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Biomedical subjects

X Xie

Publications and source records attributed to X Xie.

At least 199 records · Page 11Linked to original sources
PubMed1994

Modulation of long-term potentiation in rat hippocampal pyramidal neurons by zinc.

The phenomenon of long-term potentiation is frequently promulgated as an example of learning and memory mechanisms at the synaptic level in the mammalian central nervous system. In the CA3 region of the hippocampus there is an abundance of zinc, which is located in presynaptic mossy fibre nerve terminals. Stimulation of these fibres can cause the release of zinc, which interacts with excitatory amino acid receptors and may therefore modulate long-term potentiation. We now demonstrate in CA1 and CA3 neurons that zinc (100-300 microM) enhances non-N-methyl-D-aspartate-receptor-mediated responses whilst reducing excitatory synaptic transmission and inhibiting long-term potentiation. However, by using zinc-chelating agents, endogenously released zinc following high-frequency stimulation in the stratum lucidum does not appear to have any modulatory role in excitatory synaptic transmission and long-term potentiation. These results indicate that an increase in the level of extracellular zinc can limit excitatory synaptic transmission in the CA1 or CA3 region and further suggests that pathologies that can be related to excessive levels of endogenous zinc may have implications for synaptic plasticity in CA3 neurons.

Animals↗
PubMed1994

Application of electron energy loss spectroscopy and electron spectroscopic imaging to aluminum determination in biological tissue.

Electron energy loss spectroscopy (EELS) is a high spatial resolution electron microscopic technique with the potential to quantify elements at the subcellular level. The presence of each element is demonstrated by the electron energy loss edge at the energy characteristic of that element. The area of the edge may indicate the quantity of element present. Electron spectroscopic imaging (ESI) is a similar technique generating graphic images of elemental localization in the specimens. An ESI of an aluminum (Al)-loaded rabbit hippocampus showed Al only in pyramidal cell lysosomes, but no EELS edge could be obtained. To determine the sensitivity of EELS for Al and to be able to adjust the instrument to optimal operating conditions, standards containing 50-5000 ppm Al were produced. An Al-chloride: dicyclohexano-18-crown-6 (Al: crown) complex was synthesized. The purity of the complex was confirmed by nuclear magnetic resonance (NMR) spectroscopy and the percentage of Al in the complex was determined by electrothermal atomic absorption spectroscopy (ETAAS). The complex was introduced into a biological tissue embedding resin (Spurr medium) and appeared to be compatible with the resin at Al concentrations < or = 500 ppm. EELS signals from the Al K edge could be obtained at a spatial resolution of 3.3 nm in a 30-nm thick section from 2.78 x 10(-21) g of Al, representing a sample concentration of 1% Al.

Aluminum↗
PubMed1994

Translocation (8;21) in oligoblastic leukemia: is this a true myelodysplastic syndrome?

An 8;21 translocation with trisomy 4 is described in a 36-year-old Chinese woman who presented with an oligoblastic leukemia with myelodysplastic (MDS) features. Progression to acute myeloblastic leukemia (AML) occurred 3 months after presentation. She died of septicemia without remission. Through a review of the data in 10 cases of oligoblastic leukemia with t(8;21) in the literature, we make the following comments. (i) Oligoblastic leukemia with t(8;21) represents 2-3% of cases with this karyotype. (ii) Such cases behave in a similar manner to de novo AML. (iii) The presence of features of MDS has no affect on the behaviour of the disease. (iv) Such cases should be treated without delay with intensive chemotherapy.

Adult↗
PubMed1994

Regulation of GABAA receptor function by protein kinase C phosphorylation.

GABAA receptors possess consensus sequences for phosphorylation by PKC that are located on the presumed intracellular domains of beta and gamma 2 subunits. PKC phosphorylation sites were analyzed using purified receptor subunits and were located on up to 3 serine residues in beta 1 and gamma 2 subunits. The role of phosphorylation in receptor function was studied using recombinant receptors expressed in kidney cells and Xenopus oocytes and was compared with native neuronal GABAA receptors. For recombinant and native GABAA receptors, PKC phosphorylation caused a reduction in the amplitudes of GABA-activated currents without affecting the time constants for current decay. Selective site-directed mutagenesis of the serine residues reduced the effects of phorbol esters and revealed that serine 343 in the gamma 2 subunit exerted the largest effect on the GABA-activated response. These results indicate that PKC phosphorylation can differentially modulate GABAA receptor function.

Alanine↗
PubMed1994

m-sulphonate benzene diazonium chloride: a novel GABAA receptor antagonist.

A previously identified irreversible affinity label for the gamma-aminobutyric acid (GABA) binding site in rat brain membranes, m-sulphonate benzene diazonium chloride (MSBD), was characterized in functional studies using patch clamp and two-electrode voltage clamp recording techniques. MSBD did not exhibit any agonist activity on native GABAA receptors in cultured sympathetic ganglionic neurones but acted as an antagonist of GABA-induced membrane currents. Recombinant GABAA receptors composed of alpha 1, beta 1 and gamma 2S subunits were expressed in Xenopus oocytes following microinjection with cDNAs. Equilibrium dose-response curve analyses established that MSBD was a partially reversible, apparently non-competitive GABAA receptor antagonist. The IC50 for MSBD was estimated from an inhibition curve as 87 +/- 3 microM. In addition, the onset and recovery from MSBD-induced inhibition was independent of GABAA receptor activation. The relatively simple structure of this novel GABAA receptor antagonist, MSBD, is compared with known agonists and antagonists at the GABAA receptor. MSBD may be a useful pharmacological tool which could be used to deduce further information about the structure and function of agonist and antagonist binding sites on the GABAA receptor.

Animals↗
PubMed1994

1% lidocaine versus 0.5% diphenhydramine for local anesthesia in minor laceration repair.

STUDY OBJECTIVE: Our previous study demonstrated that 1% diphenhydramine is as effective as 1% lidocaine for anesthesia in minor laceration repair, but that it also is more painful to inject. The purpose of this study was to compare 0.5% diphenhydramine to 1% lidocaine for pain of injection and adequacy of local anesthesia. STUDY DESIGN: Randomized, double-blinded, prospective study from December 1991 through June 1992. SETTING: University-affiliated, urban, inner-city emergency department. PARTICIPANTS: Ninety-eight adults with linear skin lacerations without end-organ involvement were included; 48 received lidocaine and 50 received diphenhydramine. INTERVENTIONS: Wounds were anesthetized with either diphenhydramine or lidocaine according to a random table. Both patients and physicians rated the pain of injection and suturing according to a standard, previously tested, visual analog scale. MEASUREMENTS AND MAIN RESULTS: Patient and physician ratings were ranked without regard to treatment group, and rank sum scores were calculated for each group. General linear models and multivariate analysis of variance were used to analyze the ranked sum scores. The power of the study to detect a ranked sum difference of 15 was 0.8 with P < .05 considered statistically significant. Lidocaine was found to be significantly more effective as a local anesthetic for facial lacerations according to both patients (P < .002) and physicians (P < .004). There was no statistically significant difference between 1% lidocaine and 0.5% diphenhydramine for pain of injection or suturing for all other locations according to both patients and physicians. Overall mean and median scores for injection and suturing with diphenhydramine corresponded to the mild pain category according to patients. CONCLUSION: Although not a replacement for lidocaine, diphenhydramine is a viable alternative for anesthesia in the repair of minor lacerations.

Adult↗
PubMed1994

Diagnostics for the multivariate linear model analysis of 2 x 2 crossover designs.

The multivariate linear model Y = X beta + epsilon is used to analyze data in 2 x 2 crossover designs with either univariate or multivariate response. Diagnostics are performed on estimating the effect of interest formulated as C beta U and on testing the general linear hypothesis C beta U = k. The multivariate Cook's distance is extended to be the influence measure by incorporating the contrast matrix C and the transformation matrix U, and magnitude of F(1)-F, the difference between the F approximation of a multivariate test statistic, is proposed as a measure to detect influential observations for testing the hypothesis C beta U = k. Both measures prove to be very useful because the diagnostics are now associated with estimating and testing effects of interest in the context of the experimental design.

Biopharmaceutics↗
PubMed1994

Inhibition of leukocyte rolling with polysaccharide fucoidin prevents pleocytosis in experimental meningitis in the rabbit.

Inflammatory recruitment of leukocytes into the cerebrospinal fluid (CSF) during bacterial meningitis has been shown to contribute significantly to the neurological damage commonly associated with this serious disease. In this study we tested whether or not inhibition of leukocyte rolling, a precondition for firm leukocyte adhesion to vascular endothelium in vivo, may reduce CSF leukocyte recruitment and associated inflammatory changes in rabbits with experimental meningitis. As documented by intravital microscopy of small venules in the rabbit mesentery and tenuissimus muscle, leukocyte rolling was rapidly and profoundly reduced by intravenous treatment with the polysaccharide fucoidin, a homopolymer of sulfated L-fucose known to block the function of the leukocytic "rolling receptor" L-selectin. Moreover, fucoidin treatment dramatically reduced the accumulation of both leukocytes and plasma protein in the CSF of rabbits challenged intrathecally with pneumococcal antigen. These main findings thus illustrate that inhibition of leukocyte rolling, an early and obligatory step in the process of leukocyte extravasation, may be an effective therapeutic approach to attenuate leukocyte-dependent central nervous system damage in bacterial meningitis.

Animals↗
PubMed1994

[Effect of danazol on growth of endometrial and endometriotic cells in vitro].

The cells from entopic and ectopic endometrial tissues were primarily cultured in collagen gel and passaged for secondary culture. The grown cells were treated respectively with danazol (2.5 micrograms/ml and 5 micrograms/ml) and without danazol in medium. In control culture without danazol, the cells presented normal growth, had stellate appearance and were connected with each other by cytoplasmic projections. Cell growth was suppressed after being treated with both concentrations of danazol. Attachment potential of passaged cells in 24 hours appeared to be damaged, some cells revealed lethal pathological features. Ultrastructural changes induced by danazol included numerous vacuoles and lipid droplets, increased lysosomes including autolysosome, oncotic mitochondria in cytoplasm, irregular nucleus, etc. The results suggest that collagen gel culture is suitable for culturing endometrial cells, and danazol has a direct effect on human endometrial and endometriotic tissues.

Adult↗
PubMed1994

[Histological diagnosis and clinical features in borderline smooth muscle tumors of the uterus].

Between leiomyoma and leiomyosarcoma there exists a series of borderline smooth muscle tumors of the uterus, including cellular, bizarre, mitotically active, atypical and uncertain malignant potential leiomyomas. A histological criterion was presented in this study for diagnosis of smooth muscle tumors of the uterus. Forty-two cases originally diagnosed as uterine cellular leiomyomas were re-examined histologically, analyzed clinically and followed up. The results showed that among the 42 cases, there were 5 cases of cellular leiomyoma, 1 case of bizarre leiomyoma, 7 cases of atypical leiomyoma, 2 cases of tumors of uncertain malignant potential, 1 case of leiomyosarcoma and 26 cases of usual leiomyoma. The histological criteria of dense cellularity, cell atypia and nuclear mitosis showed a close correlation, but did not vary at different phases of menstrual cycle. Clinical features of borderline tumors were similar to those of usual leiomyomas, and their prognosis was also good. It is suggested that diagnosis of borderline smooth muscle tumors of the uterus should be made on the basis of three histological characteristics, including cellular density, cell atypia and nuclear mitotic figures. Management of the borderline cases seems to be the same as that of usual leiomyoma, but a further study may be necessary.

Adult↗
PubMed1994

Observation on the changes of plasma cardionatrion before and after microwave acupuncture in coronary heart disease.

This paper reports the therapeutic effect of microwave acupuncture (MWA) and its influence on the plasma level of cardionatrion. Twenty-eight cases with coronary heart disease (CHD) were systemically observed and investigated. Atrial natriuretic polypeptides (ANP) were determined by radioimmunoassay. Plasma level of ANP was elevated, the rising rate being 100%. The therapeutic effect of MWA in the 28 cases with CHD was 85.7%, the ECG improving rate was 82.2%. Effect of MWA was briefly discussed. The authors consider that the therapeutic effect of MWA in the treatment of CHD could be ascertained, and the measurement of plasma ANP concentration is a useful method and an objective parameter for further research.

Acupuncture Points↗
PubMed1993

Interaction of zinc with ionotropic and metabotropic glutamate receptors in rat hippocampal slices.

The actions of zinc on ionotropic and metabotropic glutamate receptors were studied using intracellular recording in acutely prepared adult rat hippocampal slices and in organotypic hippocampal slice cultures. In control Krebs, glutamate and non-N-methyl-D-aspartate (NMDA) agonist-induced responses were enhanced by zinc (25-300 microM). However, under conditions favouring NMDA receptor activation, zinc inhibited glutamate- and NMDA-induced responses. Metabotropic glutamate receptor-mediated responses activated in cultured slices by 1-amino-cyclopentane-1,3-dicarboxylate (1S,3R-ACPD) or by quisqualate, were reversibly inhibited by zinc (200 microM). These results indicate that zinc can inhibit responses induced by activation of metabotropic glutamate receptors and reaffirm that zinc has a differential effect on NMDA and non-NMDA receptors.

Animals↗
PubMed1993

Giant GABAB-mediated synaptic potentials induced by zinc in the rat hippocampus: paradoxical effects of zinc on the GABAB receptor.

The interaction of zinc with pre- and postsynaptic GABAB receptors was studied in adult rat hippocampal slices using intracellular recording in CA1 and CA3 pyramidal neurons. Zinc (50-300 microM) antagonized baclofen responses with a variable potency, whereas CGP-35348 (100 microM) or barium (300 microM) produced a more substantial and consistent inhibition. Zinc also induced giant GABAA-mediated depolarizing potentials (GDP) in these neurons. After blocking GABAA and excitatory synaptic transmission, monosynaptic hyperpolarizing inhibitory postsynaptic potentials (IPSP) mediated by GABAB receptors (IPSPB) were inhibited by CGP-35348 or barium; however, zinc increased the latency and prolonged the duration of the IPSPB and also induced the appearance of spontaneous giant GABAB-mediated hyperpolarizing potentials (GHP). In some cells, IPSPBs in zinc exhibited a multiphasic appearance. The early component was partially inhibited by 300 microM zinc and was followed by a late GHP. CGP-35348 at 100 microM inhibited the early monosynaptic IPSPB but not the GHP; however, at 300 microM both components were blocked. Paired-pulse inhibition of the IPSPB was used to assess the effect of zinc on presynaptic GABAB receptors. Neither the zinc-chelating agent CP94 (400 microM) nor zinc affected this phenomenon. CGP-35348, barium and polyvalent cations, such as cadmium, copper, cobalt, manganese, iron and aluminum, failed to induce giant potentials in hippocampal neurons. It is concluded that zinc is apparently unique in synchronizing the release of GABA to produce GDPs and GHPs.

Animals↗
PubMed1993

Promoter and regulatory regions of the rat luteinizing hormone receptor gene.

The region of transcriptional activity in the rat luteinizing hormone receptor gene was localized to the 5'-flanking 173-base pair (bp) sequence in transfected mouse Leydig tumor cells and non-expressing Chinese hamster ovarian (CHO) and HeLa cells. Repression of activity in all cell types was induced by at least two domains located between -174 and -990 bp. An additional inhibitory region between -1237 and -2056 bp observed only in CHO and HeLa cells may contribute to the absence of receptor expression in these cells. Analysis of the 173-bp region revealed a promoter domain between -1 and -137 bp containing no TATA or CAAT boxes, but with three SP1 sites and three initiator elements located at transcriptional start sites -14, -19, and -33. Gel retardation studies showed a protein-binding DNA domain about 30 bp upstream of the transcriptional start sites and an adjacent domain containing an SP1 element that are required for maximal activity in all cell types and may play a role in basal transcription. A second promoter domain (-120 to -173 bp) with a protein-binding SP1 element had minor activity in Leydig cells but was prominent in CHO and HeLa cells. Leydig cell-specific DNA-binding protein(s) for each of the promoter domains were detected and may be of importance in transcriptional regulation. The control of gene transcription by differential activation of these promoter domains could be involved in hormone-induced regulation of luteinizing hormone receptor expression in the gonads.

Animals↗