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J Ye

Publications and source records attributed to J Ye.

At least 235 records · Page 13Linked to original sources
PubMed1995

A 31p-magnetic resonance study of antegrade and retrograde cerebral perfusion during aortic arch surgery in pigs.

To evaluate the effect of hypothermic circulatory arrest on brain metabolism, we used 31P-magnetic resonance spectroscopy to monitor brain metabolites in pigs during 2 hours of ischemia and 1 hour of reperfusion. Twenty-eight pigs were divided into five groups. Anesthesia (n = 5) and hypothermic cardiopulmonary bypass groups (n = 5) served as controls. In the circulatory arrest (n = 6), antegrade perfusion (n = 6), and retrograde (n = 6) brain perfusion groups, the bypass flow rate was 60 to 100 ml.kg-1.min-1. In the antegrade group, the brain was perfused via the carotid arteries at a blood flow rate of 180 to 200 ml.min-1 during circulatory arrest at 15 degrees C. In the retrograde group, the brain was perfused through the superior vena cava at a flow rate of 300 to 500 ml.min-1 during circulatory arrest at 15 degrees C. The intracellular pH was 7.1 +/- 0.1 and 7.3 +/- 0.1 in the anesthesia and hypothermic cardiopulmonary bypass groups, respectively. In the circulatory arrest group, the intracellular pH decreased to 6.2 +/- 0.1 and did not recover to its initial value (7.0 +/- 0.1) during reperfusion (p < 0.05 compared with the value obtained from the control groups at the corresponding time). Inorganic phosphate did not return to its initial level during reperfusion. In three animals in this group, levels of high-energy phosphates, adenosine triphosphate and phosphocreatine, recovered partially but did not reach the levels observed before arrest. In the group receiving antegrade perfusion, cerebral metabolites and intracellular pH were unchanged throughout the protocol. During circulatory arrest in the retrograde perfusion group the intracellular pH decreased to 6.4 +/- 0.1 and recovered fully during reperfusion (7.1 +/- 0.1). High-energy phosphates also returned to their initial levels during reperfusion. These studies show that deep hypothermic circulatory arrest with antegrade brain perfusion provides the best brain protection of the options investigated.

Adenosine Triphosphate↗
PubMed1995

Chromium(VI)-induced nuclear factor-kappa B activation in intact cells via free radical reactions.

Incubation of chromium(VI) [Cr(VI)] with cultured Jurkat cells resulted in activation of DNA binding activity of the nuclear factor (NF)-kappa B. In a combination with glutathione reductase, a Cr(VI) reducing agent, Cr(VI) expressed an enhanced activity in induction of NF-kappa B. This activation of NF-kappa B was decreased by a metal chelator, diethylene-triaminepentaacetic acid or catalase, but increased by superoxide dismutase. Addition of Mn2+, which reacts with Cr(IV) and inhibits Cr(IV)-mediated hydroxyl radical (.OH) generation via Fenton-like reaction, attenuated the activation of NF-kappa B. Sodium formate, an .OH radical scavenger, also inhibited the activation. Electron spin resonance measurements showed that the incubation of Cr(VI) with intact Jurkat cells generated reactive Cr(V) intermediate. Glutathione reductase and NADPH enhanced Cr(V) generation. Electron spin resonance spin trapping measurements using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent provided evidence that the incubation of Cr(VI) with the Jurkat cells in the presence of glutathione reductase generated .OH radicals. H2O2 enhanced .OH radical generation and also enhanced Cr(V) formation, indicating the role of Cr(IV) in .OH radical generation. We conclude that Cr(VI) can activate NF-kappa B in vitro via Cr(IV)-mediated free radical reactions. We hypothesize that Cr(VI)-mediated NF-kappa B activation may be involved in the mechanism of Cr(VI)-induced carcinogenicity.

Base Sequence↗
PubMed1995

Analysis of clustered genes encoding both early and late steps in daunomycin biosynthesis by Streptomyces sp. strain C5.

We recently described the isolation and sequence analysis of the daunomycin polyketide synthase biosynthesis genes of Streptomyces sp. strain C5 (J. Ye, M. L. Dickens, R. Plater, Y. Li, J. Lawrence, and W. R. Strohl, J. Bacteriol. 176:6270-6280, 1994). Contiguous to the daunomycin polyketide synthase biosynthesis gene region in Streptomyces sp. strain C5 are four additional genes involved in daunomycin biosynthesis, two of the products of which show similarity to different types of methyltransferases. The dauC gene, encoding aklanonic acid methyltransferase (AAMT), complements dauC-blocked mutants of Streptomyces sp. strain C5, restores in vitro AAMT activities to the mutant strains, and confers in vitro AAMT activity on Streptomyces lividans. Partial purification through gel filtration, followed by photoaffinity labeling of enriched AAMT with S-adenosyl-L-[3H-methyl]methionine, indicates that AAMT is a homodimer with an M(r) of ca. 48,000 (subunit M(r) of ca. 24,000), which corresponds with the size of the deduced gene product. The dauD gene, encoding aklanonic acid methyl ester cyclase, is divergently arranged with respect to dauC. Immediately downstream and apparently translationally coupled with dauD is the dauK gene, encoding carminomycin 4-O-methyltransferase. The dauK gene confers in vitro carminomycin 4-O-methyltransferase activity on S. lividans and is nearly identical to a similar gene isolated from Streptomyces peucetius and characterized. Directly downstream of dauK lies a gene encoding a deduced protein that is similar to the methyl esterases.

Amino Acid Sequence↗
PubMed1995

Vascular and endocrine control of muscle metabolism.

Important differences exist between perfused and incubated (or perifused) skeletal muscle preparations with regard to their metabolism and control. A growing body of evidence suggests that the differences may be due to the role played by the vascular system. In the constant-flow perfused rat hindlimb preparation, a group of vasoconstrictors has been identified that enhance muscle metabolism and aerobic contractility. Another group of vasoconstrictors decrease muscle metabolism and aerobic contractility even though perfusate flow remains constant. All effects of both groups of vasoconstrictors are opposed by vasodilators. Because none of the vasoconstrictor effects is evident when isolated muscles are incubated or perifused, involvement of an active vascular system is indicated. Although some hormones may act directly on muscle by purely endocrine effects, a vascular component of their actions is now emerging. Mechanisms to account for vascular control of perfused skeletal muscle metabolism may involve 1) functional vascular shunts where the proportion of flow processed by these is regulated by site-specific vasomodulators, 2) a direct response to a change in the rate of supply of nutrients and removal of products, and 3) a signal substance released by vascular tissue in association with vasoconstriction that interacts with surrounding skeletal muscle cells. Impaired control at the level of the vascular system may have implications for long-term access of nutrients and hormones and therefore the control of skeletal muscle metabolism and contractile performance.

Animals↗
PubMed1995

Isolation, purification, and partial characterization of an autocrine periodontal ligament cell chemotactic factor.

Periodontal ligament (PDL) cells are believed to play a critically important role in the regeneration of the periodontium. We have suggested that polypeptide growth factors can enhance periodontal regeneration by stimulating PDL cell chemotaxis and mitogenesis. This manuscript describes the identification of a novel chemotactic factor isolated from human PDL cells which we named PDL-CTX. PDL-CTX induces the directed migration of human PDL cells in vitro and was found to be a more potent chemotactic agent than other known growth factors. Additionally, PDL-CTX has no chemotactic effect on gingival fibroblasts or gingival epithelial cells. Both tryptic digestion and boiling abolished PDL-CTX's biological activity. The designed purification method included Mono-S cation exchange, heparin-sepharose affinity, and microbore reverse-phase HPLC. The purified factor has a relative molecular weight of approximately 7000 daltons based on sodium dodecyl sulfate (SDS) gel analysis. The amino acid composition and partial amino acid sequence were determined from HPLC-purified material. These were determined to be unique. Further investigation of the biological functions of PDL-CTX on PDL cells and other ligament cells should help improve our understanding of ligament repair.

Adolescent↗
PubMed1995

[Study on inspection method of anaerobes in periodontal pockets]

This paper used two methods only use non-selective medium(CDC) and together with seven selective mediums(VS CS BS AS FS ES LS) to inspect anaerobes in periodontal pockets.The results showed that Gram-negative anaerobes were the predominant microflora of periodontitis.The method of CDC together with selective mediums was founded much simpler and faster,more valuable than the method of only use non-selective medium.It is illustrated that CDC added antibiotics or chemicals to make selective mediums was prepared convenience and was suitable for growth of relative anaerobes.But it is still necessary to establish much more,more special, more reliable selective or identical mediums.

Journal Article↗
PubMed1995

[Long-term follow-up of allotransplantation of retinal pigment epithelial cells in rabbit with special reference to morphological studies].

Dysfunction as well as pathological changes of retinal pigment epithelium (RPE) has been implicated as the causes of some retinal diseases, including age-related macular degeneration, hereditary macular degeneration and retinitis pigmentosa, etc. Transplantation of normal healthy RPE cells with an attempt to treat the retinal diseases is one of the current interests in ophthalmic research. We have developed a modified pars plana technique including vitrectomy for subretinal transplantation of homologous, cultured, natural pigment labelled RPE cells in the non-pigmented rabbit. Our results, with follow-up from one week to one year, revealed that the transplanted RPE cells not only survived and attached to Bruch's membrane of the host eyes, but also had a distinct basal and apical morphology as seen in close contact with host photoreceptors, and formed junctional complexes with neighboring RPE cells. Close contact between the microvilli of the grafted RPE cells and the photoreceptor outer segments of the host was also observed. The normal periodical sheddings of the host outer segments were phagocytosed by the transplanted RPE cells, as demonstrated in our results. Furthermore, there was practically no, if any, sign of rejection found. All the results have demonstrated that the transplantation of RPE cells in rabbits was successful and these observations provide a reliable experimental evidence for the clinical research of allotransplantation of RPE cells.

Animals↗
PubMed1995

Movement of 25-hydroxycholesterol from the plasma membrane to the rough endoplasmic reticulum in cultured hepatoma cells.

Oxysterols serve as both substrates and signal molecules in the cholesterol-utilizing pathways of mammalian cells. Their distribution and movement within these cells, however, have not been well characterized; therefore we have undertaken such an analysis. Radiolabeled cholesterol and 25-hydroxycholesterol were pulsed into the cell surface membranes of rat hepatoma cells and their esterification was determined. The esterification of both probes was stimulated by feeding cells lipoproteins, even though lipoprotein cholesterol might be viewed as a competitor. Unlabeled 25-hydroxycholesterol, another potential competitor, also stimulated the esterification of the cell-surface probes. Esterification of both sterols was inhibited by a variety of amphiphilic agents. This inhibition was reversed by unlabeled 25-hydroxycholesterol. In cells incubated at 15 degrees C the fractional rate of esterification of the oxysterol was more than 100 times greater than that of cholesterol. Furthermore, the time course of esterification of plasma membrane cholesterol but not that of 25-hydroxycholesterol, was lagged. In contrast, the rate of esterification of the two probes was similar in broken cells supplied with saturating cholesterol. Finally, the transfer of 25-hydroxycholesterol from red blood cells to plasma lipoproteins was approximately 2000-fold faster than that of cholesterol. We conclude that 25-hydroxycholesterol and cholesterol are moved between the plasma membrane and endoplasmic reticulum by a common transport mechanism but that the oxysterol enters this pathway much more rapidly, possibly through a passive transfer step akin to its unmediated transfer from red cells to plasma.

Animals↗
PubMed1995

[Prediction of retinoblastoma: linkage analysis of families with hereditary retinoblastoma by using polymorphic sites within the Rb gene].

Retinoblastoma (Rb) is one of the most common intraocular tumors in childhood. 40% of the cases are hereditary in nature. 10% are due to the transmission of a germline mutation from an affected parent, and 30% are due to new germ cell mutation. In the hereditary form, the mutation is inherited via a germ cell; therefore, the mutant gene is present in all somatic cells. The segregations of four polymorphic sites within the Rb gene were analyzed in six families with hereditary retinoblastoma. Two families were informed with probe p123M1.8, three were informed with probe p68RS2.0 and one was informed with PCR amplification of XbaI site; all six families were informed with PCR amplification of intragenic VNTR site RB1.20. Our results showed that linkage analysis of families with hereditary retinoblastoma by using intrageneic polymorphic sites could be applied to detect carriers and for prenatal diagnosis in families with hereditary retinoblastoma.

Base Sequence↗
PubMed1995

[A transplantable model of human laryngeal squamous carcinoma in nude mice].

We have successfully established a human laryngeal squamous carcinoma model in nude mice by transplantation of surgical specimen from patients with laryngeal carcinoma. Histopathological study revealed squamous carcinoma. We named it HLC14. Light and electron microscopy showed that the morphology was similar to that of the original tumor. The transplanted tumor has maintained for more than two years through 25 passages. The tumor grew steadily and fast. The successful rate of transplantation was 100%. Pingyangmycine was then used to treat the transplantable model. The result was satisfactory.

Animals↗
PubMed1994

Identification of a DNA binding site for the nuclear factor YY1 in the human GM-CSF core promoter.

It has been well documented that the repeated CATT(A/T) sequence, localized between -64 and -35 in the human GM-CSF promoter, is required for the promoter activity, and this region likely serves as a core recognition sequence for a cellular transcription factor. However, the transcription factor that interacts with this site was not identified. Here, we report that this element contains a binding site for the nuclear factor YY1, which has not been reported to play a role in the regulation of cytokine gene transcription. Results from transient transfection assays of the Jurkat T cell line revealed that this repeated CATT(A/T) element exhibited enhancer activity when linked to both the human IFN-gamma promoter and the TK promoter. Mutation of the YY1 binding site eliminated about 60% of the enhancer activity of the element. We have found that the YY1 binding site could form two specific DNA-protein complexes, A and B, with Jurkat nuclear proteins in the electrophoretic mobility shift assay and that the binding of these complexes correlates with the enhancer activity. UV cross-linking analysis revealed that the A complex is a multi-protein complex and in addition to YY1, other proteins are required for formation of the protein complex. Cotransfection assays with a YY1 expression vector revealed that overexpression of YY1 resulted in an inhibitory effect on the repeated CATT(A/T) element, indicating that in addition to YY1, cofactors also are required for the activator function of the A complex.

Base Sequence↗
PubMed1994

Differentiation of the T helper phenotypes by analysis of the methylation state of the IFN-gamma gene.

Th1 and Th2 CD4+ T cell clones have been defined by their ability to produce different lymphokines. However, the processes by which CD4+ T cells differentially regulate lymphokine gene expression have not been well defined. In this report, we demonstrate that the methylation status of a CpG dinucleotide contained within a TATA proximal regulatory element of the IFN-gamma promoter correlates with the transcription of the gene. In murine Th1 clones and two human CD4+ Th0 clones, this site is either completely or partially hypomethylated, whereas in murine Th2 clones this site is > 98% methylated. Treatment of murine Th2 clones with 5-azacytidine, an agent that inhibits methylation of the DNA, converts these cells to IFN-gamma producers. Additional targets for methylation outside the transcriptional control regions of the IFN-gamma genetic locus were found to be hypomethylated in Th2 cells but not in Th1 cells. Electrophoretic mobility shift assays (EMSA) revealed at least five distinct protein-DNA complexes that are formed with an oligonucleotide containing the IFN-gamma promoter TATA proximal regulatory element, and in vitro methylation of this site results in a loss of these three complexes. Furthermore, a comparison of nuclear extracts prepared from Th1 and Th2 clones revealed that the EMSA patterns were qualitatively similar but differed quantitatively. In addition, transient transfection of a murine IFN-gamma promoter-chloramphenicol acetyl transferase (CAT) gene construct into both Th1 and Th2 clones produced CAT activity that was not inducible by anti-CD3, indicating that hypomethylation per se of the promoter alone is not sufficient for inducible gene expression.

Animals↗
PubMed1994

Characterization of a silencer regulatory element in the human interferon-gamma promoter.

Previous analysis of the human interferon-gamma (IFN-gamma promoter indicated that the region of DNA from -251 to -215 (designated here as BE (binding element)) possessed silencer activity, as deletion of this region caused an increase in promoter activity. Based on this finding, we have conducted a series of experiments to characterize BE function and analyze the binding proteins which interact with this region. Transient transfection assays in the Jurkat T cell line revealed that the BE region possesses silencer activity, which is orientation-dependent when reinserted 5' to the IFN-gamma core promoter. However, when the BE region was inserted in front of a heterologous promoter (thymidine kinase (TK)), a mild enhancer activity was observed. Utilizing the electrophoretic mobility shift assay, we have identified two major DNA-protein complexes (designated as S and E complexes) which interact with this region. Mutational analysis indicated that the silencer activity observed with the IFN-gamma promoter correlated with the S complex and the enhancer activity correlated with the E complex. Preliminary characterization of these two DNA-protein complexes has demonstrated the presence of multiple proteins in each complex. We have found that the S protein complex has a recognition sequence similar to the nuclear factor AP2, and we have identified the nuclear factor Yin-Yang 1 (YY1) as one of the proteins in the E complex.

Base Sequence↗
PubMed1994

Discovery of a new type of sialidase, "KDNase," which specifically hydrolyzes deaminoneuraminyl (3-deoxy-D-glycero-D-galacto-2-nonulosonic acid) but not N-acylneuraminyl linkages.

The release of 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN, deaminoneuraminic acid) residues from their alpha-ketosidic linkage is required to determine the structural and functional role of KDN-glycoconjugates in sources as disparate as trout egg polysialoglycoproteins and human cancers. We report for the first time the isolation and characterization of a novel type of sialidase (KDNase), which specifically hydrolyzes KDN ketosidic but not N-acylneuraminyl linkages. KDNase activity was assayed using 4-methylumbelliferyl KDN (4-MU-KDN). A KDNase-producing microorganism was identified as Sphingobacterium multivorum. The affinity-purified enzyme was designated KDNase SM to denote its origin and that it was free of N-acylneuraminidase, proteolytic, and other glycosidase activities. KDNase SM activity toward 4-MU-KDN was not inhibited by the N-acylneuraminidase inhibitor, 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. KDNase SM released free KDN from naturally occurring substrates, including (KDN)GM3, KDN-glycoprotein, which bears a number of O-linked chains of KDN alpha 2-->3Gal beta 1-->3GalNAc alpha 1-->3 (KDN alpha 2-->(-->8KDN alpha 2-->)n-->6)GalNAc alpha 1-->, and the biantennary complex-type of N-glycan, KDN alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->6(KDN alpha 2-->3Gal beta 1-->4GlcNAc beta 1-->2Man alpha 1-->3)Man beta 1-->4GlcNAc beta 1-->4GlcNAc. KDNase SM thus exhibited a broad linkage specificity and was able to hydrolyze the KDN residues ketosidically linked alpha 2-->3, alpha 2-->6, and alpha 2-->8. The enzyme did not release Neu5Ac or Neu5Gc from 4-MU-Neu5Ac, N-acetyl-neuraminyllactose, colominic acid, or other Sia(Neu5Ac or Neu5Gc)-containing glycoconjugates.

Bacteria↗
PubMed1994

Glu192-->Gln substitution in thrombin yields an enzyme that is effectively inhibited by bovine pancreatic trypsin inhibitor and tissue factor pathway inhibitor.

Modeling studies have ascribed the remarkable resistance of thrombin to inhibition by the Kunitz type inhibitors, bovine pancreatic trypsin inhibitor (BPTI), and tissue factor pathway inhibitor (TFPI), to steric inhibition by the 60-loop insertion, especially Trp60D (in the chymotrypsin numbering system). Indeed, deletion of Pro60B, Pro60C, and Trp60D from this loop (des-PPW) enhances BPTI inhibition (Ki = 16 nM) (Le Bonniec, B. F., Guinto, E. R., MacGillivray, R. T. A., Stone, S. R., and Esmon, C. T. (1993) J. Biol. Chem. 268, 19055-19061). Activated protein C, however, lacks an equivalent insertion loop but is nevertheless resistant to inhibition by these Kunitz inhibitors. A unique feature of thrombin and activated protein C is the presence of Glu at position 192. Substitution of Glu192 with Gln in activated protein C dramatically enhances inhibition by BPTI and TFPI (Rezaie, A. and Esmon, C. T. (1993) J. Biol. Chem. 268, 19943-19948). We now demonstrate that thrombin E192Q (the Glu192-->Gln mutant) is inhibited by BPTI (Ki = 24 nM) or TFPI (Ki = 14 nM) much more effectively than wild type thrombin (Ki > 1 microM for both inhibitors). A thrombin mutant having both the des-PPW deletion and E192Q substitution binds BPTI (Ki = 35 pM) and TFPI (Ki = 25 pM) even tighter. BPTI can displace dansylarginine N-(-3-ethyl-1,5-pentanediyl)-amide from the active site of thrombin E192Q (Ki = 19 nM), indicating that BPTI interacts directly with the S1 binding site in thrombin. The E192Q mutation and PPW deletion contribute comparably and additively to the binding energy of thrombin with the Kunitz inhibitors. We suggest that access to the active center of thrombin is less restricted than predicted from previous studies.

Amino Acid Sequence↗
PubMed1994

Glycosaminoglycan contributions to both protein C activation and thrombin inhibition involve a common arginine-rich site in thrombin that includes residues arginine 93, 97, and 101.

Proteoglycans play pivotal roles in the regulation of thrombin. Thrombomodulin (TM) binds thrombin through protein-protein contacts and a chondroitin sulfate moiety. The complex activates the anticoagulant zymogen, protein C. Thrombin and a thrombin mutant with Arg93, Arg97, and Arg101 changed to Ala bind soluble TM lacking the chondroitin sulfate with comparable affinities, but the mutant binds TM containing chondroitin sulfate 45-fold weaker than thrombin. A simple hyperbolic relationship describes the Ca2+ dependence of protein C activation with the thrombin mutant-TM complex whether or not the TM contains chondroitin sulfate. A similar Ca2+ dependence is observed with wild type thrombin only when the TM contains chondroitin sulfate. Thus, charge neutralization of Arg93, Arg97, and Arg101 mimics the functional effects of the chondroitin sulfate. The mutant and wild type thrombin are inhibited at comparable rates by antithrombin +/- the pentasaccharide capable of inducing the "active" antithrombin conformation, but heparin acceleration of antithrombin inhibition of the mutant is reduced by more than 95%. Binding studies revealed that the mutant has a > or = 20-fold decrease in heparin affinity. We conclude that heparin and chondroitin sulfate interact with one or more of these Arg residues. These basic residues appear to play a critical role in the regulation of thrombin activity.

Animals↗
PubMed1994

Alterations in NF kappa B/Rel family proteins in splenic T-cells from tumor-bearing mice and reversal following therapy.

It has recently been shown that T-cell signal transduction molecules are altered in tumor-bearing mice. We have examined the expression of NF kappa B/Rel family proteins in T-cells from mice bearing Renca, a murine renal carcinoma. T-cells from Renca-bearing mice expressed undetectable levels of nuclear c-Rel, NF kappa B p65, and p50; however, two shorter forms of p50 (p48 and p46), truncated at the NH2-terminus, were present exclusively in the nucleus and were able to bind DNA. These T-cells have reduced expression of gamma-interferon mRNA. In mice successfully treated with flavone 8-acetic acid and recombinant human interleukin 2, the T-cells expressed normal levels of all three nuclear NF kappa B/Rel proteins. These results suggest that alterations in transcription factors may accompany changes in signal transduction molecules in T-cells from tumor-bearing animals; however, the changes are reversed with successful biological therapy.

Animals↗