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Biomedical subjects

Fan Zhang

Publications and source records attributed to Fan Zhang.

At least 55 records · Page 3Linked to original sources
PubMed2006

Production of NAADP and its role in Ca2+ mobilization associated with lysosomes in coronary arterial myocytes.

The present study was designed to determine the production of nicotinic acid adenine dinucleotide phosphate (NAADP) and its role associated with lysosomes in mediating endothelin-1 (ET-1)-induced vasoconstriction in coronary arteries. HPLC assay showed that NAADP was produced in coronary arterial smooth muscle cells (CASMCs) via endogenous ADP-ribosyl cyclase. Fluorescence microscopic analysis of intracellular Ca2+ concentration ([Ca2+]i) in CASMCs revealed that exogenous 100 nM NAADP increased [Ca2+]i by 711 +/- 47 nM. Lipid bilayer experiments, however, demonstrated that NAADP did not directly activate ryanodine (Rya) receptor Ca2+ release channels on the sarcoplasmic reticulum. In CASMCs pretreated with 100 nM bafilomycin A1 (Baf), an inhibitor of lysosomal Ca2+ release and vacuolar proton pump function, NAADP-induced [Ca2+]i increase was significantly abolished. Moreover, ET-1 significantly increased NAADP formation in CASMCs and resulted in the rise of [Ca2+]i in these cells with a large increase in global Ca2+ level of 1,815 +/- 84 nM. Interestingly, before this large Ca2+ increase, a small Ca2+ spike with an increase in [Ca2+]i of 529 +/- 32 nM was observed. In the presence of Baf (100 nM), this ET-1-induced two-phase [Ca2+]i response was completely abolished, whereas Rya (50 microM) only markedly blocked the ET-1-induced large global Ca2+ increase. Functional studies showed that 100 nM Baf significantly attenuated ET-1-induced maximal constriction from 82.26 +/- 4.42% to 51.80 +/- 4.36%. Our results suggest that a lysosome-mediated Ca2+ regulatory mechanism via NAADP contributes to ET-1-induced Ca2+ mobilization in CASMCs and consequent vasoconstriction of coronary arteries.

Animals↗
PubMed2006

Structure of nematic liquid crystalline elastomers under uniaxial deformation.

We have used in situ x-ray diffraction and calorimetry to study liquid crystalline elastomers prepared using a one-step photopolymerization method. We used suspended weights to stretch free-standing crystalline elastomer films. With the mechanical stress parallel to the initial director, we observed a gradual nematic to isotropic transition with increasing temperature. The thermal evolution of the nematic order parameter on cooling, together with the observation of isotropic-nematic coexistence over a broad temperature range, suggests that the heterogeneity in the samples introduces a distribution of transition temperatures. With the mechanical stress perpendicular to the initial director, we observed both uniform director rotation and stripe formation, depending on the details of sample preparation.

Journal Article↗
PubMed2006

Development of a parallel demodulation system used for extrinsic Fabry-Perot interferometer and fiber Bragg grating sensors.

A parallel demodulation system for extrinsic Fabry-Perot interferometer (EFPI) and fiber Bragg grating (FBG) sensors is presented, which is based on a Michelson interferometer and combines the methods of low-coherence interference and a Fourier-transform spectrum. The parallel demodulation theory is modeled with Fourier-transform spectrum technology, and a signal separation method with an EFPI and FBG is proposed. The design of an optical path difference scanning and sampling method without a reference light is described. Experiments show that the parallel demodulation system has good spectrum demodulation and low-coherence interference demodulation performance. It can realize simultaneous strain and temperature measurements while keeping the whole system configuration less complex.

Journal Article↗
PubMed2006

Differentiation of three pairs of aconite alkaloid isomers from Aconitum nagarum var. lasiandrum by electrospray ionization tandem mass spectrometry.

Three pairs of isomers of aconite alkaloids from Aconitum nagarum var. lasiandrum have been investigated by electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) employing ion-trap and quadrupole time-of-flight mass spectrometers in positive mode. Based on the differences of their fragmentation pathways and special fragment ions, three pairs of isomers of aconite alkaloids were differentiated. In addition, fragmentation laws of some veatchines and the discrepancy of fragmentation mechanisms between veatchine-type and aconitine-type alkaloid were also concluded. In the case of veatchines, a radical would be formed by homolysis of C18--C4 or C18--H bonds, followed by elimination of a series of C(2)H(2) and C(2)H(4). Moreover, the retro-Diels-Alder (RDA) reaction occurred in the E-ring and double-electron transfer triggered by the positive charge on C1 led to the formation of diagnostic ions at m/z 216. With regard to aconitine-type alkaloids, the N-substituent is not eliminated easily. Although there is no carbonyl group on some aconitine-type alkaloids, with hydroxyl and methoxyl on C15 and C16 respectively, CO was readily eliminated through tautomerization.

Aconitum↗
PubMed2006

QTL mapping of Fusarium moniliforme ear rot resistance in maize. 1. Map construction with microsatellite and AFLP markers.

To map the QTLs of Fusarium moniliforme ear rot resistance in Zea mays L., a total of 230 F2 individuals, derived from a single cross between inbred maize lines R15 (resistant) and Ye478 (susceptible), were genotyped for genetic map construction using simple sequence repeat (SSR) markers and amplified fragment length polymorphism (AFLP) markers. We used 778 pairs of SSR primers and 63 combinations of AFLP primers to detect the polymorphisms between parents, R15 and Ye478. From the polymorphic 30 AFLP primer combinations and 159 SSR primers, we scored 260 loci in the F2 population, among which 8 SSR and 13 AFLP loci could not be assigned to any of the linkage groups. An integrated molecular genetic linkage map was constructed by the remaining 151 SSR and 88 AFLP markers, which distributed throughout the 10 linkage groups of maize and spanned the genome of about 3463.5 cM with an average of 14.5 cM between two markers. On 4 chromosomes, we detected 5 putative segregation distortion regions (SDRs), including 2 new ones (SDR2 and SDR7). The other 3 SDRs were located near the regions where gametophyte genes were mapped, indicating that segregation distortion could be partially caused by gametophytic factors.

Chromosome Mapping↗
PubMed2006

Modulation of dragon's blood on tetrodotoxin-resistant sodium currents in dorsal root ganglion neurons and identification of its material basis for efficacy.

To clarify the modulation of dragon's blood on the tetrodotoxin-resistant (TTX-R) sodium currents in dorsal root ganglion (DRG) neurons and explore its corresponding material basis for the efficacy, using whole-cell patch clamp technique, the effects of dragon's blood and the combined effects of three components (cochinchinenin A, cochinchinenin B, and loureirin B) extracted from dragon's blood on the TTX-R sodium currents in acute-isolated DRG neurons of rats were observed. According to the operational definition of material basis for the efficacy of TCM established, the material basis of the modulation on the TTX-R sodium currents in DRG neurons of dragon's blood was judged from the experimental results. The drug interaction equation of Greco et al. was used to assess the interaction of the three components extracted from dragon's blood. This investigation demonstrated that dragon's blood suppressed the peak TTX-R sodium currents in a dose-dependent way and affected the activations of TTX-R sodium currents. The effects of the combination of cochinchinenin A, cochinchinenin B, and loureirin B were in good agreement with those of dragon's blood. Although the three components used alone could modulate TTX-R sodium currents, the concentrations of the three components used alone were respectively higher than those used in combination when the inhibition rates on the TTX-R sodium currents of them used alone and in combination were the same. The combined effects of the three components were synergistic. These results suggested that the interference with pain messages caused by the modulation of dragon's blood on TTX-R sodium currents in DRG neurons may explain some of the analgesic effect of dragon's blood and the corresponding material basis for the efficacy is the combination of cochinchinenin A, cochinchinenin B, and loureirin B.

Animals↗
PubMed2006

AsialoGM1-mediated IL-8 release by human corneal epithelial cells requires coexpression of TLR5.

PURPOSE: In this study, it was determined that human corneal epithelial cells (HCECs) express asialoganglioside ganliotetraosylceramide (asialoGM1) and toll-like receptor (TLR)-5, and their interaction induces interleukin (IL)-8 release through Ca(2+) transient activation and mitogen-activated protein kinase (MAPK) stimulation. METHODS: Expression of asialoGM1 and TLR5 was detected in SV40 HCECs by Western blot and flow cytometry analyses and their association by coimmunoprecipitation. Single-cell fluorescence imaging was used to measure intracellular free Ca(2+) transients in fura-2-loaded cells. The enzyme-linked immunosorbent assay (ELISA) was used to quantify IL-8 production in both cultured and primary HCECs. RESULTS: The HCECs expressed both asialoGM1 and TLR5 receptors. Ligation of asialoGM1 resulted in protein-protein interaction with TLR5, followed by transient increases in Ca(2+) influx through L-type voltage-dependent Ca(2+) channels. This led to P2Y receptor stimulation along with membrane depolarization, resulting from increases in ATP release into the medium. Intracellular Ca(2+) transients led to time-dependent extracellular signal-regulated kinase (ERK) MAPK pathway stimulation, followed by a 9.5-fold increase in IL-8 release. Similarly, in primary HCECs, asialoGM1 receptor stimulation resulted in an 8.1-fold increase. With a TLR5 neutralizing antibody, no asialoGM1-induced increases in IL-8 release occurred, and this response was not suppressed in the presence of a TLR2 neutralizing antibody. CONCLUSIONS: IL-8 release by HCECs is mediated through ligand-induced asialoGM1 protein-protein interactions with TLR5. This response is dependent on ATP efflux into the medium, followed by P2Y receptor stimulation. Such activation, in turn, results in increases in Ca(2+) influx through L-type voltage-dependent Ca(2+) channels, as well as stimulation of the ERK pathway.

Adenosine Triphosphate↗
PubMed2006

PKC isoform-specific enhancement of capacitative calcium entry in human corneal epithelial cells.

PURPOSE: To determine in human corneal epithelial cells (HCECs) the role of protein kinase C (PKC) in mediating epidermal growth factor (EGF)-induced stimulation of store-operated channel (SOC) activity and capacitative calcium entry (CCE). METHODS: Single-cell Ca2+ fluorescence imaging of fura2-loaded HCECs was used to evaluate CCE. PKC translocation induced by EGF or PDBu was monitored by Western blot analyses of four different subcellular fractions. Plasma membrane Ca2+ influx was measured by Mn2+ quench rates of fura2-fluorescence. The whole-cell patch clamp configuration was used to determine the SOC activation induced by EGF. RESULTS: EGF-induced increases in SOC currents through PKC stimulation, since calphostin C inhibited this response. To determine which PKC isoforms mediated EGF-induced increases in CCE, the PKC isoform enrichment of a plasma membrane-containing fraction was determined. From 5 to 30 minutes, its rank order of enrichment was: delta > betaI > alpha approximately epsilon. Preferential PKCdelta and PKCbeta translocation was in accordance with other results showing that rottlerin and hispidin have the highest efficacy in suppressing EGF-induced CCE augmentation. Furthermore, after PKCbeta and PKCdelta siRNA knockdown of gene and protein expression, declines in EGF-induced increases in CCE matched those obtained after exposure to a corresponding selective PKC isoform inhibitor. CONCLUSIONS: EGF-induced PKC stimulation in HCECs mediates SOC activation. This response contributes to CCE, which preferentially depends on PKCdelta and PKCbeta isoform stimulation. This rank order is based on the findings that either selective knockdown of their expression or exposure to PKCdelta and PKCbeta isoform inhibitors elicited the largest declines in EGF-augmented CCE.

Blotting, Western↗
PubMed2006

Thrombospondins deployed by thrombopoietic cells determine angiogenic switch and extent of revascularization.

Thrombopoietic cells may differentially promote or inhibit tissue vascularization by releasing both pro- and antiangiogenic factors. However, the molecular determinants controlling the angiogenic phenotype of thrombopoietic cells remain unknown. Here, we show that expression and release of thrombospondins (TSPs) by megakaryocytes and platelets function as a major antiangiogenic switch. TSPs inhibited thrombopoiesis, diminished bone marrow microvascular reconstruction following myelosuppression, and limited the extent of revascularization in a model of hind limb ischemia. We demonstrate that thrombopoietic recovery following myelosuppression was significantly enhanced in mice deficient in both TSP1 and TSP2 (TSP-DKO mice) in comparison with WT mice. Megakaryocyte and platelet levels in TSP-DKO mice were rapidly restored, thereby accelerating revascularization of myelosuppressed bone marrow and ischemic hind limbs. In addition, thrombopoietic cells derived from TSP-DKO mice were more effective in supporting neoangiogenesis in Matrigel plugs. The proangiogenic activity of TSP-DKO thrombopoietic cells was mediated through activation of MMP-9 and enhanced release of stromal cell-derived factor 1. Thus, TSP-deficient thrombopoietic cells function as proangiogenic agents, accelerating hemangiogenesis within the marrow and revascularization of ischemic hind limbs. As such, interference with the release of cellular stores of TSPs may be clinically effective in augmenting neoangiogenesis.

Animals↗
PubMed2006

Real-time polymerase chain reaction for the rapid detection of group B streptococcal colonization in neonates.

BACKGROUND: Group B streptococcal (GBS) infection remains a leading cause of neonatal sepsis. Currently, the management guidelines of neonates born to women with unknown GBS status at delivery are unclear. In this cohort, who undergo at least a 48-hour observation, a rapid method of detection of GBS colonization would allow targeted evaluation and treatment, as well as prevent delayed discharge. OBJECTIVE: The goal of this research was to evaluate the validity of rapid fluorescent real-time polymerase chain reaction in comparison with standard culture to detect GBS colonization in infants born to women whose GBS status is unknown at delivery. DESIGN/METHODS: Neonates at >32 weeks' gestation born to women whose GBS status was unknown at delivery were included. Samples were obtained from the ear, nose, rectum, and gastric aspirate for immediate culture and real-time polymerase chain reaction after DNA extraction using the LightCycler. Melting point curves were generated, and confirmatory agar gel electrophoresis was performed. RESULTS: The study population (n = 94) had a mean +/- SD gestational age of 38 +/- 2 weeks and birth weight of 3002 +/- 548 g. The rates of GBS colonization by culture were 17% and 51% by real-time polymerase chain reaction. The 4 surface sites had comparable rates of GBS. The overall sensitivities, specificities, and positive and negative predictive values of real-time polymerase chain reaction were: 90%, 80.3%, 28%, and 98.9%. CONCLUSIONS: Real-time polymerase chain reaction resulted in a threefold higher rate of detection of GBS colonization and had an excellent negative predictive value in a cohort of neonates with unknown maternal GBS status at delivery. Thus, real-time polymerase chain reaction would be a useful clinical tool in the management of those infants potentially at risk for invasive GBS infection and would allow earlier discharge for those found to be not at risk.

Adult↗
PubMed2006

Development and clinical evaluation of oligonucleotide microarray for HLA-AB genotyping.

BACKGROUND: The antigens encoded by human leukocyte antigen (HLA) genes are primary antigens in immunological response of transplantation, and genotypes of HLA-A, B and DRB1 must be determined on donors and recipients before the transplantation is carried out. In this study, oligonucleotide microarray for HLA-AB genotyping was prepared and evaluated. METHODS: Oligonucleotide probes were designed based on the sequence of the different genotypes of HLA-A and B and were fixed on silylated glass slides to form a microarray. Fluorescence-labeled target DNA was obtained by asymmetric polymerase chain reaction amplification of exon 2 and exon 3 of HLA-A and -B genes and hybridized to the microarray. The hybridized microarray was subsequently scanned and the result was analyzed by software in order to determine the genotypes of the tested sample. RESULTS: The sensitivity of the microarray for HLA-AB genotyping was 10 ng/microl, with a coincidence rate of 100% with international reference, and a combined variation value of detected signal below 15%. Analysis of genotyping of 1295 cases of clinical samples showed that the general coincidence rate between the microarray method and conventional method (polymerase chain reaction-sequence-specific primer and flow cytometry reverse polymerase chain reaction sequence-specific oligonucleotide) was HLA-A: 99.61% and HLA-B: 98.30%, respectively. A total of five out of seven samples that had conflicting results of genotypes were proved to be microarray-assay reliable by DNA sequencing, suggesting a higher accuracy of the microarray method. CONCLUSION: The microarray for HLA-AB genotyping is satisfactory for clinical use in HLA-AB genotyping with its good specificity, sensitivity and reproducibility.

DNA Probes↗
PubMed2006

[Clinical effect of modified forsus appliance to children with mandibular retrusion].

OBJECTIVE: To evaluate the effects of modified Forsus appliance in the treatment of Class II mandibular retrusion. METHODS: 18 children with mandibular retrusion were selected and treated with modified Forsus appliance. Cephalometric radiographs were taken and analyzed at pre-treatment and post-treatment. Students' t-test was used to determine if there were significant differences between pre-treatment and post-treatment. RESULTS: After 6-8 months of therapy, profiles were obviously improved. B moved forward (2.9+/-3.1) mm. ANB decreased (2.5+/-1.2) degrees. The overjet decreased (5.0+2.8) mm. The molar relationship was corrected to Class I from Class II. SN-OL increased (4.3+2.2) degrees. There was significant difference between pre-treatment and post-treatment. CONCLUSION: Combined with straight wire appliance, modified Forsus appliance can effectively stimulate the mandibular growth, balance the jaw relationship, and correct mandibular retrusion.

Cephalometry↗
PubMed2006

[Comparison of the treatment effects of two molar distal movement appliances: pendulum appliance and face-bow].

PURPOSE: To compare the treatment effects of pendulum appliance and traditional face-bow for distal movement of maxillary first molars. METHODS: Samples (n=30) were randomly divided into two groups, of which Group P was treated with pendulum appliance, while Group F with traditional face-bow. Cephalometric radiographs were taken and analyzed by Pancherz at the pre-treatment time (T1) and the post-treatment time (T2). Student's t test was used to determine if there were significant differences between the 2 time periods and two groups. RESULTS: There was significant difference between Group P and Group F in the treatment duration (20.6+/-4.0 weeks vs 26.0+/-3.6 weeks). There was also significant difference in the changes of (ms/olp- ss/olp) (3.1+/-0.53 mm vs 2.2+/-0.82 mm), (is/olp- ss/olp) (0.8+/-0.78 mm vs-1.0+/-0.88 mm) between the two groups. CONCLUSION: The results indicate that pendulum appliance is clinically more effective and rapid for distal movement of the maxillary first molars, but more attention should be paid to the anchorage control of maxillary anterior teeth.

Cephalometry↗
PubMed2006

[Knockout of the hprK gene in B. subtilis CcpA mutant and its influence on riboflavin fermentation].

In Bacillus subtilis , raising the amount of carbon catabolite in vivo would lead to carbon catabolite repression (CCR) and restrain the absorption of glucose. By deleting CcpA the CCR effect could be relieved, but the absorption of glucose remains restrained. The phosphoenol-pyruvate-sugar phosphotransferase system (PTS) is the main glucose transportation system in B. subtilis. HPr protein together with HprK/P participate in the glucose transportation. The HPr protein is phosphorylated at His-15 forming HPr-His-15-P transferring phosphate group from HPr to E II . While HprK/P phosphorylate HPr at Ser-46 forming HPr-Ser-46-P. HPr-Ser-46-P cannot participate in the transportation of glucose. The Knockout of ccpA gene increases the amount of fructose 1,6-bisphosphate(FBP) in vivo. And FBP could activate HPr kinase. So when CcpA is deleted, most part of the HPr will be phosphorylated at Ser-46. Absorpton of glucose is blocked. In this study, by disruption of hprk gene, the obtained B. subtilisZHc/pMX45 reaches the peak riboflavin production of 4.374mg/mL at the optimum glucose concentration of 10%, 19.2% higher than that of B. subtilis24 A1/pMX45 at the optimum glucose concentration of 8%.

Bacillus subtilis↗
PubMed2006

[Controlled study on treatment of cervical spondylopathy of the nerve root type with acupuncture, moxibustion and massage as main].

OBJECTIVE: To probe into clinical value of comprehensive program of acupuncture, moxibustion and massage as main for treatment of cervical spondylopathy of the nerve root type. METHODS: Five centers, single blind, randomized controlled method were used, 660 cases were divided into a treatment group of 317 cases and a control group of 311 cases. They were treated respectively with comprehensive program of acupuncture, moxibustion and massage as main, and comprehensive program of physical therapy as main. Establish syndrome detection scale and multiply dimensional effect assessment indexes, and evaluate the therapeutic effects and safety. RESULTS: The cured rate, the cured-markedly effective rate were 42.9%, 64.4% in the treatment group, respectively, better than 16.7%, 36.3% in the control group (P<0.01); after treatment of 2 weeks, clinical symptoms improved in the both groups, but the treatment group was better than the control group in the improvement degrees of neck-shoulder-limb pain, neck rigidity, abnormality of cervical anteflexion, etc. (P<0.01 or P<0.05); the treatment group was shorter than the control group in the time of producing the effect and therapeutic course (P<0.01). CONCLUSION: Comprehensive program of acupuncture, moxibustion and massage as main is safe and effective for treatment of cervical spondylopathy, with a better therapeutic effect compared with the comprehensive program of physical therapy.

Acupuncture Therapy↗
PubMed2005

P-TEFb is not an essential elongation factor for the intronless human U2 snRNA and histone H2b genes.

Phosphorylation of Ser2 of the heptapeptide repeat of the CTD of mammalian pol II by P-TEFb is associated with productive elongation of transcription of protein-coding genes. Here, we show that the CTD of pol II transcribing the human U2 snRNA genes is phosphorylated on Ser2 in vivo and that both the CDK9 kinase and cyclin T components of P-TEFb are required for cotranscriptional recognition of the 3' box RNA 3' end processing signal. However, inhibitors of CDK9 do not affect transcription of the U2 genes, indicating that P-TEFb functions exclusively as an RNA processing factor in expression of these relatively short, intronless genes. We also show that inhibition of CDK9 does not adversely affect either transcription of an intron-less, replication-activated histone H2b gene or recognition of the histone gene-specific U7-dependent RNA 3' end formation signal. These results emphasize that the role of P-TEFb as an activator of transcription elongation can be separated from its role in RNA processing and that neither function is universally required for expression of mammalian pol II-dependent genes.

Amino Acid Sequence↗
PubMed2005

Characteristics and actions of NAD(P)H oxidase on the sarcoplasmic reticulum of coronary artery smooth muscle.

It has been reported that nonmitochondrial NAD(P)H oxidases make an important contribution to intracellular O2-* in vascular tissues and, thereby, the regulation of vascular function. Topological analyses have suggested that a well-known membrane-associated NAD(P)H oxidase may not release O2-* into the cytosol. It is imperative to clarify the source of intracellular O2-* associated with this enzyme and its physiological significance in vascular cells. The present study hypothesized that an NAD(P)H oxidase on the sarcoplasmic reticulum (SR) in coronary artery smooth muscle (CASM) regulates SR ryanodine receptor (RyR) activity by producing O2-* locally. Western blot analysis was used to detect NAD(P)H oxidase subunits in purified SR from CASM. Fluorescent spectrometric analysis demonstrated that incubation of SR with NADH time dependently produced O2-*, which could be substantially blocked by the specific NAD(P)H oxidase inhibitors diphenylene iodonium and apocynin and by SOD or its mimetic tiron. This SR NAD(P)H oxidase activity was also confirmed by HPLC analysis of conversion of NADH to NAD+. In experiments of lipid bilayer channel reconstitution, addition of NADH to the cis solution significantly increased the activity of RyR/Ca2+ release channels from these SR preparations from CASM, with a maximal increase in channel open probability from 0.0044 +/- 0.0005 to 0.0213 +/- 0.0018; this effect of NADH was markedly blocked in the presence of SOD or tiron or the NAD(P)H oxidase inhibitors diphenylene iodonium, N-vanillylnonanamide, and apocynin. These results suggest that a local NAD(P)H oxidase system on SR from CASM regulates RyR/Ca2+ channel activity and Ca2+ release from SR by producing O2-*.

Animals↗