Chemokine platelet factor 4 accelerates peripheral nerve regeneration by regulating Schwann cell activation and axon elongation

Schwann cells in peripheral nerves react to traumatic nerve injury by attempting to grow and regenerate.Howeve r,it is unclear what factors play a role in this process.In this study,we searched a GEO database and found that expression of platelet factor 4 was markedly up-regulated after sciatic nerve injury.Platelet factor is an important molecule in cell apoptosis,diffe rentiation,survival,and proliferation.Further,polymerase chain reaction and immunohistochemical staining confirmed the change in platelet factor 4 in the sciatic nerve at different time points after injury.Enzyme-linked immunosorbent assay confirmed that platelet factor 4 was secreted by Schwann cells.We also found that silencing platelet factor 4 decreased the proliferation and migration of primary cultured Schwann cells,while exogenously applied platelet factor 4 stimulated Schwann cell prolife ration and migration and neuronal axon growth.Furthermore,knocking out platelet factor 4 inhibited the prolife ration of Schwann cells in injured rat sciatic nerve.These findings suggest that Schwann cell-secreted platelet factor 4 may facilitate peripheral nerve repair and regeneration by regulating Schwann cell activation and axon growth.Thus,platelet factor 4 may be a potential therapeutic target for traumatic peripheral nerve injury.

Synthesis of platelet-activating factor and its receptor expression in Kupffer cells in rat carbon tetrachloride-induced cirrhosis

AIM:To determine the platelet-activating factor (PAF) synthesis and its receptor expression in Kupffer cells in rat carbon tetrachloride-induced cirrhosis. METHODS:Kupffer cells, isolated from the livers of control and CCl4-induced cirrhotic rats, were placed in serum-free medium overnight. PAF saturation binding, ET-1 saturation and competition binding were assayed. ET-1 induced PAF synthesis, mRNA expression of PAF, preproendothelin-1, endothelin A (ETA) and endothelin B (ETB) receptors were also determined. RESULTS:A two-fold increase of PAF synthesis (1.42 ± 0.14 vs 0.66 ± 0.04 pg/μg DNA) and a 1.48-fold increase of membrane-bound PAF (1.02 ± 0.06 vs 0.69 ± 0.07 pg/μg DNA) were observed in activated Kupffer cells of cirrhotic rats. The application of ET-1 to Kupffer cells induced PAF synthesis in a concentration-dependent manner in both cirrhotic and normal rats via ETB receptor, but PAF synthesis in the activated Kupffer cells was more effective than that in the normal Kupffer cells. In activated Kupffer cells, PAF receptor expression and PAF binding capacity were markedly enhanced. Activated Kupffer cells raised the [125I]-ET-1 binding capacity, but changed neither the affinity of the receptors, nor the expression of ETA receptor. CONCLUSION:Kupffer cells in the course of CCl4-induced cirrhosis are the main source of increased PAF. ET-1 is involved endogenously in stimulating the PAF synthesis in activated Kupffer cells via ETB receptor by paracrine. ETA receptor did not appear in activated Kupffer cells, which may exacerbate the hepatic and extrahepatic complications of cirrhosis.

Creation of reversed phase high-performance liquid chromatographic technique to assay platelet-activating factor

Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart disease. Methods: To measure PAF levels in 100 controls, 23 elderly patients with cerebral infarction and 65 cases with coronary heart disease by reversed phase high-performance liquid chromatographic technique (rHPLC). Results:rHPLC is more convenient, sensitive,specific, and less confusing, compared with bio-assay. The level of plasma PAF in patients with cerebral infarction was higher than that in the controls (P<0.01), and in patients with coronary heart disease. Conclusion: Detection of PAF with rHPLC is more reliable and more accurate. The new assay has important significance in PAF research.

Role of platelet-activating factor in reproduction:sperm function

Since its discovery nearly thirty years ago, platelet-activating factor has emerged as one of the more important lipidmediators known. Platelet-activating factor (PAF; 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) exists en-dogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signal-ing phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a sig-nificant role in reproduction. PAF content in squirrel monkey sperm is significantly higher during the breeding seasonthan the non-breeding season. PAF content in human sperm has a positive correlation with seminal parameters and preg-nancy outcomes. High-fertility boars have significantly more PAF in their sperm than low-fertility boars. The enzymes(lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present insperm. PAF-acetylhydrolase may act as a 'decapacitation factor'. Removal of this enzyme during capacitation maypromote PAF synthesis increasing motility and fertilization. PAF also plays a significant role in the fertilization process,enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilizedwith PAF-treated sperm. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization, thus suggestingthe presence of receptors for PAF. The PAF-receptor is present on sperm, with altered transcript levels and distributionpatterns on abnormal cells. Whereas the exact mechanism of PAF in sperm function and reproduction is uncertain, itsimportance in normal fertility is substantial. The reproductive significance of PAF activity in sperm and fertility plus therole of PAF in the establishment of pregnancy requires further study.

Roles of BN52021 in platelet-activating factor pathway in inflammatory MS1 cells

AIM: To determine the effects of BN52021 on platelet-activating factor receptor (PAFR) signaling molecules under lipopolysaccharide (LPS)-induced inflammatory conditions in MS1 cells. METHODS: MS1 cells (a mouse pancreatic islet endothelial cell line) were grown in Dulbecco's modified Eagle's medium supplemented with 10% fetal bovine serum, 2 mmol/L glutamine and 100 μg/mL penicillin/streptomycin in 5% CO 2 at 37 ℃. After growth to confluency in media, the cells were processed for subsequent studies. The MS1 cells received 0, 0.1, 1 and 10 μg/mL LPS in this experiment. The viability/prolifera-tion of the cells induced by LPS was observed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay. Apoptosis and necrosis of the cells under the inflammatory condition described previously were observed using Hoechst 33342-propidium iodide staining. Adenylate cyclase (AC), phospholipase A 2 (PLA 2 ), phospholipase Cβ (PLCβ), protein tyrosine kinase (PTK), G protein-coupled receptor kinases (GRK) and p38-mitogen-activated protein kinase (p38 MAPK) mRNA in the PAFR signaling pathway were measured by real-time polymerase chain reaction. The protein expression level of phosphorylated AC (p-AC), phosphorylated PLA 2 (p-PLA 2 ), phosphorylated PTK (p-PTK), phosphorylated p38 MAPK (p-p38 MAPK), PLCβ and GRK was measured using Western blotting analysis. RESULTS: The activity of MS1 cells incubated with dif- ferent concentrations of LPS for 6 h decreased significantly in the 1 μg/mL LPS group (0.49 ± 0.10 vs 0.67 ± 0.13, P < 0.05) and 10 μg/mL LPS group (0.44 ± 0.10 vs 0.67 ± 0.13, P < 0.001), but not in 0.1 μg/mL group. When the incubation time was extended to 12 h (0.33 ± 0.05, 0.32 ± 0.03 and 0.25 ± 0.03 vs 0.69 ± 0.01) and 24 h (0.31 ± 0.01, 0.29 ± 0.03 and 0.25 ± 0.01 vs 0.63 ± 0.01), MS1 cell activity decreased in all LPS concentration groups compared with the blank control (P < 0.001). BN52021 significantly improved the cell activity when its concentration reached 50 μmol/L compared with the group that received LPS treatment alone, which was consistent with the results obtained from fluorescence staining. The mRNAs levels of AC (4.02 ± 0.14 vs 1.00 ± 0.13), GRK (2.63 ± 0.03 vs 1.00 ± 0.12), p38 MAPK (3.87 ± 0.07 vs 1.00 ± 0.17), PLA 2 (3.31 ± 0.12 vs 1.00 ± 0.12), PLCβ (2.09 ± 0.08 vs 1.00 ± 0.06) and PTK (1.85 ± 0.07 vs 1.00 ± 0.11) were up-regulated after LPS stimulation as compared with the blank control (P < 0.05). The up- regulated mRNAs including AC (2.35 ± 0.13 vs 3.87 ± 0.08), GRK (1.17 ± 0.14 vs 2.65 ± 0.12), p38 MAPK (1.48 ± 0.18 vs 4.30 ± 0.07), PLCβ (1.69 ± 0.10 vs 2.41 ± 0.13) and PLA 2 (1.87 ± 0.11 vs 2.96 ± 0.08)were significantly suppressed by BN52021 except for that of PTK. The level of p-AC (1.11 ± 0.12 vs 0.65 ± 0.08), GRK (0.83 ± 0.07 vs 0.50 ± 0.03), PLCβ (0.83 ± 0.16 vs 0.50 ± 0.10) and p-p38 MAPK (0.74 ± 0.10 vs 0.38 ± 0.05) was up-regulated after LPS stimulation as compared with the blank control (P < 0.05). The up-regulated proteins, including p-AC (0.65 ± 0.15 vs 1.06 ± 0.14), GRK (0.47 ± 0.10 vs 0.80 ± 0.06), PLCβ (0.47 ± 0.04 vs 0.80 ± 0.19) and p-p38 MAPK (0.30 ± 0.10 vs 0.97 ± 0.05), was significantly suppressed by BN52021, but p-PLA 2 and p-PTK protein level were not suppressed. CONCLUSION: BN52021 could effectively inhibit LPS-induced inflammation by down-regulating the mRNA and protein levels of AC, GRK, p38 MAPK, PLA 2 and PLCβ in the PAFR signaling pathway.

Effects of platelet-activating factor on endothelial cell monolayer permeability under hydrostatic perfusion in vitro

A simple and rapid method was established to study vascular permeability by in vitroperfused endothelial cell monolayers cultured on micropore filter membrane.It can be used todetermine filtration coefficient （Kf） to small molecules and osmotic reflection coefficient （σ） toproteins of the endothelial monolayer.Hanks’ balanced salt solution （HBSS） or 5g/L albuminin HBSS was used to perfuse the confluent endothelial monolayer at the hydrostatic pressure of2.45kPa （25cm H2O）.Control Kf values were 10.1±0.75 and 3.6±0.75μl·min-1·cm-2·kPa（-1）（±,n=3） respectively for the perfusion of HBSS and albumin HBSS,suggesting that al-bumin may decrease endothelial monolayer permeability to water and small molecules.After ex-posure of endothelial monolayer to 10-8mol/L platelet-activating factor （PAF） for 30min,Kfvalues increased to 193.1% and 133.3% respectively.Protein clearance rate (μl.min-1·cm-2)and osmotic reflection coefficient of the control endothelial monolayer were 8.0±3.22 and 0.37±0.09 respectively and those of the PAF treated endothelial monolayer 12.2±2.95μl·min-1·cm-2 and 0.18±0.06,revealing increased permeability to albumin.Computer-assisted imageprocessing demonstrated that PAF treatment decreased cell area while increased cell form factorand intercellular space,suggesting that endothelial cells retracted and rounded,which may bean important mechanism of PAF-induced increase of vascular permeability.

The actions,detection and synthesis of platelet-activating factor (PAF) in mammalian pregnancy

Platelet-activating factor (PAF) exhibits a variety of biological activities and it be thought to involved in various pathophysiological process. In this paper, some studies were summarized about those roles ofPAF in a variety productive processes of female of mammalian that inctude fertilization, implantation and parturition, and that was involved in the concentration, synthesis, deiradation and some assay methods of PAF. Therelationship between PAF and early pregnancy factor (EPF) was reviewed.

The Activity of Plasma Platelet-activating Factor Derived from Pregnant Women before and after Delivery and lts Relation to Pregnancy-induced Hypertension

The activity of plasma platelet-activating factor(PAF) from pregnant women before and after delivery was determined. Plasma samples were taken from 74 pregnant women, among whom 24 were normotensive controls, 30 mild and moderate hypertensive and 20 severe hypertensive. Of the two hypertensive groups(pregnancy-induced hypertension, PIH), PAF activity measured by a bioassay was significantly higher than that of normotensive control at 38 weeks in gestation , indicating a possible role of this potent lipid mediator in the pathophysiological mechanism of PIH. After delivery, PAF activity was obviously increased in all three groups , showing the regulation of placenta in PAF metabolism.

The inhibitory effects of β-adrenoceptor activation on vascular permeability increment induced by platelet-activating factor and histamine

The effects of isoproterenol (IPN) on histamine and platelet-activating factor (PAF)-induced vascular permeability increment in rat skin and in cultured confluent endothelial cell monolayer were investigated. The results showed that after intravenous administration of 20 mg/kg Evans blue (EB) dye, the intradermal injection of 0. 2 ml PAF(10-7mol/L) or histamine (0. 5 mmol/L) could induce the exudation of 16. 82+2. 05 μg/g tissue and 21. 86+2. 86μg/g tissue of EB respectively into the injected skin. Pretreatment of the rats with intravenous IPN (10 μg/kg) decreased the EB exudation by 56. 2% and 43. 6% respectively. Propranolol (PPN), a β-adrenoceptor blocker, reversed the inhibitory effects of IPN. In rats treated with PPN alone, intradermal injection of PAF and histamine induced significant increase of skin EB exudation in comparison with the control, indicating that catecholamines at physiologic concentration in vivo may have inhibitory effects on vascular permeability. When cultured endothelial cell monolayers were perfused with 1% albumin in Hanks' balanced salt solution the increased fluid flux and protein clearance caused by PAF were significantly decreased by IPN pretreatment. The results confirmed the inhibitory effects of IPN on vascular permeability increment induced by PAF at the cellular level.

Physiological Roles of Platelet-activating Factor in Mammalian and Human Reproduction

This review described origination, biosynthesis and functions of platelet-activating factor （PAF） in the reproductive system of mammals and human beings. The article mainly focused on biological roles of the phospholipid mediator in sperm fertilization and embryonic implantation. As an autocrine product of sperm and embryos, PAF markedly stimulates sperm motility and fertilization and serves as a capacitation factor in a ligand-receptor manner, After fertilization, embryo-derived PAF improves its own development, especially from fertilized ova to blastocyst stage and is thought to act as an embryo growth factor in the same manner as on sperm. Its mechanism of action was also clarified. At the end, it was presented some advances in its clinical application, followed by discussion of some issues possibly concerning in its current application.

Platelet-activating factor mediates hydrogen peroxide induced endothelial-leukocyte adhesion

The effects of hydrogen peroxide（H2O2）on endothelial-polymorphonuclear leuko-cyte（EC-PMN）adhesion and their mechanisms were studied in cultured bovine pulmonaryartery endothelial monolayers in vitro.H2O2 at various concentrations(10-3,10-2,10-1mol/Lrespectively)stimulated EC-dependent PMN adhesion,of which 10-2mol/L H2O2 was the mostpotent one,increasing adhesion to 2.3 times that of the control.Pretreatment of PMNs with SRI63-441,a platelet-activating factor（PAF）receptor antagonist,had no inhibition effect on H2O2induced EC-PMN adhesion.Pretreatment of ECs with SRI 63-441 before H2O2 exposure signifi-cantly decreased PMN adherence to ECs.Pretreatment of ECs with phospholipase A2 inhibitorp-bromophenacyl-bromide or calmodulin antagonist chlorpromazine and calcium ion chelate EG-TA obviously decreased H2O2 induced increment of EC-PMN adhesion.These results suggestthat H2O2 may activate ECs,causing the inflow of extracellular calcium or the release of calciumfrom intracellular deposits.Increased intracellar Ca2+may bind with calmodulin to activate phos-pholipase A2,thus initiating PAF synthesis and promoting EC-PMN adhesion.

Platelet factor 4 induces bone loss by inhibiting the integrinα5-FAK-ERK pathway

Background:The effect of platelet factor 4(PF4)on bone marrow mesenchymal stem cells(BMMSCs)and osteoporosis is poorly understood.Therefore,this study aimed to evaluate the effects of PF4-triggered bone destruction in mice and determine the underlying mechanism.Methods:First,in vitro cell proliferation and cell cycle of BMMSCs were assessed using a CCK8 assay and flow cytometry,respectively.Osteogenic differentiation was confirmed using staining and quantification of alkaline phosphatase and Alizarin Red S.Next,an osteoporotic mouse model was established by performing bilateral ovariectomy(OVX).Furthermore,the PF4 concentrations were obtained using enzymelinked immunosorbent assay.The bone microarchitecture of the femur was evaluated using microCT and histological analyses.Finally,the key regulators of osteogenesis and pathways were investigated using quantitative real-time polymerase chain reaction and Western blotting.Results:Human PF4 widely and moderately decreased the cell proliferation and osteogenic differentiation ability of BMMSCs.Furthermore,the levels of PF4 in the serum and bone marrow were generally increased,whereas bone microarchitecture deteriorated due to OVX.Moreover,in vivo mouse PF4 supplementation triggered bone deterioration of the femur.In addition,several key regulators of osteogenesis were downregulated,and the integrinα5-focal adhesion kinase-extracellular signalregulated kinase(ITGA5-FAK-ERK)pathway was inhibited due to PF4 supplementation.Conclusions:PF4 may be attributed to OVX-i nduced bone loss triggered by the suppression of bone formation in vivo and alleviate BMMSC osteogenic differentiation by inhibiting the ITGA5-FAK-ERK pathway.

Clinical Evaluation of Platelet Rich Growth Factors (PRGFS) in Treatment of Temporomandibular Joint Disc Displacement—Study Report

Objective: The aim of the study was to evaluate the effect of platelet rich growth factors (PRGFs) in treatment of temporomandibular joint disc displacement. Materials and Methods: The study subjects included 8 females having bilateral anterior disc displacement with reduction and 1 female having bilateral anterior disc displacement without reduction with the age range between 20 - 35 years. The process of obtaining PRGFs was carried out following the Anitua Technique. Results: Clinical parameters of Interincisal distance, Lateral excursion of mandible using digital caliper in millimeters and Visual Analogue Scale (VAS 0/10) for pain intensity score were used. All of these parameters were running through the intervals of two, four, and eight weeks till the end of the follow-up period at twenty-six weeks (six months). The participated patients showed the clinical improvement in the different clinical statuses such as interincisal distance;lateral excursion of mandible and Pain Score. Conclusion: the study reported early efficacy of PRGFs after the arthrocentesis of the joint in treatment of TMJ disc displacement, and according to our results, the injection of PRGFs could be a possible alternative treatment for patients who did not respond to standard treatment.

An anti-aging skin strategy:promoting repair and regeneration in UV-induced photoaging micro-environment using growth factors-rich platelet lysates composite Self-protection Collagen Hydrogel

Skin photoaging is induced and sustained by UV-induced oxidative damage,and stimulating regeneration of the UV-induced aging has remained a great challenge due to high-level oxidative stress factor(ROS)-induced chronic oxidative damage and inactivation of bio-macromolecule-based regeneration in oxidative photoaging micro-environment.In this study,we designed a“seed and soil”strategy to pursue a safer and more efficient way to prevent and treat photoaging by simultaneously changing UV-induced ROS-rich micro-environment into a proregenerative one(the“soil”)and providing growth factor-rich platelet lysates(PL,the“seed”)using PL-impregnated,collagen-reinforce hydrogel(PL/Col).SD rats were used to establish photoaging model by 8 weeks of UV irradiation.The effectiveness of different treatments was evaluated by making pathological sections and detecting photoaging-related indicators.Rats treated with PL/Col demonstrated a significant acceleration in skin healing and enhancement in the quality of trauma repairing.After treated with PL/Col,the rats showed smooth yellowish appearance,integral structure of skin collagen fiber and epidermis,a decrease in inflammation and a reshaped active micro-environment with reduced levels of SOD enzyme activity,GSH enzyme activity and MDA toxic products.Treatment of PL/Col in skin photoaging has shown potential anti-oxidation and anti-aging effects and is worthy of further study in related field.

Lipopolysaccharide-induced cerebral inflammatory damage and the therapeutic effect of platelet activating factor receptor antoganist

Objective To investigate lipopolysaccharide （LPS） induced acute cerebral inflammatory damage and the therapeutic effect of ginkgolide B （BN52021）. Methods Thirty Sprague-Dawley rats were randomly divided into 3 groups （n = 10 for each group）： Control group, Model group and Treatment group （treated with BN52021）. LPS were injected into the fourth ventricle of rat to make a neuroinflammatory murine model. Morris water maze was used to detect the learning and memory ability of rats; changes of synapse number and subcellular ultrastructures were observed under a transmission electron microscope; OX-42 positive microglia in the brain was detected by immunohistochemical method. Results The average escape latency in the Treatment group were significantly shortened than that in the Model group; and the percentage of swimming distance traveled in platform quadrant accounting for total distance increased markedly. The rough endoplasmic reticulum and polyribosomes in the Treatment group were more than that in the Model group, but the number of synapses seemed to have no obvious change. The number of OX-42 positive microglia in the Treatment group decreased markedly than that in the Model group, and the grey density of OX-42-positive cells increased significantly. Conclusion LPS can induce inflammatory damages to the brain, but the damage could be antagonized by BN52021. Platelet activating factor receptor antagonist may offer an effective therapy for neurodegeneration diseases.

Are the changes in the peripheral brain-derived neurotrophic factor levels due to platelet activation?

Brain-derived neurotrophic factor(BDNF) plays an important role in central nervous system development, neurogenesis and neuronal plasticity. BDNF is also expressed in several non-neuronal tissues, and it could play an important role in other processes, such as cancer, angiogenesis, etc. Platelets are the major source of peripheral BDNF. However, platelets also contain high amounts of serotonin; they express specific surface receptors during activation, and a multitude of pro-inflammatory and immunomodulatory bioactive compounds are secreted from the granules. Until recently, there was insufficient knowledge regarding the relationship between BDNF and platelets. Recent studies showed that BDNF is present in two distinct pools in platelets, in α-granules and in the cytoplasm, and only the BDNF in the granules is secreted following stimulation, representing 30% of the total BDNF in platelets. BDNF has an important role in the pathophysiology of depression. Low levels of serum BDNF have been described in patients with major depressive disorder, and BDNF levels increased with chronic antidepressant treatment. Interestingly, there is an association between depression and platelet function. This review analyzed studies that evaluated the relationship between BDNF and platelet activation and the effect of treatments on both parameters. Only a few studies consider this possible confounding factor, and it could be very important in diseases such as depression, which show changes in both parameters.

Elevated Platelet Activating Factor Level in Ischemia-Related Arrhythmia and Its Electrophysiological Effect on Myocardium

Objective 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. Methods （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 papillarymuscles. Results 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 （APD 90 ）under non-ischemic conditions and a more pronounced shortening under early simulated ischemic conditions. Conclusion 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.

Significance of platelet activating factor receptor expression in pancreatic tissues of rats with severe acute pancreatitis and effects of BN52021

AIM:To investigate the dynamic changes and significance of platelet activating factor receptor (PAF-R) mRNA and protein in pancreatic tissues of rats with severe acute pancreatitis (SAP) and effects of BN52021 (Ginkgolide B). METHODS:Wistar male rats were randomly assigned to the negative control group (NC group),SAP model group (SAP group),and BN52051-remedy group (BN group),and each of the groups was divided into 6 subgroups at different time points after operation (1 h,2 h,3 h,6 h,12 h,and 24 h) (n=10 in each). PT-PCR and Western blot methods were used to detect PAF-RmRNA and protein expression in pancreatic tissues of rats respectively. Pathological examination of pancreatic tissues was performed and the serum amylase change was detected. RESULTS:Serum amylase and pathological results showed the that SAP model was successfully prepared,BN52021 was able to decrease serum amylase,and the pathological ratings in BN group at 3 h,6 h,and 12 h significantly decreased compared with those in the SAP group (8.85 ± 0.39 vs 5.95 ± 0.19,9.15 ± 0.55 vs 5.55 ± 0.36,10.10 ± 0.65 vs 6.72 ± 0.30,P < 0.05). The result of PAF-mRNA showed dynamic changes in SAP and BN groups,which increased gradually in early stage,reached a peak at 3 h (0.71 ± 0.14 vs 0.54 ± 0.14,0.69 ± 0.13 vs 0.59 ± 0.04,P < 0.05),and decreased gradually later. There were significant differences at each time point except 1 h and 2 h,when compared with those in the NC group (0.71 ± 0.14 or 0.69 ± 0.13 vs 0.47 ± 0.10,0.38 ± 0.08 or 0.59 ± 0.04 vs 0.47 ± 0.09,0.25 ± 0.07 or 0.29 ± 0.05 vs 0.46 ± 0.10,0.20 ± 0.06 or 0.20± 0.04 vs 0.43 ± 0.09,P < 0.05),whereas there was no significant difference between BN and SAP groups at each time point. The result of PAF-R protein showed that the change of PAF-R protein in the SAP group and the BN group was consistent with that of PAF-R mRNA. There were significant differences at each time point except 1 h,when compared with those in the NC group (0.90 ± 0.02 or 0.80 ± 0.05 vs 0.48 ± 0.02,1.69 ± 0.06 or 1.58 ± 0.02 vs 0.48 ± 0.03,1.12 ± 0.10 or 0.98 ± 0.03 vs 0.49 ± 0.09,1.04 ± 0.14 or 0.87 ± 0.02 vs 0.52 ± 0.08,0.97 ± 0.16 or 0.90 ± 0.05 vs 0.49 ± 0.10,P < 0.05),whereas there was no significant difference between the BN group and the SAP group. CONCLUSION:PAF-R plays an important role in occurrence and development of SAP. BN52021 exerts biological effects through competitively inhibiting the binding of increased both PAF and PAF-R expression rather than through decreasing PAF-R expression in pancreatic tissues.

Vascular endothelial growth factor A promotes platelet adhesion to collagen Ⅳ and causes early brain injury after subarachnoid hemorrhage

The role of vascular endothelial growth factor A in platelet adhesion in cerebral microvessels in the early stage of subarachnoid hemorrhage remains unclear.In this study,the endovascular puncture method was used to produce a rat model of subarachnoid hemorrhage.Then,30 minutes later,vascular endothelial growth factor A antagonist anti-vascular endothelial growth factor receptor 2 antibody,10μg,was injected into the right ventricle.Immunohistochemistry and western blot assay were used to assess expression of vascular endothelial growth factor A,occludin and claudin-5.Immunohistochemical double labeling was conducted to examine co-expression of GP Ⅰa-Ⅱ integrin and type Ⅳ collagen.TUNEL was used to detect apoptosis in the hippocampus.Neurological score was used to assess behavioral performance.After subarachnoid hemorrhage,the expression of vascular endothelial growth factor A increased in the hippocampus,while occludin and claudin-5 expression levels decreased.Co-expression of GP Ⅰa-Ⅱ integrin and type Ⅳ collagen and the number of apoptotic cells increased,whereas behavioral performance was markedly impaired.After treatment with anti-vascular endothelial growth factor receptor 2 antibody,occludin and claudin-5 expression recovered,while co-expression of GP Ⅰa-Ⅱ integrin and type Ⅳ collagen and the number of apoptotic cells decreased.Furthermore,behavioral performance improved notably.Our findings suggest that increased vascular endothelial growth factor A levels promote platelet adhesion and contribute to early brain injury after subarachnoid hemorrhage.This study was approved by the Biomedical Ethics Committee,Medical College of Xi’an Jiaotong University,China in December 2015.

Pathogenetic effects of platelet activating factor on enterogenic endotoxemia after burn

INTRODUCTION Previous clinical and experimental studies haveindicated that an early endotoxemia occurred after amajor burn.It is unlikely that burn wound sepsis isthe source of circulating endotoxin in less than 12hour after burn.Increasing evidence demonstratesthat the bacteria and endotoxin in thegastrointestinal tract can pass through the gutbarrier into blood circulation to form enterogenicendotoxemia following burn.However。