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K Bi

Publications and source records attributed to K Bi.

At least 19 recordsLinked to original sources
PubMed2006

Identification of intergenomic recombinations in unisexual salamanders of the genus Ambystoma by genomic in situ hybridization (GISH).

Unisexual salamanders in the genus Ambystoma (Amphibia, Caudata) are endemic to eastern North America and are mostly all-female polyploids. Two to four of the bisexual species, A. laterale, A. jeffersonianum, A. texanum and A. tigrinum, contribute to the nuclear genome of unisexuals and more than 20 combinations that range from diploid to pentaploid have been identified in this complex. Because the karyotypes of the four bisexual species are similar, homologous and homoeologous chromosomes in the unisexuals can not be distinguished by conventional or banded karyotypes. We chose two widespread unisexual genomic combinations (A.laterale-2 jeffersonianum [or LJJ] and A. 2 laterale-jeffersonianum [or LLJ]) and employed genomic in situ hybridization (GISH) to identify the genomes in these unisexuals. Under optimum conditions, GISH reliably distinguishes the respective chromosomes attributed to both A.laterale and A. jeffersonianum. Of four populations examined, two were found to have independently evolved homoeologous recombinants that persist in both LJJ and LLJ individuals. Our results refute the previous hypothesis of clonal integrity and independent evolution of the genome combinations in these unisexuals. Our data provide evidence for intergenomic interactions between maternal chromosomes during meiosis in unisexuals and help to explain previously observed non-homologous bivalents and/or quadrivalents among lampbrush chromosomes that were possibly initiated by partial homosequential pairing among the homo(eo)logues. To explore the utility of GISH in other members of the complex, probes developed from A. laterale were also applied to unisexuals that contained A. tigrinum and A. texanum genomes. GISH is an effective tool that can be used to identify and to quantify genomic constituents and to investigate intergenomic interactions in unisexual salamanders. GISH also has potential application to examine possible genomic evolution in other unisexuals.

Ambystoma↗
PubMed2001

Vav1/Rac-dependent actin cytoskeleton reorganization is required for lipid raft clustering in T cells.

Formation of the immunological synapse (IS) in T cells involves large scale molecular movements that are mediated, at least in part, by reorganization of the actin cytoskeleton. Various signaling proteins accumulate at the IS and are localized in specialized membrane microdomains, known as lipid rafts. We have shown previously that lipid rafts cluster and localize at the IS in antigen-stimulated T cells. Here, we provide evidence that lipid raft polarization to the IS depends on an intracellular pathway that involves Vav1, Rac, and actin cytoskeleton reorganization. Thus, lipid rafts did not translocate to the IS in Vav1-deficient (Vav1-/-) T cells upon antigen stimulation. Similarly, T cell receptor transgenic Jurkat T cells also failed to translocate lipid rafts to the IS when transfected with dominant negative Vav1 mutants. Raft polarization induced by membrane-bound cholera toxin cross-linking was also abolished in Jurkat T cells expressing dominant negative Vav1 or Rac mutants and in cells treated with inhibitors of actin polymerization. However, Vav overexpression that induced F-actin polymerization failed to induce lipid rafts clustering. Therefore, Vav is necessary, but not sufficient, to regulate lipid rafts clustering and polarization at the IS, suggesting that additional signals are required.

Actins↗
PubMed2001

Determination of Danshensu, a major active compound of Radix Salvia miltiorrhiza in dog plasma by HPLC with fluorescence detection.

A simple and sensitive high performance liquid chromatography method has been developed for the determination of Danshensu (3, 4-dihydroxyphenyllactic acid) in dog plasma. Plasma samples were extracted with ethyl acetate. Analysis of the extracts was performed on a reversed-phase column with an aqueous phosphate buffer-acetonitrile (93:7, v/v) mobile phase, and 4-hydroxybenzoic acid was used as the internal standard. Fluorescence detection at 285 nm (excitation) and 320 nm (emission) was employed. Standard curves were linear in the range from 0.125 to 11.3 microg/mL (regression coefficient r > 0.993) on three different days. Mean recovery was determined as 96.4% by analysis of plasma standard containing 0.63, 5.65 and 11.3 microg/mL of Danshensu. The inter-day precision (RSD) ranged from 3.4 to 8.6% at concentrations of 0.125, 1.88, 6.28 and 11.3 microg/mL, and the intra-day precision was better than 7.2%. The detection and quantitation limits were 0.063 and 0.125 microg/mL, respectively. This validated assay was applied to the determination of Danshensu concentration in dog plasma after oral administration of Radix Salvia miltiorrhiza extracts.

Administration, Oral↗
PubMed2001

Membrane lipid microdomains and the role of PKCtheta in T cell activation.

Productive T cell activation depends on the assembly of a highly ordered and compartmentalized immunological synapse or supramolecular activation complex (SMAC). Reorganization of the actin cytoskeleton and clustering of specialized membrane microdomains, or lipid rafts, occur early following TCR/CD3 and costimulatory receptor ligation. Many key signaling molecules localize in lipid raft patches during T cell activation. Lipid raft reorganization is required for T cell activation, where it plays an apparently important role in stabilizing the T cell synapse. Here we review recent evidence supporting the role of lipid rafts in T cell activation. Particular emphasis is placed on the coupling of protein kinase C-theta(PKCtheta), which is selectively expressed in T cells and is known to function as an essential signal for T cell activation, and lipid rafts.

Animals↗
PubMed2001

Antigen-induced translocation of PKC-theta to membrane rafts is required for T cell activation.

Protein kinase C-theta (PKC-theta) is essential for mature T cell activation; however, the mechanism by which it is recruited to the TCR signaling machinery is unknown. Here we show that T cell stimulation by antibodies or peptide-major histocompatibility complex (MHC) induces translocation of PKC-theta to membrane lipid rafts, which localize to the immunological synapse. Raft translocation was mediated by the PKC-theta regulatory domain and required Lck but not ZAP-70. In addition, PKC-theta was associated with Lck in the rafts. An isolated PKC-straight theta catalytic fragment did not partition into rafts or activate the transcription factor NF-kappa B, although addition of a Lck-derived raft-localization sequence restored these functions. Thus, physiological T cell activation translocates PKC-theta to rafts, which localize to the T cell synapse; this PKC-theta translocation is important for its function.

Antigen-Presenting Cells↗
PubMed2001

Immunolocalisation of phospholipase D1 on tubular vesicular membranes of endocytic and secretory origin.

We have examined the localisation of overexpressed phospholipase D1 (PLD1) using antibodies against its amino- and carboxyl-terminal domains. PLD1 overexpressed in COS-7 cells showed variable distribution by immunofluorescence but was mainly in punctate structures in the perinuclear region and at the plasma membrane. Downregulation by an anti-sense plasmid resulted in almost exclusively perinuclear distribution in punctate structures that contained immunoreactivity for the endogenous KDEL receptor and the early endosomal antigen EEA1 protein. Influenza haemagglutinin (HA) and HA-derived mutants designed to locate primarily to secretory or endocytic membranes were present in PLD1-positive membranes. Immunofluorescence analysis in permanent CHO cell lines that express PLD1 inducibly confirmed the presence of PLD1 on both endocytic and secretory membranes. Analysis of PLD1 distribution by immunocytochemistry and electron microscopy of intact CHO cells and of isolated membranes revealed that PLD1 was present in tubulovesicular elements and multivesicular bodies. Some of these were close to the Golgi region whereas others stained positive for endocytic cargo proteins. Morphometric analysis assigned the majority of PLD1 immunoreactivity on endosomal membranes and a smaller amount on membranes of secretory origin. PLD1, via signals that are currently not understood, is capable of localising in tubulovesicular membranes of both endocytic and secretory origin.

Animals↗
PubMed2001

Detection of virulence associated genes in clinical strains of vibrio mimicus.

A total of 42 clinical strains of Vibrio mimicus were examined for the presence of virulence associated genes toxR, toxS, toxT, tcpP, ctx and tcpA by PCR assay. Almost all strains were shown to have the toxR gene, while the toxS gene was found in 27 strains. On the other hand, five strains possessed both toxT and tcpP genes, but others had neither. Only two strains were positive for amplification of the ctx gene, whereas no PCR product with tcpA primers was detected. The results indicate the incomplete copies of virulence cascade in V mimicus strains. The pathogenesis and epidemic potential of this species is also discussed.

Bacterial Outer Membrane Proteins↗
PubMed2001

[Pharmacodynamics study of suanzaoren decoction extracted by different technological process].

OBJECTIVE: To select the optimal technological process for Suanzaoren decoction. METHOD: The effects of extracts from different technological processes on spontaneous motion and sleep time in mice induced by pentobarbital sodium (subthreshold dosage) were studied. RESULTS: Both the decoction and 95% alcohol extract of Suanzaoren possess sedative and hypnotic effects. CONCLUSION: Suanzaoren aqueous decoction was selected as the optimal technological process.

Animals↗
PubMed2000

Inhibition of the c-Jun N-terminal kinase/AP-1 and NF-kappaB pathways by PICOT, a novel protein kinase C-interacting protein with a thioredoxin homology domain.

Protein kinase C-theta (PKCtheta) is a Ca(2+)-independent PKC isoform that is selectively expressed in T lymphocytes (and muscle), and is thought to play an important role in T cell receptor-induced activation. To gain a better understanding of the function and regulation of PKCtheta, we have employed the yeast two-hybrid system to identify PKCtheta-interacting proteins. We report the isolation and characterization of a cDNA encoding a novel 335-amino acid (37. 5-kDa) PKCtheta-interacting protein termed PICOT (for PKC-interacting cousin of thioredoxin). PICOT is expressed in various tissues, including in T cells, where it colocalizes with PKCtheta. PICOT displays an N-terminal thioredoxin homology domain, which is required for the interaction with PKC. Comparison of the unique C-terminal region of PICOT with expressed sequence tag data bases revealed two tandem repeats of a novel domain that is highly conserved from plants to mammals. Transient overexpression of full-length PICOT (but not its N- or C-terminal fragments) in T cells inhibited the activation of c-Jun N-terminal kinase (but not extracellular signal-regulated kinase), and the transcription factors AP-1 or NF-kappaB. These findings suggest that PICOT and its evolutionary conserved homologues may interact with PKC-related kinases in multiple organisms and, second, that it plays a role in regulating the function of the thioredoxin system.

Amino Acid Sequence↗
PubMed2000

Determination of resibufogenin and cinobufagin in heart-protecting musk pill by HPLC.

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of resibufogenin and cinobufagin in traditional Chinese medicine (heart-protecting musk pill, shexiang baoxin wan in Chinese) was developed. A reversed-phase system with a Hypersil (ODS2) C(18) column and tetrahydrofuran: methanol: water (8:31:61) mobile phase was employed for the separation of resibufogenin and cinobufagin. The detection was set at 299 nm and ethinyl estradiol was chosen as the internal standard. The limit of detection was 1.5 ng for resibufogenin and 2.0 ng for cinobufagin at a signal-to-noise ratio of 4:1. It is a rapid, simple and accurate method for quantitative analysis of resibufogenin and cinobufagin in heart-protecting musk pill.

Bufanolides↗
PubMed2000

A precolumn derivatization high-performance liquid chromatographic method with improved sensitivity and specificity for the determination of astragaloside IV in Radix Astragali.

A reversed-phase high-performance liquid chromatographic method is developed for the determination of astragaloside (AGS) IV, which is known as the active constituent of Radix Astragali. The method uses precolumn derivatization with benzoyl chloride to form the benzoyl ester of AGS IV quantitatively and is carried out with a wide-ranging concentration (0.004-0.080 mg/mL) of the derivatized AGS IV. The eluent consists of 90% methanol, 4% tetrahydrofuran, 6% water, and 0.2% triethylamine, with vitamin D3 added as the internal standard.

Chromatography, High Pressure Liquid↗
PubMed2000

Analysis of Vibrio mimicus clinical strains by arbitrarily primed polymerase chain reaction.

A total of 51 Vibrio mimicus clinical strains from different geographic locations were examined by arbitrarily primed polymerase chain reaction (AP-PCR). The primer VMH-3 divided them into 28 groups, although 18 groups consisted of a single strain at present. All groups had a common 1.0-kb amplification fragment. Most of the groups consisted of strains from same region, although two exceptional groups showed a few amplification fragments including strains from different regions. AP-PCR groups were not consistently associated with serogroups. AP-PCR is thought to be a valuable and easy method for the epidemiological study of V. mimicus.

DNA Primers↗
PubMed2000

[Drug resistance of acute promyelocytic leukemia (APL) to all-trans retinoic acid (ATRA) and its reversion].

OBJECTIVE: To study the mechanism of drug resistance of APL to ATRA and the methods of reversion. METHODS: ATRA-resistant HL60 cell line and bone marrow (BM) leukemia cells from recurrent APL patients who did not respond to ATRA treatment were used in this study. Multiple drug resistance gene (mdr1) expression was determined by RT-PCR and flow cytometry. Cell proliferation and differentiation were assessed by MTT uptake and NBT reduction respectively. RESULTS: The response of ATRA-resistant HL60 and APL cells from recurrent patients to the differentiation inducing activity of ATRA was significantly reduced, and ATRA had little effect on cell proliferation. Expression of mdr-1 was nagative in ATRA-resistant HL60 cells. It was negative in resistant APL cells even after ATRA treatment. Arsenic trioxide and homoharringtonine (HHT) could inhibit proliferation of HL60 and ATRA-resistant HL60 cells, indicating no cross-resistance with ATRA. Interferon alpha (IFN-alpha) and PGE1 could significantly inhibit proliferation of ATRA-resistant HL60 cells and restore cell differentiation induced by ATRA. CONCLUSION: Drug resistance of APL to ATRA is not related to mdr-1. It can be reversed by IFN-alpha. There is no cross-resistance between HHT or arsenic trioxide and ATRA.

Alprostadil↗
PubMed2000

[Quality evaluation of indigowoad root and leaf by chemical pattern recognition].

27 samples of indigowoad root and 5 samples of indigowoad leaf from different species and in different habital were collected. The chemical constituents were analyzed by HPLC, and ten original chemical features as a whole obtained. Meanwhile, extrinsic bacteriostasis experiments were carried out for each of the 32 samples. Canonical correlation analysis was applied to the intercorrelation between the chemical and the pharmacologic data, and five chemical features were found to be the effective constituents. In the end, the 32 samples were divided into five classes by the fuzzy clustering technique ISODATA(interachive self-organizing data analysis technique A).

Brassicaceae↗
PubMed1999

Phospholipase D as an effector for ADP-ribosylation factor in the regulation of vesicular traffic.

A mammalian phospholipase D (PLD) activity that is stimulated by ADP-ribosylation factor (ARF) has been identified in Golgi-enriched membrane fractions. This activity is due to the PLD1 isoform and evidence from several laboratories indicates that PLD1 is important for the polymerization of vesicle coat proteins on membranes. When expressed in Chinese hamster ovary cells, PLD1 localized to dispersed small vesicles that overlapped with the location of the ERGIC53 protein, a marker for the endoplasmic reticulum (ER)-Golgi intermediate compartment. Cells having increased PLD1 expression had accelerated anterograde and retrograde transport between the ER and Golgi. Membranes from cells having elevated PLD1 activity bound more COPI, ARF, and ARF-GTPase activating protein. These membranes also produced more COPI vesicles than did membranes from control cells. It is likely that PLD1 participates in both positive and negative feedback regulation of the formation of COPI vesicles and is important for controlling the rate of this process.

ADP-Ribosylation Factors↗