Biomedical subjects

C H Chen

Publications and source records attributed to C H Chen.

At least 55 records · Page 3Linked to original sources

PubMed2002

Self-organized nanoscale pattern formation on vicinal Si(111) surfaces via a two-stage faceting transition.

We demonstrate a self-organized pattern formation on vicinal Si(111) surfaces that are miscut toward the [2;11] direction. All the patterns, consisting of a periodic array of alternating (7 x 7) reconstructed terraces and step-bunched facets, have the same periodicity and facet structure, independent of the miscut angle, while the width of the facets increases linearly with miscut angle. We attribute such unique pattern formation to a surface faceting transition that involves two transition stages: the first stage forms a stress-domain structure defining the universal periodicity; the second stage forms the low-energy facets controlling the facet width.

Journal Article↗

PubMed2002

Laser desorption mass spectrometry for microbial DNA analysis.

Recently, we demonstrated that a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF MS) can be used to determine the molecular weight of polymerase chain reaction (PCR) products of intact 16S rRNA regions and to profile their restriction digests. This is the first time that MALDI-TOF MS with ultraviolet (UV) photoionization has been used to analyze a PCR product of approximately 1600 nucleotides in length.

DNA, Bacterial↗

PubMed2002

Urodynamic findings 3 months after radiotherapy in patients treated with conformal external beam radiotherapy for prostate carcinoma.

OBJECTIVE: To quantify the effect of radiotherapy (RT) on urodynamic function 3 months after RT in patients with prostate cancer undergoing definitive external beam RT. PATIENTS AND METHODS: Seventeen patients with clinically localized prostate cancer were accrued into a single-arm prospective study. Sixteen of the patients completed a scheduled multichannel video-urodynamic study at baseline and again 3 months after RT; the urodynamic variables were then compared to assess the nature and extent of urodynamic change caused by RT. Correlations were assessed between these quantitative changes and those in self-assessed qualitative urinary function measured by International Prostate Symptom Score (IPSS), Quality of Life assessment index (QoL) and urinary functional enquiry. RESULTS: There were significant changes detected by the urodynamic study 3 months after RT in bladder volume at capacity (mean decrease 70 mL) and bladder volume at first sensation when supine (mean decrease 85 mL), and a lower postvoid residual volume (mean 50 mL). There was no significant change in the remaining urodynamic variables (including maximum flow rate and voided volume), nor in bladder compliance, bladder instability or bladder outlet obstruction. The self-assessed qualitative urological function measured by the IPSS, QoL and median urinary frequency/24 h showed no significant change after RT. CONCLUSIONS: This is the first quantitative study to prospectively evaluate the effect of RT on urodynamics in patients with prostate cancer. Only a few urodynamic variables changed significantly 3 months after RT, while most, including self-assessed qualitative urinary function, did not. This finding corresponds well with the notion that most patients tolerate RT well and that acute RT-induced urinary symptoms resolve successfully, with the return of lower urinary tract function to baseline levels by 3 months after RT.

Aged↗

PubMed2002

A novel mutation in neonatal isolated sulphite oxidase deficiency.

Isolated sulphite oxidase deficiency (ISOD) is a very rare hereditary metabolic disorder. Imaging findings of the neonatal form of ISOD, including multicystic leukoencephalopathy with brain atrophy, resemble those of severe ischemic changes of the brain. We report the case of a ten-month-old boy who exhibited neonatal seizures on the 24th day after birth. Excessive quantities of sulphite and S-sulphocysteine in the urine and normal blood uric acid were noted. These findings were consistent with those of ISOD. Point mutations were found in two alleles of the sulphite oxidase (SUOX) gene. One of the mutations was a 1029 C > G mutation, which resulted in an amino acid substitution of tyrosine to a stop code (Y343 X); and the other was a 479 G > A mutation, which resulted in an amino acid substitution of arginine to glutamine (R160 Q). Y343 X is a novel SUOX gene mutation. A review of the literature, including data from this report, showed that 3 of 6 cases had typical imaging findings characterized by initial cerebral edema followed by dramatic multicystic leukoencephalopathy. We emphasize that neonatal ISOD should be included in the differential diagnosis of neonates with unexplained hypoxic-ischemic changes on neuroimaging studies.

Deficiency Diseases↗

PubMed2002

Adsorption of paraquat on the physically activated bleaching earth waste from soybean oil processing plant.

A series of regeneration experiments with physical activation were carried out on bleaching earth waste from the soybean refining process in a rotary reactor. The influence of activation parameters on the spent clay by varying the holding time of 1 to approximately 4 hours and temperature of 700 to approximately 900 degrees C was determined. The variations of pore properties as well as the change of chemical characteristics in the resulting solids were also studied. Results showed that the resulting samples were type IV with hysteresis loops corresponding to type H3 from nitrogen adsorption-desorption isotherms, indicating slit-shaped mesoporous characteristics. However, the regenerated clays had smaller surface areas (70 to approximately 117 m2/g) than that (245 m2/g) of fresh bleaching earth. Under the physical activation conditions investigated, the holding time of 1 hour and temperature of 700 degrees C were found to be optimal conditions for producing mesoporous clay with physical activation. The adsorption of paraquat on regenerated sample was also evaluated. The isotherm showed that the regenerated sample still had a high affinity for this herbicide. Thus, the regeneration of this agro-industrial waste is one option for utilizing the clay resource, and it may be used for water treatment applications to remove organic contaminants.

Adsorption↗

PubMed2002

In vitro study of ultrasound based real-time tracking for renal stones in shock wave lithotripsy: Part II--a simulated animal experiment.

PURPOSE: We have previously developed and reported an ultrasound based real-time tracking system for renal stones. In the current study we continued to verify the reliability of this tracking system by a simulated animal test. MATERIALS AND METHODS: We used 13 prerecorded ultrasound stone trajectories to test the system. The real-time tracking system was implemented on the Litemed 9200 electrohydraulic lithotriptor (LiteMed Co., Taipei, Taiwan). An artificial stone and tap water were sealed in a balloon. The balloon was inserted into the pelvis of a pig kidney. While the kidney was affixed to and moved by a simulator, it was immersed in a specifically designed simulated animal model tank containing tap water. The stone was localized by ultrasound. The kidney was moved by the simulator according to a prerecorded stone trajectory. A total of 3,000 shock waves were delivered to the stone. For each recorded stone trajectory experiments were done under nontracking and tracking conditions. We performed tests of the fragment-to-weight ratio, which denotes the performance of a shock wave lithotriptor when fragmenting a stone. RESULTS: The mean fragment-to-weight ratio was 55.3% +/- 25.9% in the nontracking and 100% +/- 0% in the tracking group. The difference in these 2 groups was statistically significant (paired t test p <0.01). CONCLUSIONS: The ultrasound based real-time tracking system proved to improve the performance of a shock wave lithotriptor significantly when fragmenting stones in a simulated animal test. We believe that the tracking system would greatly reduce the number of shocks and time needed for treating renal stones.

Animals↗

PubMed2002

Ozonation of domestic secondary effluent for recycling and reuse--a pilot plant study.

In this study, a pilot plant combined ozonation with sand filtration is established. Wastewater from the secondary effluent was taken as the sample for looking into the feasibility of domestic wastewater recovery and recycling. At the beginning, a series of hydraulic analysis and ozone transfer tests was conducted in the bubble column reactor. From these tests, it was found that when the gas flow is controlled to within 0.2 to approximately 1.0 L/min and liquid flow within 0.5 to approximately 2.5 L/min, using series connected mixing tank model for our calculation, the result J (CSTR) is 1 to approximately 2. From the ozone transfer test it is known that the smaller the gas flow, the better the transfer rate, and the same pattern occurs on ozone gas concentration. After sand filtration and ozone treatment, the G/L ratio within the ozone column reactor can be maintained within 0.2 to approximately 0.4 and the ozone dosage within 8 to approximately 12 mg/L. The removal rate for coliform bacillus, BOD, turbidity and color is 99.96%, 62.2%, 89.6% and 67% respectively. After ozonation treatment, coliform bacillus content can be controlled under 10 CFU/mL, BOD under 10 mg/L, turbidity within 2.0 to approximately 2.5 (NTU), and color within 10.3 to approximately 13.7 degree. The recycled water is almost colorless and odorless, and is capable of reaching the reference standard for recycled water.

Conservation of Natural Resources↗

PubMed2001

Mutation analysis of the human NR4A2 gene, an essential gene for midbrain dopaminergic neurogenesis, in schizophrenic patients.

Recent studies have revealed that an orphan receptor gene of the steroid/thyroid hormone nuclear receptor superfamily, the Nurr1 gene, is essential for the neurogenesis and differentiation of dopaminergic neurons in the midbrain of mice. Transgenic mice lacking the Nurr1 gene soon die after birth and are devoid of dopaminergic neurons in the midbrain. Heterozygous mice survive postnatally without obvious locomotor deficits; however, they have increased vulnerability to dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In view of the importance of dopamine neurotransmission in brain function, we were interested to know if the human homologous gene of murine Nurr1, the NR4A2 gene, may play a role in the pathogenesis of schizophrenia. We systematically sequenced all the exons of the human NR4A2 gene to search for molecular variants in a cohort of Chinese schizophrenic patients from Taiwan. Two molecular variants were identified: a G-insertion in intron 6 (designated IVS6 + 17 [see text] + 18insG), and a G-deletion in the untranslated exon 1 (designated c.-469delG). The IVS6 + 17 [see text] + 18insG is a polymorphic one; further case control study, however, did not reveal association of this polymorphism with schizophrenia. The c.-469delG is a rare variant found in two unrelated patients among 177 schizophrenic patients, but not in 130 nonpsychotic controls. The result suggests that the c.-469delG and possibly other variants of the NR4A2 gene may be of relevance to the complex factors involved in the pathogenesis of schizophrenia.

DNA↗

PubMed2001

The role of the third beta strand in gp120 conformation and neutralization sensitivity of the HIV-1 primary isolate DH012.

Neutralization of HIV-1 primary isolates has been a tremendous challenge for AIDS vaccine development. Here, we identify a single amino acid change (T198P) in gp120 that alters the neutralization sensitivity of the primary isolate DH012 to antibodies against multiple neutralization epitopes that include the V3, CD4-induced, and CD4 binding sites in gp120. This mutation is located in the V1/V2 stem region that forms the third beta strand (beta3) of the bridging sheet of gp120. The conformation of variable loops, especially V1/V2 and V3, was proposed to regulate the accessibility of these neutralization epitopes. The results of this study indicate a direct association between the V1/V2 and V3 loops of DH012 gp120. The single amino acid mutation T198P in the beta3 severely compromises the interaction between the V1/V2 and V3 loops. These results suggest that interaction of V1/V2 and V3 can mask the neutralization epitopes and that the beta3 plays a critical role in determining the neutralization sensitivity by modulating the interaction. This study provides an insight into why primary isolates are relatively resistant to antibody neutralization and might facilitate the development of anti-HIV strategies against HIV-1 infection.

Base Sequence↗

PubMed2001

Functional correlates of central arterial geometric phenotypes.

We have assessed the functional correlates of common carotid artery (CCA) arterial geometry, derived by combining a measure of vascular mass (VM) with the wall-to-lumen (W/L) ratio in both untreated hypertensive (HT) and normotensive (NT; blood pressure <140/90 mm Hg) subjects of a broad age span (30 to 79 years) of both genders. Brachial systolic, diastolic, and pulse (SBP, DBP, PP) pressures; CCA SBP and PP; CCA diameter (D); intima-media thickness (IMT); relative distensibility; circumferential wall stress (MBPxW/L); fluid shear stress (FSS); strain; augmentation index (AGIh); and aortic pulse wave velocity (PWV) were measured in 680 NT and 635 untreated HT Taiwanese men and women. Carotid geometric phenotypes (CGPs) were derived from ultrasonographic measures of VM and W/L ratio. A normal CGP (CGP1) was defined as that within the 95th NT percentile of age- and gender-specific VM and W/L means. Three "deviant" CGPs were defined as follows: CGP2 or remodeling, ie, a normal VM coupled with an increased W/L; CGP3 or hypertrophy, ie, an increase in both VM and W/L; and CGP4 or hypertrophy with dilation, ie, an increased VM with normal W/L. The prevalence of specific CGPs in the total sample was 83.4% for CGP1, 5.5% for CGP2, 2.2% for CGP3, and 8.9% for CGP4. Compared with CGP1, all deviant CGPs had increased carotid resistance, had higher CCA circumferential wall stress, and varied in blood flow velocity. Compared with CGP1, CGP2 subjects were more likely to be women (69.3% versus 45.9%), were on average 10 years older, and had similar central and brachial BP levels, PWV, and AGIh but had increased strain, higher distensibility, lower flow, and a higher FSS. CGP3 subjects did not differ in age or gender but had a higher prevalence of HT; higher circumferential stress, PWV, and distensibility; and lower flow, as well as a trend toward higher SBP, PP, and AGIh and lower FSS. CGP4 subjects did not differ in age or gender but exhibited higher AGIh and aortic PWV, lower distensibility and FSS, and unchanged strain and flow. CGP4 was the only deviant CGP in which the average brachial or central arterial pressures were significantly increased. CGP4 subjects also had the highest prevalence of HT among all the CGPs (77.8% versus 45% in CGP1). CGPs exhibit some common mechanical or functional properties but each also exhibits a unique profile. Although differing quantitatively in NT and HT and at young and older age, the characteristic functional profile of a given CGP is preserved, regardless of age or BP status. A normal CGP is characterized by a low circumferential wall stress and high FSS. Each deviant CGP is characterized by a unique combination of increased circumferential wall stress, with variable FSS, strain, distensibility, central BP, and late pressure augmentation. The interplay among these factors, particularly circumferential wall and FSS, likely determines the CGP; conversely, the resultant CGP may modulate the FSS and wall stress for a given pressure and flow.

Adult↗

PubMed2001

Boundary sequences of the NADPH oxidase p67(phox) C-terminal SH3 domain play on its specificity.

SH3 domains are found in many signal transduction proteins where they mediate protein-protein binding by recognizing specific peptides rich in proline. Based on the analysis of sequence alignment data, the NADPH oxidase p67(phox) C-terminal SH3 domain possesses a typical compact beta-barrel consisting of five beta-strands arranged in two antiparallel beta-sheets of three and two beta-strands. Multiple amino acid substitutions were made at beta e and its flanking residues to determine the role of the boundary sequences in binding activity and conformational specificity of the domain. Analysis of amino acid P55 indicated that all mutants were completely abolished in their binding activities. The substitution of F58 with Y58 showed no effect of the binding, whereas substitution with stop codon abolished activity. Furthermore, when amino acid V59 was substituted with stop codon, activity was also completely abolished. Substitution of E60 with stop codon showed no effect of binding. Moreover, our data show that V59 particularly could not be replaced by Leu. Taken together, these data suggest that V59 may not only contribute the exact boundary site but also play on the specificity for protein-protein interactions in phagocyte NADPH oxidase.

Amino Acid Sequence↗

PubMed2001

Predicting the elution behavior of proteins in affinity chromatography on non-porous particles.

Affinity chromatography on non-porous particles of microsize is particularly useful for the rapid analysis and micropreparative separation of proteins. The elution behavior of proteins in an affinity column packed with non-porous copolymerized particles of styrene, methyl methacrylate and glycidyl methacrylate was investigated both theoretically and experimentally, using the lysozyme-Cibacron Blue 3G-A affinity system. Equations used to predict the elution profiles, resulting from the elution by increasing the ionic strength (NaCl concentration) in the mobile phase, were obtained. The maximum adsorbate concentration, desorption rate constant and equilibrium constant under elution conditions were determined by matching experimental data with predicted elution profiles. Based on the parameters determined at a flow-rate of 0.5 ml/min and with 1 M NaCl in the elution buffer, the model equations could predict the elution profiles for other experimental runs, where different flow-rates and sodium chloride concentrations were used. Both the experimental and predicted results revealed that the affinity interaction kinetics are not significantly influenced by the flow-rate and, hence, the film mass transfer. To elute bound lysozyme from immobilized dye ligand, a higher value of the ionic strength leads to a faster elution and a sharper elution peak. The influence of elution conditions on the kinetic and thermodynamic parameters and, consequently, on the elution peak profiles was evaluated. The model equations can also predict the behavior of protein elution from an affinity column by changing the pH of the mobile phase, according to a previous study.

Adsorption↗

PubMed2001

Analysis of transition from long-term nonprogressive to progressive infection identifies sequences that may attenuate HIV type 1.

Long-term nonprogressive human immunodeficiency virus type 1 (HIV-1) infection and its transition to progressive infection presents an opportunity to identify the molecular determinants of HIV-1 attenuation and pathogenesis. We studied an individual who underwent a transition from long-term nonprogressive to rapidly progressive infection. Because HIV-1 RNA genomes in plasma represent replicating virus, we developed a technique to clone full-length HIV-1 RNA genomes from plasma and used this technique to obtain clones from this individual before and during the transition. Most clones assayed were infectious, demonstrating that the RNA genomes encoded viable virus. Analysis of 20 complete HIV-1 RNA genomic sequences revealed one major difference between sequences found during the two phases of infection. During the nonprogressive phase, the predominant sequences had a large deletion in an Sp1-binding site and adjacent promoter in the U3 part of the long terminal repeat (LTR); when the infection became progressive, all viruses had intact Sp1 and promoter sequences and were derived from a minor species present earlier. Analysis of 184 clones of the LTR region obtained at five time points spanning a 7-year period confirmed this switch. In an in vitro assay, the deletion downregulated LTR-driven transcription of a reporter gene. In addition, analysis of cytotoxic T lymphocyte (CTL) epitopes predicted from the complete viral RNA genomes revealed multiple potential escape mutants that accumulated by the time of progression. These studies suggest that during the nonprogressive phase, the Sp1 enhancer-promoter deletion is likely to have played a role in decreasing replication, thereby attenuating HIV-1. The accumulation of CTL escape mutants suggests that a breakdown in immunologic surveillance may have allowed proliferation of intact virus, thus leading to rapid disease progression. These data reveal the viral and immune interactions characterizing a transition from long-term nonprogressive to rapidly progressive infection.

Base Sequence↗

PubMed2001

Opposing cardioprotective actions and parallel hypertrophic effects of delta PKC and epsilon PKC.

Conflicting roles for protein kinase C (PKC) isozymes in cardiac disease have been reported. Here, deltaPKC-selective activator and inhibitor peptides were designed rationally, based on molecular modeling and structural homology analyses. Together with previously identified activator and inhibitor peptides of epsilonPKC, deltaPKC peptides were used to identify cardiac functions of these isozymes. In isolated cardiomyocytes, perfused hearts, and transgenic mice, deltaPKC and epsilonPKC had opposing actions on protection from ischemia-induced damage. Specifically, activation of epsilonPKC caused cardioprotection whereas activation of deltaPKC increased damage induced by ischemia in vitro and in vivo. In contrast, deltaPKC and epsilonPKC caused identical nonpathological cardiac hypertrophy; activation of either isozyme caused nonpathological hypertrophy of the heart. These results demonstrate that two related PKC isozymes have both parallel and opposing effects in the heart, indicating the danger in the use of therapeutics with nonselective isozyme inhibitors and activators. Moreover, reduction in cardiac damage caused by ischemia by perfusion of selective regulator peptides of PKC through the coronary arteries constitutes a major step toward developing a therapeutic agent for acute cardiac ischemia.

Amino Acid Sequence↗

PubMed2001

A novel platelet-rich arterial thrombosis model in rabbits. Simple, reproducible, and dynamic real-time measurement by using double-opposing inverted-sutures model.

Though numerous animal thrombosis models have been introduced, an easy, reliable, and reproducible arterial thrombosis model remains a continuing challenge prior to a thrombolytic study. In an effort to evaluate the efficiency of various recombinant thrombolytic agents with specific affinity to activated platelets in vivo, we developed a novel double-opposing inverted-sutures model to create a platelet-rich thrombus in the femoral artery of rabbits. The arteriotomy was done semicircumferentially, and variously sized microsurgical sutures were introduced intraluminally in a double-opposing inverted manner. The animals were divided into three groups according to the double-opposing inverted-sutures used: Group 1 with 10-0 nylon (n=6), Group 2 with 9-0 nylon (n=6), and Group 3 with 8-0 nylon (n=22). The superficial epigastric branch was cannulated with a thin polyethylene (PE) tube for intraarterial administration of the studied thrombolytic agent. The blood flow was continuously measured with a real-time ultrasonic flow meter. Within 2 h of installation of the sutures, there was no thrombus formation in either Group 1 or 2. In Group 3, the thrombosis rate was 91% (20 of 22) under a steady baseline flow (with an average of 12.23+/-2.40 ml/min). It was highly statistically significant with a P-value of .0000743 using Fisher's Exact Test. The averaged time to thrombosis was 21.8+/-9.8 min. The ultrasonic flow meter to record the dynamic real-time measurement of blood flow was a guideline for thrombus formation or dissolution, which was correlated with the morphological findings of stenotic status of the vessel detected by the Doppler sonography. The components of the thrombus were proven to be platelet-rich predominant by histological examination via hematoxylin and eosin (H&E) stain and transmission electron microscopy (TEM). To confirm that the double-opposing inverted-sutures model would be useful for a study of thrombolytic agents, we evaluated the effects of recombinant tissue-type plasminogen activator (rt-PA) and streptokinase-human plasminogen (SK-HPlg). The average time to thrombolysis post rt-PA infusion was 16.0+/-8.2 min and that of SK-HPlg was 79.6+/-23.1, which were similar to the previous reports. In conclusion, the novel double-opposing inverted-sutures (8-0 nylon) model provides a simple, reliable, and reproducible platelet-rich arterial thrombosis model with noninvasive and dynamic real-time measurement. It may be applied in assessing the efficiency of the recombinant thrombolytic agents and offers many advantages of an arterial platelet-rich in vivo thrombosis model.

Animals↗

PubMed2001

[Simultaneously analysis of 15 parameters in the patients with the liver-blood deficiency syndrome].

OBJECTIVE: Using HPLC-ED or RIA, we determined simultaneously 15 indexes in 27 patients with the liver-blood deficiency syndrome (LDBD). By means of multivarivate hierarchical cluster analysis and selections of typical variate, the results showed that 15 indexes were classified into 5 groups, and the typical variates of each groups were NE, T3, TXB2, ALD and cGMP. It suggests that LBDS has some pathopysiological characteristics such as decreased functions of sympathetic nerve activation, lower T3 syndrome, imbalance of the active substance regulating cardiovascular function and metabolism of salt and water, and abnormalities second signal substance in cellular membrane.

Adolescent↗

PubMed2001

Cofactor and tryptophan accessibility and unfolding of brain glutamate decarboxylase.

Cofactor and tryptophan accessibility of the 65-kDa form of rat brain glutamate decarboxylase (GAD) was investigated by fluorescence quenching measurements using acrylamide, I-, and Cs+ as the quenchers. Trp residues were partially exposed to solvent. I- was less able and Cs+ was more able to quench the fluorescence of Trp residues in the holoenzyme of GAD (holoGAD) than the apoenzyme (apoGAD). The fraction of exposed Trp residues were in the range of 30-49%. In contrast, pyridoxal-P bound to the active site of GAD was exposed to solvent. I- was more able and Cs+ was less able to quench the fluorescence of pyridoxal-P in holoGAD. The cofactor was present in a positively charged microenvironment, making it accessible for interactions with anions. A difference in the exposure of Trp residues and pyridoxal-P to these charged quenchers suggested that the exposed Trp residues were essentially located outside of the active site. Changes in the accessibility of Trp residues upon pyridoxal-P binding strongly supported a significant conformational change in GAD. Fluorescence intensity measurements were also carried out to investigate the unfolding of GAD using guanidine hydrochloride (GdnHCl) as the denaturant. At 0.8-1.5 M GdnHCl, an intermediate step was observed during the unfolding of GAD from the native to the denatured state, and was not found during the refolding of GAD from the denatured to native state, indicating that this intermediate step was not a reversible process. However, at >1.5 M GdnHCl for holoGAD and >2.0 M GdnHCl for apoGAD, the transition leading to the denatured state was reversible. It was suggested that the intermediate step involved the dissociation of native dimer of GAD into monomers and the change in the secondary structure of the protein. Circular dichroism revealed a decrease in the alpha-helix content of GAD from 36 to 28%. The unfolding pattern suggested that GAD may consist of at least two unfolding domains. Unfolding of the lower GdnHCl-resisting domain occurred at a similar concentration of denaturant for apoGAD and holoGAD, while unfolding of the higher GdnHCl-resisting domain occurred at a higher concentration of GdnHCl for apoGAD than holoGAD.

Acrylamide↗

PubMed2001

Oxidized low-density lipoprotein downregulates endothelial basic fibroblast growth factor through a pertussis toxin-sensitive G-protein pathway: mediator role of platelet-activating factor-like phospholipids.

BACKGROUND: Oxidized LDL (oxLDL) inhibits angiogenesis in part by downregulating endothelial basic fibroblast growth factor (bFGF). To determine the mechanism of the downregulation, we investigated the signal transduction pathway involving potential phospholipid mediators. METHODS AND RESULTS: Cultured bovine aortic endothelial cells were incubated with PBS (lipoprotein-free control), LDL, or copper oxLDL under serum-free conditions. At 24 hours, oxLDL (50 microg/mL) decreased bFGF mRNA (Northern blot), bFGF protein (Western blot and ELISA), and concomitant DNA synthesis, all by 40% to 50% compared with PBS. LDL had no effect. Pretreating the cells with 100 ng/mL pertussis toxin (PTX) for 18 hours before oxLDL exposure almost completely blocked the inhibitory effects of oxLDL. In contrast, inhibiting other major cellular signal transduction pathways with PD-98059 (mitogen-activated protein kinase kinase inhibitor), HA-1004 (inhibitor of cGMP- and cAMP-dependent protein kinase), or Ro-31-8220 (protein kinase C inhibitor) or chelating intracellular Ca(2+) with BAPTA-AM failed to attenuate any of the oxLDL effects assayed. Addition to the cultures of WEB 2086, a specific antagonist of the PTX-sensitive G protein-coupled platelet-activating factor (PAF) receptor, blocked the action of oxLDL. Whereas PAF dispersed in the culture medium failed to produce oxLDL-like effects, degradation of PAF and PAF-like phospholipids accumulated in oxLDL with a recombinant human PAF acetylhydrolase eliminated the inhibitory effects of oxLDL on bFGF expression and DNA synthesis. CONCLUSIONS: OxLDL suppresses endothelial bFGF expression and DNA synthesis through a PTX-sensitive heterotrimeric G-protein pathway involving mediator phospholipids similar, but not identical, to PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗