Role of CAGA boxes in the plasminogen activator inhibitor-1 promoter in mediating oxidized low-density lipoprotein-induced transcriptional activation in mesangial cells

Oxidized low-density lipoprotein (Ox-LDL) activates transforming growth factor-beta (TGF-beta)/Smad signaling to stimulate plasminogen activator inhibitor-1 (PAI-1) expression in mesangial cells. Smad-binding sequences, termed CAGA boxes, are present in the promoter of human PAI-1 gene, and they mediate TGF-beta transcriptional induction. However, the functional role of each CAGA box in the Ox-LDL-induced PAI-1 promoter activation is unknown. In this study, mutation of 1 of the 3 CAGA boxes located at -730, -580, and -280 of the PAI-1 promoter decreased the Ox-LDL-induced luciferase activity by 40 to 58%, whereas mutations in 2 sites reduced it over 75% or completely abolished it. Overexpression of Smad3 in N-terminal tagged Smad3-transfected cells increased the Ox-LDL-induced transcriptional activation of the PAI-1 promoter, whereas mutation of Smad3 abolished it. Electrophoretic mobility shift assay showed that the labeled -280, -580, and -730 CAGA box probes detected DNA/protein complexes induced by Ox-LDL, whereas mutant probes did not. When nuclear extracts were preincubated with a 100-fold of an unlabeled -280, -580, and -730 CAGA oligonucleotide, the formation of complexes was prevented but not with mutant CAGA box competitors. The addition of anti-Smad3 to the reaction with the labeled -280 or -580 CAGA box probe resulted in a supershift, but not with the -730 CAGA box probe. These results suggest that the 3 CAGA elements in the PAI-1 promoter mediate the Ox-LDL-induced PAI-1 transcription to a different degree, of which the -280 and -580 CAGA regions directly bind to Smad3.

Clinical significance of anti-Saccharomyces cerevisiae antibody (ASCA) in Korean patients with Crohn's disease and its relationship to the disease clinical course

BACKGROUNDS/AIMS

The implications of anti-Saccharomyces cerevisiae antibody for the diagnosis and the clinical course of Crohn's disease have been reported in Western countries, but rarely in Korea with its very different environmental and genetic backgrounds. We aimed to evaluate whether anti-S. cerevisiae antibody expression is associated with diagnostic findings, stratified Vienna classification phenotypes, disease activity and clinical course in Korean patients with Crohn's disease.

MATERIALS/METHODS

One hundred and fifteen patients with Crohn's disease, diagnosed and treated between 1990 and 2004 at Severance Hospital, Yonsei University and followed for at least 2 years, were included in this study. Anti-S. cerevisiae antibody was detected by an indirect immunofluorescence assay using EUROIMMUN kits. Information collected during treatment included demography, Vienna classification phenotype, clinical manifestation, laboratory tests, treatment modality and surgery rate. Disease activity was measured monthly using the Harvey-Bradshaw index.

RESULTS

The anti-S. cerevisiae antibody prevalence was 38.3% in Crohn's disease patients. There was no difference in anti-S. cerevisiae antibody expression between genders. The mean age at diagnosis was younger for the anti-S. cerevisiae antibody positive group than the negative group (25.3 years versus 29.7 years, p<0.05). Clinical manifestations and laboratory tests at diagnosis did not differ between the groups. The anti-S. cerevisiae antibody positive group had increased fibrostenosis (B2) and penetration (B3) compared to negative group, as determined by the Vienna classification (75.0% versus 53.5%, p<0.05). Anti-S. cerevisiae antibody positive patients were admitted to the hospital more frequently than anti-S. cerevisiae antibody negative patients (p<0.05). The yearly cumulative Harvey-Bradshaw index score was higher in the anti-S. cerevisiae antibody positive group than in the negative group during the follow-up period (p<0.05). In addition, steroid (72.7% versus 52.1%, p<0.05) and immunosuppressive (45.5% versus 23.9%, p<0.05) treatments were more frequently given to the anti-S. cerevisiae antibody positive group.

CONCLUSIONS

Our data demonstrate that anti-S. cerevisiae antibody positive Crohn's disease patients had a more severe clinical course and thus often required more aggressive medical treatment.

Brief exposure to cycloheximide prior to electrical activation improves in vitro blastocyst development of porcine parthenogenetic and reconstructed embryos

To investigate the effects of cycloheximide exposure before electrical activation of in vitro-matured porcine oocytes on the subsequent development of parthenogenetic embryos, cumulus-free mature oocytes were exposed to NCSU-23 medium containing cycloheximide (10 microg/mL) for 0, 5, 10, 20, 30 and 60 min, activated by electrical pulse treatment (1.5 kV/cm, 100 micros) and then cultured in PZM-3 for 7 days. To evaluate the effects of cycloheximide on the activation of nuclear transfer embryos, reconstructed embryos were electrically activated by two DC pulses (1.2 kV/cm, 30 micros) before or after exposure to cycloheximide. The reconstructed embryos were allocated into four groups: electrical pulse treatment alone (Ele); exposure to cycloheximide for 10 min followed by electrical activation (CHX+Ele); electrical activation followed by exposure to cycloheximide for 6h (Ele+CHX); exposure to cycloheximide for 10 min, followed by electrical activation and a further exposure to cycloheximide for 6h (CHX+Ele+CHX). The activated reconstructed embryos were cultured in PZM-3 for 6 days. Oocytes treated with 10 min exposure to cycloheximide followed by electrical activation had a significantly higher percentage of blastocyst formation compared to control oocytes and oocytes exposed for > or =30 min. In the reconstructed embryos, the blastocyst development rates of embryos exposed to cycloheximide (CHX+Ele, Ele+CHX and CHX+Ele+CHX) were significantly higher than those of the control group (Ele). Among the cycloheximide-treated groups, the CHX+Ele group had increased development rate and total blastocyst cell number, though these values were not significantly different from those observed in the other cycloheximide-treated groups. To evaluate the quality of NT embryos treated with cycloheximide, apoptosis in blastocysts was analyzed by TUNEL assay. The 10 min exposure to cycloheximide prior to electrical activation significantly reduced cell death compared with longer exposure to cycloheximide after electrical fusion. In conclusion, brief exposure to cycloheximide prior to electrical activation may increase the subsequent blastocyst development rates in porcine parthenogenetic and reconstructed embryos.

Transverse momentum and centrality dependence of high-pT nonphotonic electron suppression in Au+Au collisions at sqrt[s NN]=200 GeV

The STAR collaboration at the BNL Relativistic Heavy-Ion Collider (RHIC) reports measurements of the inclusive yield of nonphotonic electrons, which arise dominantly from semileptonic decays of heavy flavor mesons, over a broad range of transverse momenta (1.2<p(T)<10 GeV/c) in p+p, d+Au, and Au+Au collisions at sqrt[s_{NN}]=200 GeV. The nonphotonic electron yield exhibits an unexpectedly large suppression in central Au+Au collisions at high p(T), suggesting substantial heavy-quark energy loss at RHIC. The centrality and p(T) dependences of the suppression provide constraints on theoretical models of suppression.

TGF-beta type II receptor deficiency prevents renal injury via decrease in ERK activity in crescentic glomerulonephritis

The role of transforming growth factor-beta (TGF-beta) receptor complex in the pathogenesis of crescentic glomerulonephritis (GN) is not clear. To test the hypothesis that TGF-beta signaling plays a crucial role in the development and progression of crescentic GN by inducing the activation of extracellular signal-regulated kinase (ERK) and expression of its target genes, anti-glomerular basement membrane (GBM) GN was induced in TGF-beta type II receptor (TGF-betaIIR) gene heterozygous (TGF-betaIIR(+/-)) C57BL/6J mice and wild-type animals. GN was initiated in preimmunized mice by administration of rabbit anti-mouse GBM serum. TGF-betaIIR deficiency was significantly associated with decreased renal damage at days 14, 21, and 28 after induction of GN: renal function impairment, proteinuria, proportion of crescents, glomerular accumulation of periodic acid-Schiff-positive material, relative cortical interstitial volume, as well as renal cortical phosphorylation of ERK and plasminogen activator inhibitor type I (PAI-1) and alpha2(I) collagen mRNA levels were significantly decreased in TGF-betaIIR(+/-) mice compared with wild-type animals. These results provide the first direct evidence that TGF-betaIIR deficiency protects against renal injury in crescentic GN, possibly by inhibiting the sustained activation of ERK and PAI-1 and alpha2(I) collagen gene expression. Thus, TGF-beta signaling appears to play an important role in the development and progression of crescentic GN by inducing the ERK activity, and PAI-1 and alpha2(I) mRNA expression.

Scaling properties of hyperon production in Au+Au collisions at square root [sNN]=200 GeV

We present the scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV. The yield of multistrange baryons per participant nucleon increases from peripheral to central collisions more rapidly than that of Lambda, indicating an increase of the strange-quark density of the matter produced. The strange phase-space occupancy factor gamma_{s} approaches unity for the most central collisions. Moreover, the nuclear modification factors of p, Lambda, and Xi are consistent with each other for 2<p_{T}<5 GeV/c in agreement with a scenario of hadron formation from constituent quark degrees of freedom.

Longitudinal double-spin asymmetry and cross section for inclusive jet production in polarized proton collisions at square root of s = 200 GeV

We report a measurement of the longitudinal double-spin asymmetry A(LL) and the differential cross section for inclusive midrapidity jet production in polarized proton collisions at square root of s = 200 GeV. The cross section data cover transverse momenta 5 < pT < 50 GeV/c and agree with next-to-leading order perturbative QCD evaluations. The A(LL) data cover 5 < pT < 17 GeV/c and disfavor at 98% C.L. maximal positive gluon polarization in the polarized nucleon.

Direct observation of dijets in central Au+Au collisions at sqrt[sNN]=200 GeV

The STAR Collaboration at the Relativistic Heavy Ion Collider reports measurements of azimuthal correlations of high transverse momentum (pT) charged hadrons in Au+Au collisions at higher pT than reported previously. As (pT) is increased, a narrow, back-to-back peak emerges above the decreasing background, providing a clear dijet signal for all collision centralities studied. Using these correlations, we perform a systematic study of dijet production and suppression in nuclear collisions, providing new constraints on the mechanisms underlying partonic energy loss in dense matter.

Comparison of histochemical characteristics in various pork groups categorized by postmortem metabolic rate and pork quality

The purpose of the present study was to investigate the variations in histochemical characteristics of muscle samples segregated according to metabolic rates (MR) and pork quality attributes. A total of 231 crossbred Duroc x (Yorkshire x Landrace) pigs was evaluated. Samples of the LM were taken to evaluate histochemical characteristics, postmortem MR, and meat quality. Samples were classified into fast, normal, and slow MR groups based on muscle pH at 45 min and R-value. Drip loss and lightness (L*) were used to assign samples to 1 of 4 quality classes. Pale, soft, and exudative pork belonging in the fast group had the greatest (P < 0.05) percentage of type IIb fibers, and RSE (reddish-pink, soft, and exudative) pork belonging in the fast group had a similar tendency. Additionally, RFN (reddish-pink, firm, and nonexudative) pork belonging in the normal group showed a lower (P < 0.05) percentage of type IIb fibers than PSE or RSE, regardless of MR, and DFD pork had the lowest (P < 0.05) percentage of type IIb fibers. In general, the fast-glycolyzing PSE pork with the lowest pH at both 45 min and 24 h had greater percentages of type IIb fibers than the fast-glycolyzing RFN pork. There were more fiber-type composition differences between quality classes in pork undergoing a fast rate of metabolism compared with pork undergoing a normal rate of metabolism. It can be concluded that muscle histochemical characteristics are associated with early postmortem MR, the extent of glycolysis, and, thereby, pork quality; however, these effects are limited to the pigs exhibiting a fast glycolytic rate.

Identified baryon and meson distributions at large transverse momenta from Au + Au collisions at square root sNN=200 GeV

Transverse momentum spectra of pi+/-, p, and p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at square root sNN=200 GeV are presented. In central Au + Au collisions, both pi +/- and p(p) show significant suppression with respect to binary scaling at pT approximately >4 GeV/c. Protons and antiprotons are less suppressed than pi+/-, in the range 1.5 approximately < pT approximately < 6 GeV/c. The pi-/pi+ and p/p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at pT approximately >5 GeV/c. The results at high pT indicate that the partonic sources of pi+/-, p, and p have similar energy loss when traversing the nuclear medium.

Forward neutral pion production in p + p and d + Au collisions at square root sNN=200 GeV

Measurements of the production of forward pi0 mesons from p + p and d + Au collisions at square root sNN=200 GeV are reported. The p + p yield generally agrees with next-to-leading order perturbative QCD calculations. The d + Au yield per binary collision is suppressed as eta increases, decreasing to approximately 30% of the p + p yield at eta =4.00, well below shadowing expectations. Exploratory measurements of azimuthal correlations of the forward pi0 with charged hadrons at eta approximately 0 show a recoil peak in p + p that is suppressed in d + Au at low pion energy. These observations are qualitatively consistent with a saturation picture of the low-x gluon structure of heavy nuclei.

ERK contributes to the effects of Smad signaling on oxidized LDL-induced PAI-1 expression in human mesangial cells

Oxidized low-density lipoprotein (Ox-LDL) stimulates plasminogen activator inhibitor-1 (PAI-1) expression in human mesangial cells mediated by transforming growth factor-beta (TGF-beta)/Smad signaling pathway. TGF-beta activates extracellular signal-regulated kinase (ERK) in mesangial cells, and ERK is involved in activation of Smad2/3. This study examines whether an interaction exists between Ox-LDL-induced TGF-beta/Smad signaling pathways and ERK activation leading to PAI-1 transcription in human mesangial cells. Ox-LDL (50 microg/mL) induced an acute increase in ERK activity within 15 min, which decreased to control value at 2 h. Incubation with anti-TGF-beta or SB-431542, an inhibitor of the TGF-beta type I receptor, along with Ox-LDL, inhibited the expected increase in ERK phosphorylation. Treatment with PD98059 or UO126, mitogen-activated ERK-activating kinase 1/2 inhibitors, significantly inhibited the Ox-LDL-induced increase in PAI-1 mRNA and nuclear Smad3 expression, DNA/protein complex formation, and PAI-1 promoter activity. These results suggest that phosphorylation of ERK is induced by Ox-LDL through the induction of the TGF-beta signaling pathway and that activated ERK, in turn, participates in the Ox-LDL-induced Smad3 activation and subsequent PAI-1 gene expression in mesangial cells.

Strange baryon resonance production in sqrt s NN=200 GeV p+p and Au+Au collisions

We report the measurements of Sigma(1385) and Lambda(1520) production in p+p and Au+Au collisions at sqrt[s{NN}]=200 GeV from the STAR Collaboration. The yields and the p(T) spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur.

Application of a multi-channel system for continuous monitoring and an early warning system

A multi-channel continuous toxicity monitoring system developed in our laboratory, based on two-stage mini-bioreactors, was successfully implemented in the form of computer-based data acquisition. The multi-channel system consists of a series of a two-stage minibioreactor systems connected by a fiber optic probe to a luminometer, and uses genetically engineered bioluminescent bacteria for the detection of the potential toxicity from the soluble chemicals. This system can be stably and continuously operated due to the separation of the culture reactor from the test reactor and accomplish easy and long-term monitoring without system shut down by abrupt inflows of severe polluting chemicals. Four different recombinant bioluminescent bacteria were used in different channels so that the modes of the samples toxicities can be reasonably identified and evaluated based upon the response signature of each channel. The bioluminescent signatures were delivered from four channels by switching one at once, while the data is automatically logged to an IBM compatible computer. We also achieved the enhancement of the system through the manipulation of the dilution rate and the use of thermo-lux fusion strains. Finally, this system is now being implemented to a drinking water reservoir and river for remote sensing as an early warning system.

Oxidized LDL activates PAI-1 transcription through autocrine activation of TGF-beta signaling in mesangial cells

BACKGROUND

Lipid abnormalities and oxidative stress may be involved in the development of glomerulosclerosis. Plasminogen activator inhibitor-1 (PAI-1) is a component of extracellular matrix (ECM) and target gene of transforming growth factor-beta (TGF-beta). Smad proteins play a key role in TGF-beta signaling, and Smad binding CAGA boxes are present in the PAI-1 promoter. This study examined whether oxidized low-density lipoprotein (Ox-LDL) activates PAI-1 transcription in human mesangial cells, mediated by increased Smad/DNA interactions.

METHODS

Quiescent HMC were incubated with 50 microg/mL of Cu(++)-catalyzed Ox-LDL for 15 minutes to 4 hours, and the effects of Ox-LDL on TGF-beta1 and PAI-1 mRNA expression, PAI-1 promoter activity, and DNA binding activity of Smad proteins were examined.

RESULTS

Ox-LDL induced TGF-beta1 and PAI-1 mRNA expression. Ox-LDL increased the transiently transfected PAI-1 promoter activity as compared with controls to 3.9-fold. Ox-LDL-treated cells increased Smad3 protein levels two times the control levels in the nuclei. Electrophoretic mobility shift assay (EMSA) performed using a CAGA sequence probe and nuclear extracts showed that Ox-LDL increased DNA/protein complexes. When nuclear extracts were preincubated with 100 molar excess of unlabeled CAGA oligonucleotide or SB-431542, an inhibitor of the TGF-beta type I receptor, the formation of complex was prevented. The DNA binding protein was shown to be Smad3 by antibody supershift. Transfection of phosphorothioate CAGA oligonucleotides, which compete with the CAGA-containing PAI-1 promoter for Smad3 binding, inhibited the Ox-LDL-induced PAI-1 mRNA expression. Cotransfection of phosphorothioate CAGA oligonucleotides with PAI-1 reporter vector also blocked the Ox-LDL-induced PAI-1 promoter activity.

CONCLUSION

These results suggest that Ox-LDL activates TGF-beta/Smad signaling to stimulate PAI-1 transcription in human mesangial cells. Thus, progression of glomerular disease may be promoted by PAI-1 up-regulation in human mesangial cells mediated by the Ox-LDL-induced TGF-beta/Smad signaling pathways.

The relationship between muscle fiber characteristics, postmortem metabolic rate, and meat quality of pig longissimus dorsi muscle

The aim of this study was to investigate the histochemical parameters of muscle fibers, and to estimate the correlation of muscle fiber characteristic to postmortem metabolic rate and meat quality traits in pigs. A total of 231 crossbred pigs were evaluated. Samples of the longissimus dorsi muscle were taken to evaluate the histochemical characteristics, postmortem metabolic rate and meat quality. Fiber type composition was mainly related to postmortem metabolic rate and meat quality traits among various muscle fiber characteristics. The percentage of type IIb fiber was negatively related to pH(45min) (r=-0.33) and positively to R-value (r=0.32). Drip loss was negatively related to fiber area percentages of type I and IIa (r=-0.25 and -0.26, respectively) and positively related to type IIb percentage (r=0.39). A similar tendency was found between lightness and fiber area percentage. In conclusion, increasing the percentage of type IIb fiber is related to increasing the postmortem metabolic rate, and is related to the deterioration of meat quality.

Effects of different levels of dietary supplemental selenium on performance, lipid oxidation, and color stability of broiler chicks

This study examined the effects of supplemental dietary selenium on growth performance, lipid oxidation, and color stability of broiler chicks. Male broiler chicks (Arbor Acres, 1 d old, total 900 chicks) were randomly assigned to 6 pens containing 30 chicks each, corresponding to each of 6 dietary treatments. Six different diets were supplied to the chicks from 3 to 6 wk of age. After 42 d of feeding, all the broilers were slaughtered conventionally at a slaughtering plant. The carcasses were packed in polyethylene bags in a manner similar to that used for retail trade and stored for 12 d at 4 degrees C. Body weight and feed efficiency were not affected by dietary selenium levels, and no adverse effect on growth was observed during the experimental period. The dietary selenium and alpha-tocopherol levels did not affect surface meat color or level of metmyoglobin accumulation. Lipid stability was improved by supplementation with 100 IU of alpha-tocopherol (P < 0.05). Dietary selenium supplementation at 8 ppm in combination with 100 IU of alpha-tocopherol, however, was more effective in reducing lipid oxidation compared with 100 IU of alpha-tocopherol/kg feed only (P < 0.05). Supplementation with 100 IU of alpha-tocopherol affected cholesterol oxidation product levels on d 7 and 12, but selenium supplementation did not have an additional effect on the reduction of cholesterol oxidation products. Therefore, an increase in the dietary selenium from 1 to 8 ppm revealed only minor improvements in the oxidative stability of chicken meat during refrigerated storage.

Heterozygous mice for TGF-betaIIR gene are resistant to the progression of streptozotocin-induced diabetic nephropathy

BACKGROUND

Transforming growth factor-beta (TGF-beta) receptor complex and its downstream Smad signaling intermediates constitute an extracellular matrix (ECM) accumulation pathway.

METHODS

In the present study, we examined whether decreased expression of the TGF-beta type II receptor (TGF-betaIIR) in TGF-betaIIR gene heterozygous (TGF-betaIIR+/-) (HT) mice could inhibit the Smad signaling pathway and subsequent progression of renal lesions when streptozotocin (STZ) diabetes is induced.

RESULTS

At the end of the 28-week experiment after STZ injections, wild-type diabetic mice showed severe glomerular hypertrophy and mesangial matrix accumulation occasionally featuring nodular glomerulosclerosis. In contrast, mean glomerular area and mesangial volume density were significantly decreased in the HT diabetic mice as compared with the wild-type diabetic mice. Immunostaining for phosphorylated Smad2/Smad3 and TGF-betaIIR in the glomerular cells was also significantly reduced in the HT diabetic mice. Southwestern histochemistry using digoxigenin-labeled CAGA sequence probes showed that localization of labeled probes to the nuclei of glomerular cells in the HT diabetic mice was significantly less frequent than that in the wild-type diabetic animals. Northern blot analysis showed that alpha1(IV) collagen mRNA levels were significantly reduced in the kidney tissue of HT diabetic mice as compared with the wild-type diabetic mice.

CONCLUSION

These results suggest that decreased expression of TGF-betaIIR in the HT diabetic mice can inhibit the progression of diabetic renal injury by inhibiting the downstream Smad signaling pathway and subsequent ECM gene expression. Thus, TGF-betaIIR appears to play an important role in the progression of diabetic nephropathy by mediating intracellular Smad signaling.

Glycated albumin activates PAI-1 transcription through Smad DNA binding sites in mesangial cells

Amadori-modified glycated albumin stimulates extracellular matrix and transforming growth factor-β (TGF-β) expression in cultured mesangial cells. Smad proteins transduce the TGF-β-mediated signal, and Smad-binding CAGA sequences are present in the plasminogen activator inhibitor-1 (PAI-1) promoter. This study examined whether glycated albumin induces PAI-1 transcription in human mesangial cells (HMC) through Smad-binding sites in the PAI-1 promoter. Quiescent HMC were exposed to 200 μg/ml bovine serum albumin (BSA) or glycated BSA (Gly-BSA) for 12–72 h. At 24 h, Gly-BSA stimulated TGF-β1and PAI-1 mRNA expression in HMC to 1.8 and 3.2 times that in the BSA-treated control cells. Gly-BSA also activated the PAI-1 promoter luciferase activity 2.3-fold. Gly-BSA-treated cells enhanced Smad2 and Smad3 protein levels 2.5 times the control levels in the nuclei. An electrophoretic mobility shift assay performed using CAGA sequences as a probe showed that Gly-BSA increased DNA/protein complexes. When nuclear extracts were preincubated with 100-fold molar excess of unlabeled CAGA oligonucleotide, the formation of complex was prevented. The DNA-binding protein was shown to be Smad3 by antibody supershift. Transfection of phosphorothioate CAGA oligonucleotide, a CAGA antisense analog, inhibited Gly-BSA-induced PAI-1 mRNA expression. Cotransfection of phosphorothioate CAGA oligonucleotides with PAI-1 reporter vector also blocked Gly-BSA-induced PAI-1 promoter luciferase activity. These results indicate that Gly-BSA increases DNA binding activity of Smad3 and that it stimulates PAI-1 transcription through Smad-binding CAGA sequences in the PAI-1 promoter in HMC. Thus progression of diabetic nephropathy may be promoted by PAI-1 upregulation mediated by the glycated albumin-induced Smad/DNA interactions.

Glycated Albumin Induces Superoxide Generation in Mesangial Cells

BACKGROUND/AIMS

Reactive oxygen species are involved in the pathogenesis of diabetic nephropathy. Amadori-modified glycated albumin modulates signaling pathways in mesangial cells that contribute to the development of diabetic nephropathy. However, the effects of glycated albumin on mesangial cell superoxide (O2-) production are unknown. Thus, we examined whether glycated albumin induces mesangial cell O2- generation and whether increased O2- production elicits cell growth.

METHODS

Quiescent human mesangial cells (HMC) were exposed to bovine serum albumin (BSA) or glycated BSA (Gly-BSA) with or without diphenylene iodonium (DPI) or apocynin, inhibitors of NAD(P)H oxidase, GF109203X (GFX), a protein kinase C (PKC) inhibitor.

RESULTS

Gly-BSA increased PKC activity, particularly PKC-alpha and -alpha1, within 15 min of incubation with HMC, which decreased to the control value at 2 h. Gly-BSA incubated with HMC increased O2- production by 2 times vis-á-vis BSA-treated cells. The Gly-BSA-induced increased O2- generation was suppressed by DPI or GFX. Gly-BSA significantly increased mesangial [3H]-leucine incorporation, whereas these processes were abrogated by DPI, apocynin or GFX.

CONCLUSIONS

Gly-BSA induces PKC/NAD(P)H oxidase-dependent O2- production in HMC, which in turn results in cell hypertrophy. Thus, O2- induced by glycated albumin might cause mesangial cell alterations in diabetes participating in the pathophysiology of diabetic nephropathy.

Angiotensin II mediates LDL-induced superoxide generation in mesangial cells

Lipid abnormalities and activation of the local renin-angiotensin system (RAS) may be involved in the pathogenesis of chronic glomerular disease. This study investigated whether low-density lipoprotein (LDL) activates local RAS in cultured human mesangial cells (HMC) and, at the same time, whether ANG II mediates LDL-induced mesangial cell proliferation, hypertrophy, and superoxide (O2-) generation. Quiescent HMC were exposed to 50 to 200 microg/ml of LDL or 10-7 to 10-10 M ANG II for 0.5 to 24 h in the presence or absence of 10-6 M losartan, an ANG II type I (AT1) receptor antagonist, or 10-5 M diphehylendieodonium (DPI) or 10-4 M apocynin, inhibitors of nicotinamide adenine dinucleotide phosphate oxidase. LDL induced an up to threefold increase in the ANG II levels in the culture medium of HMC. LDL upregulated AT1 receptor and angiotensinogen mRNA expression in HMC. LDL incubated with HMC increased O2- production by up to 3.3 times compared with the level of control cells. The LDL-induced, increased O2- generation was suppressed by losartan, DPI, or apocynin. LDL significantly increased mesangial [3H]thymidine or [3H]leucine incorporation, whereas these processes were abrogated by losartan. In conclusion, LDL increases ANG II production by mesangial cells, which in turn results in increased O2- production, and cell proliferation and hypertrophy, these effects of ANG II being mediated by the AT1 receptor.

Release of ciprofloxacin from poloxamer-graft-hyaluronic acid hydrogels in vitro

Recently, in situ gel formation has extensively been studied to enhance ocular bioavailability and duration of the drug activity. In this study, we report grafting of poloxamer onto the hyaluronic acid for application of tissue engineering oriented ophthalmic drug delivery system. Graft copolymers were prepared by coupling mono amine-terminated poloxamer (MATP) with hyaluronic acid (HA) backbone using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxylsuccinimide (NHS) as coupling agents. The coupling of MATP with HA was clarified by 1H NMR and FT-IR spectroscopy. The gelation temperature of graft copolymers was dependent on the content of HA and the concentration of poloxamer. From drug release studies in vitro, ciprofloxacin was sustainedly released from the poloxamer-g-hyaluronic acid hydrogel due to the in situ gel formation of the copolymer and viscous properties of HA.

A fatal case of Vibrio vulnificus meningoencephalitis

The objective of this paper is to report a rare case of Vibrio vulnificus presenting as meningoencephalitis without a wound infection. Vibrio vulnificus is capable of causing severe and often fatal infections in susceptible individuals. It commonly causes necrotizing wound infections, primary septicemia, and gastroenteritis. A 69-year-old man had meningoencephalitis with lesion on the red nucleus, substantia nigra, basal ganglia, and dentate nucleus as the initial clinical manifestation of a V. vulnificus infection. This is the first case of V. vulnificus infection in which MRI demonstrated the involvement of deep nuclei of the brain.

Degradation of polyvinyl alcohol by Sphingomonas sp. SA3 and its symbiote

A total of 800 samples was taken from Taegu province, Korea, where many textile factories provide a source of polyvinyl alcohol (PVA) waste. These samples were screened for PVA-degrading bacteria. A new strain, SA3, was discovered which formed yellow colonies and used PVA as the sole carbon and energy source. Strain SA3 was identified as a Sphingomonas sp., based on the partial nucleotide sequence analysis of 16S ribosomal RNA, the presence of 2-hydroxymyristic acid (14:O 2-OH) and sphingolipids with d-17:0, d-18:0, d-19:1, and d-20:1 as the main dihydrosphingosines. This genus has not previously been reported as a PVA-degrading bacterium. Sphingomonas sp. SA3 needs a symbiote strain, SA2, for PVA degradation as a growth factor producer. In mixed cultures of these strains, the optimum temperature for PVA biodegradation ranged from 30 degrees C to 35 degrees C. The optimum pH was 8.0 and the most effective nitrogen source was NH(4)(+).

Biphasic regulation of plasminogen activator/inhibitor by LDL in mesangial cells

Lipid abnormalities and dysregulation of the plasminogen activator (PA)/plasmin system may be involved in the development of glomerulosclerosis. We investigated the effects of low-density lipoprotein (LDL) on PA inhibitor-1 (PAI-1), urokinase-type PA (uPA), and tissue-type PA (tPA) in relationship to protein kinase C (PKC) in cultured human mesangial cells (HMC). LDL (200 microg/ml) induced two peaks of PKC activation at hours 0.25 and 6, with translocation of PKC-alpha, -beta(1), and -delta from cytosol to the membrane. The second increase in PKC activity gradually decreased to the control value by hour 18. LDL downregulated 2.4-kb PAI-1, uPA, and tPA mRNA expression within 6 h of incubation with HMC. On the other hand, after 12-48 h, LDL-treated cells showed a significant increase in PAI-1, tPA, and uPA mRNA levels. LDL induced up to a twofold increase in PAI-1 antigen levels in the extracellular matrix of HMC after 24-48 h as well as increased PA inhibitory activity in the culture medium. Analysis of the adhesion plaques from cells incubated with LDL for 48 h by zymography showed increased intensity of lysis near molecular weights of approximately 55,000 and 100,000. LDL slightly increased tPA release at hours 24 and 48 but did not increase PA activity in culture medium. The stimulatory effects of LDL on PAI-1, tPA, and uPA gene regulation in HMC were blocked by the inhibition of PKC using GF-109203X 12 h after treatment with LDL or downregulation of PKC using phorbol myristate acetate. In summary, LDL regulates PAI-1, uPA, and tPA in biphasic patterns in HMC, and the upregulation of PAI-1, uPA, and tPA after long-term LDL exposure seems to be mediated by a delayed PKC activation associated with an increased PA inhibitory activity. These results suggest that LDL, after prolonged incubations with HMC, causes a PA/inhibitor imbalance favoring accumulation of matrix.