulder, 1991, Cancer Res., 51:2256-2262). In contrast, highly aggressive, growth factor-independent HCT116 human colon carcinoma cells aberrantly upregulated this autocrine activity in the quiescent state (Mulder, 1991, Cancer Res., 51:2256-2262; Howell et al., 1998, Mol. Cell. Biol., 18:303-313). In this report, the role of autocrine TGFalpha and the mechanism of its regulation of expression during reentry into the cell cycle from a noncycling growth state were determined in FET cells. Optimal induction of DNA synthesis from a quiescent state in FET cells is dependent upon autocrine TGFalpha as well as exogenous transferrin and insulin. Reentry into the cell cycle resulting from treatment with exogenous transferrin and insulin resulted in approximately 3-fold induction of TGFalpha expression within 1 hr. TGFalpha induction was controlled at the transcription level, and the cis-controlling element was localized to the region between bp -370 - -201 relative to the translation start codon within the TGFalpha promoter. Thus neutralization of autocrine TGFalpha protein revealed that the induced TGFalpha autocrine activity was necessary for DNA synthesis and acted only in the early G1 phase of the cell cycle. Blockade of autocrine TGFalpha expression early in the cell cycle resulted in the reduction of DNA synthesis, whereas treatment with neutralization antibody at later times had no effect. This suggested that autocrine TGFalpha functions to initiate cell growth from noncycling states. This was further confirmed by the dependence of FET cells upon autocrine TGFalpha for colony formation in experiments where the plating density was sufficiently low to generate a lag phase in tissue culture. In contrast, TGFalpha autocrine activity was not required for exponential phase cells, as evidenced by the failure of TGFalpha neutralizing antibody to inhibit proliferation in this growth state. Taken together, these results suggest that autocrine TGFalpha acts primarily in the process of growth initiation by moving cells from a noncycling state back into the cell cycle, rather than supporting cell growth already initiated.

Autocrine Communication↗
PubMed1998

Overproduction and purification of glutaryl 7-amino cephalosporanic acid acylase.

The gene encoding glutaryl 7-amino cephalosporanic acid acylase (GL-7ACA acylase) from Pseudomonas sp. 130 has been cloned and expressed in Escherichia coli using a high-level expression system. The specific activity of the acylase in the crude extract of cells in this system is approximately 10 times that in the previous one. The overproduced enzyme can be easily isolated within 3 days to a purity of over 90% by a simple and inexpensive two-step preparative chromatographic method with an overall yield of nearly 50%. The deletion of the signal peptide and mutation in the alpha-subunit of the acylase have little influence on its posttranslational processing and its kinetic parameters.

Amidohydrolases↗
PubMed1998

Depression and social support in elderly patients with cardiac disease.

BACKGROUND: Depression is common among patients with cardiac disease. A number of psychosocial factors may affect the relationship between physical health and depression. There is evidence from the psychiatric literature suggesting that negative life events and social support are important factors in the development and outcome of depression. It is unknown if these factors are important in the context of depression in medically ill patients. Thus it is important to examine the relationship among social support, negative life events, and the presence of depression in elderly patients with cardiac disease. METHODS: Patients with coronary artery disease were assessed with the Duke Depression Evaluation Schedule for the Elderly. This includes the mood and anxiety disorder section of the Diagnostic Interview Schedule modified for Diagnostic and Statistical Manual of Mental Disorders diagnoses, life events, and multidimensional assessment of social support. Two hypotheses were tested: (1) the number of concurrent negative life events will be higher in patients with coronary artery disease with major depression than those without depression, and (2) social support will be less in patients with major depression than in those without. RESULTS: Presence of major depression was associated with increased negative life events and lowered subjective social support after accounting for age, sex, and race. CONCLUSIONS: The finding that subjective social support and negative life events are related to major depression suggests that even in the context of medical illness, social factors are still important in the development of major depression.

Aged↗
PubMed1998

Nucleic acid immunization protects dogs against challenge with virulent canine parvovirus.

Nucleic acid vaccines (NAVs) use expression vectors encoding one or more antigen genes to transfect host cells inducing both humoral and cellular immunity against the expressed antigen. NAV offers major advantages over conventional vaccines for the protection of humans and animals. This study shows that a plasmid DNA (pGT36VP1) encoding the full length VP1 region of canine parvovirus (CPV) induces immunity that protects dogs against challenge with virulent virus. Five dogs without anti-CPV antibodies were injected at 9 months of age with increasing doses of pGT36VP1 or saline. NAV vaccinated dogs showed an increase of serum IgG titer starting 1 week post-injection which peaked at week 2 and remained detectable for at least 14 weeks. A second dose of NAV resulted in an anamnestic response within 1 week. IgG titers peaked at week 3 and 4 after the second injection. All pGT36VP1 vaccinated dogs were protected against infection after virulent CPV challenge regardless of dose and the unvaccinated control dog was fully susceptible. This study demonstrated for the first time that a NAV can protect dogs against an infectious disease.

Animals↗
PubMed1998

Higher order iminodiacetic acid libraries for probing protein-protein interactions.

Full details of the preparation of iminodiacetic acid diamide dimer (2040 compounds), trimer (560 compounds), and tetramer (1596 compounds) libraries by multistep convergent solution-phase synthesis for studying protein-protein interactions are provided. The libraries were assembled in a format providing small 8-10 compound mixtures and the deconvolution of many of the small mixtures to identify screening leads by resynthesis of the individual components have been conducted for 320 of the individual compounds to date. A representative example of the subsequent exploration of the structure-activity relationships for an identified receptor binding antagonist (200 additional individual compounds) and steps taken for potential elaboration to a receptor dimerization agonist are defined with preparation of representative linked dimers (70 compounds).

Imides↗
PubMed1998

PRC1: a human mitotic spindle-associated CDK substrate protein required for cytokinesis.

We have identified a novel human protein, PRC1, that is involved in cytokinesis. PRC1 is a good substrate for several CDKs in vitro and is phosphorylated in vivo at sites that are phosphorylated by CDK in vitro, strongly suggesting that PRC1 is an in vivo CDK substrate. PRC1 has sequence homology to the budding yeast anaphase spindle elongation factor Ase1p. Like Ase1p, PRC1 protein levels are high during S and G2/M and drop dramatically after cells exit mitosis and enter G1. PRC1 is a nuclear protein in interphase, becomes associated with mitotic spindles in a highly dynamic manner during mitosis, and localizes to the cell mid-body during cytokinesis. Microinjection of anti-PRC1 antibodies into HeLa cells blocked cellular cleavage, but not nuclear division, indicating a functional role for PRC1 in the process of cytokinesis.

Amino Acid Sequence↗
PubMed1998

Humoral and cellular immune responses of dogs immunized with a nucleic acid vaccine encoding human carcinoembryonic antigen.

A nucleic acid vaccine encoding human carcinoembryonic antigen (CEA) was administered to 10 juvenile dogs, 10-15 weeks of age, by four parenteral routes. The routes tested were intramuscular injection using a needle and syringe, intramuscular injection using the Biojector needleless injection device, intradermal injection or intravenous injection. All groups received 150 micrograms of plasmid DNA on weeks 0, 4, 7 and 13. All dogs were bled weekly for 17 weeks and tested for antibody against human CEA. Dogs given plasmid intramuscularly either by needle and syringe or Biojector showed significant antibody responses by week 9 which peaked by week 15. Dogs receiving plasmid intravenously showed slight, unsustained increases in antibody titers while dogs receiving plasmid intradermally had significant titers, but at levels approximately one log less than those induced by intramuscular injection. The five dogs immunized by intramuscular delivery of plasmid DNA were examined for cellular immune responses to human CEA by lymphoblast transformation (LBT) assay. All five showed significant CEA-specific lymphoproliferation when compared with unvaccinated dogs. Physical examination, clinical chemistry, hematology and histopathology examinations revealed no abnormalities associated with nucleic acid immunization.

Animals↗
PubMed1998

Effect of corticosterone administration on mammary gland development and p27 expression and their relationship to the effects of energy restriction on mammary carcinogenesis.

The inhibitory activity against mammary carcinogenesis mediated by energy restriction is accompanied by a reduction in the degree of mammary ductal branching, and an increase in adrenal cortical activity. Levels of p27/kip1 protein, a gene product associated with cell cycle growth arrest, have also been shown to be elevated in mammary epithelium and in mammary lesions of energy-restricted animals. Based on these data we have proposed that increased secretion of adrenal cortical steroids accounts, in part, for the effects of energy restriction. In this experiment the hypothesis tested was that corticosterone administration would mimic the effects of energy restriction, both on mammary gland development and on levels of p27 protein in mammary ductal epithelium. To test this hypothesis corticosterone was fed to female rats for 4 weeks. Dietary corticosterone increased serum and urinary corticosterone levels in a dose-dependent manner (P < 0.01). The effects of corticosterone treatment on mammary gland development were analyzed digitally; p27 protein was detected immunohistochemically. The ductal extension and branching of the mammary gland were reduced in a dose-dependent manner by corticosterone treatment (P < 0.05); however, the magnitude of the effect was greater on ductal branching. Overall, increasing dietary corticosterone reduced the total volume of mammary epithelium in a dose-dependent manner, an effect that remained even after adjustments for differences among animals in body mass. Consistent with this effect, the amount of p27 protein present in ductal mammary epithelial cells increased dose-dependently in response to increasing corticosterone administration (P < 0.01). The hypothesis is proposed that dietary administration of corticosterone may imitate the effects of energy restriction on mammary carcinogenesis by regulation of mammary tissue size homeostasis via p27/kip1 mediated arrest of cell cycle progression.

Adrenal Cortex Hormones↗
PubMed1998

Intestinal inflammation reduces expression of DRA, a transporter responsible for congenital chloride diarrhea.

The pathogenesis of diarrhea in intestinal inflammatory states is a multifactorial process involving the effects of inflammatory mediators on epithelial transport function. The effect of colonic inflammation on the gene expression of DRA (downregulated in adenoma), a chloride-sulfate anion transporter that is mutated in patients with congenital chloridorrhea, was examined in vivo as well as in an intestinal epithelial cell line. DRA mRNA expression was diminished five- to sevenfold in the HLA-B27/beta2m transgenic rat compared with control. In situ hybridization showed that DRA, which is normally expressed in the upper crypt and surface epithelium of the colon, was dramatically reduced in the surface epithelium of the HLA-B27/beta2m transgenic rat, the interleukin-10 (IL-10) knockout mouse with spontaneous colitis, and in patients with ulcerative colitis. Immunohistochemistry demonstrated that mRNA expression of DRA reflected that of protein expression in vivo. IL-1beta reduced DRA mRNA expression in vitro by inhibiting gene transcription. The loss of transport function in the surface epithelium of the colon by attenuation of transporter gene expression, perhaps inhibited at the level of gene transcription by proinflammatory cytokines, may play a role in the pathogenesis of diarrhea in colitis.

Animals↗
PubMed1998

Inner ear damage in guinea pigs exposed to stable and impulse noise.

OBJECTIVE: To investigate the inner ear damage after exposure to stable noise, impulse noise and stable plus impulse noise in guinea pigs. METHODS: Ninety-six healthy guinea pigs were divided into 3 equal groups. (1) Stable noise group: exposed to 110 dBA stable noise for 3 days, 4 hours per day. (2) Impulse noise group: exposed to 165 dBA simulated cannon fire impulse noise 10 times successively at an interval of 10 seconds. (3) stable plus impulse noise group: exposed to the same stable noise as that in the first group, then after a 2-hour rest, the animals were followed with impulse noise exposures as that in the second group. After those exposure, each of the 3 groups was further divided into 4 subgroups according to the time after the noise exposure, namely, the right after, 7 d, 14 d and 30 d groups. The evoked cortical potential responses to click and tone burst stimulation sound were examined. The surface preparation and celloidine embedded serial section of the cochlea were observed under a light microscope. RESULTS: Both the stable and impulse noise could increase the hearing threshold and damage the inner ear hair cells. The damage in the first group was relatively slight, whereas in group 3 the damage was more severe than that in the other 2 groups. CONCLUSION: For seamen who are working in heavy noise environment, corresponding measures should be taken to protect their ears from noise which induces hearing loss.

Animals↗
PubMed1998

A clinical study on bing gan ling oral liquid for treatment of hepatitis C.

Based on the principles of cooling the blood to expel the pathogenic toxins and regulating the function of liver and activating the spleen in traditional Chinese medicine, 60 cases of chronic hepatitis C were treated with Bing Gan Ling (BGL), an oral liquid, which is composed mainly of Shuiniujiao (Cornu Bubali), Huzhang (Rhizoma Polygoni Cuspidati), Chishao (Radix Paeoniae Rubra), and Huangqi (Radix Astragali), etc. The total effective rate was 86.7%, which is considerably better than that of the control group (P < 0.01). The animal experiments and pathological studies suggest that the above-mentioned prescription has marked action of protecting the liver and lowering the activity of enzymes; and that it can ameliorate the acute liver injury induced by D-galactosamine.

Adult↗