Buyang Huanwu decoction enhances cell membrane fluidity in rats with cerebral ischemia/reperfusion

After bilateral carotid artery occlusion for 30 minutes and reperfusion for 2 hours, distinct pathological changes presented in the cerebral cortex and cerebellum of rats. Compared with normal rats, nerve cell membrane fluidity significantly decreased in ischemia/reperfusion rats as detected by spin-labeling electron spin resonance, consistent with order parameter S and rotational correlation time TC measurements. Brain nerve cells from rats with ischemia/reperfusion injury were cultured with 1-100 mg/mL Buyang Huanwu decoction. Results showed that Buyang Huanwu decoction gradually increased membrane fluidity dose-dependently to normal levels, and eliminated hydroxide （OH＇） and superoxide （O2＇） free radicals dose-dependenUy. These findings suggest that Buyang Huanwu decoction can protect against cell membrane fluidity changes in rats with ischemia/ reperfusion injury by scavenging free radicals.

Differential effects of insecticides on mitochondrial membrane fluidity and ATPase activity between the wolf spider and the rice stem borer

Differential effects of methamidophos and three pyrethroids on ATPase activity and membrane fluidity of mitochondria were investigated between the wolf spider（Pirata subpiraticus（Boes.et Str.））and the rice stem borer（Chilo suppressalis（Walker））.Based on a comparison of LD_（50） values,the toxicities of the tested insecticides were higher to the wolf spider than to the rice stem borer.Cyhalothrin at 1×10^（–4） mmol L^（–1） caused inhibition of the mitochondrial Na~＋-K~＋-ATPase and Ca^（2＋）-Mg^（2＋）-ATPase activities,and it’s inhibitions on Na＋-K＋-ATPase and Ca^（2＋）-Mg^（2＋）-ATPase activities were significantly higher in the wolf spider（44 and 28%）than in the rice stem borer（19 and 11%）.Methamidophos at 1×10^（–4） mmol L^（–1） decreased Ca^（2＋）-Mg^（2＋）-ATPase activity by 16 and 27%in the wolf spider and the rice stem borer,respectively,but no significant effect on the specific activity of Na＋-K＋-ATPase was observed.The DPH（1,6-diphenyl-1,3,5-hexatriene）fluorescence polarization values of mitochondrial membranes were not significantly affected by methamidophos in either species.However,cyhalothrin and alpha-cypermethrin induced the values of DPH polarization of mitochondrial membrane increasing with the concentration of cyhalothrin and alpha-cypermethrin from 20 to 100μmol L^（–1） in the rice stem borer and the wolf spider.Effect of ethofenprox on fluidity of the wolf spider and the rice stem borer was contrary.These results suggest that both inhibition of membrane ATPase and changes of membrane fluidity could be appended to the action mechanisms of pyrethroid insecticides.

Changes of cell membrane fluidity for mesenchymal stem cell spheroids on biomaterial surfaces

BACKGROUND The therapeutic potential of mesenchymal stem cells(MSCs)in the form of threedimensional spheroids has been extensively demonstrated.The underlying mechanisms for the altered cellular behavior of spheroids have also been investigated.Cell membrane fluidity is a critically important physical property for the regulation of cell behavior,but it has not been studied for the spheroid-forming cells to date.AIM To explore the association between cell membrane fluidity and the morphological changes of MSC spheroids on the surface of biomaterials to elucidate the role of membrane fluidity during the spheroid-forming process of MSCs.METHODS We generated three-dimensional(3D)MSC spheroids on the surface of various culture substrates including chitosan(CS),CS-hyaluronan(CS-HA),and polyvinyl alcohol(PVA)substrates.The cell membrane fluidity and cell morphological change were examined by a time-lapse recording system as well as a highresolution 3D cellular image explorer.MSCs and normal/cancer cells were prestained with fluorescent dyes and co-cultured on the biomaterials to investigate the exchange of cell membrane during the formation of heterogeneous cellular spheroids.RESULTS We discovered that vesicle-like bubbles randomly appeared on the outer layer of MSC spheroids cultured on different biomaterial surfaces.The average diameter of the vesicle-like bubbles of MSC spheroids on CS-HA at 37℃ was approximately 10μm,smaller than that on PVA substrates(approximately 27μm).Based on time-lapse images,these unique bubbles originated from the dynamic movement of the cell membrane during spheroid formation,which indicated an increment of membrane fluidity for MSCs cultured on these substrates.Moreover,the membrane interaction in two different types of cells with similar membrane fluidity may further induce a higher level of membrane translocation during the formation of heterogeneous spheroids.CONCLUSION Changes in cell membrane fluidity may be a novel path to elucidate the complicated physiological alterations in 3D spheroid-forming cells.

EFFECTS OF QUERCETIN ON MEMBRANE FLUIDITY OF INJURED VASCULAR ENDOTHELIAL CELLS WITH HYPOXIA AND THE LACK OF GLUCOSE

Objective To study the effects of different concentrations of Quercetin on nitric oxide (NO) production and membrane fluidity of the injured human umbilical vein vascular endothelial cell line(ECV 304) with hypoxia and the lack of glucose. Methods The experiments were performed in the culture of ECV 304 injured with hypoxia and the lack of glucose in vitro. The releases of intracellular lactate dehydrogenase(LDH) of ECV 304 was measured with automatic biochemistry analysis. NO level of ECV 304 was monitored with colorimetry. The membrane fluidity of ECV 304 was measured with the fluorescence polarization method. Results After ECV 304 was cultured in hypoxia and the the lack of glucose for 24 hours, the release of LDH and the membrane fluidity were increased significantly; NO level was decreased. Preincubation of ECV 304 with 20, 80,160 μ mol·L -1 of Quercetin for 24 hours reduced LDH activity, membrane fluidity and increased the level of NO in hypoxia and the lack of glucose induced ECV 304. Conclusion These results demonstrate that Quercetin can produce the protective effect on hypoxia and the lack of glucose induced injury of ECV 304 by increasing release of NO and changing membrane fluidity.

Preliminary study on plasma membrane fluidity of Psychrophilic Yeast Rhodotorula sp.NJ298 in low temperature

The ability of cell to modulate the fluidity of plasma membrane was crucial to the survival of microorganism at low temperature.Plasma membrane proteins,fatty acids and carotenoids profiles of Antarctic psychrophilc yeast Rhodotorula sp.NJ298 were investigated at-3 ℃,0 ℃ and 8 ℃.The results showed that plasma membrane protein content was greater at-3 ℃ than that at 8 ℃,and a unique membrane polypeptide composition with an apparent molecular mass of 94.7 kDa was newly synthesized with SDS-PAGE analysis;GC analysis showed that the main changes of fatty acids were the percentage of unsaturated fatty acids(C18:1 and C18:2) and shorter chain saturated fatty acid(C10:0) increased along with the decrease of the culture temperature from 8 ℃ to-3 ℃;HPLC analysis indicated that astaxanthin was the major functional carotenoids of the plasma membrane,percentage of which increased from 54.6±1.5% at 8 ℃ to 81.9±2.1% at-3 ℃.However the fluidity of plasma membrane which was determined by measuring fluorescence anisotropy was similar at-3 ℃,0 ℃ and 8 ℃.Hence these changes in plasma membrane’s characteristics were involved in the cellular cold-adaptation by which NJ298 could maintain normal plasma membrane fluidity at near-freezing temperature.

EFFECTS OF SALVIA MILTIORRHIZA BUNGE（SMB）ON LIPID PEROXIDATION AND PLASMA MEMBRANE FLUIDITY OF CULTU

In order to investigate the effect of salvia miltiorrhiza hunge(SMB)on the plasma membrane fluidity and the relationship between the lipid peroxidation and the Plasma membrane fluidityin cultured human fetdal hepatocytes,the plasma membrane fluidity,using 1,6-dipheny-1,3,5-hexatriene(DPH)as a fluorescence probe, malondialdehyde(MDA)production as well as alanine aminotransferase(ALT)release of human fetal hepatocytes cultured in Presence of carbon tetrachloride(CCl4)or SMB puls CCl4 were estimated. In the cultured hepatocytes injured by CCl4,significant increments of the MDA production and the ALT release,and significant decrease in the plasma membrane fluidity were observed.when the culture medium was supplied with SMB prior to the additionof CCl4,the CCl4 induced increments in MDA production and ALT release was suppressed signifi cantly and a concomitant raise of plasma membrane fluidity towards normal occurred.The resultssuggested that SMB could suppress the lipid peroxidation in bepatocytes,thereby normal membranefluidity might be retained.

Effects of Chuanxiongqin hydrochloride on increasing the fluidity of brain cell membrane and scavenging free radicals in model rats with ischemia/reperfusion injury

BACKGROUND: The fluidity of cell membrane can be affected by various factors. Many experiments have confirmed that the ischemia/reperfusion of organic tissue can increase the contents of free radicals, which lead to high rigidity and low fluidity of cell membrane, and the conditions can be changed by Chuanxiongqin. OBJECTIVE: To observe the effect and mechanism of Chuanxiongqin hydrochloride on the fluidity of brain cell membrane in rat models of ischemia/reperfusion. DESIGN: A completely randomized controlled animal trial. SETTINGS: Institute of Brain Sciences; Department of Physiology, Medical College, Datong University. MATERIALS: Twenty male grade Ⅰ Wistar rats of 170-220 g were randomly divided into model group (n =10) and control group (n =10). Chuanxiongqin hydrochloride (molecular mass was 172.2) was purchased from the National Institute for the Control of Pharmaceutical and Biological Products (batch number: 0817-9803); Spin labelers: 5-doxyl-stearlic acid methylester (5DS), 16-doxyl-stearlic acid methylester (16DS), xanthine, xanthine oxidase (XOD) and 5,5-dimeth-1-pyrroline- N-oxide (DMPO) from Sigma Company; Bruker ESP 300 electron paramagnetic resonance (EPR) spectrometer by Bruker Company (Germany). METHODS: The experiments were carried out in the State Key Laboratory of Natural and Biomimetic Drugs, Peking University from June 2001 to July 2002. In the model group, rats were made into models of cerebral ischemia by 30-minute ligation and 2-hour reperfusion of common carotid arteries; The rats in the control group were not made into models. The order parameter (S) and rotational correlation time (τc) were detected with the ESR spectrometer by means of spin labeling. The greater the S and τc, the smaller the fluidity. Meanwhile, the clearance rate of free radicals was detected with ESR spin trapping. The measurement data were compared using the t test. MAIN OUTCOME MEASURES: The S, τc and clearance rates of O2 · and OH· free radicals were compared between the model group and control group. RESULTS: The S and τc in the model group [0.738 4±0.003 5; (8.472±0.027)×10-10 s/circle] were obviously different from those in the control group [0.683 9±0.008 3; (7.945±0.082)×10-10 s/circle, t =5.731, 5.918, P < 0.05], which suggested that ischemia/reperfusion injury decreased the fluidity of brain cell membrane. After adding Chuanxiongqin hydrochloride, there were no obvious differences between the model group [0.688 5±0.030 5; (7.886±0.341)×10-10 s/circle] and control group (P > 0.05), indicating that Chuanxiongqin hydrochloride could recover the fluidity of brain cell membrane after ischemia/reperfusion injury close to the level in the normal control group. Chuanxiongqin hydrochloride could directly scavenge the O2 · and OH· free radicals, and the maximal clearance rates were 83.92% and 44.99% respectively. CONCLUSION: Chuanxiongqin hydrochloride increases the fluidity of membrane of ischemia-injured brain cell by scavenging both O2 ·and OH· free radicals.

THE EFFECT OF RETINOIC ACID ON CELL MEMBRANE AND METASTATIC ABILITY OF MOUSE FORESTOMACH CARCINOMA C

We studied the effect of all-trans-retinoic acid (RA)on the expression of several surface lectin receptors and cell membrane fluidity of mouse forestomach carcinoma cell line (MFC) in vitro. The results showed that cells treated with RA manifested decreased expression of lectin receptors, increased memhrane fluidity and reduced spontaneous metastasis. These results suggest that the effect of RA on tumor cell membrane may be one of the mechanisms involved in the alternation of cell metastatic phenotype.

Assessment of Membrane Erythrocyte Cholesterol Level in Sickle Cell Disease

Objective: The aim of this study was to assess the level of erythrocyte membrane cholesterol in sickle cell patients, which is one of the essential parameters of membrane fluidity that contributes to understanding the hemolytic state of the erythrocyte. Methods: We worked with blood specimens from 20 controls and 50 sickle cell patients. The blood count and the isoelectric focusing (IEF) were performed on the samples in order to select them. The titration of the erythrocyte membrane cholesterol was made after washing and lysing the erythrocytes with the hemolyzing solution (EDTA, 2 Mercapto-Ethanol, NADP, NaOH). The cholesterol level was assessed by the enzymatic colorimetric method. The results were analyzed by Student’s test. Results: We worked with 16 control subjects with a hemoglobin status and a normal hemogram. The evaluation of the erythrocyte membrane cholesterol level of the samples allows us to define the reference interval (α = 0.05) at 17.55 ± 3.83 mg of cholesterol/g of hemoglobin. The erythrocyte membrane cholesterol levels of sickle cell patients found in this study were 11.58 ± 2.98 mg cholesterol/g of hemoglobin. In this study, 38 sickle cell patients (76%) were found with a low erythrocyte membrane cholesterol level compared to the reference interval. Statistical analysis showed that there was a significant difference (α = 5%) between the erythrocyte membrane cholesterol level of normal subjects and sickle cell patients. Conclusion: Most of the sickle cells patients had a decreased erythrocyte membrane cholesterol level. This reduces the membrane fluidity making the erythrocyte membrane rigid and more fragile. This may be one of the factors responsible for the lyses of erythrocytes.

An Experimental Study on Membrane Malignant Phenotype of Tumour Cells and Their Reversion

A human promyelocytic leukemic cell line (HL-60 cells)was induced to differentiate along the myeloid pathway in vitro by 1.25% dimethylsulfoxide(DMSO)as an inducer.The membrane fluidity, the quantity of ConA binding sites on the cell membrane surface,and the protein tyrosine kinase(Tyr-PK)activity existing in NP-40 membrane extract and cytoplasma extract were determined respectively.The activity of tumour-derived immunosuppressive factor(TDSF)secretedby HL-60 cells into culture suppernatant was also determined.The results demonstrated that:(1)HL-60 cells were capableof undergoing differentiation onto the myeioid pathway in the presence of DMSO The growth of DMSO-treated HL-60 cells became slow and synthesis rate of DNA decreased by about 50%.(2)Both membrane fluidity and the quantity of ConA binding sites on membrane were obviously lower after induced with DMSO than those before induction.(3)The TyrPK activity in the NP-40 membrane extract incresed during the period of induced differentiation.The phosphorylation level of endogenous protein in cytoplasma extract decreased with the process of induced differentiation.It may be reasoned that the phosphatase activity is much higher than the phosphorylase activity.4)The secretive level of TDSF by HL60 cells during the period of induced differentiation revealed no change.The preliminary results showed that the malignant phenotypes of tumour cells we used may undergo reversible changes with induced differentiation of tumour cells except the secretion of TDSF.

DYNAMIC PARAMETER OF MEMBRANE LIPID IN LUNG CANCER CELL LINES, CARCINOGENESIS CELLS AND CANCER CELLS ISOLATED FROM PATIENTS WITH LUNG CANCER

With the aid of the Fluorescent lipophilic probe DPH (1, 6- diphenyl- 1, 3, 5- hexatriene ), the degree of microviscosity (η) and lipid fluidity (LFU) obtained from lung cancer lines and carcinogenesis cells induced by irradiation as well as the patients with lung cancer were quantitatively monitored by Fluorescence polarization. The results have shown a marked decreased in η and a significant increase in LFU in various tumor cells as compared to normal cells. Sometime, the degree of fluidity in carcinogenesis cells Induced by radiation and the patients with lung cancer have shown to be similar pattern. The possibility that these dynamic parameter may serve as a diagnostic tool for an early detection of lung cancer is discussed.

Study on Biologic Activity for Membrane of Normal Bone Marrow Cells with Infection of Epidemic Hemorrhagic Fever Virus

Using DPH fluorescence probe, the membrane of normal bone marrow cells with infection of epidemic hemorrhagic fever virus (EHFV) was labeled. The membrane lipid fluidity was obviously decreased from the membrane lipid fluorescence polarization. The membrane lipid fluidity of lympho- cyte, monocyte and neutrophilic granulocyte was dynamically observed. After culturing the cells for 1, 6, 24 and 72 h, it was found that all the membrane lipid fluidity of the infected cells was de- creased obviously with the longer the culturing time, the more obvious it. Compared with the normal control groups, there was a significant difference statistically (P<0. 05-0. 01). It was suggested that the decrease of the membrane lipid fluidity of normal bone marrow cell with infection of EHFV had correlation with the degree of virus invading and cellfunction injury.

Effect of oxide nanoparticles on the morphology and fluidity of phospholipid membranes and the role of hydrogen bonds

Engineered oxide nanoparticles（NPs） are widely applied in insulators,catalyzers,paints,cosmetic products,textiles and semiconductors.Their attachment on cell membrane may lead to cytotoxicity.The effects of Al_2O_3,Fe_2O_3,SiO_2,TiO_2and ZnO NPs on membrane integrity and fluidity were studied using giant or small unilamellar vesicles in this study.Al_2O_3 and SiO_2NPs disrupted the oppositely charged membrane,indicating the important role of electrostatic attraction.However,Fe_2O_3,TiO_2and ZnO NPs did not cause serious membrane disruption as Al_2O_3 and SiO_2 NPs.Membrane fluidity was evaluated by the generalized polarity（GP） values of Laurdan fluorescent emission.SiO_2 NPs induce the membrane gelation of both positively and negatively charged membrane.Al_2O_3 and ZnO NPs induced the gelation of the oppositely charged membrane,but did not cause obvious membrane gelation to the like charged membrane.The phospholipid molecular structural changes after NP exposure were analyzed by Fourier transform infrared（FT-IR） spectroscopy.FT-IR spectra revealed the hydrogen bond formation between NPs and the carbonyl/phosphate groups of phospholipids.Al_2O_3 and SiO_2 NPs showed strongest evidence of hydrogen bonding on their FT-IR spectra.It was consistent with the microscopic observation and fluorescent data that Al_2O_3 and SiO_2 NPs caused more serious membrane disruption and gelation.This study on membrane damage provides further knowledge on the cytotoxicity of nanomaterials and the safety of NP application.

Role of ions and ion channels in capacitation and acrosome reaction of spermatozoa

Capacitation and acrosome reaction are important prerequisites of the fertilization process. Capacitation is a highlycomplex phenomenon occurring in the female genital tract, rendering the spermatozoa capable of binding and fusionwith the oocyte. During capacitation various biochemical and biophysical changes occur in the spermatozoa and thespermatozoal membranes. Ions and ion channels also play important roles in governing the process of capacitation bychanging the fluxes of different ions which in turn controls various characteristics of capacitated spermatozoa. Alongwith the mobilization of ions the generation of free radicals and efflux of cholesterol also plays an important role in thecapacitation state of the spermatozoa. The generation of free radical and efflux of cholesterol change the mechano-dynamic properties of the membrane by oxidation of the polyunsaturated lipids and by generating the cholesterol freepatches. The process of capacitation renders the spermatozoa responsive to the inducers of the acrosome reaction. Theglycoprotein zona pellucida 3 (ZP3) of the egg coat zona pellucida is the potent physiological stimulator of the acro-some reaction; progesterone, a major compoent of the follicular fluid, is also an induce of the acrosome reaction.The inducers of the acrosome reaction cause the activation of the various ion-channels leading to high influxes of calci-um, sodium and bicarbonate. The efflux of cholesterol during the process of capacitation alters the permeablity of themembrane to the ions and generate areas which are prone to fusion and vesculation process during the acrosome reac-tion. Ths review focuses mainly on effects of the ion and ion-channels, free radicals, and membrane fluidity changesduring the process of capacitation and acrosome reaction. (Asian J Androl 1999 Sep; 1: 95-107)

Effect of Sodium Ferulate on Fluidity and Morphology of Cell Membrane in Ozone Induced Lung Injury

To study the effect of sodium ferulate （SF）, an active component of Radix Angelica, on lung damage induced by ozone （O3）. Methods： Mice model of lung injury was induced by ozone inhalation and treated with SF. The level of lipid peroxide and microviscosity in alveolar epithelial cell membrane of the mice was determined, and the structural change of lung cells was observed by microscopy. Results： Ozone could increase the level of malondialdehyde （MDA） and the microviscosity in alveolar epithelial cell membrane, and induce inflammatory changes in morphologic structure. These abnormal changes were improved after SF administration, which was manifested as alleviation of heightened microviscosity, increase of membrane fluidity, as well as the basically normalized pulmonary cellular structure under microscope. Conclusion： SF has a preventive effect against oxidized pulmonary injury induced by ozone, the action of which could be through scavenging oxygen free radicals, reducing lipid peroxide production, increasing membranous fluidity and mitigating inflammatory changes in cell structure.

Strategy for Detecting Systemic Treatment Sensitivity of Primary Liver Cancer Based on a Novel Infrared-emissive Organic Nanoparticle

In this study,we synthesized an organic material with near-infrared emission capabilities:4-(2-(4-(9-(4-(diphenylamino)phenyl)naphtho[2,3-c][1,2,5]thiadiazol-4-yl)phenyl)-1H-phenol-1-ylidene)malononitrile(TPA).Furthermore,TPA-PEG2000 fluorescent nanoparticles were prepared via coating the shells with PEG2000.TPA-PEG2000 exhibited strong near-infrared emission near 700 nm,with a photoluminescence quantum yield of 15.09%,indicating a high emission efficiency.Molecular biology experiments have confirmed its low toxicity and excellent biocompatibility.Increased cholesterol and phospholipid levels in liver cancer cell membranes with low sensitivity or high drug resistance lead to increased rigidity,reduced membrane fluidity,reduced endocytic efficiency,and reduced uptake.Therefore,the uptake of TPA-PEG2000 nanoparticles into cells and the near-infrared fluorescence intensity can be used to evaluate the sensitivity of systemic liver cancer treatment in a simple and efficient manner.

New insights into the regulation of cholesterol eft from the sperm membrane

Cholesterol is an essential component of the mammalian plasma membrane because it promotes membrane stability without comprising membrane fluidity. Given this important cellular role, cholesterol levels are tightly controlled at multiple levels. It has been clearly shown that cholesterol redistribution and depletion from the sperm membrane is a key part of the spermatozoon＇s preparation for fertilization. Some factors that regulate these events are described （e.g., bicarbonate, calcium） but the mechanisms underlying cholesterol export are poorly understood. How does a hydrophobic cholesterol molecule inserted in the sperm plasma membrane enter the energetically unfavorable aqueous surroundings？ This review will provide an overview of knowledge in this area and highlight our gaps in understanding. The overall aim is to better understand cholesterol redistribution in the sperm plasma membrane, its relation to the possible activation of a cholesterol transporter and the role of cholesterol acceptors. Armed with such knowledlze, sl）erm handlin~ techniques can be adapted to better prepare spermatozoa for in vitro and in vivo fertilization.

Study on Effect and Mechanism of Sodium Ferulate in Preventing and Treating Ozone Induced Lung Injury in Mice

Objective： To study the effect and mechanism of sodium ferulate （SF） in preventing and treating ozone （O3） induced lung oxidative injury in mice. Methods： Lung oxidative injury model mice were established by making them inhale O3. The activitY of anti-oxidase and membranous microviscosity in epithelial cells in the lung of mice were determined, and the ultrastructural change of lung tissues was observed with electromicroscopy. Results, Activities of superoxide dismutase （SOD） and giutathione peroxidase （GSH-Px） were reduced, while membranous lipo-microviscosity significantly increased in the pulmonary epithelial cells of model mice, revealing ultrastructural change. These abnormal changes were reversed by SF treatment, which was manifested as the significantly raised activities of SOD and GSH-Px after treatment with high and moderate doses of SF, showing a significant difference compared with those in the model group （P〈0.01）. Membranous lipo-microviscosity basically approached that in the control group （P〉0.05）; electron microscopic examination showed a basically normal morphological structure of pulmonary epithelial cells, with the change in lung injury significantly milder than that in the model group. Conclusion： O3 could induce oxidative injury of lungs in mice, and SF could enhance the anti-oxidation capacity of mice and scavenge the oxygen free radicals so as to alleviate the injury.