Functional expression of CXCR4 in S. cerevisiae: development of tools for mechanistic and pharmacologic studies.
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Animals↗
Biomedical subjects
W B Zhang
Publications and source records attributed to W B Zhang.
Pseudoginsenoside-F11 attenuates morphine-induced signalling in Chinese hamster ovary-mu cells.
Pseudoginsenoside-F11 (PF11), an ocotillol type saponin isolated from Panax quinquefolium L., has been shown to antagonize the behavioral actions of morphine. Biochemical experiments revealed that PF11 could inhibit diprenorphine (DIP) binding with an IC50 of approximately 6.1 microM and reduced the binding potency of morphine in Chinese hamster ovary (CHO)-mu cells. Furthermore, PF11 significantly attenuated morphine-stimulated [35S]GTPgammaS binding in a dose dependent manner, and strongly decreased the efficacy of morphine to inhibit intracellular cAMP production. In addition, PF11 pretreatment could also significantly inhibit naloxone induced cAMP overshoot in the morphine-pretreated cells. However, PF11 per se had no effect on either [35S]GTPgammaS binding or intracellular cAMP accumulation. These data suggested that PF11 antagonized the morphine stimulated opioid receptor signalling directly at the cellular level.
Adenylyl Cyclases↗
[A new method for predicting retention time of solutes under linear gradient elution conditions in RP-HPLC].
A new method for predicting the retention time of solutes under linear gradient elution has been established. In this method, the migration distance of solutes in column and the mobile phase gradient were modified simultaneously according to the distribution of mobile phase in column. The prediction results of retention time of both weakly and strongly retentive solutes were accurate in different instrumental systems using this method. In order to test and verify this method, the retention time of fifteen amino acids and eight homologous compounds of benzene were predicted. The predicted results were compared with those predicted by the method in common use. The relative average errors between predicted and experimental values were 3.70% and 4.90% for the weakly retentive solutes, far smaller than those obtained by the reference method (23.61% and 31.16%). For the strongly retentive solutes, the relative average errors were 0.21% and 6.01% respectively, slightly smaller than those obtained by the reference method (0.81% and 6.69%). It is seen that this new method has many advantages.
Amino Acids↗
[Advances in chromatography and related techniques in China--status report in 1998-1999].
This report covers developments in chromatography and related techniques in China during the period of 1998-1999. The papers published in 23 domestic and a few foreign periodicals which are closely related to chromatography, and presented at 1999 Beijing Conference and Exhibition on Instrumental Analysis and the 12th National Symposium of Chromatography are reviewed. Specific topic areas covered include gas chromatography (GC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and capillary electrochromatography (CEC), solid phase extraction (SPE) and solid phase microextraction (SPME).
Animals↗
[Addition internal standard method in chromatographic quantitative analysis].
Internal standard method is a conventional chromatographic quantitative method which requires one or several internal standards added. The internal standard component must not be contained in the sample and need a good separation between the internal standard and sample components. In many cases selecting an internal standard is not convenient or even restricted by the seperation of components. In this paper, we try to combine the internal standard method and the addition method to form a new chromatographic quantitation method named addition internal standard method. The principles of addition internal standard method are suitable to not only chromatographic quantitation but also polarography etc. The related theory and foundation of the method are defined. The operation steps and the conditions suitable to the method are discussed. The advantages and disadvantages of this method are explained in detail.
Chromatography↗
[Study on the determination of NO, AsH3, COS and other impurities in cracked gas by chromatography/mass spectrometry method].
The selected ion monitoring(SIM) mode of capillary column gas chromatography coupled with mass spectrometry has been used for the determination of NO, AsH3, COS, thio-ether, thio-alcohol etc. in gases from catalytic cracking of heavy oils. The interference of CO, CO2, ethylene, ethane and N2 which affected the determination of NO was eliminated by chromatographic separation and subtraction of responses. The interference to the determination of selected ion was studied. Only C2H5SH was affected at m/z = 62 and the interference could be eliminated by using the ions at m/z = 47. The impurities in practical sample gas were determined. The detection limit of NO was 100 nL/L. The detection limits of other impurities were between 15 nL/L and 50 nL/L.
English Abstract↗
Lysophosphatidylcholine activates p38 and p42/44 mitogen-activated protein kinases in monocytic THP-1 cells, but only p38 activation is involved in its stimulated chemotaxis.
Oxidized LDLs (OxLDLs) have been shown to be involved in recruitment of blood monocytes into the arterial subendothelial space, which is the earliest step in atherogenesis, but the underlying molecular mechanisms are poorly understood. The present study demonstrated that lysophosphatidylcholine (LPC), a major phospholipid component of OxLDL, strongly evoked phosphorylation and activation of p38 and p42/44 mitogen-activated protein kinases in monocytic cells. The stimulation of p38 and p42/44 occurred in a dose- and time-dependent manner, reaching the maximal activation at 25 microg/mL LPC within 5 minutes. Interestingly, inhibition of p38 activation by OxLDL or LPC, using its selective inhibitors (SB203580 and SKF86002), completely blocked OxLDL- or LPC-stimulated chemotaxis of THP-1 cells, which was measured in a transwell chemotaxis assay. In contrast, inhibition of p42/44 activation by its potent inhibitor (PD98059) did not block OxLDL- or LPC-stimulated chemotaxis. Moreover, expression of a p38 dominant-negative mutant (p38AF) reduced cell chemotaxis significantly. In addition, activation of p38 by LPC was apparently mediated neither by scavenger receptors nor by tyrosine kinase receptors. It was, however, effectively blocked by pertussis toxin and substantially reduced by phospholipase C inhibitor (U73122) and phosphatidylinositol 3-kinase inhibitors (wortmannin and LY294002). LPC also inhibited forskolin-stimulated cAMP accumulation in a pertussis toxin-sensitive manner, indicating that Gi/Go proteins likely mediated the effects of LPC. Our results suggested that OxLDL/LPC efficiently activated both p38 and p42/44, but only the activation of p38 was functionally associated with OxLDL-/LPC-induced chemotaxis in THP-1 cells.
Cells, Cultured↗
Distribution of interstitial fluid pressure and fluid volumes in hind-limb skin of rats: relation to meridians?
To determine the distribution of interstitial fluid pressure (Pi) and volume (Vi), and to relate the distribution of these parameters to the distribution of potential meridians located by measurement of electrical impedance, we measured Pi, extracellular fluid (Ve) and plasma volumes (Vp) in 14 pre-defined skin areas, 2 x 2 mm, and in concave and convex regions on the hind-limb and groin of rats in control conditions. Pi was measured with sharpened glass capillaries connected to a servo-controlled counter-pressure system, while Ve and Vp were determined as the extravascular distribution spaces of 51Cr-EDTA and 125I-human serum albumin, respectively. Vi was calculated as Ve - Vp, and Vw as the difference between skin wet and dry weight. Grand mean Pi averaged -0.81 mmHg (SD 0.83, n=95). Pi in skin was significantly higher in lateral and medial parts of the medial aspect of hind-limb compared to pressures in the intermediate area (P<0.05). Pressures in the concave groin and the convex knee area were more negative and positive, respectively, than in the flat intermediate central hind-limb area. There was a significantly higher Vi (P<0.05) and Vw (P<0.05) in the lateral side than that in the medial side. Vp was higher medially and laterally than in the intermediate area (P<0.05 for both comparisons), and correlated positively and significantly with Pi (r=0.66, P<0.05). No correlation was found between Pi and electrical impedance. The study suggests that the distribution of Pi, Vi, Vp and Vw is heterogeneous in hind-limb skin at a macroscopic level without obvious relations to potential meridians.
Animals↗
[Advances in nonaqueous capillary electrophoresis].
Advances in nonaqueous capillary electrophoresis are reviewed with 71 references in this paper. Capillary electrophoresis is generally performed in aqueous buffer. In fact, it can provide some advantages to use organic solvent as a separation medium instead of water. The choice of organic solvent and electrolyte, the detection mode and solute-additive interactions are summarized. Furthermore, the separation of inorganic ions, neural compounds, organic acids, pharmaceuticals, metabolites and chiral substance is also described.
Electrophoresis, Capillary↗
[Determination of residual acetone in soybean phospholipids by headspace gas chromatography].
Soybean phospholipids have many functions and alimentary actions. In our country, powder soybean phospholipids are generally got by extraction with acetone, followed by vacuum drying. There may be some residual acetone present in the soybean phospholipids, which is harmful to health. So, we must know residual acetone content in the soybean phospholipids. However we have not found a method to determine the residual acetone in the soybean phospholipids. In this paper, headspace GC was used to determine residual acetone in powder soybean phospholipids. The headspace bottle was glass with a volume of 15 milliliters. Certain amounts of water, ammonium sulfate, and sample were added into the bottle. The mixture was made into a brei as soon as possible. The bottle was put into a water bath at 40 degrees C for an hour. The GC column was a 2 m x 3 mm i.d. stainless steel tube packed with GDX-103 stationary phase. Temperatures of both injector and detector were kept at 120 degrees C. Column temperature was 160 degrees C. Injection volume was 1 mL. External standard method was used for quantitation. The RSD was 1.2%. The recoveries in the range of 25.0 micrograms/g-100 micrograms/g were 98.4%-104%.
Acetone↗
Activation of p38 mitogen-activated protein kinase by oxidized LDL in vascular smooth muscle cells: mediation via pertussis toxin-sensitive G proteins and association with oxidized LDL-induced cytotoxicity.
Oxidized low-density lipoproteins (oxLDL) have been shown to play a crucial role in atherosclerosis, but the underlying molecular mechanisms have not been fully understood. The present study showed that oxLDL strongly evoked phosphorylation and activation of p38 mitogen-activated protein kinase (MAPK) in rat vascular smooth muscle cells (VSMCs) in concentration- and time-dependent manners, reaching the maximal activation at 100 microg/mL within 5 minutes. The results from immunofluorescence staining also revealed that p38 MAPK was activated by oxLDL in 5 minutes, and the activated p38 MAPK was translocated from cytoplasm to nucleus of VSMCs in 15 minutes. Activation of p38 MAPK by oxLDL was apparently not mediated by their classical scavenger receptors and was not affected by tyrosine kinase inhibitors. However, activation of p38 MAPK was effectively blocked by pretreatment with pertussis toxin and was significantly reduced by phospholipase C inhibitor U-73122. OxLDL also inhibited forskolin-stimulated cAMP accumulation and increased inositol phosphate formation. More interestingly, inhibition of p38 MAPK by its specific inhibitor SB203580 significantly blocked oxLDL-induced cytotoxicity (increased leakage of cytoplasmic lactate dehydrogenase to the culture medium, reduced [3H]thymidine incorporation, and attenuated mitochondrial metabolism of tetrazolium salt, (3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-s ulfophenyl)- 2H-tetrazolium), MTS) in VSMCs, and pretreatment with pertussis toxin also inhibited oxLDL-induced cytotoxicity. Taken together, our data clearly demonstrated that oxLDL effectively activated p38 MAPK in VSMCs, which was likely mediated via pertussis toxin-sensitive G proteins, and the p38 activation was functionally associated with oxLDL-induced cytotoxicity in VSMCs.
Animals↗
Suppression of angiotensin II stimulated responses in aortic vascular smooth muscle cells of experimental cirrhotic rats.
Functional responses to angiotensin II (AT-II) were determined in aortic vascular smooth muscle cells (VSMCs) from experimental cirrhotic rats. Our data showed that AT-II-stimulated extracellular acidification rate (ECAR), which was measured by Cytosensor microphysiometry, was significantly reduced in the aortic VSMCs from the cirrhotic rats as compared to those from the control animals. The ability of AT-II to promote formation of inositol phosphates, the second messenger produced by the activation of Gq-coupled receptors, was also considerably suppressed in the cirrhotic VSMCs. Furthermore, the maximal p42/44 MAPK phosphorylation stimulated by AT-II was significantly reduced in the cirrhotic VSMCs in contrast to that in the normal VSMCs. Taken together, our data clearly demonstrated that the functional responses to AT-II was severely suppressed in aortic VSMCs in cirrhosis, indicating the impairment of general Gq-coupled receptor signaling and subsequent biological function in the cirrhotic VSMCs.
Angiotensin II↗
Endogenous delta-opioid and ORL1 receptors couple to phosphorylation and activation of p38 MAPK in NG108-15 cells and this is regulated by protein kinase A and protein kinase C.
The p38 mitogen-activated protein kinase (MAPK) cascade transduces multiple extracellular signals from cell surface to nucleus and is employed in cellular responses to cellular stresses and apoptotic regulation. The involvement of the p38 MAPK cascade in opioid- and opioid receptor-like receptor-1 (ORL1) receptor-mediated signal transduction was examined in NG108-15 neuroblastoma x glioma hybrid cells. Stimulation of endogenous delta-opioid receptor (DOR) or ORL1 resulted in activation of p38 MAPK. It also induced the activation of extracellular signal-regulated kinases (ERKs), another member of the MAPK family, with slower kinetics. Activation of p38 MAPK was abolished by selective antagonists of DOR or ORL1, pretreatment with pertussis toxin, or SB203580, a specific inhibitor of p38 MAPK. Inhibition of p38 MAPK had no significant effect on opioid-induced ERK activation, indicating that p38 MAPK activity was not required for ERK activation, though its stimulation preceded ERK activation. Inhibition of protein kinase A (PKA) strongly diminished p38 activation mediated by DOR or ORL1 but had no significant effect on ERK activation, and protein kinase C (PKC) inhibitors potentiated stimulation of p38 while inhibiting activation of ERKs. Taken together, our results provide the first evidence for coupling of DOR and ORL1 to the p38 MAPK cascade and clearly demonstrate that receptor-mediated activation of p38 MAPK both involves PKA and is negatively regulated by PKC.
Animals↗
Influence of particle size on diffusion-limited aggregation.
The influence of particle size on diffusion-limited aggregation (DLA) has been investigated by computer simulations. For DLA clusters consisting of two kinds of particles with different sizes, when large particles are in the minority, the patterns of clusters appear asymmetrical and nonuniform, and their fractal dimensions D(f) increase compared with one-component DLA. With increasing size of large particles, D(f) increases. This increase can be attributed to two reasons: one is that large particles become new growth centers; the other is the big masses of large particles. As the concentration ratio x(n) of large particles increases, D(f) will reach a maximum value D(f(m)) and then decrease. When x(n) exceeds a certain value, the morphology and D(f) of the two-component DLA clusters are similar to those of one-component DLA clusters.
Journal Article↗
Suppression of phospholipase C blocks Gi-mediated inhibition of adenylyl cyclase activity.
The potential effect of inhibition of phospholipase C on the response of Gi-coupled receptors was investigated in neuroblastoma x glioma hybrid (NG108-15) cells. The phospholipase C specific inhibitor 1-[6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]-1H -pyrrole-2,5-dione (U73122), which did not affect basal and forskolin-stimulated adenylyl cyclase activities, time- and dose-dependently blocked delta-opioid receptor-mediated inhibition of adenylyl cyclase activity, the EC50 (0.5 microM) of which was consistent with that for inhibition of bradykinin-dependent phospholipase C activation (EC50 = 1 microM). U73122 treatment also blocked functional responses of m4 muscarinic receptor and alpha2-adrenoceptor in NG108-15 cells and three opioid receptors (mu, delta and opioid receptor-like receptor (ORL1)) in human neuroblastoma SK-N-SH cells. 1-[6-((17Beta-3-Methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]-2, 5-pyrrolidinedione (U73343), an inactive analog of U73122, did not show any effect, which suggests that the blockade by U73122 of Gi-coupled receptor-mediated signaling is probably mediated through inhibition of phospholipase C, although a possible direct modification of G proteins can not be excluded. Furthermore, treatment with U73122 but not U73343 blocked the GTP-induced inhibition of adenylyl cyclase, indicating blockade at the level of Gi proteins.
Adenylyl Cyclases↗
Absence of an analgesic effect of qigong "external qi" in rats.
The analgesic effect of "external Qi" emitted from the Qigong practitioner was investigated in rats. In behavioral experiments, the rat's tail-flick and head-movement threshold measurements were used to determine if the "external Qi" had analgesic effect. The results were negative. In electrophysiological study, the "external Qi" shows no significant changes in the pain-related evoked cortical potentials to tooth-pulp stimulation. Thus the results of this study are different from those reported by other investigators. It is proposed that this research be repeated and extended.
Analgesia↗
A study on the stability of bronopol in bronopol lotion by ion-paired reversed-phase high performance liquid chromatography.
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Anti-Infective Agents, Local↗
'Double toxicity' of glycine solution in the mouse.
OBJECTIVE: To study whether glycine, which may contribute to the symptoms of the transurethral resection syndrome promotes death in a mouse model and whether a modification of the glycine concentration offers a better chance of survival. MATERIALS AND METHODS: Mortality was determined in 120 mice after an intravenous infusion of increasing volumes and concentrations of glycine solution. The animals were divided into groups of 10 and given 150, 180, 200 or 220 mL/kg body weight of 1.1, 1.5 or 2.2% glycine solution. As a control, 220 mL/kg of a 5% mannitol solution was given to 12 mice. RESULTS: After receiving an isosmotic (2.2%) glycine solution 70% of the animals died, while the overall death rate for 1.5% glycine was only 20%. When 1.1% glycine was used, the mortality was 10% after infusion of 150 and 180 mL/kg and 80% after infusion of > or = 200 mL/kg. Logistic regression analysis showed that the outcome for the two highest glycine concentrations was directly related to the dose of glycine and not to the water load. Of 12 mice receiving the isosmotic 5% mannitol solution, three died. CONCLUSIONS: A 1.5% glycine solution offered the best chance of survival. The mortality was governed both by the glycine dose (2.2 and 1.5%) and the tendency of the solution to produce overhydration of the cells (1.1%). Glycine toxicity was most important when small volumes were infused.
Animals↗