Hae-Rahn Bae

Serial Measurement of Surface Expressions of CD63, P-Selectin and CD40 Ligand on Platelets in Atherosclerotic Ischemic Stroke

Background: Platelet activation is a key step in the progression of atherosclerosis. The CD40 ligand (CD40L) on platelets may be a critical factor to develop the acute vascular events from atheroma. Methods: To determine the role of CD40L on platelets in atherosclerotic ischemic stroke, we serially measured the expressions of CD63, P-selectin and CD40L on platelets in patients with atherosclerotic ischemic stroke (n = 25) and compared them with those in patients with asymptomatic carotid stenosis (n = 20) and in normal subjects (n = 24). Results: The expressions of CD63 and P-selectin on platelets were significantly higher in patients with atherosclerotic ischemic stroke (n = 25) than in normal subjects (n = 24). The extents of surface expressions of CD63 and P-selectin on platelets showed no significant differences between atherosclerotic ischemic stroke and asymptomatic carotid stenosis. However, the CD40L expression on platelets was significantly higher in atherosclerotic ischemic stroke when compared to that in asymptomatic carotid stenosis. Conclusions: In our data, among the population with large artery atherosclerosis, the patients with symptomatic ischemic events showed a significantly elevated expression of CD40L on platelets compared to those without ischemic events. Therefore, the upregulation of CD40L on platelets may be a specific marker of platelet activation to provoke ischemic stroke from large artery atherosclerosis.

Changes in platelet P-selectin and in plasma C-reactive protein in acute atherosclerotic ischemic Stroke treated with a loading dose of clopidogrel

AbstractBackground: The surface expression of P-selectin on platelets contributes to the progression of inflammatory processes and thrombosis in atherothrombosis. In this study, we showed that the combination regimen of clopidogrel with aspirin could downregulate the P-selectin expression on platelets and the plasma concentration of C-reactive protein (CRP) in acute stage of atherosclerotic ischemic stroke. Methods: Patients with acute ischemic stroke (<24 hours) were randomized for 7 days to combined regimen of clopidogrel and aspirin (n = 24) or intravenous heparin with aspirin (n = 28). We measured the changes of National Institute of Health Stroke Scale (NIHSS) scores, CRP concentration, and surface expressions of P-selectin on platelets during 7 days. Results: The combined regimen of clopidogrel and aspirin significantly reduced platelet P-selectin expression (93.6 ± 16.6, p < 0.01) and plasma concentration of CRP (1.2 ± 1.5 mg/dl, p < 0.01) after 7 days of stroke onset compared with the values (P-selectin; 115.5 ± 20.7, CRP; 2.5 ± 2.8 mg/dl) of initial 24 hr. Also, the clinical improvement, as measured by NIHSS score, was significant in the clopidogrel loading group at 7 days (6.2 ± 5.5, p < 0.05) compared to the initial 24 hrs (10.1 ± 7.6). Conclusion: Our results indicate that the combined regimen of clopidogrel and aspirin has beneficial effects on regulating platelet activation and inflammatory processes in acute atherosclerotic ischemic stroke. Thus, this combination regimen deserves further evaluation in clinical trial for the treatment of acute atherosclerotic ischemic stroke.

Effect of omega-3 fatty acids on the modification of erythrocyte membrane fatty acid content including oleic acid in peritoneal dialysis patients

Erythrocyte membrane fatty acids (FA), such as oleic acid, are related to acute coronary syndrome. There is no report about the effect of omega-3 FA on oleic acid in peritoneal dialysis (PD) patients. We hypothesized that omega-3 FA can modify erythrocyte membrane FA, including oleic acid, in PD patients. In a double-blind, randomized, placebo-controlled study, 18 patients who were treated with PD for at least 6 months were randomized to treatment for 12 weeks with omega-3 FA or placebo. Erythrocyte membrane FA content was measured by gas chromatography at baseline and after 12 weeks. The erythrocyte membrane content of eicosapentaenoic acid and docosahexaenoic acid was significantly increased and saturated FA and oleic acid were significantly decreased in the omega-3 FA supplementation group after 12 weeks compared to baseline. In conclusion, erythrocyte membrane FA content, including oleic acid, was significantly modified by omega-3 FA supplementation for 12 weeks in PD patients.

Associations between Oxidized LDL to LDL Ratio, HDL and Vascular Calcification in the Feet of Hemodialysis Patients

Cardiovascular mortality is associated with vascular calcification (VC) in hemodialysis (HD) patients. The present study was designed to find factors related with medial artery calcification on the plain radiography of feet by comparing C-reactive protein (CRP), plasminogen activator inhibitor type 1 (PAI-1) and lipid profile including oxidized low density lipoprotein (ox-LDL) and to elucidate associations among these factors in HD patients. Forty-eight HD patients were recruited for this study. VC in the feet was detected in 18 patients (37.5%) among total patients and 12 patients (85.7%) among diabetic patients. Diabetes, cardiovascular disease (CVD), pulse pressure, ox-LDL/LDL were higher and high density lipoprotein (HDL) was lower in patients with VC than in patients without VC. Negative associations were found between HDL and CRP, PAI-1. PAI-1 had positive association with ox-LDL/LDL. History of CVD was the only determinant of vascular calcification on the plain radiography of feet. Ox-LDL/LDL, HDL, CRP, and PAI-1 were closely related with one another in HD patients. History of CVD is the most important factor associated with the presence of VC and low HDL and relatively high oxidized LDL/LDL ratio may affect VC formation on the plain radiography in the feet of HD patients.

Characterization of K + Channels in the Basolateral Membrane of Rat Tracheal Epithelia

Abstract. To study K+ channels in the basolateral membrane of chloride-secreting epithelia, rat tracheal epithelial monolayers were cultured on permeable filters and mounted into an Ussing chamber system. The mucosal membrane was permeabilized with nystatin (180 μg/ml) in the symmetrical high K+ (145 mm) Ringer solution. During measurement of the macroscopic K+ conductance properties of the basolateral membrane under a transepithelial voltage clamp, we detected at least two types of K+ currents: one is an inwardly rectifying K+ current and the other is a slowly activating outwardly rectifying K+ current. The inwardly rectifying K+ current is inhibited by Ba2+. The slowly activating K+ current was potentiated by cAMP and inhibited by clofilium, phorbol 12-myristae 13-acetate (PMA) and lowering temperature. This is consistent with the biophysical characteristics of ISK channel. RT-PCR analysis revealed the presence of ISK cDNA in the rat trachea epithelia. Although 0.1 mm Ba2+ only had minimal affect on short-circuit current (Isc) induced by cAMP in intact epithelia, 0.1 mm clofilium strongly inhibited it. These results indicate that ISK might be important for maintaining cAMP-induced chloride secretion in the rat trachea epithelia.

Association of adiponectin and leptin with serum lipids and erythrocyte omega-3 and omega-6 fatty acids in dialysis patients.

AIMS Besides regulating energy metabolism, leptin promotes and adiponectin suppresses inflammation which is a common feature of end-stage renal disease (ESRD). Omega-3 fatty acids (n-3FA) exert anti-inflammatory actions by inhibiting pro-inflammatory signal transduction pathways whereas arachidonic acid (an n-6FA) facilitates inflammation by mediating inflammatory signals and serving as precursor of pro-inflammatory eicosanoids. Given the functional overlap between adipokines and n-3FA and n-6FA, we sought to explore their interrelationship in patients with ESRD. METHODS 44 ESRD patients maintained on hemodialysis (HD), 29 patients receiving peritoneal dialysis (PD), and 10 healthy subjects were enrolled. Body mass index (BMI), plasma leptin, adiponectin, lipids and CRP and erythrocyte fatty acids were measured. RESULTS Compared to controls adiponectin was elevated and leptin level was reduced in the ESRD group. Adiponectin levels were comparable among PD and HD patients, but leptin and BMI were higher in PD than in HD patients. Despite comparable BMIs, female patients had higher leptin than male patients. Leptin levels were positively associations with BMI, total and LDL cholesterol whereas adiponectin was inversely related with BMI, triglycerides and CRP and directly associated with HDL cholesterol in ESRD patients. Plasma adiponectin was directly associated with erythrocyte n-3 FA (r = 0.581, p = 0.023) and inversely associated with n-6FA (r = -0.640, p = 0.010) in the HD patients. CONCLUSION A direct association was found between plasma levels of adiponectin and HDL and erythrocyte n-3FA in ESRD patients. Prospective trials are needed to explore the effect of n-3FA supplementation on plasma adipokines and markers of oxidative stress and inflammation in this population.

Increased platelet CD63 and P-selectin expression persist in atherosclerotic ischemic stroke

Platelet activation is an important process in the pathogenesis of atherothrombosis. However, the serial changes of platelet activation in atherosclerotic ischemic stroke have not been determined. In this study, we measured serially platelet expression of CD63 and P-selectin and platelet aggregability to ADP and collagen. Measurements were made 24 and 72 h and 7 and 90 days after the ischemic event in 29 patients with atherosclerotic ischemic stroke. Platelet aggregability was significantly decreased after 72 h compared to that at 24 h of stroke onset. However, platelet CD63 and P-selectin expression remained high even 90 days after the events. These findings suggest that platelet hyperactivation in atherosclerotic ischemic stroke may be sustained for a considerable period.

Protein Tyrosine Kinase Inhibitors Modulate Radiosensitivity and Radiation-Induced Apoptosis in K562 Cells

Abstract Jeong, S-J., Jin, Y-H., Moon, C-W., Bae, H-R., Yoo, Y-H., Lee, H-S., Lee, S-H., Lim, Y-J., Lee, J-D. and Jeong, M-H. Protein Tyrosine Kinase Inhibitors Modulate Radiosensitivity and Radiation-Induced Apoptosis in K562 Cells. Radiat. Res. 156, 751–760 (2001). We studied the modulating effect of protein tyrosine kinase inhibitors on the response of cells of the human chronic myelogenous leukemia cell line K562 to radiation. The radiosensitivity of the cells was increased by treatment with herbimycin A and decreased by treatment with genistein. This modulating effect of protein tyrosine kinase inhibitors on radiation sensitivity was associated with the alteration of the mode of radiation-induced cell death. After X irradiation, the cells arrested in the G2 phase of the cell cycle, but these TP53–/– cells were unable to sustain cell cycle arrest. This G2-phase checkpoint deficit caused cell death. The morphological pattern of cell death was characterized by swelling of the cytoplasmic compartments, cytosolic vacuolation, disruption of the plasma membrane, less evident nuclear condensation, and faint DNA fragmentation, all of which were consistent with oncosis or cytoplasmic apoptosis. The nonreceptor protein tyrosine kinase inhibitor herbimycin A accelerated the induction of typical apoptosis by X irradiation, which was demonstrated by morphological assessments using nuclear staining and electron microscopy as well as oligonucleosomal fragmentation and caspase 3 activity. Herbimycin A is known to be a selective antagonist of the BCR/ABL kinase of Philadelphia chromosome-positive K562 cells; this kinase blocks the induction of apoptosis after X irradiation. Our results showed that the inhibition of protein tyrosine kinase by herbimycin A enhanced radiation-induced apoptosis in K562 cells. This effect was associated with the activation of caspase 3 and rapid abrogation of the G2-phase checkpoint with progression out of G2 into G1 phase. In contrast, the receptor-type protein tyrosine kinase inhibitor genistein protected K562 cells from all types of radiation-induced cell death through the inhibition of caspase 3 activity and prolonged maintenance of G2-phase arrest. Further investigations using this model may give valuable information about the mechanisms of radiation-induced apoptosis and about the radiosensitivity and radioresistance of chronic myelogenous leukemia cells having the Philadelphia chromosome.

Three-dimensional culture and interaction of cancer cells and dendritic cells in an electrospun nano-submicron hybrid fibrous scaffold

An artificial three-dimensional (3D) culture system that mimics the tumor microenvironment in vitro is an essential tool for investigating the cross-talk between immune and cancer cells in tumors. In this study, we developed a 3D culture system using an electrospun poly(ε-caprolactone) (PCL) nanofibrous scaffold (NFS). A hybrid NFS containing an uninterrupted network of nano- and submicron-scale fibers (400 nm to 2 µm) was generated by deposition onto a stainless steel mesh instead of an aluminum plate. The hybrid NFS contained multiplanar pores in a 3D structure. Surface-seeded mouse CT26 colon cancer cells and bone marrow-derived dendritic cells (BM-DCs) were able to infiltrate the hybrid NFS within several hours. BM-DCs cultured on PCL nanofibers showed a baseline inactive form, and lipopolysaccharide (LPS)-activated BM-DCs showed increased expression of CD86 and major histocompatibility complex Class II. Actin and phosphorylated FAK were enriched where unstimulated and LPS-stimulated BM-DCs contacted the fibers in the 3D hybrid NFS. When BM-DCs were cocultured with mitoxantrone-treated CT26 cells in a 3D hybrid NFS, BM-DCs sprouted cytoplasm to, migrated to, synapsed with, and engulfed mitoxantrone-treated CT26 cancer cells, which were similar to the naturally occurring cross-talk between these two types of cells. The 3D hybrid NFS developed here provides a 3D structure for coculture of cancer and immune cells.

Comparison of Erythrocyte Membrane Fatty Acid Contents in Renal Transplant Recipients and Dialysis Patients

BACKGROUND Alterations of erythrocyte membrane fatty acid (FA) composition play important roles in cellular function because they change the membrane microenvironment, including transmembrane receptors. The erythrocyte membrane oleic acid content is higher among patients with acute coronary syndrome and also in dialysis patients. However, available data are limited concerning erythrocyte membrane FA content in kidney transplant recipients (KTP). We sought to test the hypothesis that erythrocyte membrane FA content among KTP were different from those in dialysis patients. METHODS In this cross-sectional study, we recruited 35 hemodialysis, 33 peritoneal dialysis 49 KTP, and 33 normal control subjects (CTL). Their erythrocyte membrane FA content were measured by gas chromatography. RESULTS The mean ages of the enrolled dialysis patients, KTP, and CTL were 56.4 ± 10.1, 48.9 ± 10.4, and 49.5 ± 8.3 years, respectively. Mean kidney transplant duration was 89.8 ± 64.8 months and mean dialysis duration, 49.0 ± 32.6 months. The intakes of vegetable lipid and vegetable protein including total calories were significantly increased among KTP versus dialysis patients. Total cholesterol (P < .001) and high density lipoprotein cholesterol (HDL; P < .001) levels were significantly higher and C-reactive protein was significantly lower among KTP compared with dialysis patients. The erythrocyte membrane content of palmitoleic acid (P < .001) was significantly higher but oleic acid (P < .001) significantly lower in KTP compared with dialysis patients. The erythrocyte membrane contents of arachidonic acid and docosahexaenoic acid were significantly higher, and linoleic acid and the omega-6 FA to omega-3 FA ratio (P < .001) significantly lower in KTP compared with dialysis patients. The erythrocyte membrane content of oleic acid was independently associated with monounsaturated fatty acid (beta = 0.771, P < .001), eicosapentaeonic acid (beta = -0.244, P = .010), and HDL (beta = -0.139, P = .049) in KTP. CONCLUSIONS FA contents of erythrocyte membranes were significantly different in KTP compared with dialysis patients. These differences may have been associated with improved dietary intake and immunosuppression after kidney transplantation.