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Biomedical subjects

C Cui

Publications and source records attributed to C Cui.

At least 37 records · Page 2Linked to original sources
PubMed1999

Effect of eotaxin on the generationof reactive oxygen species from eosinophil cell line, YY-1.

BACKGROUND: The CC chemokine eotaxin is a selective chemoattractant for eosinophils. Eosinophils have been considered to be the major effector cells in allergic inflammation, since not only eosinophil-specific granule proteins but also reactive oxygen species (ROS) from eosinophils may cause the damage to the cells or tissue of the mucosal epithelium. In this study, we examined the effect of eotaxin on ROS from an eosinophil cell line, YY-1. METHODS: ROS in luminol-dependent reaction were examined. Calcium ionophore A23187 were added to the mixture of YY-1 cells with luminol, and then ROS were determined. RESULTS: Eotaxin primed the production of ROS from YY-1 cells. ROS from untreated YY-1 cells evoked with calcium ionophore A23187 in luminol-dependent chemiluminescence gave a maximal value of 1,928 +/- 223 intensity counts (IC; mean +/- SE, n = 4) and an integral value of 17.04 +/- 1. 51 IC (x10(-4)), while eosinophils that were treated with eotaxin gave a maximal value of 2,264 +/- 86 IC (10 nM), 2,691 +/- 124 IC (100 nM) and an integral value of 21.22 +/- 0.67 IC (x10(-4); 10 nM), 26.20 +/- 1.41 IC (x10(-4); 100 nM). CONCLUSION: Eotaxin might play important roles in the pathogenesis of allergic inflammation through eosinophil activation by priming of eosinophil oxidative metabolism as well as involvement in selective eosinophil chemotaxis.

Cell Line↗
PubMed1999

[The measurement of QT dispersion using wavelet transformation].

This paper addressed the application of wavelet to the measurement of QT dispersion and presented a new method using multi-thresholds to determinate the end point of T-wave. The results geined by computer and human were compared. We also suggested that QT dispersion be defined as the SD of 12 QT intervals.

Algorithms↗
PubMed1998

Carbon structures with three-dimensional periodicity at optical wavelengths

Porous carbons that are three-dimensionally periodic on the scale of optical wavelengths were made by a synthesis route resembling the geological formation of natural opal. Porous silica opal crystals were sintered to form an intersphere interface through which the silica was removed after infiltration with carbon or a carbon precursor. The resulting porous carbons had different structures depending on synthesis conditions. Both diamond and glassy carbon inverse opals resulted from volume filling. Graphite inverse opals, comprising 40-angstrom-thick layers of graphite sheets tiled on spherical surfaces, were produced by surface templating. The carbon inverse opals provide examples of both dielectric and metallic optical photonic crystals. They strongly diffract light and may provide a route toward photonic band-gap materials.

Journal Article↗
PubMed1998

Materials with negative compressibilities in one or more dimensions

Rare crystal phases that expand in one or more dimensions when hydrostatically compressed are identified and shown to have negative Poisson's ratios. Some of these crystals (i) decrease volume and expand in two dimensions when stretched in a particular direction and (ii) increase surface area when hydrostatically compressed. Possible mechanisms for achieving such negative linear and area compressibilities are described for single crystals and composites, and sensor applications are proposed. Materials with these properties may be used to fabricate porous solids that either expand in all directions when hydrostatically compressed with a penetrating fluid or behave as if they are incompressible.

Journal Article↗
PubMed1998

Choice of reference axis in ocular wave-front aberration measurement.

The geometrical center of the pupil has often been used as the reference axis in ocular wave-front aberration measurement. However, the geometrical center of the pupil may shift when the pupil size changes under different conditions. In particular, for subjective methods, defining the center of the pupil precisely during the actual measurement is not always practical. Furthermore, the geometrical center of the pupil may not define the chief ray of the ocular optics because of the Stiles-Crawford apodization effect, which has a peak location that often deviates from the geometrical center of the pupil. We present the coefficient transformation table of the Taylor polynomial up to the sixth order with respect to reference axis shift. We illustrate the effect of wave-front aberration change with reference axis shift with experimental data. This type of wave-front aberration change could be a true measurement error if there is an error in defining the reference axis. We also propose using the coaxially sighted corneal reflex as a better reference axis in aberration measurement.

Humans↗
PubMed1998

[Effect of different prescriptions for tonifying kidney on RNA transcription activity in isolated nuclei and protein synthesis activity in free-cell extracts of the different organs of presenile mice].

OBJECTIVE: To study the anti-aging mechanism of Zuoguiyin (a prescription for tonifying Kindney Yin) and Yishenbao (a prescription for tonifying Kidney Yang) in presenile mice. METHODS: Using male, 14 months old presenile mice as a model of Kidney-Asthenia, the effects of Zuoguiyin and Yishenhao on RNA transcription activity in isolated nuclei and protein synthesis activity in free-cell extracts of the liver, brain, kidney and testes of the presenile mice were observed. RESULTS: RNA transcription activity in isolated nuclei and protein synthesis activity in free-cell extracts of the four organs of the presenile mice group were distinctly lower than those of young mice group (3 months old). After above-mentioned two prescriptions were given to the presenile mice for two months, RNA transcription activity in isolated nuclei and protein synthesis activity in free-cell extracts of the four organs of the two treated groups were obviously higher than those of control group (P < 0.05 or P < 0.01), but there was no difference between two treated groups. CONCLUSIONS: Both Zuoguiyin and Yishenbao could promote RNA transcription activity in isolated nuclei and protein synthesis activity in free-cell extracts of Kidney-Asthenia and presenile mice.

Aging↗
PubMed1998

Effects of radiation on wound healing.

The pathological changes of radiation on wound healing in rats were observed by macroscopic, microscopic, and electronmicroscopic examination and detection of collagen types. We found that the wound healing process was obviously delayed by irradiation. First, the early phase inflammatory response was severely inhibited. In particular, the number of infiltrating macrophages and neutrophils was decreased, blood vessels were injured, and hemorrhage was evident. Second, the formation and maturation of granulation tissue were slowed down, fibroblasts were injured, and transcription of types and collagen mRNAs and synthesis and secretion of collagen were reduced. Finally, the reepithelialization process was delayed and the healing time was prolonged.

Animals↗
PubMed1997

Probing the structure of the diphtheria toxin channel. Reactivity in planar lipid bilayer membranes of cysteine-substituted mutant channels with methanethiosulfonate derivatives.

Previous work has established that the 61 amino acid stretch from residue 322 to 382 in the T-domain of diphtheria toxin forms channels indistinguishable in ion-conducting properties from those formed by the entire T-domain. In the crystal structure of the toxin's water-soluble form, the bulk of this stretch is an alpha-helical hairpin, designated TH8-9. The present study was directed at determining which residues in TH8-9 line the ion-conducting pathway of the channel; i.e., its lumen or entrances. To this end, we singly mutated 49 of TH8-9's 51 residues (328-376) to cysteines, formed channels with the mutant T-domain proteins in planar lipid bilayers, and then determined whether they reacted with small, charged, lipid-insoluble, sulfhydryl-specific methanethiosulfonate (MTS) derivatives added to the bathing solutions. The indication of a reaction, and that the residue lined the ion-conducting pathway, was a sudden change in single-channel conductance and/or flickering behavior. The results of this study were surprising in two respects. First, of the 49 cysteine-substituted residues in TH8-9 tested, 23 reacted with MTS derivatives in a most unusual pattern consisting of two segments: one extending from 329 to 341 (11 of 13 reacted), and the other from 347 to 359 (12 of 13 reacted); none of the residues outside of these two segments appeared to react. Second, in every cysteine mutant channel manifesting an MTS effect, only one transition in single-channel conductance (or flickering behavior) occurred, not the several expected for a multimeric channel. Our results are not consistent with an alpha-helical or beta-strand model for the channel, but instead suggest an open, flexible structure. Moreover, contrary to common sense, they indicate that the channel is not multimeric but is formed from only one TH8-9 unit of the T-domain.

Amino Acid Sequence↗
PubMed1996

Organization of diphtheria toxin T domain in bilayers: a site-directed spin labeling study.

The diphtheria toxin transmembrane (T) domain was spin-labeled at consecutive residues in a helical segment, TH9. After binding of the T domain to membranes at low pH, the nitroxide side chains generated by spin labeling were measured with respect to their frequency of collision with polar and nonpolar reagents. The data showed that the helical structure of TH9 in solution is conserved, with one face exposed to water and the other to the hydrophobic interior of the bilayer. Measurement of the depth of the nitroxide side chains from the membrane surfaces revealed an incremental change of about 5 angstroms per turn, which is consistent with a transmembrane orientation of an alpha helix. These results indicate that the helix forms the lining of a transmembrane water-filled channel.

Amino Acid Sequence↗
PubMed1996

Effect of mutation of potassium-efflux system, KefA, on mechanosensitive channels in the cytoplasmic membrane of Escherichia coli.

The effect of a kefA mutation on the mechanosensitive channels in the cytoplasmic membrane of Escherichia coli was established by introducing a mutation of the kefA gene into wild-type E. coli by P1 transduction. The mutation of the kefA gene not only made the cells sensitive to K+ in the medium but also changed the mechanosensitive channel activity. The kefA mutation did not change the conductances of the two mechanosensitive channels in the cytoplasmic membrane of E. coli, but it prolonged the channel open time. Also, the kefA mutation made the cells more sensitive to pressure in comparison to wild-type cells. The high sensitivity to pressure of the kefA mutant was not modulated by betaine or by the potassium gradient across the membrane. The effect of the kefA mutation on mechanosensitive channels was not due to a membrane fluidity change. KefA might be a regulator for mechanosensitive channels.

Biomechanical Phenomena↗
PubMed1995

Characterization of mechanosensitive channels in Escherichia coli cytoplasmic membrane by whole-cell patch clamp recording.

Whole-cell patch clamp recordings were done on giant protoplasts of Escherichia coli. The pressure sensitivity of the protoplasts was studied. Two different unit conductance mechanosensitive channels, 1100 +/- 25 pS and 350 +/- 14 pS in 400 mM symmetric KCl solution, were observed upon either applying positive pressure to the interior of the cells or down shocking the cells osmotically. The 1100 pS conductance channel discriminated poorly among the monovalent ions tested and it was permeable to Ca2+ and glutamate-. Both of the two channels were sensitive to the osmotic gradient across the membrane; the unit conductances of the channels remained constant while the mean current of the cell was increased by increasing the osmotic gradient. Both of the channels were voltage sensitive. Voltage-ramp results showed that the pressure sensitivity of protoplasts was voltage dependent: there were more channels active upon depolarization than hyperpolarization. The mechanosensitive channels were reversibly blocked by gadolinium ion. Also they could reversibly be inhibited by protons. Mutations in two of the potassium efflux systems, KefB and KefC, did not affect the channel activity, while a null mutation in the gene for KefA changed the channel activity significantly. This indicates a potential modulation of these channels by KefA.

Antiporters↗
PubMed1995

Peripherin assembles into homopolymers in SW13 cells.

The properties of full-length and mutant peripherins were studied in intermediate filament-less SW13 cells to define regions of peripherin that are essential for initiation of filament assembly. A full-length rat peripherin gene transfected into SW13 cells resulted in filament formation, consistent with the close structural relationship of peripherin to other type III intermediate filament proteins that readily form homopolymers. Translation of full-length rat peripherin is initiated predominantly at the second of two inframe AUGs. Deletions within the amino terminus of wild-type peripherin abolished its ability to form filaments in SW13 cells. In contrast, deletion of the entire carboxyl-terminal tail of peripherin did not affect its ability to form filamentous arrays in transfected SW13 cells. These results indicate that, of the intermediate filament proteins that are expressed in mature neurons, only peripherin and alpha-internexin are capable of making homopolymer intermediate filaments. In addition, mutations of the carboxyl tail of peripherin generally do not interfere with filament network formation.

Animals↗
PubMed1995

[Antidepressant active constituents in the roots of Morinda officinalis How].

Five compounds having antidepressant activities have been isolated from the roots of Morinda officinalis, a Chinese traditional Yang-tonic drug. These compounds were identified as succinic acid (1), nystose (2), 1F-fructofuranosylnystose (3), inulin-type hexasaccharide (4) and heptasaccharide (5) by chemical and spectroscopic methods. All of the compounds are isolated from the species of genus Morinda for the first time.

Animals↗
PubMed1994

Interaction of the protein kinase Raf-1 with 14-3-3 proteins.

Members of a family of highly conserved proteins, termed 14-3-3 proteins, were found by several experimental approaches to associate with Raf-1, a central component of a key signal transduction pathway. Optimal complex formation required the amino-terminal regulatory domain of Raf-1. The association of 14-3-3 proteins and Raf-1 was not substantially affected by the activation state of Raf.

14-3-3 Proteins↗