Biomedical subjects

Min Chen

Publications and source records attributed to Min Chen.

At least 199 records · Page 11Linked to original sources

PubMed2003

The hepatic retinyl ester hydrolase activity is depressed at the onset of diabetes in BB rats.

Dietary vitamin A as retinyl ester is hydrolysed and re-esterified with long-chain fatty acids in the small intestine. The esterified vitamin A is subsequently stored in the liver, where it is hydrolysed to free retinol to be transported by carrier proteins to the target tissue. A decreased availability of retinol carrier proteins has been suggested to be responsible for affecting metabolic availability of vitamin A in type 1 diabetes. Using BB Wistar rats, the present study was undertaken to examine whether the presence of a hyperglycaemic state modifies retinyl ester hydrolase (REH) activity in the intestine and the liver. At the onset of diabetes, hepatic REH enzymatic activity was significantly decreased. However, REH activity remained unaffected in the small intestine, including both ileum and jejunum. Diabetes also resulted in decreased plasma and liver concentrations of retinol. An in vitro study was conducted to examine the effect of diabetes on the intestinal uptake of retinyl palmitate. Jejunum and ileum from diabetic and non-diabetic BB rats were incubated with labelled retinyl palmitate at different concentrations ranging from 32 to 256 nmol/l. The uptake of retinyl palmitate was increased in both diabetic and non-diabetic rats together with the increase of substrate concentration. However, no significant difference was observed in the uptake of retinyl palmitate between diabetic and non-diabetic rats. These present results suggest that the depressed hepatic REH activities may contribute to the diabetes-associated metabolic derangement of vitamin A.

Animals↗

PubMed2003

Molecular determination of agouti-related protein binding to human melanocortin-4 receptor.

Agouti-related protein (AGRP) is an endogenous antagonist of the melanocortin-4 receptor (MC4R) that functions in the hypothalamic control of feeding behavior. Our previous studies have suggested that in addition to exoloops 2 and 3, several transmembrane domains of MC4R may be important for AGRP binding. However, the detailed molecular basis of MC4R domains in AGRP binding is presently unclear. The present studies were designed to determine the specific contribution of MC4R exoloops and transmembrane domains to AGRP binding by using chimeric receptor constructs of the human melanocortin-1 receptor (hMC1R), a receptor that is not inhibited by AGRP, and the human MC4R (hMC4R), a receptor that is potently inhibited by AGRP. Our results indicate that substitutions of the second and third extracellular loops of the MC4R with homologous domains of the MC1R dramatically decreased AGRP 87-132 binding affinity, but did not affect AGRP 110-117 binding affinity. In contrast, cassette substitutions of the third or fourth transmembrane domain of the MC4R with the homologous domain of the MC1R resulted in a substantial decrease of AGRP 87-132 binding affinity and loss of AGRP 110-117 binding affinity. These data suggest that the AGRP fragment 110-117 has no binding sites at exoloops of hMC4R and that transmembrane domains of MC4R may play an important role in AGRP 110-117 binding and function, whereas the exoloops do not. The second and third extracellular loops of MC4R are important for AGRP 87-132 N-terminal binding, whereas the third and fourth transmembrane domains of hMC4R are crucial for AGRP 110-117 binding.

Agouti-Related Protein↗

PubMed2003

Analytical solution for irradiance due to inhomogeneous Lambertian polygonal emitters.

We present an analytic solution for the irradiance at a point due to a polygonal Lambertian emitter with radiant exitance that varies with position according to a polynomial of arbitrary degree. This is a basic problem that arises naturally in radiative transfer and more specifically in global illumination, a subfield of computer graphics. Our solution is closed form except for a single nonalgebraic special function known as the Clausen integral. We begin by deriving several useful formulas for high-order tensor analogs of irradiance, which are natural generalizations of the radiation pressure tensor. We apply the resulting tensor formulas to linearly varying emitters, obtaining a solution that exhibits the general structure of higher-degree cases, including the dependence on the Clausen integral. We then generalize to higher-degree polynomials with a recurrence formula that combines solutions for lower-degree polynomials; the result is a generalization of Lambert's formula for homogeneous diffuse emitters, a well-known formula with many applications in radiative transfer and computer graphics. Similar techniques have been used previously to derive closed-form solutions for the irradiance due to homogeneous polygonal emitters with directionally varying radiance. The present work extends this previous result to include inhomogeneous emitters, which proves to be significantly more challenging to solve in closed form. We verify our theoretical results with numerical approximations and briefly discuss their potential applications.

Journal Article↗

PubMed2003

Examination of the photophysical processes of chlorophyll d leading to a clarification of proposed uphill energy transfer processes in cells of Acaryochloris marinas.

A comprehensive study of the photophysical properties of chlorophyll (Chl) d in 1:40 acetonitrile-methanol solution is performed over the temperature range 170-295 K. From comparison of absorption and emission spectra, time-dependent density-functional calculations and homologies with those of Chl a, we assign the key features of the absorption and fluorescence spectra. Possible photophysical energy relaxation mechanisms are summarized, and thermal equilibration processes are studied in detail by monitoring the observed emission profiles and quantum yields as a function of excitation energy. In particular, we concentrate on emission subsequent to excitation in the extreme far-red tail of the Qy absorption spectrum, with this emission partitioned into contributions from hot-band absorptions as well as uphill energy transfer processes that occur subsequent to absorption. No unusual photophysical processes are detected for Chl d; it appears that all intramolecular relaxation processes reach thermal equilibration on shorter timescales than the fluorescence lifetime even at 170 K. The results from these studies are used to reinterpret a previous study of photochemical processes observed in intact cells and their acetone extracts of the photosynthetic system of Acaryochloris marina. In the study of Mimuro et al., light absorbed by Chl d at 736 nm is found to give rise to emission by another species, believed to also be Chl d, at 703 nm; this uphill energy transfer process is easily rationalized in terms of the thermal equilibration processes that we deduced for Chl d. However, no evidence is found in the experimental results of Mimuro et al. to support claims that (nonequilibrium) uphill energy transfer is additionally observed to Chl a species that emit at 670-680 nm. This finding is relevant to broader issues concerning the nature of the special pair in photosystem II of A. marina because suggestions that it is comprised of Chl a can only be correct if nonthermal uphill energy transfer processes from Chl d are operative.

Chlorophyll↗

PubMed2003

[Clinical research on the treatment effect of autologous dendritic cell vaccine on the patients with chronic hepatitis B].

OBJECTIVE: To investigate the treatment effect of autologous HBsAg-loaded dendritic cells (DCs) on patients with chronic hepatitis B (CHB). METHODS: Monocytes were isolated from fresh peripheral blood of 19 CHB patients by Ficoll-Hypaque density gradient centrifugating and cultured with plastic -adherence method. DCs were induced and proliferated from the monocytes with granulocyte-macrophage clony stimulating factor (GM-CSF) and interleukin-4 (IL-4) for seven days. After being incubated with HBsAg for two hours, DCs were injected to patients subcutaneously twice at the interval of two weeks. HBV DNA level, alanine aminotransferase (ALT) level, and HBV markers in the serum of patients were tested every two months. RESULTS: 11 of the 19 (57.9%) patients responded to DC-treatment clinically. The rates of HBeAg clearance and HBeAg/anti-HBe seroconversion were 52.6% (10/19) and 26.3% (5/19) respectively, and the copies of HBV DNA decreased by 10(1.77 2.39) (t = 3.13, P < 0.01). Two patients who were treated in combination with lamivudine had complete clinical response. There was no difference in the trial effect between the DC treatment and the other two antiviral methods, and in the efficient rate between the patients whose ALT levels were high before treatment and those whose ALT levels were normal. CONCLUSION: The autologous HBsAg-loaded DCs can effectively suppress HBV replication, reduce virus load in serum, eliminate HBeAg and promote HBeAg/ anti-HBe seroconversion. The patients whose ALT levels are high or normal can response clinically to DCs treatment. DCs in combination with lamivudine can eliminate virus more effectively.

Adjuvants, Immunologic↗

PubMed2003

[Heat shock protein 70-HBsAg complex inducing antigen-specific cytotoxic T lymphocyte immune response].

OBJECTIVE: To explore the possibility of cell-medicated immune response induced with heat shock protein 70 (HSP70)-HBsAg protein complex in vitro. METHODS: HSP70-HBsAg complex was reconstituted in vitro which was injected into mice in order to observe that whether HSP70-HBsAg would stimulate humoral and cellular immune responses. HSP70, HSP70-HBsAg complex and HBsAg were used to activate the dentritic cell (DC) individually, which would initiate homogeneic T lymphocyte to transform to cytotoxic T lymphocyte (CTL). The cytotoxicity of CTL was detected with MTT assay. RESULTS: HSP70-HBsAg complex elicited both humoral and cellular immune responses against HBsAg in mice. Specific CD8+ CTL response was readily induced by HSP70-HBsAg complex and HBsAg, especially the former. CONCLUSIONS: HSP70-HBsAg complex is immunogenic and HSP70 can lead to great efficient CTL response. And HSP70-HBsAg complex may be used as a protein vaccine for immunotherapy for chronic hepatitis B.

Animals↗

PubMed2003

[Endoscope-assisted supraorbital keyhole approach for excision of suprasellar region tumor].

OBJECTIVE: To study endoscope-assisted microsurgical technique with supraorbital keyhole approach for the treatment of suprasellar region tumor so as to maximize tumor removal and minimize operative-trauma. METHODS: According to high resolution CT and MR images before operation, individual operation schemes were worked out. Skin incision was made in the eyebrow, and the diameter of supraorbital craniotomy was approximately 2 cm. Endoscope-assisted microsurgical technique was used to resect lesions in 16 consecutive patients. RESULTS: Total Tumors were removed in all of the 16 patients via the supraorbital keyhole approach. No postoperative complications occurred. CONCLUSIONS: Supraorbital keyhole approach may diminish tissue injury considerably and has proven to provide sufficient operating space in the suprasellar region for tumor removal.

Adolescent↗

PubMed2003

[The effects of ginaton on cochlear microcirculation].

OBJECTIVE: This study was undertaken to investigate the effects of Ginaton, a kind of extract of gingko biloba with vasoactive, on cochlear blood flow, and to provide the experimental basis for the clinical drug usage. METHOD: Ninety-six guinea pigs were divided into two groups at random, 56 for intravenous infusion (i.v.) group, and 40 for round window membrane (RWM) application group. According to the preliminary results, i.v. group had five subgroups: control, 2.8 mg/kg, 3.5 mg/kg, 3.85 mg/kg, 4.2 mg/kg. RWM group had four sub-groups: control, 3.5 g/L, 0.35 g/L, 0.035 g/L. Ginaton and vehicle were infused through the cervical vein by micropump in 5 minutes. In RWM group, 2 microliters vehicle were dropped into RWM. Cochlear microcirculation was monitored by laser doppler flowmeter (LDF), and mean arterial blood pressure (MABP), which transferred by force transducers and preamplifier, were simultaneously recorded at the computer. RESULT: Cochlear blood flow (CBF) decreased 4.95% and CMBC decreased 6.32% in 3.5 g/L RWM group, and in 0.35 g/L RWM group, these two figures decreased individually 4.75%, 7.61%. In control and 2.8 mg/kg group cochlear microcirculation and MABP had no significant changes. In other i.v. groups, CBF increased 4.53%, 5.21%, 6.65% after 3.5 mg/kg, 3.85 mg/kg, 4.2 mg/kg drugs had been infused, and dosage-effect relation existed. Only in 3.85 mg/kg group, MABP decreased 8.69%. CONCLUSION: Ginaton could improve CBF in a limited dosage range, and this increase showed dose-dependent relation. The mechanism that Ginaton affected the cochlear microcirculation was different because of the way of drug usage.

Administration, Topical↗

PubMed2003

[Three-dimensional structure of collagen fibril of pigskin].

OBJECTIVE: To probe deply into the three-dimensional structure of pigskin collagen fibril and provide the basic data for using the pigskin tissue as tissue engineering material. METHODS: Scanning Probe Microscope (SPM) and Transmission Electron Microscope (TEM) were employed to study the three-dimensional structure of collagen fibril in pigskin tissue. RESULTS: Microscopy revealed that pigskin collagen fibril had periodic transverse groove (i.e. D-periodicity) which was about 67 nm. The diameter of fibril ranged from 57 to 135 nm, showing much difference among the papillary layer, reticular layer and infra-reticular layer. The length of fibril varied from 5 to 13 microns. Both ends of fibril were rotund and slightly bulgy. The fibrils assembled and the D-periodicities were homologous in flank. In axial direction fibrils were found staggered end by end. CONCLUSION: The data obtained in this study on the three-dimensional structure of pigskin collagen fibril are of significance to researches in tissue engineering materials.

Animals↗

PubMed2003

Shenfu injection reduces toxicity of bupivacaine in rats.

OBJECTIVE: To investigate the effects of injecting Shenfu, an extract of traditional Chinese herbal medicines, on the central nervous system (CNS) and the cardiac toxicity of bupivacaine in rats. METHODS: Sixteen male Sprague-Dawley rats, weighing form 280 to 320 g, were randomly assigned to two groups (n = 8 in each group). Animals in the control group received a saline injection 10 ml/kg while animals in the Shenfu group received an injection of Shenfu 10 ml/kg intraperitoneally 30 minutes before intravenous infusion of bupivacaine. Lead II of an electrocardiogram (EEG) was continuously monitored after 3 needles were inserted into the skin of both forelimbs and the left hind-leg of each rat. The femoral artery was cannulated for measurement of arterial blood pressure and blood sampling. The femoral vein was cannulated for the infusion of bupivacaine. After baseline measurement (arterial blood pressure, heart rate and arterial blood gas), 0.5% bupivacaine was infused intravenously at a rate of 2 mg.kg(-1).min(-1) to all animals until asystole occurred. The time of bupivacaine-induced convulsions, arrhythmia and asystole were determined. The dose of bupivacaine was then calculated at the corresponding time point. RESULTS: The doses of bupivacaine that induced convulsions, arrhythmia and cardiac arrest were remarkably larger in Shenfu injection-treated animals than in saline-treated rats [convulsions, (10.5 +/- 1.9) mg/kg vs (7.2 +/- 1.5) mg/kg; arrhythmia (10.5 +/- 2.0) mg/kg vs (7.2 +/- 1.9) mg/kg; asystole, (32.8 +/- 8.5) mg/kg vs (25.0 +/- 5.0) mg/kg; P = 0.006, 0.009 and 0.044, respectively]. CONCLUSION: The Shenfu injection is able to reduce the toxicity of bupivacaine to CNS and cardiac system in rats.

Anesthetics, Local↗

PubMed2003

[Anti-mesangial cell autoantibodies and their target antigens in lupus nephritis].

OBJECTIVE: Anti-mesangial cell autoantibodies (anti-MC) have been reported in patients with IgA nephropathy and Henoch-Schoenlein purpura. The aim of the current study was to identify anti-MC autoantibodies in sera from patients with lupus nephritis (LN). METHODS: 96 serum samples were collected from 96 patients with renal biopsy proven LN. Anti-MC autoantibodies were examined by cellular ELISA and Western blot analysis. In vitro cultured human mesangial cells were used as cell substrate in ELISA and the their soluble proteins in non-reducing conditions were used as antigens in Western-blot analysis. RESULTS: 37.5% and 97.9% of the serum samples from patients with LN had anti-MC autoantibodies in cellular ELISA and Western blot analysis respectively, and 12 protein bands could be blotted by the LN sera in Western blot analysis. The percentage of anti-63 000 autoantibody positive samples was significant higher in female patients than that in the male (59.8% vs 21.4%, P < 0.01). The prevalence of anti-74 000, 46 000, and 36 000 autoantibodies were significantly higher in patients with hematuria than that in patients without hematuria (36.8% vs 5.0%, P < 0.01; 34.2% vs 10.0%, P < 0.05; 31.6% vs 5.0%, P < 0.05; respectively). The prevalence of anti-63 000 autoantibodies was also significantly higher in patients with ANA than that in patients without (67.6% vs 16.7%, P < 0.001). The prevalence of anti-18 000 autoantibodies was significantly higher in patients with anti-dsDNA antibodies than that in patients without (61.5% vs 34.4%, P < 0.05). CONCLUSIONS: There are heterogeneous anti-MC autoantibodies in sera from patients with LN. Anti-MC autoantibodies may have a pathogenic role in lupus nephritis and some anti-MC autoantibodies may be associated with different clinical manifestations.

Adolescent↗

PubMed2003

[Serological characteristics of a hepatitis E outbreak].

OBJECTIVE: To look into the serological characteristics of a hepatitis E outbreak. METHODS: Sera from the first five patients with acute icteric hepatitis who developed the disease successively within ten days and the 1,675 employees routinely having their lunch in a dining hall of a department (outbreak population) were examined for anti.HEV IgM and IgG at 26th days after the outbreak, and the 883 employees of a neighboring department not having their lunch in the hall were selected as control (control population). RESULTS: The five patients were all positive for anti-HEV IgM and IgG. The positive rates of anti-HEV IgM and IgG in outbreak population were 8.7% and 38.4% respectively, both significantly higher than those in control population which were only 0.1% and 28.6%. The numbers with abnormal ALT in the 145 individuals with anti-HEV IgM(+) of outbreak population were significantly higher than those in the IgM(-) individuals of the same group as well as in control, while the abnormal ALT ratio in the IgM(-) individuals of the outbreak was not higher than that in control. The results from the four patients' serial sera showed that the anti-HEV IgM titers declined gradually and were undetectable at about 4th month after infection, and the IgG titers increased to peak in about 2-3 months after infection, then declined very slowly. The mean IgG titer of the anti-HEV IgM(+) individuals was significantly higher than that of the IgM(-) but IgG(+) individuals in outbreak population, and the latter was significantly higher than the IgG(+) individuals in control, which suggested that the post-infection individuals' immunities to HEV were boosted during the outbreak. There was no difference between sex or age groups for the anti-HEV IgM(+) ratio, but the abnormal ALT was much more frequent in the anti-HEV IgM(+) male than in the female, and no difference was observed between age groups. CONCLUSION: The pathogen of the outbreak of acute icteric hepatitis was hepatitis E virus and associated with food intake. Anti-HEV IgM and IgG were used not only for diagnosis of hepatitis E but also for surveilance in mass population. The attack risk was not associated with age or sex, but the abnormal ALT was much more frequent fresh infectors in male.

Adult↗

PubMed2003

[Orange fluorescent protein--modification of green fluorescent protein GFPxm].

Recently, we have reported a new gfp gene isolated from Aequorea macrodactyla. The protein purified from expressed E. coli exhibited an excitation peak at 476 nm and an emission peak at 496 nm. However, the drawback of only maturing to fluorescence at low temperature limited its applications. In this paper, we further describe twelve mutants of GFPxm. Seven mutants produced enhanced fluorescence when expressed in E. coli at higher temperature (37 degrees C). After six hours of induction at 25 degrees C, 32 degrees C and 37 degrees C respectively, the relative fluorescent intensities of GFPxm16, GFPxm18 and GFPxm19 were higher than that of EGFP, moreover GFPxm16 and GFPxm163 could preserve high fluorescent intensity even expressed at 42 degrees C. Four mutants of the seven could reach high expression level in three kind of mammalian cells. Another 6 mutants had red-shift of excitation-emission maxima, and longest excitation-emission maxima were 514nm and 525nm. Another three mutants had two excitation peaks, and one mutant had only one UV-excitation peak. The most exciting result is the mutant of OFPxm with orange color. The mutant has an excitation peak at 509 nm and an emission peak at 523nm. 523nm is yellowish green but the protein is orange observed by eyes. The mutant could reach high expression level and matured at higher temperature but the fluorescent intensity was comparatively low because of low quantum yield.

Animals↗

PubMed2003

[Rapid and efficient expression of foreign genes in mammalian cells by baculovirus vectors].

The baculovirus insect cell expression system has been used extensively for the expression of recombinant proteins in insect cells. Recently, reports have described that recombinant baculoviruses can transduce a broad spectrum of primary and established mammalian cells, which shows the baculoviruses could serve as a new gene-transfer vehicle for mammalian cells. In this report, we further research the modification of baculovirus vector and the way to deliver exogenous gene into mammalian cells. On the base of Bac-to-Bac baculovirus insect cell expression system, two recombinant baculoviruses (BacV-CMV-EGFPA, BacV-CMV-EGFPB) were constructed containing different direction of CMV promoters which controll the expression of a reporter gene (EGFP). We found that CMV promoter could direct expression of reporter gene in Sf9 cells with relatively low efficiency. The culture supernatant of Sf9 cells which have been infected by the recombinant baculoviruses for four days were collected and the titers of the viruses in culture supernatant were determined by plaque assay on Sf9 cells. The HepG2 cells, an human hepatocellular carcinoma cell line, were directly incubated with the collected culture supernatant which contains the recombinant baculoviruses for 8 hours in 37 degrees C CO2 incubator (moi = 100). Twenty-four hours post transduction the efficiencies of gene-transfer and expression were analyzed by flow cytometry (FCM) which detect the green fluorescence of individual cells. Results show that these two recombinant baculoviruses have similar gene-transfer and expression efficiency in HepG2 cells, which means the direction of CMV promoters has no effects on reporter gene expression. The optimal transduction conditions of incubating the mammalian cells with the culture supernatant of Sf9 cells infected by recombinant baculoviruses for four days were determined by FCM assay in HepG2 cells. The HepG2 cells inoculated in 24-well plate (5 x 10(4)/well) were incubated with the culture supernatant (BacV-CMV-EGFPA, 1.2 x 10(7) pfu/mL) serially diluted by DMEM culture medium containing 10% FBS and the transduction times ranged from 1 to 24 hours. Twenty-four hours post transduction the efficiencies of gene-transfer and expression were analyzed by FCM. Results show that incubating the target cells with the 1:1 diluted culture supernatant (moi = 50) for 12 hours in 37 degrees C CO2 incubator would achieve the highest infection and expression efficiency with the least impairment on cell viability. We compared the gene-transfer and expression efficiency of recombinant baculovirus in HepG2 and CV1 cells with lipofectAMINE and recombinant retrovirus system, results show that under the similar conditions the recombinant baculovirus could achieve the highest gene-transfer and expression efficiency than the other two systems. So we can draw a conclusion that directly incubating the mammalian cells with the culture supernantant of the infected Sf9 cells could serve as a very convenient way for rapid and efficient expression of foreign gene in mammalian cells.

Animals↗

PubMed2003

[Biodiversity of bacterial isolates on three different media from coking wastewater treatment system].

Bacteria from coking wastewater treatment sludge samples were directly plated on three different isolation media (YPG, LB and WW) and the biodiversity of isolates was examined with DNA fingerprinting. Plate counts with YPG, LB and WW media were 1.6 x 10(6) CFU/mL, 7.0 x 10(5) CFU/mL and 9.8 x 10(5) CFU/mL respectively. 137 single colony isolates were obtained from these three media. ARDRA with enzymes Hinfl revealed 14 operational taxonomic units (OUT) which were dominated by YPG-OTU1 group accounting for 34 isolates and WW-OTU6 group for 25 isolates. The biodiversity of isolates from these two dominant OUT groups was further investigated by a genomic fingerprinting technique, ERIC-PCR. The results indicated that there were 20 different ERIC-PCR types present among the YPG-OTU1 group and only 3 among the WW-OTU6 group. The data showed that the populations of bacteria isolated on three different media were significantly different from each other and a higher degree of genetic diversity was observed among strains isolated from YPG media. So YPG may be recommended to be used for a non-selective medium for isolating more diversified bacteria from wastewater bio-treatment systems.

Bacteria↗

PubMed2002

Raman spectroscopy of chlorophyll d from Acaryochloris marina.

The Raman spectroscopy of chlorophyll (Chl) d isolated from Acaryochloris marina has been measured in the range of 250-3200 cm(-1) at 77 K following excitation of its B(x) band at 488 nm. A peak at 1659 cm(-1) of medium intensity arising from Cz=O stretching vibration in the formyl group 3(1) specific to Chl d was observed clearly. Peaks due to other Cz=O stretching vibrations of the 13(1) keto-, 13(3) ester- and 17(3) groups have also been observed with much weaker intensities. Intense Raman peaks in the range of 1000-1800 cm(-1) are reported and homologous comparison with corresponding Raman shifts of Chl a, Chl b and BChl a are presented.

Bacterial Proteins↗

PubMed2002

E2F-1 regulates nuclear factor-kappaB activity and cell adhesion: potential antiinflammatory activity of the transcription factor E2F-1.

BACKGROUND: The transcription factor E2F-1 promotes vascular smooth muscle cell apoptosis and is reported to inhibit apoptosis induced by tumor necrosis factor (TNF)-alpha in endothelial cells. Whether E2F-1 overexpression exerts potentially antiinflammatory effects in endothelial cells is not known. METHODS AND RESULTS: By immunoblotting and immunofluorescence, TNF-alpha treatment of human aortic endothelial cells (HAECs) with the control vector Ad.null was followed by rapid nuclear translocation of nuclear factor (NF)-kappaB p65, whereas nuclear translocation of p65 was markedly reduced in HAECs overexpressing E2F-1. Electrophoretic mobility shift assay and gel shift analysis of nuclear cell extracts confirmed that HAECs treated with a recombinant adenovirus encoding E2F-1 failed to associate with the binding domain of p65. Stimulation of the Ad.null-infected endothelial cells with TNF-alpha resulted in enhanced expression of endothelial intracellular adhesion molecule-1, vascular cellular adhesion molecule-1, and E-selectin and enhanced adhesion of monocytic U937 cells to the HAECs. Adhesion molecule expression and cell adhesion were reduced in E2F-1-transduced HAECs, associated with a marked decrease in phosphorylated IkappaB-alpha, required for nuclear translocation of NF-kappaB p65. CONCLUSIONS: These findings suggest that E2F-1 stabilizes IkappaB and thereby may inhibit NF-kappaB-dependent processes involved in atherogenesis, including endothelial expression of E-selectin, vascular cellular adhesion molecule-1, and intracellular adhesion molecule-1 and cell adhesion to perturbed endothelial cells.

Active Transport, Cell Nucleus↗

PubMed2002

Activation of NMDA receptors and L-type voltage-gated calcium channels mediates enhanced formation of Fyn-PSD95-NR2A complex after transient brain ischemia.

Recent studies have indicated that tyrosine phosphorylation of NMDA receptor subunit 2A (NR2A) by Src family kinases (Src, Fyn, etc.) up-regulates NMDA receptors activity and postsynaptic density protein 95 kDa (PSD95) may mediate the regulation. To investigate whether the above processes are involved in brain ischemia-induced enhancement of NMDA receptors function, we examined the effects of transient (15 min) brain ischemia followed by reperfusion on interactions involving Fyn, NR2A and PSD95 in rat hippocampus by co-immunoprecipitation. Transient brain ischemia was induced by the method of four-vessel occlusion in Sprague-Dawley rats. Association between Fyn and NR2A increased immediately after brain ischemia and the increase was maintained for at least 24 h during followed reperfusion, up to about 1.7-1.8-fold relative to sham-groups. The 15-min reperfusion after brain ischemia induced enhanced co-immunoprecipitation of PSD95, Fyn and NR2A with one another. The associations of PSD95 with Fyn and NR2A increased at 0-24 h, 0-1 h of reperfusion, up to 6.9- and 2.1-fold relative to sham groups, respectively. Inhibiting activation of NMDA receptors or L-type voltage-gated calcium channels (L-VGCC) by ketamine or nifedipine attenuated the above increases of associations. These results suggest that stimulation of NMDA receptors and L-VGCC facilitates formation of a ternary complex: Fyn-PSD95-NR2A during transient brain ischemia followed by reperfusion, which may result in potentiation of NMDA receptor function and contribute to ischemic neuronal cell death.

Animals↗