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X Xie

Publications and source records attributed to X Xie.

At least 145 records · Page 8Linked to original sources
PubMed1997

Novel expression mechanism for synaptic potentiation: alignment of presynaptic release site and postsynaptic receptor.

A combination of experimental and modeling approaches was used to study cellular-molecular mechanisms underlying the expression of short-term potentiation (STP) and long-term potentiation (LTP) of glutamatergic synaptic transmission in the hippocampal slice. Electrophysiological recordings from dentate granule cells revealed that high-frequency stimulation of perforant path afferents induced a robust STP and LTP of both (+/-)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) and N-methyl-D-aspartic acid (NMDA) receptor-mediated synaptic responses. However, the decay time constant for STP of the AMPA receptor-mediated excitatory postsynaptic potential was approximately 6 min, whereas the decay time constant for STP of the NMDA receptor-mediated excitatory postsynaptic potential was only 1 min. In addition, focal application of agonists during the expression of STP revealed that the magnitude of conductance change elicited by NMDA application was significantly enhanced, whereas the magnitude of conductance change elicited by application of AMPA remained constant. These findings are most consistent with a postsynaptic mechanism of STP and LTP. Different putative mechanisms were evaluated formally using a computational model that included diffusion of glutamate within the synaptic cleft, different kinetic properties of AMPA and NMDA receptor/channels, and geometric relations between presynaptic release sites and postsynaptic receptor/channels. Simulation results revealed that the only hypothesis consistent with experimental data is that STP and LTP reflect a relocation of AMPA receptor/channels in the postsynaptic membrane such that they become more closely "aligned" with presynaptic release sites. The same mechanism cannot account for STP or LTP of NMDA receptor-mediated responses; instead, potentiation of the NMDA receptor subtype is most consistent with an increase in receptor sensitivity or number.

Animals↗
PubMed1997

Diagnostic and prognostic value of nucleolar organizer regions in normal epithelium, dysplasia, and squamous cell carcinoma of the oral cavity.

BACKGROUND: Nucleolar organizer regions (AgNORs) are associated with proliferative activity and represent a diagnostic aid and prognostic marker in several neoplastic entities. METHODS: Sections from 51 T1-2 squamous cell carcinomas (SCC), 20 cases of dysplasia, and 8 specimens with normal epithelium were evaluated by 2 AgNOR counting methods: 1) the mean number of AgNORs per nucleus (mAgNOR) and 2) the percentages of nuclei with > 1, > 2, > 3, and > 4 AgNORs (pAgNOR > 1, pAgNOR > 2, pAgNOR > 3, and pAgNOR > 4, respectively). RESULTS: Both mAgNOR and pAgNOR counts enabled significant discrimination between normal epithelium and dysplasia (P < 0.0003) and between dysplasia and SCC (P < 0.0001). For SCC, no correlation was found between AgNOR counts and clinical classification. Univariate analysis using the log rank test showed that the overall means for mAgNOR and pAgNORs correlated with the disease free period and survival time (P < 0.0040). Patient age, gender, type of treatment, and T and N classification failed to predict the outcome. Multivariate analysis showed that pAgNOR > 1 (cutoff level of 88%) was the best discriminator regarding the disease free period and survival time (P = 0.0001 and P = 0.0076, respectively). CONCLUSIONS: AgNOR enumeration, in particular pAgNOR > 1, appears to be a useful tool in distinguishing between normal epithelium, dysplasia, and SCC of the oral cavity. In this study, AgNOR counts were strong prognostic markers for patients with SCC.

Adult↗
PubMed1997

Loss of intracellular putrescine pool-size regulation induces apoptosis.

Synthesis and uptake are two important regulated mechanisms by which eukaryotic cells maintain polyamine levels. The role that loss of synthesis and/or uptake regulation plays in mediating putrescine toxicity was investigated by comparing toxicity in an ornithine decarboxylase (ODC)-deficient Chinese hamster ovary cell line (C55.7) with a functional putrescine transport system and an ODC-overproducing rat hepatoma cell line (DH23b), which are transport regulation deficient. When C55.7 cells were transfected with either mouse ODC (M) or trypanosome ODC (Tb), intracellular putrescine content increased slightly in C55.7(Tb-ODC), compared to C55.7(M-ODC), due to the lack of response of Tb-ODC to polyamine regulation. The increase in putrescine content resulting from loss of ODC regulation had no impact on cell growth and viability. When the feedback repression of polyamine uptake was blocked with cycloheximide, C55.7 cells transfected with either ODC construct accumulated very high levels of putrescine from the medium, and underwent apoptosis in a putrescine dose-dependent manner. A similar correlation of deregulated putrescine uptake and increased apoptotic cells was observed in DH23b cells. These data demonstrate that loss of feedback regulation on the polyamine transport system, but not ODC activity, is sufficient to induce apoptosis. Thus, downregulation of the transport system is necessary to prevent accumulation of cytotoxic putrescine levels in rodent cells.

Animals↗
PubMed1997

Prognostic significance of nucleolar organizer regions in adenoid cystic carcinomas of the head and neck.

OBJECTIVE: To determine the prognostic use of nucleolar organizing region (AgNOR) counts and clinical and histopathological features in adenoid cystic carcinoma. DESIGN: Argyrophilic staining was applied to ordinary formalin-fixed, paraffin-embedded specimens and evaluated to obtain the mean number of AgNORs and the percentage of nuclei with more than 1 (pAgNOR > 1), more than 2, more than 3, and more than 4 AgNORs. RESULTS: Using the log rank test, the mean AgNOR count showed no correlation with the disease-free period. All pAgNOR parameters exceeding the respective overall mean had poorer prognosis when compared with those below the mean (P = .02). The pAgNOR > 1 appeared as the best discriminator, singling out all treatment failures (P < or = .001). This parameter also showed a high degree of intraobserver and interobserver reproducibility. Stage of the disease, violated resection margins, and presence of the histopathological solid subtype were markers of an unfavorable prognosis. Multivariate analysis by the Cox model showed that pAgNOR > 1 (P < or = .001) and tumor stage (P = .03) were the only statistically significant parameters. CONCLUSIONS: Estimation of pAgNOR > 1 is easy, quick, and highly reproducible. It may become a useful prognostic parameter in adenoid cystic carcinoma, but larger studies should be performed to confirm the reliability of this method.

Carcinoma, Adenoid Cystic↗
PubMed1997

Nucleolar organizer regions and prognosis in glottic squamous cell carcinoma.

BACKGROUND: The quantity of nucleolar organizer regions (AgNORs) appear to be prognostic significant in several tumor types. METHODS: Sections from 93 routinely processed pretreatment biopsies from patients with glottic carcinomas were stained by silver nitrate and evaluated by two counting methods: (1) the mean number of AgNOR per tumor nucleus (mAgNOR), and (2) the number of tumor nuclei with one, two, three, four, and more than four AgNOR grains. From these figures the percentage of nuclei with one, two or less, three or less, and four or less AgNORs (pAgNOR1, aAgNOR < or = 2 etc) were calculated. RESULTS: The median mAgNOR was 4.3, and low counts correlated favorably with the disease-free period (p = 0.0433). The median percentages for pAgNORs were 14, 26, 38, and 51 for pAgNor1, PAgNOR < or = 2, pAgNor < or = 3 and pAgNOR, < or = 4 respectively. Values above the medians correlated positively with the disease-free period (p-values ranging from 0.0005 to 0.0001). Although pAgNOR < or = 3 appeared to be the best discriminator by multivariate analysis, pAgNOR1 is the method of choice because this parameter is the easiest and quickest to perform. CONCLUSION: pAgNOR counts appear to be a potent prognostic marker and may become useful in treatment decisions.

Adult↗
PubMed1997

In vivo rolling and endothelial selectin binding of mononuclear leukocytes is distinct from that of polymorphonuclear cells.

In inflammation, rolling of leukocytes along the microvascular endothelium is a precondition for subsequent integrin-mediated firm adhesion and extravasation. Rolling characteristics of polymorphonuclear leukocytes (PMNL) and mononuclear leukocytes (MNL) in small venules (15-25 microns) of the rat mesentery were studied by intravital fluorescence microscopy under basal conditions and after intravenous treatment with an anti-rat neutrophil serum (ANS). The baseline rolling fraction of the venular total leukocyte flux was 36 +/- 15% (mean +/- SD). The PMNL fraction of the systemic leukocyte count was 27 +/- 9%. Treatment with ANS resulted in total depletion of circulating PMNL and reduced the leukocyte rolling fraction to 12 +/- 5%, in this situation represented only by MNL. In rats treated intraperitoneally with interleukin (IL)-1 beta for 4 h, the leukocyte rolling fraction was 53 +/- 13% and was reduced to 33 +/- 11% after ANS treatment. These data indicated that most, if not all, circulating PMNL rolled along the venular endothelial lining in the rat mesentery prepared for intravital microscopy, whereas MNL rolling was minor (approximately 10%) under the same basal condition. In cytokine-activated tissue, on the other hand, the number of rolling MNL was greatly increased. While PMNL rolling is known to be entirely selectin dependent, the increased MNL rolling after IL-1 stimulation was likely mediated by alpha 4 integrins, inasmuch as the rolling fraction of isolated peripheral blood lymphocytes injected into the microcirculation of the cytokine-stimulated mesentery was reduced from 31 +/- 14% to 6 +/- 2% by pretreatment of the cells with a monoclonal antibody against the rat integrin alpha 4 chain. In accordance with the in vivo rolling characteristics of the two cell populations, binding of soluble P- or E-selectin (selectin/IgG chimeras) was less intense for blood lymphocytes than for granulocytes, as determined by flow cytometric analyses of rat and human leukocytes. Taken together, our findings in vivo indicate that the adhesive interactions responsible for rolling of PMNL and MNL, respectively, are distinct in terms of receptor occupancy, and may help explain the temporal selectivity in recruitment of different leukocyte subpopulations in inflammatory or immune reactions.

Animals↗
PubMed1997

Translocation t(7;11)(P15;P15) in a patient with therapy-related acute myeloid leukemia following bimolane and ICRF-154 treatment for psoriasis.

The t(7;11)(p15;p15) translocation is an uncommon balanced aberration which has been found predominantly in Orientals, frequently presenting as de novo acute myeloid leukemia (AML) and occasionally as chronic myeloid leukemia in blastic crisis. This paper reports the first case of therapy-related AML (t-AML) with t(7;11). The patient was a 36-year-old Chinese man with a longstanding psoriasis for which he had received bimolane and ICRF-154 therapy. His cytology and cytochemistry were compatible with M2 subtype of AML. He achieved a complete remission after two courses of HA regimen (homoharringtonine and Ara-c). Six months later, he relapsed and died of overwhelming infection after 3 months. Chromosome analysis on bone marrow cells using short-term culture and R-banding at presentation revealed his karyotype to be 46,XY,t(7;11)(p15;p15)/ 46,XY,t(7;11)(p15;p15),del(12)(p12)/ 46,XY. This case implies: (1) dioxopiperazine derivatives can induce AML with t(7;11) in addition to inducing AML with t(15;17) or t(8;21); (2) t(7;11) may be found not only in de novo AML, but also in t-AML. Chromosomal translocation t(7;11) should be added to t(8;21), t(15;17) and inv(16) as favourable cytogenetic abnormalities associated with t-AML.

Acute Disease↗
PubMed1997

Histone-like transcription factors in eukaryotes.

Histone proteins have long been recognized as important regulators of eukaryotic gene expression. Condensation of DNA into chromatin by the core (H2A, H2B, H3, H4) and linker (H1, H5) histones effectively represses transcription initiation from the promoters of genes that have been packaged. Recently, eukaryotic transcriptional activators and coactivators (both positive and negative) resembling core and linker histone proteins have been discovered. Substantial progress has been made on structural and mechanistic studies of histones and histone-like transcription factors. Three-dimensional structures solved include the core histone octamer, an archael histone homodimer, two core histone-like subunits of transcription factor IID, a linker histone, and a linker histone-like transcriptional activator.

Amino Acid Sequence↗
PubMed1997

Inhibitory effect of locally administered heparin on leukocyte rolling and chemoattractant-induced firm adhesion in rat mesenteric venules in vivo.

1. Anti-inflammatory actions of heparin and related glycosaminoglycans have been described in the literature. Here, we used intravital microscopy of the rat mesentery microcirculation to examine effects of locally administered heparin on leukocyte rolling and chemoattractant-induced firm adhesion. 2. It was found that topical application of heparin reduced N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced leukocyte adhesion. Notably, the inhibitory action of heparin was not dose-dependent, but rather a biphasic dose-response was found, i.e. low (2 and 20 iu ml(-1)) and high (1000 iu ml(-1)) concentrations of heparin significantly reduced adhesion, whereas an intermediate dose (200 iu ml(-1)) was less effective. 3. Heparin, 2 and 20 iu ml(-1), decreased rolling leukocyte flux, while having no effect on blood flow or total leukocyte flux. By contrast, heparin, 200 and 1000 iu ml(-1), increased total leukocyte flux in parallel with a rise in volume blood flow resulting in recovery of the rolling leukocyte flux at these doses. Thus, the biphasic inhibitory action of heparin on fMLP-induced firm adhesion could in part be attributed to changes in leukocyte delivery (i.e. blood flow) and rolling leukocyte flux induced by heparin. 4. When compensating for the influence of different rolling levels on fMLP-evoked adhesion, a dose-related inhibitory effect of heparin on the firm adhesive response per se was revealed. Similar results were obtained in a static adhesion assay in vitro where heparin 200 and 1000 iu ml(-1) (but not 2 and 20 iu ml(-1)) significantly inhibited fMLP-induced leukocyte adhesion in the absence of any modulatory influence on changes in rolling. 5. Our data show that locally administered heparin inhibits leukocyte rolling as well as chemoattractant-induced firm adhesion in vivo which thus may contribute to the postulated anti-inflammatory activity of this compound. However, because of interference with several microvascular functions, strict dose-dependent responses to heparin treatment were not found, which illustrates the complex interplay between local blood flow, leukocyte rolling and chemoattractant-induced adhesion as determinants of leukocyte recruitment to tissues in inflammation.

Administration, Topical↗
PubMed1997

t(8;20)(q22;p13): a novel variant translocation of t(8;21) in acute myeloblastic leukaemia.

A novel variant translocation t(8;20)(q22;p13) detected by karyotype analysis of bone marrow cells using R- and G-banding techniques, is reported in a case of M2-acute myeloid leukaemia (AML). The leukaemic cells were indistinguishable morphologically from that of M2-AML with t(8;21)translocation. RT-PCR revealed no AML1/ETO fusion transcript, but the wild-type ETO-3' was expressed in the bone marrow cells suggesting that t(8;20) is a true simple variant translocation of t(8;21), and that a fusion gene consisting of ETO and an unidentified gene located in band 20p13 may exist in our case. Further study is required to clarify the entity of the assumed fusion gene.

Aged↗
PubMed1997

Scores on loneliness of Chinese and American college students.

197 American college students going to school in Oklahoma and 91 Chinese college students going to school in China participated. Chinese students from extended families (families with three generations) reported less loneliness than those from nuclear families. In the younger group (aged 18 to 20 yr.), Chinese students scored higher on loneliness than American students as did all freshman compared with all sophomore students. Significant interactions between nation and years in college and between nation and family structure (extended families vs nuclear families) were found within the same age group.

Adolescent↗
PubMed1997

[Influence of cryotherapy on the concentration of malondialdehyde in rats serum].

Malondialdehyde (MDA) consistency in rats serum was measured when performing cryotherapy by means of fluorescence method. The rsult showed MDA consistency in rats serum increased after cryotherapy, and the highest MDA consistency appeared respectively in the 2nd week, 4th week and 7th week (P < 0.01). The variation of MDA consistency in mice serum is identical to that when carrying out cryotherapy, which demonstrates that lipid peroxidation involves the whole course of injury and recovery of cryotherapy.

Animals↗
PubMed1997

[The usefulness of dye endoscopy in diagnosis esophageal diseases].

OBJECTIVE: To investigate the usefulness of Dye endoscopy in the diagnosis of the esophageal disorders. METHODS: 87 cases with esophageal diseases underwent dye endoscopy examination with Toluidin-staining and Iodine-staining or double-staining method. RESULTS: In the conventional group, the conformity rate of the endoscopy to biopsy results is 80%, but in the Dye one is 95% and the accurate rate of diagnostic is 100%. Under the guiding of Dye endoscopy, the occurrence rate of Ca cell on the incisal edge is 0%. CONCLUSION: The methods enable diffentinal diagnose of benign and malignant lesion, conforming the type of esophagitis. And it is more helpful to conform the area of surgical resection and when conventional endoscopy cannot satisfactorily diagnosis. We think it is a useful and simple diagnostic method for esophageal diseases.

Diagnosis, Differential↗
PubMed1997

[Tetraploid clones characterized by double 8;21 translocations in two patients with acute myeloid leukemia].

OBJECTIVE: To report two cases of leukemia with t(8;21) and tetraploid clones. METHODS: R-banding technique was used. RESULTS: Cytogenetic studies of BM cells at diagnosis revealed that each of the two cases had three related abnormal clones besides a normal one: 46, XY, t(8;21) (2%), 46, idem, add((7)(q31)(6.8%) and 92, idem x 2 (80.6%) in case 1 and 46, XX, t(8;21) (13.4%), 47, idem, + 4 (46.3%) and 94, idem x 2 (39.1%) in case 2. They did not obtain complete remission on chemotherapy and survived 4 and 6 months, respectively. CONCLUSION: Tetraploid or near tetraploid clones are secondary events which are specifically associated with t(8;21) leukemia and the prognosis of patients with this kind of abnormal karyotype is poor.

Adult↗
PubMed1997

[The use of enthalpy-entropy compensation in the study of retention mechanism of aromatic positional isomers].

In this paper, the thermodynamic parameters of the separation process of six groups of aromatic positional isomers on nine crown ether polysiloxane, OV-1701 and Carbowax-20M capillary chromatographic columns have been investigated systematically. The Gibbs free energies for every compound at harmonic mean temperature, calculated were given. The enthalpy-entropy compensation effect of these chromatographic process was examined by using of Krug's ANOVA method. In the light of the axiom of extrathermodynamic relationship, the retention mechanisms of these aromatic compounds on each crown ether stationary phase have been expounded. We come to conclusion that, as a whole, the separation of various aromatic isomers on crown ether stationary phase is governed by multiple retention mechanisms, but the separation of some groups of aromatic isomer on the same crown ether phase can be led to single interaction mechanism since the phenomena of enthalpy-entropy compensation is observed. It may be that a kind of interaction parameter, which varies with the configuration of solutes, plays the main role in retention process of these isomers.

English Abstract↗