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J Zhou

Publications and source records attributed to J Zhou.

At least 523 records · Page 29Linked to original sources
PubMed1998

Long lasting facilitation of the rabbit cardiac Ca2+ channel: correlation with the coupling efficiency between charge movement and pore opening.

Facilitation of Ca2+ entry into cells enhances Ca(2+)-activated events such as transmitter release and stimulation of second messenger systems. We have found a long lasting prepulse facilitation (up to 3-fold) of the cardiac Ca2+ channel alpha1Cbeta1b that lasts for tens of seconds without altering current kinetics. The voltage- and time-dependence of the installation of facilitation was characterized as well as the time- and use-dependence of the decay of facilitation. The degree of facilitation was correlated with the coupling efficiency between the charge movement and pore opening channels that were poorly coupled prior to facilitation exhibited the largest facilitation.

Animals↗
PubMed1998

Gangliosides enhance apoptosis of thymocytes.

Monosialogangliosides, normal components of cell membranes, regulate cell development and differentiation in several organs. Our previous observation of dramatic premature thymic involution in cats with feline GM1 gangliosidosis, whose thymocytes have abnormally high cell surface gangliosides, suggested that excess GM1 ganglioside (GM1) could modulate thymocyte apoptosis in this disease (Cox et al., "Thymic Alterations in Feline GM1 Gangliosidosis," submitted). In these studies, we added exogenous GM1 to murine primary thymocyte cultures and demonstrated enhanced apoptosis in treated cells by DNA fragmentation, apoptotic body, and electrophoretic analyses. GM1-enhanced apoptosis was blocked by common apoptotic pathway inhibitors including aurintricarboxylic acid (inhibitor of endonuclease activity), actinomycin D (inhibitor of RNA transcription), and cycloheximide (inhibitor of protein synthesis). GM1 treatment primarily affected the immature CD4+ CD8+ subset, as shown by flow cytometric evaluation of fetal thymic organ culture and primary thymocyte cultures. Apoptosis also could be induced by GM2, GM3, and GT1b, whereas asialo-GM1 failed to do so, suggesting that the sialic acid moiety may play an important role in the induction of thymocyte apoptosis.

Animals↗
PubMed1998

Identification of the first mammalian sphingosine phosphate lyase gene and its functional expression in yeast.

Sphingosine-1-phosphate (S-1-P) has been shown to participate in the proliferative signal transduction pathways of mammalian cells. Sphingosine-1-phosphate lyase (SPL) catalyzes the breakdown of S-1-P. Using the C. elegans SPL nucleotide sequence, we identified a mouse EST as a putative candidate for the homologous gene encoding this enzyme. Sequencing of the mouse EST revealed an open reading frame of 1707 nucleotides. This putative mouse SPL gene is 62% similar and 39% identical to the C. elegans SPL gene and 59% homologous and 39.6% identical to the yeast SPL gene. Expression of the mouse SPL gene in a yeast strain-delta bst1, which carries a deletion of the SPL gene and is hypersensitive to sphingosine, restored a sphingosine-resistant phenotype, suggesting this mouse gene can functionally complement the yeast defect when expressed. In vitro enzyme assay using extracts from these sphingosine-resistant transformants confirmed the SPL activities encoded by this mouse cDNA clone. Northern analysis indicated the mouse SPL gene is expressed at various levels in different tissues. Chromosomal localization mapped this SPL gene to Chromosome 10 at 32 cM. Here, we report the identification of the first mammalian sphingosine phosphate lyase gene.

Aldehyde-Lyases↗
PubMed1998

Characterization of N-(Nitrosomethyl)urea in Nitrosated Fermented Fish Products.

To characterize chemical carcinogens in acidic-nitrosated fish sauce sample, N-nitrosamides in the sample were separated by two kinds of reversed-phase HPLC columns, and with detection by photolysis-pyrolysis-thermal energy analyzer. A strong chromatographic peak at t(R) 12 or 4.5 min, same as that for N-(nitrosomethyl)urea (NMU), was obtained on PRP-1 or C(18) HPLC column from fish sauce sample with 10 mM trifluoroacetic acid as the basic mobile; acetonitrile, as organic modifier after the sample was nitrosated by 5 mmol/L of sodium nitrite (final concentration) at 37 degrees C and pH 2.0 for 1 h. No response above t(R) could be observed from the nitrosated sample in the detection system without photolysis. Such a peak could not be obtained from the unnitrosated fish sauce either. These results indicated that the component was NMU. Furthermore, this component, NMU, could also be detected in the nitrosated human gastric juice sample spiked with fish sauce. The formation of NMU in the sample was pH- and nitrite-dependent. This paper provides direct evidence that NMU formation could occur in fish sauce from the high-risk area for stomach cancer and in the fish sauce spiked human gastric juice during nitrosation under simulated gastric conditions.

Journal Article↗
PubMed1998

Papillomavirus virus-like particles can deliver defined CTL epitopes to the MHC class I pathway.

To evaluate an antigen delivery system in which exogenous antigen can target the major histocompatibility complex (MHC) class I pathway, a single human papillomavirus (HPV) 16 E7 cytotoxic T lymphocyte (CTL) epitope and a single HIV gp160 CTL epitope were separately fused to the C-terminus of bovine papillomavirus 1 (BPV1) L1 sequence to form hybrid BPV1L1 VLPs. Mice immunized with these hybrid VLPs mounted strong CTL responses against the relevant target cells in the absence of any adjuvants. In addition, the CTL responses induced by immunization with BPV1L1/HPV16E7CTL VLPs protected mice against challenge with E7-transformed tumor cells. Furthermore, a high titer-specific antibody response against BPV1L1 VLPs was also induced, and this antiserum could inhibit papillomavirus-induced agglutination of mouse erythrocytes, suggesting that the antibody may recognize conformational determinates relevant to virus neutralization. These data demonstrate that hybrid BPV1L1 VLPs can be used as carriers to target antigenic epitopes to both the MHC class I and class II pathways, providing a promising strategy for the design of vaccines to prevent virus infection, with the potential to elicit therapeutic virus-specific CTL responses.

Animals↗
PubMed1998

Identification, distribution, and tissular origin of the alpha5(IV) and alpha6(IV) collagen chains in the developing human intestine.

The basement membrane type IV collagen is a family composed of six genetically distinct but structurally similar polypeptide chains, alpha1-alpha6. The alpha1(IV) and alpha2(IV) chains are ubiquitous components of all BMs whereas the other four have a restricted tissue distribution. In the present study, we have analyzed the expression, distribution, and cellular origin of the alpha5(IV) and alpha6(IV) chains in the developing and adult human small intestine and in well-characterized in vitro models by indirect immunofluorescence, Western blot, and RT-PCR. We have found that in the fetal small intestine, alpha(IV) and alpha6(IV) are present in the epithelial BM and, in contrast to alpha1(IV) and alpha2(IV), are produced by both epithelial and mesenchymal cells. A distinct tissular origin for the alpha1/alpha2(IV) and alpha5/alpha6(IV) chains suggests that alpha5(IV) and alpha6(IV) associate as a heterotrimer in this organ. We have also found that a particular situation of alpha5(IV)/alpha6(IV) chain expression occurs in the adult intestine. Indeed, as compared with the fetal intestine, alpha6(IV) chain production is maintained while the expression of the alpha5(IV) chain is substantially reduced. Altered expression of the alpha5(IV) chain was also observed in the differentiating enterocytic-like Caco-2/15 cells, suggesting that in the intestinal model, the alpha5(IV) chain is subject to a regulated expression. Taken together, these observations indicate that the human intestinal epithelial BM contains up to four type IV collagen chains: the classical alpha1(IV)/alpha2(IV) chains, which originate from mesenchymal cells, and the alpha5(IV)/alpha6(IV) chains, which are of both epithelial and mesenchymal origin and have their expression regulated throughout development.

Caco-2 Cells↗
PubMed1998

Inhibition of TCR/CD3-mediated signaling by a mutant of the hematopoietically expressed G16 GTP-binding protein.

We have investigated the role of the hematopoietically expressed G16 GTP-binding protein on T cell activation. We constructed transfectants of Jurkat T cells that express a function-deficient mutant of G alpha 16 predicted to prevent activation of this G protein. Upon stimulation with anti-CD3 epsilon antibodies, mutant G alpha 16 transfectants display a profound defect in the production of IL-2 and IL-10, as well as in the expression of CD69. In contrast, the phorbol 12-myristate 13-acetate (PMA)-induced IL-10 production and CD69 expression, and the ionomycin plus PMA-induced IL-2 production are not affected. Consistent with the reduction in cytokine production is the inhibition of early signaling events in the mutant G alpha 16-expressing cells. There are significant reductions in anti-epsilon-induced tyrosine phosphorylation of zeta, epsilon, ZAP-70, and phospholipase C gamma 1, as well as in intracellular Ca2+ mobilization. In accordance with the effects on tyrosine phosphorylation is the reduction of TCR/CD3-mediated Fyn and Lck activities in G alpha 16 mutant cells. Even though the mechanism through which the G alpha 16 mutant mediates inhibition of T cell activation is not known, the data suggest a model where G proteins become activated upon TCR/CD3 engagement and regulate the activation of tyrosine kinases and subsequent downstream signaling events that lead to the activation of cytokine genes.

Alanine↗
PubMed1998

FAIR excluding radiation damping (FAIRER).

It is shown that the flow-sensitive alternating inversion recovery (FAIR) technique is complicated by the effect of radiation damping, leading to problems in calibrating this method on phantoms and to inaccuracies in measured flows. A modified scheme called FAIRER (FAIR excluding radiation damping) is proposed, which suppresses the damping effects by employing very weak magnetic field gradients (0.06 G/cm) during the inversion recovery, spin-echo, and predelay periods. Results on phantoms and in vivo on cat brain are presented that demonstrate that FAIRER effectively solves these problems.

Animals↗
PubMed1998

The protein expression of Bcl-2, Bax, Fas/Apo-1 in acute myeloid leukemia.

The protein expression of bcl-2, bax, Fas/Apo-1 in 19 cases of acute myeloid leukemia (AML) were investigated by Western blot and ApAAp techniques. High expression of bcl-2 protein was found in most of the AML cases, and some of the cases expressed Fas/Apo-1 and bax. High expression of bcl-2 protein was associated with a bad clinical prognosis and a poor response after intensive chemotherapy. Bax seemed to coexpress with bcl-2 and so appeared to be a bad prognostic factor instead of a good one. The expression of Fas/Apo-1 was inversely correlated with bcl-2 and seemed to be a good prognostic factor which may reflect the relative homeostasis of apoptotic pathway. It is concluded that apoptosis-induced pathways in AML often exhibit disturbance features. Coregulation of bcl-2, Bax and Fas/Apo-1 genes formed the apoptosis-induced pathway, which is the biological factor affecting response to chemotherapy.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Interaction of the copper(II) macrocyclic complexes with DNA studied by fluorescence quenching of ethidium.

The fluorescence quenching of DNA bound ethidium ion by copper(II) macrocyclic complexes has been investigated. The binding constant indicates that the stable assembly can be formed between the DNA and the metal complex. The replacement of the fluorophore by the metal complexes results in a decrease of the ethidium moles intercalating to the molar DNA base pair and the binding constant of the ethidium to the DNA. The quenching of the ethidium excited state by the Cu(II) complex follows linear Stern-Volmer behavior. The quenching constant decreases regularly with an increase of the ratio of the concentration of the bound ethidium to that of DNA base pair. The dependence of the quenching constant on the ratio can be used to estimate binding constants for the fluorescent molecule and metal complexes to DNA. This method does not depend strongly on the type and the extent of interaction of metal complexes with DNA, allowing for the determination of binding constants for metal complexes that exhibit small changes in absorption spectra upon binding. The precision of this method will ultimately be governed by outstanding agreement between the quenching constant measured and that calculated by using a correlation function of the ratio or the DNA bound concentration of ethidium with quenching constant.

Animals↗
PubMed1998

Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation.

OBJECTIVES: To develop and validate an automated noninvasive method to quantify mitral regurgitation. BACKGROUND: Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR). METHODS: First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied. RESULTS: In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml). CONCLUSIONS: We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.

Adult↗
PubMed1998

Expression of mRNA for type IV collagen alpha1, alpha5 and alpha6 chains by cultured dermal fibroblasts from patients with X-linked Alport syndrome.

COL4A5 mutations causing X-linked Alport syndrome (XLAS) are frequently associated with absence of the alpha3, alpha4,alpha5 and alpha6 chains of type IV collagen from basement membranes and increased amounts of the alpha1(IV) and alpha2(IV) chains in glomerular basement membrane. Although many COL4A5 mutations have been described in XLAS, the mechanisms by which these mutations influence the basement membrane appearance of chains other than alpha5(IV) remain poorly understood. In this study, we used dermal fibroblasts from eight normal individuals and nine males with XLAS to test the hypotheses that COL4A5 mutations increase transcription of COL4A1 and suppress transcription of COL4A6. Ribonuclease protection assays revealed that alpha1(IV), alpha5(IV) and alpha6(IV) transcripts were expressed in cultures of dermal fibroblasts. The mRNA levels for alpha1(IV) in eight of nine patients with XLAS were not increased compared to controls; one patient with a large COL4A5 deletion showed significant elevation of alpha1(IV) mRNA levels. No differences in steady-state mRNA levels for alpha6(IV) were found when XLAS fibroblasts were compared with controls, even though little or no alpha6(IV) protein was detectable at the dermal-epidermal junction by immunofluorescence study. This finding suggests that post-transcriptional events account for the absence of alpha6(IV) in the Alport dermal-epidermal junction.

Adolescent↗
PubMed1998

A human B cell line AF10 expressing HIL-17.

AF10, a human B cell line, is a mycoplasma-free variant cloned from the human IgE myeloma cell line U266. Total RNA isolated from the AF10 cells was used as template for RT-PCR, and a specific product of about 411bp corresponding to the coding region of hIL-17 lack of a leading sequence obtained. The sequence of the RT-PCR product is the same to that reported in the literature. The expressed rhIL-17 in E. coli can induce 10- to 15-fold increase of IL-6 secretion by mouse fibroblast 3T3 cells. It is for the first time until now that hIL-17 messager has been detected in B cell. There may exist some potential relationship between hIL-17 and myeloma cells.

3T3 Cells↗
PubMed1998

Effect of bay K 8644 (-) and the beta2a subunit on Ca2+-dependent inactivation in alpha1C Ca2+ channels.

Ca2+ currents recorded from Xenopus oocytes expressing only the alpha1C pore-forming subunit of the cardiac Ca2+ channel show Ca2+-dependent inactivation with a single exponential decay. This current-dependent inactivation is not detected for inward Ba2+ currents in external Ba2+. Facilitation of pore opening speeds up the Ca2+-dependent inactivation process and makes evident an initial fast rate of decay. Facilitation can be achieved by (a) coexpression of the beta2a subunit with the alpha1C subunit, or (b) addition of saturating Bay K 8644 (-) concentration to alpha1C channels. The addition of Bay K 8644 (-) to alpha1Cbeta2a channels makes both rates of inactivation faster. All these maneuvers do not induce inactivation in Ba2+ currents in our expression system. These results support the hypothesis of a mechanism for the Ca2+-dependent inactivation process that is sensitive to both Ca2+ flux (single channel amplitude) and open probability. We conclude that the Ca2+ site for inactivation is in the alpha1C pore-forming subunit and we propose a kinetic model to account for the main features of alpha1Cbeta2a Ca2+ currents.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1998

The myristylation motif of Pto is not required for disease resistance.

The tomato Pto kinase confers resistance to bacterial speck disease caused by strains of Pseudomonas syringae pv. tomato that express the avirulence gene avrPto. Pto contains a putative myristylation site at its amino terminus that was hypothesized to play a role in localizing Pto in the plant cell. Site-directed mutagenesis was used to change the invariant glycine residue in the myristylation motif to an alanine. Transgenes encoding the mutant Pto(G2A) and wild-type Pto were placed behind the cauliflower mosaic virus 35S promoter and transformed into tomato plants that are susceptible to bacterial speck disease. Both the mutant and wild-type forms of Pto conferred resistance to a strain of P. syringae pv. tomato expressing avrPto. These results indicate that the myristylation motif of Pto is not required for bacterial speck disease resistance.

Alanine↗
PubMed1998

Fibroblast growth factors 1 and 2 in the primate uterus.

Fibroblast growth factors (FGF) 1 and 2 are paracrine effectors of proliferation and angiogenesis in many tissues. To elucidate potential roles for these growth factors in uterine plasticity, we used in situ hybridization histochemistry to identify the cellular sources of FGF-1 and -2 production, and immunohistochemistry to identify the cellular and extracellular deposition sites of the peptides in the primate uterus. To evaluate the effects of estradiol on uterine FGFs, uteri from ovariectomized rhesus monkeys treated with estradiol- or vehicle-containing pellets were investigated. FGF-1 and -2 mRNAs were both expressed in uterine epithelial and myometrial cells. Quantitative comparison of their mRNA levels using computerized grain counting showed no significant difference between estradiol- and vehicle-treated animals. FGF-1 immunoreactivity was detected in scattered epithelial, vascular, and myometrial cells in the vehicle-treated animals but found to be significantly more intense and widespread in estradiol-treated animals. In both conditions, FGF-1 immunostaining was predominantly nuclear. FGF-2 immunoreactivity was concentrated extracellularly in the basal lamina of both glandular and surface epithelium and was abundant and diffusely distributed within myometrial and vascular cells in both cytoplasm and nucleus. There was no apparent difference in the pattern or intensity of FGF-2 immunostaining related to estradiol treatment. These data demonstrate that major uterine cell types synthesize both FGF-1 and -2, and that the two peptides are differentially localized in uterine cellular and extracellular compartments and differentially sensitive to regulation by estradiol.

Animals↗
PubMed1998

Method to assist in the scheduling of add-on surgical cases--upper prediction bounds for surgical case durations based on the log-normal distribution.

BACKGROUND: A problem that operating room (OR) managers face in running an OR suite on the day of surgery is to identify "holes" in the OR schedule in which to assign "add-on" cases. This process necessitates knowing the typical and maximum amounts of time that the case is likely to require. The OR manager may know previous case durations for the particular surgeon performing a particular scheduled procedure. The "upper prediction bound" specifies with a certain probability that the duration of the surgeon's next case will be less than or equal to the bound. METHODS: Prediction bounds were calculated by using methods that (1) do not assume that case durations follow a specific statistical distribution or (2) assume that case durations follow a log-normal distribution. These bounds were tested using durations of 48,847 cases based on 15,574 combinations of scheduled surgeon and procedure. RESULTS: Despite having 3 yr of data, 80 or 90% prediction bounds would not be able to be calculated using the distribution-free method for 35 or 49% of future cases versus 22 or 22% for the log-normal method, respectively. Prediction bounds based on the log-normal distribution overestimated the desired value less often than did the distribution-free method. The chance that the duration of the next case would be less than or equal to its 90% bound based on the log-normal distribution was within 2% of the expected rate. CONCLUSIONS: Prediction bounds classified by scheduled surgeon and procedure can be accurately calculated using a method that assumes that case durations follow a log-normal distribution.

Algorithms↗