Chemical Constituents and Biological Activities of Mitrella Kentii (Blume) Miq. Leaf Oil (Komponen Kimia dan Aktiviti Biologi Minyak Daun Mitrella Kentii (Blume) Miq.) / Jurnal Sains Kesihatan Malaysia

@#Chemical constituents and biological activities of the Mitrella kentii leaf oil were investigated in this study. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to determine the chemical constituents of the oil. The oil was evaluated for its ability to inhibit prostaglandin E2 (PGE2 ) and thromboxane B2 (TXB2 ) productions in human whole blood using a radioimmunoassay technique. Its inhibitory effect on plateletactivating factor (PAF) receptor binding with rabbit platelets using 3 H-PAF as a ligand and its free radical scavenging effect on DPPH were also investigated. Caryophyllene oxide (33.8%w/w), E,Z-farnesol (6.9%), benzyl benzoate (6.5%w/w) and viridiflorol (6.5%w/w) were among the major components of the oil. Even though weak inhibitory activities were observed in both PGE2 and TXB2 assays, significant results were obtained in both PAF receptor binding inhibition and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging effect with IC50 value of 6.6 µg/mL and 155.6 µg/mL respectively. These promising activities warrant the development of the oil as an anti-inflammatory agent.

Platelet activating factor receptor antagonists improve the efficacy of experimental chemo- and radiotherapy

Platelet activating factor is a lipid mediator of inflammation, and in recent decades, it has emerged as an important factor in tumor outcomes. Platelet activating factor acts by specific binding to its receptor, which is present in both tumor cells and cells that infiltrate tumors. Pro-tumorigenic effects of platelet activating factor receptor in tumors includes promotion of tumor cell proliferation, production of survival signals, migration of vascular cells and formation of new vessels and stimulation of dendritic cells and macrophages suppressor phenotype. In experimental models, blocking of platelet activating factor receptor reduced tumor growth and increased animal survival. During chemotherapy and radiotherapy, tumor cells that survive treatment undergo accelerated proliferation, a phenomenon known as tumor cell repopulation. Work from our group and others showed that these treatments induce overproduction of platelet activating factor-like molecules and increase expression of its receptor in tumor cells. In this scenario, antagonists of platelet activating factor markedly reduced tumor repopulation. Here, we note that combining chemo- and radiotherapy with platelet activating factor antagonists could be a promising strategy for cancer treatment.

Effects of ginkgolide A, B and K on platelet aggregation / 中国中药杂志

To investigate the effects of ginkgolide A (GA), ginkgolide B (GB) and ginkgolide K (GK) on platelet aggregation in rabbits, and compare the similarities and differences among these three components. The effects of different doses of ginkgolide A, B and K on platelet aggregation induced by platelet activating factor (PAF) were observed by using in vitro experiment. The results showed that three compounds could inhibit platelet aggregation induced by PAF in vitro, and the intensity was GK> GB> GA. It was further found that all of them can mobilize [Ca2+]i and enhance intracellular c-AMP level in a dose-dependent manner, which was consistent to the ability to antagonize PAF receptor. These findings indicated that GK was highly selective for PAF receptor, and may inhibit platelet aggregation by activating cAMP signaling pathway and inhibiting intracellular [Ca2+]i mobilization; GB and GA also had strong antagonism to PAF receptor, but the effect was weaker than that of GK.

Analysis of platelet activation factor and ultrastructure in patients with acute cerebral infarction / 中国基层医药

Objective To discuss the expression and significance of platelet ultrastructure and platelet acti-vating factor(PAF)relationship in patients with acute cerebral infarction.Methods 40 patients with cerebral infarc-tion were chosen onset in 6-24 hours as the observation group,while at the same time 20 cases of healthy adults were selected as the control group.The observation group was given 1-7d of aspirin enteric-coated metformin hydrochloride 300mg,qd,and 8-14d had worship of aspirin enteric-coated metformin hydrochloride 100mg,qd.And before and 1,7, 14 days after treatment,control group and observation group respectively preclude the use of transmission electron microscopy ultrastructure of platelets,before and 1,14 days after treatment automatic blood cell analyzer test was used to analyze the average platelet volume (MPV),platelet count (PLT),platelet volume distribution width (PDW)of the two groups.And 1,2,3,7,14 days after treatment,enzyme-linked immunosorbent determination of double clamp method was used to test the concentration of PAF.Results Before treatment,MPV,PDW and PAF in peripheral blood of the observation group were (9.22 ±1.30)fL,(17.89 ±1.23)%,(211.31 ±11.22)pg/mL,which were sig-nificantly higher than those of the control group (8.68 ±1.03)fL,(16.06 ±1.03)%,(155.49 ±8.70)pg/mL(t =2.082,2.563,14.401,all P <0.05),while PLT was (173.22 ±63.40)×109 /L,which was significantly lower than that in the control group (231.22 ±56.76)×109 /L(t =3.048,P <0.05).After treatment in patients with acute cer-ebral infarction,the MPV,PDW of peripheral blood were (8.43 ±1.28)fL,(16.66 ±1.11)%,which were signifi-cantly lower than before treatment (9.22 ±1.30)fL,(17.89 ±1.23)% (t =1.937,3.320,all P <0.05),while PLT (195.33 ±61.45)×109 /L was significantly higher than before treatment (173.22 ±63.40)×109 /L(t =1.915, P <0.05).PAF peaked in the treatment of 3 days,which was (240.12 ±13.78)pg/mL,and gradually declined after 7 days,which was (215.33 ±16.43)pg/mL,and that after 14 days was(170.27 ±11.40)pg/mL,compared with before treatment (211.31 ±11.22)pg/mL,the difference was statistically significant (t =16.24,P <0.05).Before treatment,platelet shape had irregular,increased pseudopodia,several visible platelet aggregation,and was blend together.And after 14 days treatment in the observation group,platelet ultrastructure greatly recovered.Conclusion Monitoring of MPV,PDW,PAF and PLT in peripheral blood of patients with acute cerebral infarction before and after treatment has important clinical value for disease diagnosis and treatment.

Establishment of Caco-2 cell monolayer model and barrier permeability / 国际儿科学杂志

Objective To establish and evaluate intestinal epithelial barrier model using Caco-2 cell so as to play a foundation for next study of barrier permeability.Methods Caco-2 cells were cultured in vitro then seeded into Transwell cell culture inserts.The permeability of the intestinal epithelial barrier was detected by transepithelial electrical resistance(TEER)and lucifer yellow flux,and verified by transmission electron micro-scope.Different concentrations of PAF(0,50,100,and 200 nmol /L)were exposed for 24 hours to Caco-2 mono-layer when cultured 21 days.The tight junction was observed under transmission electron microscope.Assess-ment of ZO-1 protein localization and expression were detected by immunofluorescence and Western blot analy-sis.Results Cultured Caco-2 cell confluencd as monolayer with time passed.From 5th day,TEER increased, then reached 600Ω?cm2 at 15th day and lasted to 21 st day,there was little flux of lucifer yellow,transmission e-lectron microscopy also found cells differentiated better,had well-arranged villi and polarity alined as monolayer, forming completed tight junction which was the marker of intestinal epithelial barrier model in vitro.TEER de-creased and lucifer yellow flux increased in cells exposed to PAF.The permeability reached the peak when ex-posed to 100 nmol /L PAF(P <0.01 ),tight junction disrupted,ZO-1 protein expression downregulated,abnor-mal localization and distribution was assessed by immunofluorescence staining.Conclusion Cultured Caco-2 cells for 2-3w can be used to study intestinal epithelial barrier as a model in vitro.PAF increased intestinal epi-thelial permeability,which would correlate to the decreased protein expression and abnormal distribution of ZO-1.

Elevated platelet activating factor level in ischemia-related arrhythmia and its electrophysiological effect on myocardium / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>The mechanism through which platelet activating factor (PAF) induces cardiac electrical activity and arrhythmia is not well understood and previous studies have suggested a potential involvement of ion channels in its action. The present study was aimed to clarify the role of PAF in fatal arrhythmias following acute myocardia infarction (AMI) and the underlying mechanism.</p><p><b>METHODS</b>(1) Blood PAF levels were measured among 72 AMI patients at the time of diagnosis with AMI and 48 h later, and their electrocardiogram (ECG) was recorded continuously. (2) Ischemia simulation and surface electrocardiogram were conducted in 20 pigs and their PAF levels were measured. (3) PAF perfusion and standard microelectrode recording were performed on guinea pig papillary muscles.</p><p><b>RESULTS</b>In both humans and pigs, elevated PAF levels were detected in AMI and simulated ischemia, respectively, and even higher PAF levels were found when fatal arrhythmias occurred. In guinea pig myocardium, PAF induced a shortening of action potential duration at 90% level of repolarization (APD90)under non-ischemic conditions and a more pronounced shortening under early simulated ischemic conditions.</p><p><b>CONCLUSION</b>AMI and ischemia are associated with increased PAF levels in humans and pigs, which are further raised when fatal arrhythmia follows. The effects of PAF on the myocardium may be mediated by multiple ion channels.</p>

Atividade pró-trombótica da toxina ExoU de Pseudomonas aeruginosa detectada em modelos experimentais in vivo e in vitro / Prothrombotic activity of the Pseudomonas aeruginosa toxin ExoU detected in experimental models in vivo and in vitro

Pseudomonas aeruginosa é um importante agente de pneumonia, particularmente em pacientes submetidos à ventilação mecânica, que pode evoluir para sepse, com elevadas taxas de letalidade. Na sepse, o processo inflamatório sistêmico exacerbado favorece o desequilíbrio entre as vias de coagulação e fibrinólise e a instalação de um estado pró-coagulante, com o aparecimento de trombose microvascular, coagulação intravascular disseminada e falência de múltiplos órgãos. Conhecendo a potente atividade pró-inflamatória da toxina ExoU produzida por P. aeruginosa, decorrente de sua atividade fosfolipásica A2, o objetivo desta tese foi investigar seu potencial de indução de alterações hemostáticas relacionadas à patogênese da sepse. Utilizando modelo de sepse em camundongos inoculados, por via intratraqueal, com suspensões de P. aeruginosa produtora de ExoU (PA103) ou de cepa com deleção do gene exoU, não produtora da toxina, foi mostrado que ExoU determinou maior gravidade da infecção, maior taxa de letalidade, leucopenia, trombocitose, hiperpermeabilidade vascular e transudação plasmática, evidenciadas, respectivamente, pela maior concentração de proteínas nos lavados broncoalveolares (LBAs) e acúmulo do corante Azul de Evans, previamente inoculado nos animais, por via endovenosa, no parênquima renal. ExoU favoreceu, também, a ativação plaquetária, confirmada pela maior concentração de plaquetas expressando P-seletina em sua supefície, maior número de micropartículas derivadas de plaquetas e maior concentração plasmática de tromboxano A2. A histopatologia dos pulmões e rins dos animais infectados com PA103 confirmou a formação de microtrombos, que não foram detectados nos animais controles ou infectados com a cepa mutante. Nos pulmões, a produção de ExoU determinou intensa resposta inflamatória com maior concentração de leucócitos totais e polimorfonucleados, interleucina-6 e fator de necrose tumoral-alfa nos LBAs. A análise imunohistoquímica mostrou intensa deposição...

Pseudomonas aeruginosa is an important agent of pneumonia, mainly in patients undergoing mechanical ventilation, which can progress to sepsis with high mortality rates. In sepsis, the systemic inflammatory process favors exacerbated imbalance between the coagulation and fibrinolysis pathways and the installation of a procoagulant state, leading to microvascular thrombosis, disseminated intravascular coagulation and multiple organ failure. Knowing the powerful proinflammatory activity of the P. aeruginosa toxin ExoU, secondary to its phospholipase A2 activity, the goal of this study was to investigate the ExoU potential to induce hemostatic changes related to sepsis pathogenesis. By using a murine model of pneumosepsis, obtained by the intratracheal injection of suspensions of the ExoU-producing PA103 P. aeruginosa strain or of its isogenic mutant PA103 exoU, defective in the toxin synthesis, ExoU was shown to enhance the severity of the infection and to induce higher mice mortality rate as well as leukopenia, thrombocytosis, vascular hyperpermeability and plasma transudation, evidenced, respectively, by the higher protein concentration in the bronchoalveolar lavage fluids (BALF) and accumulation of Evans blue dye, previously intravenous infectioned, in mice renal parenchyma. ExoU also favored platelet activation, evidenced by the higher concentration of platelets expressing P-selectin on their surface, greater number of platelet-derived microparticles and increased plasma concentration of thromboxane A2. Histopathology of the lungs and kidneys of PA103 - infected animals confirmed the formation of microthrombi, which were not detected in controls or in animals infected with the bacterial mutant. In lungs, ExoU induced an intense inflammatory response with high concentrations of total and polymorphonuclear leukocytes, interleukin-6 and tumor necrosis factor-alfa in mice BALF. Immunohistochemical analysis showed intense fibrin deposition in the alveoli...

Investigation of platelet activating factor (PAF) in acute myocardial infarction / 中华急诊医学杂志

Objective To investigate the level of platelet activating factor (PAF) in acute myocardial infarction (AMI) in minipig model and patients, and to study the relationship between PAF and lethal arrhythmia referring to ventricular fibrillation and ventricular tachycardia. Method ( 1 ) The levels of PAF in minipig models ( n = 20) were measured by using ELISA before and 1h after occlusion of left anterior descending coronary artery with balloon at the junction of 1/3 middle and distal portion. The lethal arrythmia was recorded by using electrocardiography. (2) In patients with AMI (n = 72), the levels of PAF were measured on arrival, and 24 h,48 h and 72 h later. The lethal arrythmia, acute heart failure and cardiogenic shock were documented. Results ( 1 ) In minipigs with occlusion of coronary artery for one hour, the mean level of PAF increased from (4.66± 2.89)ng/mL to (6.00±2.82) ng/mL,and thus the increment in PAF was (1 .34± 1.40) ng/mL (P ＜ 0.05). In 13 minipigs with lethal anythmia after occlusion of coronary artery for one hour, the increment in mean level of PAF was ( 1.92 ± 1 .34) ng/mL, whereas the increment in mean level of PAF in other 7 minipigs without lethal arrythmia after occlusion of coronary artery for one hour was as low as (0.28 ± 0. 74 ) ng/mL ( P ＜ 0. 05 ). ( 2 ) In patients, the mean levels of PAF on arrival, 24 h,48 h,and 72 hous after admission were (0.47 ± 0.05) ng/mL,(2.38±0.12) ng/mL,(3.65±0.15) ng/mL and (3.02±0.10) ng/mL, respectively. Of 72 ACI patients, 40 (55%) had complication of lethal arrythnia, heart failure or cardiogenic shock and their mean level of PAF 48 h after admission was (4.72 ± 0.16) ng/mL, whereas mean level of PAF in other 32 (44.44%) without complications was (2.31 ±0.03) ng/mL ( P ＜0.05). Conclusions The level of PAF increased after acute myocardial infarction, and the minipigs and AMI patients complicated with lethal arrythmia had higher levels of PAF.

Role of Nuclear Factor (NF)-kappaB Activation in Tumor Growth and Metastasis

BACKGROUND: Platelet-activating factor (PAF) induces nuclear factor (NF)-kappaB activation and angiogenesis and increases tumor growth and pulmonary tumor metastasis in vivo. The role of NF-kappaB activation in PAF-induced angiogenesis in a mouse model of Matrigel implantation, and in PAF-mediated pulmonary tumor metastasis were investigated. METHODS: Angiogenesis using Matrigel and experimental pulmonary tumor metastasis were tested in a mouse model. Electrophoretic mobility shift assay was done for the assessment of NF-kappaB translocation to the nucleus. Expression of angiogenic factors, such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1alpha, basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) were tested by RT-PCR and ELISA. RESULTS: PAF induced a dose- and time-dependent angiogenic response. PAF-induced angiogenesis was significantly blocked by PAF antagonist, CV6209, and inhibitors of NF-kappaB expression or action, including antisense oligonucleotides to p65 subunit of NF-kappaB (p65 AS) and antioxidants such as alpha-tocopherol and N-acetyl-L-cysteine. In vitro, PAF activated the transcription factor, NF-kappaB and induced mRNA expression of TNF-alpha, IL-1alpha, bFGF, VEGF, and its receptor, KDR. The PAF-induced expression of the above mentioned factors was inhibited by p65 AS or antioxidants. Also, protein synthesis of VEGF was increased by PAF and inhibited by p65 AS or antioxidants. The angiogenic effect of PAF was blocked when anti-VEGF antibodies was treated or antibodies against TNF-alpha, IL-1alpha, and bFGF was co-administrated, but not by antibodies against TNF-alpha, IL-1alpha, and bFGF each alone. PAF-augmented pulmonary tumor metastasis was inhibited by p65 AS or antioxidants. CONCLUSION: These data indicate that PAF increases angiogenesis and pulmonary tumor metastasis through NF-kappaB activation and expression of NF-kappaB-dependent angiogenic factors.

Nitric Oxide Synthase Inhibitor Inhibits Platelet Activating Factor: Induced Microvascular Leakage in Rat Nasal and Tracheal Mucosa / 대한이비인후과학회지

BACKGROUND AND OBJECTIVE: Platelet-activating factor (PAF), a potent chemical mediator in inflammation and allergic reaction, induces microvascular leakage in several tissues. In rat airways, PAF-induced microvascular leakage is not dependent on cyclooxygenase or lipoxygenase products nor on circulating platelets, and it is probably mediated by receptors on vascular endothelium. Nitric oxide (NO), first identified as endothelium-derived relaxing factor, has been reported recently to be an important mediator of the neurogenic vascular exudative process. The aim of this study was to investigate the role of NO in PAF-induced microvascular leakage in rat nasal and tracheal mucosa. METHODS: PAF (1 ug/kg) was injected intravenously to induce microvascular leakage. The degree of microvascular leakage was measured with the amount of extravasated Evans blue (30 mg/kg) using both spectrophotometry and fluorescence microscopy. Five Sprague-Dawley rats were pretreated with Nw-nitro-L -arginine methyl ester (L-NAME, 10 mg/kg, intravenously, 1 hour before the injection of PAF) to inhibit the NO synthase, while four control rats(n=4) were pretreated with normal saline. RESULT: The average amounts of extravasated Evans blue in the nasal mucosa and trachea of the control rats were 24.789 and 28.238 ug/mg wet tissue, and those of the L-NAME pretreated rats were 6.643 and 6.987 ug/mg wet tissue respectively. Tissue sections of the L-NAME pretreated rats showed a definitely decreased extravasation of Evans blue under fluorescence microscopy. CONCLUSION: Pretreatment with L-NAME clearly inhibited PAF-induced microvascular leakage in the nasal and tracheal mucosa of rat. This finding implies that NO may mediate PAF-induced microvascular leakage in rat airways.

Determination of the Platelet Activating Factor in Silicotic Patients and its Effect on Fibroblasts

Platelet-activation factor (PAF), one of the potent proinflammatory mediators, is produced from a large range of cells, including polymorphonuclear neutrophils, monocytes, and natural killer cells. To study the role of PAF in the pathogenesis of silicosis, we determined the PAF in silicotic patients and in healthy persons. The results showed that the concentration of PAF in the plasma of silicotic patients was significantly higher than that of healthy persons. Our in vitro experimental results showed that the total numbers of fibroblasts were markedly raised with added PAF from 0 to 1 μ g/ml. Adding 1 μ g/ml PAF significantly increased the total numbers of fibroblasts after culture for 48, 72, 96 hrs. Therefore, we suggest that PAF be possibly involved in the pathogenesis of silicosis. However, the mechanism remains to be further elucidated.

Experimental research into the effects of Yumian Decoction anti-asthma formula(DYA) on the plasma cAMP、cGMP and PAF contents in asthmatic guinea pigs / 中成药

Objective: To investigate the anti asthmatic effects and its mechanism of Yumian Anti asthma Formula (DYA) on asthmatic guinea pigs. Methods: Observe the change of the latent period of asthma inducing of normal guinea pigs and that of them after DYA preventing. Determine the plasma cAMP and cGMP contents. Results: The latent period of asthma inducing was obviously prolonged in guinea pigs prevented by DYA when compared with that of normal guinea pigs and guinea pigs before given DYA ( P

PAF inhibits protein kinase C(PKC) activation in T cells / 中国免疫学杂志

Abstract Objective: To investigate the regulatory effect of PAF on early events in signal transduction during T-cell activation. Methods:T-cell activation was achieved by stimulation of human T cells with CD3 mAb or PMA/ionomycin in the presence or absence of PAF. T cell Pro-liferatilon was determined by 3 H-thymidine incorporation, IL-2 production was measured by MTT method, IL-2R(CD25)expression was evaluatedby flow cytometry and,PKC activity was assayed by the method described by Hauschildt. Results:PAF inhibited CD3 mAb-induced T-cell pro-liferation, IL-2 production and CD25 expression. AIthough it inhibited T-cell proliferation and IL-2 production induced by PMA/ionomycin, PAFfailed to inhibit IL-2 production induced by PMA/ionomycin.The translocation of PKC was also inhibited by PAF if T cells were activated byCD3mAb. Conclusion: PAF inhibits T-cell activation via its inhibitory effect on PKC activation. Its differential effect on IL-2 production suggeststhat PAF regulatory more early events in signal transduction such as the activation of phospholipase C ?-1.

Platelet-activating factor and its receptor related with skin inflammation / 第二军医大学学报

Platelet activating factor(PAF), a potent phospholipid mediator of inflammation, has diverse physiological actions and participates in many diseases in vivo . In recent years, it has been revealed that PAF system involve in the expression of keratinocytes function and reaction of skin inflammation. Therefore, PAF system was found closely associated with inflammatory skin disease. Keratinocytes could express functional PAF receptors (PAF R) and involve in the action of epidermis cytokine system. The interaction between PAF system and other inflammatory mediators can lead to skin inflammatory cascade.