Prognostic Benefits of Carvedilol, Bisoprolol, and Metoprolol Controlled Release/Extended Release in Hemodialysis Patients with Heart Failure: A 10-Year Cohort.

BACKGROUND: Heart failure is a highly prevalent cardiovascular complication among patients receiving long-term hemodialysis, but the benefits of carvedilol, bisoprolol, and metoprolol controlled release/extended release on the outcomes of these patients remain unclear. In this study, we address the use of these 3 ß-blockers and their associations with mortality. METHODS AND RESULTS: Long-term hemodialysis patients, aged ≥35 years, with new-onset heart failure and receiving various medications were identified through the use of 1999-2010 data from the Taiwan National Health Insurance Research Database. From the total of 4435 heart failure patients, we selected 1700 new users of the 3 ß-blockers (study group) and 1700 nonusers (control group), by using matched cohorts according to their propensity scores, and then compared the 5-year all-cause mortality rates by using Cox proportional hazard regressions and time-dependent covariate adjustment. During 3944 person-years of follow-up, 666 (39.2%) deaths occurred within the study group, compared with 918 (54%) deaths during 2893 person-years of follow-up in the control group. The 5-year mortality rate for the study (control) group was 54.5% (70.3%); P<0.001. Adjusted hazard regression analyses revealed that the therapeutic effects of ß-blockers remained significant for all-cause mortality (hazard ratio 0.80, 95% CI 0.72 to 0.90). Subgroup analyses revealed that patients in the study group receiving ß-blockers plus renin-angiotensin system antagonists exhibited the lowest mortality rate, while the highest mortality rate was found among patients in the control group receiving neither ß-blockers nor renin-angiotensin system antagonists. CONCLUSIONS: This study demonstrates that the 3 ß-blockers were associated with improved survival in long-term hemodialysis patients with heart failure.

Chinese translation of English textbooks on internal medicine from the 1850s to the 1940s.

During the 100 years from 1850 to 1949, six English textbooks on internal medicine were translated into Chinese and published. Publication of these books was a response to the increased demand for Chinese textbooks after the opening of several Western-style hospitals and medical schools in China where the instruction was in Chinese. Throughout this period, textbooks translated from English were regarded as symbols of mainstream and authority within medical communities in China. There was a shift of translators from British and American medical missionaries to Chinese medical elites. Publishers also changed from missionary hospitals or missionary organizations to the Chinese Medical Association, which was led by ethnic Chinese. After the 1950s, translation activity continued in Taiwan, but it was halted in China until after the Cultural Revolution. This paper provides bibliographic information about these books. The transition of medical authority in China during this 100-year period is also reviewed through the successive publication of translated textbooks on internal medicine.

Connective tissue growth factor induces collagen I expression in human lung fibroblasts through the Rac1/MLK3/JNK/AP-1 pathway.

Connective tissue growth factor (CTGF) plays an important role in lung fibrosis. In this study, we investigated the role of Rac1, mixed-lineage kinase 3 (MLK3), c-Jun N-terminal kinase (JNK), and activator protein-1 (AP-1) in CTGF-induced collagen I expression in human lung fibroblasts. CTGF caused concentration- and time-dependent increases in collagen I expression. CTGF-induced collagen I expression was inhibited by the dominant negative mutant (DN) of Rac1 (RacN17), MLK3DN, MLK3 inhibitor (K252a), JNK1DN, JNK2DN, a JNK inhibitor (SP600125), and an AP-1 inhibitor (curcumin). Treatment of cells with CTGF caused activation of Rac1, MLK3, JNK, and AP-1. The CTGF-induced increase in MLK3 phosphorylation was inhibited by RacN17. Treatment with RacN17 and the MLK3DN inhibited CTGF-induced JNK phosphorylation. CTGF caused increases in c-Jun phosphorylation and the recruitment of c-Jun and c-Fos to the collagen I promoter. Furthermore, stimulation of cells with the CTGF resulted in increases in AP-1-luciferase activity; this effect was inhibited by Rac1N17, MLK3DN, JNK1DN, and JNK2DN. Moreover, CTGF-induced α-smooth muscle actin (α-SMA) expression was inhibited by the procollagen I small interfering RNA (siRNA). These results suggest for the first time that CTGF acting through Rac1 activates the MLK3/JNK signaling pathway, which in turn initiates AP-1 activation and recruitment of c-Jun and c-Fos to the collagen I promoter and ultimately induces collagen I expression in human lung fibroblasts.

Renin-angiotensin system blockade in heart failure patients on long-term haemodialysis in Taiwan.

AIMS: Heart failure is among the most frequent complications of patients on long-term haemodialysis. The benefits of renin-angiotensin system (RAS) blockade on the outcomes of these patients have yet to be determined. METHODS AND RESULTS: We conducted a nationwide observational study using data from the Taiwan National Health Insurance claims database, between 1999 and 2010. We enrolled patients aged ≥35 years with new-onset heart failure [diagnosed by International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM) codes] under treatment with medications. New users of a RAS blocker (RASB; i.e., an ACE inhibitor or an ARB used as monotherapy or dual therapy) were selected to compare with non-RASB users. We used Cox proportional hazards regression with and without propensity score adjustment to compare the risk of 3-year all-cause and cardiovascular mortality. Stratified analyses and RASB therapy duration as a time-dependent covariate were also performed. In all, 4771 were treated with an RASB (n = 3024) or without an RASB (n = 1747). RASB users had a higher prevalence of hypertension and diabetes, and a higher number of hospitalization. Among RASB users, 1148 deaths (38.0%) occurred during 5272 person-years of follow-up compared with 734 deaths (42.0%) among non-RASB users during 2683 person-years of follow-up. Three-year mortality rates were 45.4% and 49.1% for patients receiving and those not receiving an RASB, respectively (log-rank test, P < 0.001). Adjusted hazard analysis revealed that RASB therapeutic effects remained significant on all-cause [hazard ratio (HR) 0.8; 95% confidence interval (CI) 0.72-0.89; P < 0.001] and cardiovascular mortality (HR 0.76; 95% CI 0.64-0.90; P < 0.01). CONCLUSIONS: RASB therapy reduced all-cause and cardiovascular mortality in heart failure patients on long-term haemodialysis.

Nicotinuric acid: a potential marker of metabolic syndrome through a metabolomics-based approach.

OBJECTIVE: Metabolic syndrome is a multiplex disorder and puts patients on the road to type 2 diabetes and atherosclerotic cardiovascular diseases. However, a surrogate biomarker in plasma or urine in fully reflecting features of metabolic syndrome has not been explored. RESEARCH DESIGN AND METHODS: Urine metabolomics has potential utility in metabolic profiling because urine metabolites analysis reflects global outflux of metabolic change. Accordingly, we collected data on subjects (n = 99) with overweight, dyslipidemia, hypertension or impaired glucose tolerance and took a metabolomics approach to analyze the metabolites of urine revealed in metabolic syndrome by high-performance liquid chromatography-time-of-flight mass spectrometry and elicit potential biomarkers to picture metabolic syndrome. RESULTS: Our results revealed that the urine nicotinuric acid value of subjects with diabetes (HbA1c ≥ 6.5% or those receiving diabetes medications) (n = 25) was higher than subjects without diabetes (n = 37) (221 ± 31 vs. 152 ± 13 × 10(3) mAU, P = 0.0268). Moreover, urinary nicotinuric acid level was positively correlated with body mass index, blood pressure, total cholesterol, low-density lipoprotein cholesterol, triacylglycerol and high sensitivity C-reactive protein, but negatively correlated with high-density lipoprotein cholesterol. CONCLUSIONS: This is the first study, to our knowledge, to propose that nicotinuric acid represents an important pathogenic mechanism in process from metabolic syndrome to diabetes and atherosclerotic cardiovascular disease.

Denbinobin induces human glioblastoma multiforme cell apoptosis through the IKKα-Akt-FKHR signaling cascade.

Denbinobin, a phenanthraquinone derivative, was shown to exert antitumor activities in several types of cancer cell lines. However, the precise mechanism underlying denbinobin-induced cell death remains unclear. In this study, we investigated the apoptotic signaling cascade elicited by denbinobin in human glioblastoma multiforme (GBM) cells. Denbinobin concentration-dependently caused a decrease in the cell viability of GBM cells. A flow cytometric analysis of propidium iodide (PI)-stained cells demonstrated that denbinobin induced GBM cell apoptosis. Denbinobin evoked caspase-3 activation and degradation of poly (ADP-ribose) polymerase (PARP) and N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk), a broad-spectrum caspase inhibitor that prevented denbinobin-induced cell death. In addition, denbinobin-induced cell death was diminished by the transfection of wild-type (WT) Akt or IκB kinase (IKK) into GBM cells. Denbinobin reduced IKK phosphorylation in a time-dependent manner, and denbinobin-dephosphorylated IKK was accompanied by a decrease in Akt phosphorylation. The phosphorylation status of forkhead in rhabdomyosarcoma (FKHR), a downstream signal molecule of Akt, was also diminished by the presence of denbinobin. Furthermore, transfection of GBM cells with WT IKKα markedly suppressed the decreases in Akt and FKHR phosphorylation caused by denbinobin. In contrast, transfection with WT IKKß only slightly affected denbinobin's action against IKK, Akt, and FKHR. These results suggest that IKKα inactivation, followed by Akt and FKHR dephosphorylation and caspase-3 activation, contributes to denbinobin-induced GBM cell apoptosis.

Thrombin-induced CCN2 expression in human lung fibroblasts requires the c-Src/JAK2/STAT3 pathway.

Thrombin is a multifunctional serine protease and an important fibrotic mediator that induces CCN2 expression. We previously showed that thrombin induces CCN2 expression via an ASK1-dependent JNK/AP-1 pathway in human lung fibroblasts. In this study, we further investigated the roles of c-Src, JAK2, and STAT3 in thrombin-induced CCN2 expression. Thrombin-induced CCN2 expression and CCN2-Luc activity were attenuated by a JAK inhibitor (AG490) and JAK2DN, STAT3DN, and the STAT decoy ODN. Moreover, transfection of cells with a CCN2-mtSTAT-Luc construct inhibited thrombin-induced CCN2-Luc activity. Treatment of cells with thrombin caused JAK2 phosphorylation at Tyr1007/1008 and STAT3 phosphorylation at Tyr705 in time-dependent manners. Thrombin-induced STAT3 phosphorylation was inhibited by AG490 and JAK2DN. Thrombin-induced STAT3 binding to the CCN2 promoter was analyzed by a DNA-binding affinity pull-down assay. In addition, thrombin-induced CCN2 expression and CCN2-Luc activity were inhibited by c-SrcDN and PP2 (an Src inhibitor). Transfection of cells with c-SrcDN also inhibited thrombin-induced JAK2 and STAT3 phosphorylation. Taken together, these results indicate that thrombin might activate c-Src to induce JAK2 activation, which in turn, causes STAT3 activation, and finally induces CCN2 expression in human lung fibroblasts.

Students' view upon graduation: a survey of medical education in Taiwan.

BACKGROUND: Improving the quality of medical education is a key goal of government policy in Taiwan. The aim of this study was to reflect the responses of medical education from the perspective of graduating medical students in Taiwan. This is the first survey study of medical education in Taiwan. METHODS: Using the Medical School Graduation Questionnaire from the Association of American Medical Colleges (AAMC), we distributed 406 questionnaires to medical students of four medical schools in their last semester, and received 270 back (response rate, 66.5%). There were 11 medical schools in Taiwan. Most questions were assessed on a 5-point Likert scale. RESULTS: Students identified genetics, biochemistry, and ethics as the three most important premedical subjects preparing them for medical education and gross anatomy, physiology, and pharmacology as the three most helpful basic science subjects preparing them for clinical clerkships and electives. Most Taiwanese students were satisfied with their learning experience in internal medicine. Only 55.9% of students were confident that they had acquired the clinical skills required to become a resident, and 70.7% were satisfied with the quality of their medical education. CONCLUSION: The study offers preliminary results on the views of graduating students on the medical education system in Taiwan. In particular, our government and medical educators need to continuously put more effort into building students' confidence in their clinical skills.

Zerumbone suppresses IKKα, Akt, and FOXO1 activation, resulting in apoptosis of GBM 8401 cells.

BACKGROUND: Zerumbone, a sesquiterpene compound isolated from subtropical ginger, Zingiber zerumbet Smith, has been documented to exert antitumoral and anti- inflammatory activities. In this study, we demonstrate that zerumbone induces apoptosis in human glioblastoma multiforme (GBM8401) cells and investigate the apoptotic mechanism. METHODS: We added a caspase inhibitor and transfected wild-type (WT) IKK and Akt into GBM 8401 cells, and measured cell viability and apoptosis by MTT assay and flow cytometry. By western blotting, we evaluated activation of caspase-3, dephosphorylation of IKK, Akt, FOXO1 with time, and change of IKK, Akt, and FOXO1 phosphorylation after transfection of WT IKK and Akt. RESULTS: Zerumbone (10~50 µM) induced death of GBM8401 cells in a dose-dependent manner. Flow cytometry studies showed that zerumbone increased the percentage of apoptotic GBM cells. Zerumbone also caused caspase-3 activation and poly (ADP-ribose) polymerase (PARP) production. N-benzyloxycarbonyl -Val-Ala-Asp- fluoromethylketone (zVAD-fmk), a broad-spectrum caspase inhibitor, hindered zerumbone-induced cell death. Transfection of GBM 8401 cells with WT IKKα inhibited zerumbone-induced apoptosis, and zerumbone significantly decreased IKKα phosphorylation levels in a time-dependent manner. Similarly, transfection of GBM8401 cells with Akt suppressed zerumbone-induced apoptosis, and zerumbone also diminished Akt phosphorylation levels remarkably and time-dependently. Moreover, transfection of GBM8401 cells with WT IKKα reduced the zerumbone-induced decrease in Akt and FOXO1 phosphorylation. However, transfection with WT Akt decreased FOXO1, but not IKKα, phosphorylation. CONCLUSION: The results suggest that inactivation of IKKα, followed by Akt and FOXO1 phosphorylation and caspase-3 activation, contributes to zerumbone-induced GBM cell apoptosis.

Cardiovascular protection of magnolol: cell-type specificity and dose-related effects.

Magnolia officinalis has been widely used in traditional Chinese medicine. Magnolol, an active component isolated from Magnolia officinalis, is known to be a cardiovascular protector since 1994. The multiplex mechanisms of magnolol on cardiovascular protection depends on cell types and dosages, and will be reviewed and discussed in this article. Magnolol under low and moderate dosage possesses the ability to protect heart from ischemic/reperfusion injury, reduces atherosclerotic change, protects endothelial cell against apoptosis and inhibits neutrophil-endothelial adhesion. The moderate to high concentration of magnolol mainly acts on smooth muscle cells and platelets. Magnolol induces apoptosis in vascular smooth muscle cells at moderate concentration and inhibits proliferation at moderate and high concentration. High concentration of magnolol also abrogates platelet activation, aggregation and thrombus formation. Magnolol also serves as an smooth muscle relaxant only upon the high concentration. Oral intake of magnolol to reach the therapeutic level for cardiovascular protection is applicable, thus makes magnolol an agent of great potential for preventing cardiovascular diseases in high-risk patients.

Thrombin induced connective tissue growth factor expression in rat vascular smooth muscle cells via the PAR-1/JNK/AP-1 pathway.

AIM: To investigate the signaling pathways involved in thrombin-induced connective tissue growth factor (CTGF) expression in rat vascular smooth muscle cells (VSMCs). METHODS: Experiments were preformed on primary rat aortic smooth muscle cells (RASMCs) and a rat VSMC line (A10). CTGF protein levels were measured using Western blotting. Luciferase reporter genes and dominant negative mutants (DNs) were used to investigate the signaling pathways mediating the induction of CTGF expression by thrombin. RESULTS: Thrombin (0.3-3.0 U/mL) caused a concentration- and time-dependent increase in CTGF expression in both RASMCs and A10 cells. Pretreating A10 cells with the protease-activated receptor 1 (PAR-1) antagonist SCH79797 (0.1 µmol/L) significantly blocked thrombin-induced CTGF expression, while the PAR-4 antagonist tcY-NH(2) (30 µmol/L) had no effect. The PAR-1 agonist SFLLRN-NH(2) (300 µmol/L) induced CTGF expression, while the PAR-4 agonist GYPGQV-NH(2) (300 µmol/L) had no effect. Thrombin (1 U/mL) caused time-dependent phosphorylation of c-Jun N-terminal kinase (JNK). Pretreating with the JNK inhibitor SP600125 (3-30 µmol/L) or transfection with DNs of JNK1/2 significantly attenuated thrombin-induced CTGF expression. Thrombin (0.3-3.0 U/mL) increased activator protein-1 (AP-1)-luciferase activity, which was inhibited by the JNK inhibitor SP600125. The AP-1 inhibitor curcumin (1-10 µmol/L) concentration-dependently attenuated thrombin-induced CTGF expression. CONCLUSION: Thrombin acts on PAR-1 to activate the JNK signaling pathway, which in turn initiates AP-1 activation and ultimately induces CTGF expression in VSMCs.

Multiple intravenous transplantations of mesenchymal stem cells effectively restore long-term blood glucose homeostasis by hepatic engraftment and ß-cell differentiation in streptozocin-induced diabetic mice.

Depletion of pancreatic ß-cells results in insulin insufficiency and diabetes mellitus (DM). Single transplantation of mesenchymal stem cells exhibits short-term effects in some preclinical studies. Here, we further investigated the long-term therapeutic effects of multiple intravenous MSC transplantations. In this study, multiple human MSC transplantations (4.2 × 10(7) cells/kg each time) were performed intravenously at 2-week intervals into streptozocin (STZ)-induced diabetic mice for 6 months. Blood sugar, insulin, renal function, cholesterol, and triglyceride levels were monitored. We demonstrated that compared to single intravenous transplantation, which only transiently decreased hyperglycemia, multiple MSC transplantations effectively restored blood glucose homeostasis. Systemic oxidative stress levels were reduced from the seventh week of treatment. From the 11th week, production of human insulin was markedly increased. When MSC transplantation was skipped after blood sugar level returned to normal at the end of 15th week, a sharp rebound of blood sugar occurred, and was then controlled by subsequent transplantations. At the end of 6 months, histopathology examination revealed MSCs specifically engrafted into liver tissues of the recipients. Fifty-one percent of human cells in the recipient liver coexpressed human insulin, especially those surrounding the central veins. Taken together, intravenous MSC delivery was safe and effective for blood glucose stabilization in this preclinical DM model. Multiple transplantations were essential to restore and maintain glucose homeostasis through decreasing systemic oxidative stress in the early stage and insulin production in the late stage. Liver engraftment and differentiation into insulin-producing cells account for the long-term therapeutic effects of MSCs.

Elevated expression of connective tissue growth factor in human atrial fibrillation and angiotensin II-treated cardiomyocytes.

BACKGROUND: Atrial fibrosis is a feature of structural remodeling in atrial fibrillation (AF). Connective tissue growth factor (CTGF) is a potent profibrotic factor, but its role of CTGF in AF is not yet fully understood. METHODS AND RESULTS: Right atrial appendages were obtained from 20 patients who underwent cardiac surgery (10 with sinus rhythm, 10 with AF). The mRNA level, protein level and immunohistochemical staining of CTGF were significantly increased in AF patients. In a porcine AF model, tissue angiotensin II (Ang II) and CTGF levels were significantly upregulated in both atria. In perfused rat hearts, Ang II stimulation increased CTGF expression, which could be inhibited by Ang II type I receptor antagonist. In a cell culture system, both atrial fibroblasts and myocytes were responsible for the increased CTGF expression under Ang II treatment. Ang II type I receptor antagonist could inhibit the Ang II-induced CTGF expression. Treating with recombinant CTGF, atrial fibroblasts expressed an increased level of collagen I. Furthermore, the CTGF level was highly correlated with tissue Ang II content in AF pigs. CONCLUSIONS: AF patients and animals exhibited a significantly increased expression of CTGF. Ang II stimulation upregulated CTGF expression in both atrial fibroblasts and myocytes. Ang II-induced CTGF expression might be involved in atrial substrate remodeling.

Salvianolic acids: small compounds with multiple mechanisms for cardiovascular protection.

Salvianolic acids are the most abundant water-soluble compounds extracted from Radix Salvia miltiorrhiza (Danshen). In China, Danshen has been wildly used to treat cardiovascular diseases for hundreds of years. Salvianolic acids, especially salvianolic acid A (Sal A) and salvianolic acid B (Sal B), have been found to have potent anti-oxidative capabilities due to their polyphenolic structure. Recently, intracellular signaling pathways regulated by salvianolic acids in vascular endothelial cells, aortic smooth muscle cells, as well as cardiomyocytes, have been investigated both in vitro and in vivo upon various cardiovascular insults. It is discovered that the cardiovascular protection of salvianolic acids is not only because salvianolic acids act as reactive oxygen species scavengers, but also due to the reduction of leukocyte-endothelial adherence, inhibition of inflammation and metalloproteinases expression from aortic smooth muscle cells, and indirect regulation of immune function. Competitive binding of salvianolic acids to target proteins to interrupt protein-protein interactions has also been found to be a mechanism of cardiovascular protection by salvianolic acids. In this article, we review a variety of studies focusing on the above mentioned mechanisms. Besides, the target proteins of salvianolic acids are also described. These results of recent advances have shed new light to the development of novel therapeutic strategies for salvianolic acids to treat cardiovascular diseases.

Thrombin induces NF-kappaB activation and IL-8/CXCL8 expression in lung epithelial cells by a Rac1-dependent PI3K/Akt pathway.

We previously showed that thrombin induces interleukin (IL)-8/CXCL8 expression via the protein kinase C (PKC)α/c-Src-dependent IκB kinase α/ß (IKKα/ß)/NF-κB signaling pathway in human lung epithelial cells. In this study, we further investigated the roles of Rac1, phosphoinositide 3-kinase (PI3K), and Akt in thrombin-induced NF-κB activation and IL-8/CXCL8 expression. Thrombin-induced IL-8/CXCL8 release and IL-8/CXCL8-luciferase activity were attenuated by a PI3K inhibitor (LY294002), an Akt inhibitor (1-L-6-hydroxymethyl-chiro-inositol-2-((R)-2-O-methyl-3-O-octadecylcarbonate)), and the dominant negative mutants of Rac1 (RacN17) and Akt (AktDN). Treatment of cells with thrombin caused activation of Rac and Akt. The thrombin-induced increase in Akt activation was inhibited by RacN17 and LY294002. Stimulation of cells with thrombin resulted in increases in IKKα/ß activation and κB-luciferase activity; these effects were inhibited by RacN17, LY294002, an Akt inhibitor, and AktDN. Treatment of cells with thrombin induced Gßγ, p85α, and Rac1 complex formation in a time-dependent manner. These results imply that thrombin activates the Rac1/PI3K/Akt pathway through formation of the Gßγ, Rac1, and p85α complex to induce IKKα/ß activation, NF-κB transactivation, and IL-8/CXCL8 expression in human lung epithelial cells.

Apoptosis signal-regulating kinase 1 in peptidoglycan-induced COX-2 expression in macrophages.

In this study, we investigated the role of ASK1 in PGN-induced C/EBPbeta activation and COX-2 expression in RAW 264.7 macrophages. The PGN-induced COX-2 expression was attenuated by the DNs of ASK1, JNK1, JNK2, a JNK inhibitor (SP600125), and an AP-1 inhibitor (curcumin). PGN caused ASK1 dephosphorylation time-dependently at Ser967, dissociation from the ASK1-14-3-3 complex, and subsequent ASK1 activation. In addition, PGN activated PP2A and suppression of PP2A by okadaic acid markedly inhibited PGN-induced ASK1 Ser967 dephosphorylation and COX-2 expression. PGN induced the activation of the JNK-AP-1 signaling cascade downstream of ASK1. PGN-increased C/EBPbeta expression and DNA-binding activity were inhibited by the ASK1-JNK-AP-1 signaling blockade. COX-2 promoter luciferase activity induced by PGN was attenuated in cells transfected with the COX-2 reporter construct possessing the C/EBP-binding site mutation. In addition, the ASK1-JNK-AP-1-C/EBPbeta cascade was activated in human peripheral mononuclear cells exposure to PGN. The TLR2 agonist Pam(3)CSK(4) was also shown to induce ASK1 Ser967 dephosphorylation, JNK and c-jun phosphorylation, C/EBPbeta activation, and COX-2 expression in RAW 264.7 macrophages. PGN-induced COX-2 promoter luciferase activity was prevented by selective inhibition of TLR2 and c-Jun in RAW 264.7 macrophages. Our data demonstrate that PGN might activate the TLR2-mediated PP2A-ASK1-JNK-AP-1-C/EBPbeta cascade and subsequent COX-2 expression in RAW 264.7 macrophages.

Involvement of phosphatidylcholine-phospholipase C and protein kinase C in peptidoglycan-induced nuclear factor-kappaB activation and cyclooxygenase-2 expression in RAW 264.7 macrophages.

In this study, we examined the role of phosphatidylcholine-phospholipase C (PC-PLC) and protein kinase C (PKC) in peptidoglycan (PGN)-induced nuclear factor-kappaB (NF-kappaB) activation and cyclooxygenase-2 (COX-2) expression in RAW 264.7 macrophages. PGN-induced COX-2 expression was attenuated by a PC-PLC inhibitor (D609) and by PKC inhibitors (Go 6976 and Ro 31-8220), but not by a phosphatidylinositol-PLC (PI-PLC) inhibitor (U-73122). PGN caused an increase in PKC activity, and this effect was inhibited by D609, Go 6976, and Ro 31-8220, but not by U-73122. Furthermore, the PGN-mediated increases in kappaB-luciferase activity were also inhibited by D609 and Ro 31-8220. Our data demonstrate that PGN activates PC-PLC which induces PKC activation; this in turn initiates NF-kappaB activation, and ultimately induces COX-2 expression in RAW 264.7 macrophages.

Antioxidative and hepatoprotective effects of magnolol on acetaminophen-induced liver damage in rats.

Acute liver failure (ALF), an often fatal condition characterized by massive hepatocyte necrosis, is frequently caused by drug poisoning, particularly with acetaminophen (N-acetyl-p-aminophenol/APAP). Hepatocyte necrosis is consecutive to glutathione (GSH) depletion and mitochondrial damage caused by reactive oxygen species (ROS) overproduction. Magnolol, one major phenolic constituent of Magnolia officinalis, have been known to exhibit potent antioxidative activity. In this study, the anti-hepatotoxic activity of magnolol on APAP-induced toxicity in the Sprague-Dawley rat liver was examined. After evaluating the changes of several biochemical parameters in serum, the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) were elevated by APAP (500 mg/kg) intraperitoneal administration (8 and 24 h) and reduced by treatment with magnolol (0.5 h after APAP administration; 0.01, 0.1, and 1 mug/kg). Histological changes around the hepatic central vein, lipid peroxidation (thiobarbituric acid-reactive substance/TBARS), and GSH depletion in liver tissue induced by APAP were also recovered by magnolol treatment. The data show that oxidative stress followed by lipid peroxidation may play a very important role in the pathogenesis of APAP-induced hepatic injury; treatment with lipid-soluble antioxidant, magnolol, exerts anti-hepatotoxic activity. Our study points out the potential interest of magnolol in the treatment of toxic ALF.

Magnolol depresses urotensin-II-induced cell proliferation in rat cardiac fibroblasts.

1. Accumulating evidence suggests that oxidative stress plays a key role in the development of cardiac fibrosis. Urotensin-II (U-II) has been reported to play an important role in cardiac remodelling and fibrosis. Recently, we demonstrated the involvement of reactive oxygen species (ROS) production in U-II-induced cardiac fibroblast proliferation. Magnolol is an anti-oxidant compound extracted from the cortices of Magnolia officinalis. Thus, it is feasible that magnolol may attenuate cardiac fibroblast proliferation by inhibiting ROS production. Therefore, the aims of the present study were to determine whether magnolol alters U-II-induced cell proliferation and to identify the putative underlying signalling pathways in rat cardiac fibroblasts. 2. Cultured rat cardiac fibroblasts were pretreated with magnolol (1, 3 and 10 micromol/L) for 30 min, followed by exposure to U-II (30 nmol/L) for 24 h, after which cell proliferation and endothelin-1 (ET-1) protein secretion was examined. The effects of magnolol on U-II-induced ROS formation and extracellular signal-regulated kinase (ERK) phosphorylation were examined to elucidate the intracellular mechanisms by which magnolol affects cell proliferation and ET-1 expression. 3. Urotensin-II (30 nmol/L) stimulated cell proliferation, ET-1 protein secretion and ERK phosphorylation, all of which were inhibited by magnolol (10 micromol/L). Pretreatment of cardiac fibroblasts with N-acetylcysteine (5 mmol/L) for 30 min prior to exposure to U-II resulted in inhibition of U-II increased ROS formation. Similar effects were observed with 10 micromol/L magnolol. 4. In conclusion, the results suggest that magnolol inhibits cardiac fibroblast proliferation by interfering with ROS generation. Thus, the present study provides important new insights into the molecular pathways involved, which may contribute to our understanding of the effects of magnolol on the cardiovascular system.