Effects of sodium butyrate on the transfer of arachidonic acid to phosphatidylcholine in a clonal oligodendrocyte cell line (CB-II)

The effect of sodium butyrate on membrane phospholipid metabolism in a neonate rat cerebellum derived clonal oligodendrocyte cell line (CB-II) was investigated. Sodium butyrate is an agent known to induce cell differentiation and morphological transformations. A comparison of thein vivo phospholipid labeling patterns obtained by incubating CB-II cells with [³H]choline, [¹⁴C]myristic acid or [³H]arachidonic acid indicated that butyrate altered the route of acylation-deacylation in phosphatidylcholine (PC) biosynthesis. Using anin vitro incubation system containing homogenates of CB-II cells, the largest proportion of radioactivity was found in PC, and addition of sodium butyrate resulted in a further increase in the transfer of arachidonic acid to PC, but not to phosphatidylinositol. Similar results were obtained when thisin vitro acylation activity was tested using homogenates from sodium butyrate pretreated cells. The butyrate effect was observed regardless of whether or not exogenous lysophosphatidylcholine (LPC) was added to the incubation system. Addition of butyrate did not result in a change in the activity of LPC:acyl-CoA (coenzyme A) acyltransferase (EC 2.3.1.23) in CB-II cells upon incubating cell homogenates with [1-¹⁴C]arachidonoyl-CoA and LPC. However, when cell homogenates were incubated with [³H]arachidonic acid in the presence of 2.5–10 mM sodium butyrate, arachidonoyl-CoA synthesis was stimulated. A time course study demonstrated that significant stimulation occurred after three minutes. Taken together, the results suggest that in CB-II cells, sodium butyrate stimulates the transfer of arachidonic acid into PC and that this effect is at least partially due to a stimulation of arachidonoyl-CoA ligase (EC 6.2.1.3).     

Effect of the surface topography and chemistry of poly(3-hydroxybutyrate) substrates on cellular behavior of the murine neuroblastoma Neuro2a cell line

Interactions between cells and substrates play an important role in tissue development during the process of tissue regeneration. Substrates that mimic the surface topography and chemical composition of the extracellular matrix (ECM) lead to enhanced cellular interactions. Electrospinning can easily produce aligned fibrous substrates with an architecture that structurally resembles tissue ECM and can provide contact guidance during tissue regeneration. However, the sole use of substrate materials may not be sufficient for the treatment of damaged tissue due to a lack of biochemical guidance, which helps to promote cell adhesion and proliferation. In the present contribution, we evaluated the effect of the surface properties of various surface-modified electrospun fibrous and solution-cast film PHB substrates in vitro on the murine neuroblastoma Neuro2a cell line. A neat electrospun fibrous and a solution-cast PHB scaffolds were used as the internal control. The results from cell studies suggest that the laminin–PHB fibrous substrate provided better support for the attachment and proliferation of Neuro2a cells than the other substrates. The cellular viability increased from 116% for 4 h of cell seeding to 187% for 3 days of cell seeding. These results suggest that the surface topography and chemistry significantly impact the Neuro2a cell line. The introduction of contact guidance, such as that provided by the fiber diameter and alignment, and biochemical guidance, such as that achieved by the immobilization of adhesive proteins, enhanced cell attachment and proliferation. These results emphasize the importance of surface properties with respect to cellular behavior.     

Effect of tocotrienols on the growth of a human breast cancer cell line in culture

The tocotrienol-rich fraction (TRF) of palm oil consists of tocotrienols and some α-tocopherol (α-T). Tocotrienols are a form of vitamin E having an unsaturated side-chain, rather than the saturated side-chain of the more common tocopherols. Because palm oil has been shown not to promote chemically-induced mammary carcinogenesis, we tested effects of TRF and α-T on the proliferation, growth, and plating efficiency (PE) of MDA-MB-435 estrogen-receptor-negative human breast cancer cells. TRF inhibited the proliferation of these cells with a concentration required to inhibit cell proliferation by 50% of 180 μg/mL, whereas α-T had no effect at concentrations up to 1000 μg/mL as measured by incorporation of [³H]thymidine. The effects of TRF and α-T also were tested in longer-term growth experiments, using concentrations of 180 and 500 μg/mL. We found that TRF inhibited the growth of these cells by 50%, whereas α-T did not. Their effect on the ability of these cells to form colonies also was studied, and it was found that TRF inhibited PE, whereas α-T had no effect. These results suggest that the inhibition is due to the presence of tocotrienols in TRF rather than α-T. Based on a paper presented at the PORIM International Palm Oil Congress (PIPOC) held in Kuala Lumpur, Malaysia, September 1993.     

Effect of phosphatidylcholine on the α-lactalbumin-induced fusion of vesicles

Previous studies on α-lactalbumin induced fusion of phosphatidylserine/phosphatidylethanolamine vesicles are extended to vesicles composed of various combinations of phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine and cardiolipin. It was found that inclusion of phosphatidylcholine in the vesicles results in a depression of fusion. This depression of fusion appears to be caused by a reduction in the amount of irreversibly bound α-lactalbumin to vesicles containing phosphatidylcholine. It is suggested that in this system fusion is dependent upon the extent by which a particular protein segment penetrates the bilayer.     

基于磷酰胆碱有效基团的功能材料的结构及生化特性

综述了磷酰胆碱类功能材料,包括磷酰胆碱有效基团分别在侧链和主链的聚合物,其包含季铵基和磷酸根结构而同时带有正负两种电荷,具有良好的血液相容性和强吸湿特性,对其在生物医学、生物化学以及化妆品领域的应用研究进行了介绍,包括作为抗凝血仿生材料、药用载体材料、基因运载体系材料、生物传感器基材和人造器官等.     

Effect of PbII on the secondary structure and biological activity of trypsin

The effects of Pb(II) on the secondary structure and biological activity of trypsin have been examined by monitoring changes in its conductivity and IR and circular dichroism (CD) spectra. The results show that Pb(II) reacts with trypsin, and that the binding sites might be -OH and -NH groups in pepsin. The CD spectra indicate that interaction with Pb(II) significantly affects the secondary structure of trypsin, the beta-sheet-structure content being increased by about 42%, whilst those of alpha-helix and beta-turn structures are decreased by 13% and 21%, respectively. The results clearly demonstrate that Pb(II) affects the biological activity of trypsin by modifying its secondary structure. Most interesting is that Pb(II) up-regulates the activity of trypsin at low concentrations while down-regulating it at high concentrations.     

Production of pectic extracts from sugar beet pulp with antiproliferative activity on a breast cancer cell line

In the last years, sugar beet pectins have been the subject of several investigations involving extraction methodologies, chemical composition and functional properties. The structure of pectins, which depends on the extraction method, is decisive in their capacity to induce apoptosis on several cancer cell lines like colon, prostate and breast. In this work, sugar beet pectin extraction was performed in the following steps: lipid extraction with hexane, removal of soluble complex carbohydrates and proteins, and enzymatic treatment with amyloglucosidase, protease, and pectinase. The enzymatic treatment was carried out with Rohapect DA6L under the following conditions: 50°C, pH 4.0, 2% enzyme/substrate (E/S) ratio, 15 h, and a solid to liquid ratio of 1 ∶ 10. The pectic extract showed a degree of polymerization (DP) profile of 55.8% with DP≥7; 4.9% with DP6; 5.8% between DP2 and DP6 ; 4.7% with DP2; and 28.8% with DP1. The pectic extract was examined for its antiproliferative activity on the MCF-7 breast cancer cell line. At a concentration range of 12.5–25 mg/mL the pectic extract killed 80.6% of the cells, exhibiting a higher antiproliferative activity than 4-hydroxytamoxifen (4-OHT), a classical anticancer drug, which killed 56.5% of the cells.     

孔道结构对渣油加氢脱金属催化剂活性的影响

选择性制备3种不同孔道结构的渣油加氢脱金属催化剂,并进行渣油加氢脱金属和加氢脱硫活性评价。结果表明,一定量大孔(>50 nm)的存在,能够提高催化剂单位表面积的加氢脱金属活性;加氢脱硫活性与体积比表面积成正比。     

Effect of diethyl ether on phosphatidylcholine biosynthesis in hamster organs

The effect of diethyl ether anesthesia on phosphatidylcholine biosynthesis in hamster organs was investigated. Ether administration did not affect the incorporation of radioactive choline into phosphatidylcholine in the liver, heart, lung, brain and spleen. A significant (29%) decrease in the labeling of phosphatidylcholine was detected in the kidney of ether-treated hamsters. Reduction in phosphatidylcholine labeling was not due to a diminished radioactive choline uptake but a decrease in the conversion of phosphocholine to CDP-choline. The accumulation of labeled phosphocholine was caused by the translocation of CTP:phosphocholine cytidylyltransferase from microsomal (more-active) form to cytosolic (less-active) form. Ether administration appears to modulate the cytidylyltransferase in hamster kidney differently than that in other hamster organs.     

Effect of dietary linseed oil on tumoricidal activity and eicosanoid production in murine macrophages

Diets that contain high levels of n−3 fatty acids from fish oil have been shown to significantly effect macrophage cytolytic capacity, tumor necrosis factor alpha production and eicosanoid production. The present study was undertaken to determine whether n−3 fatty acids from vegetable origin [linseed oil (LIN)] would have the same effects on murine macrophage tumoricidal capacity and eicosanoid production as would fish oil. Mice were fed for three weeks diets that contained 10% (wt/wt) of either LIN, which is high in linolenic acid (18∶3n−3), menhaden fish oil (MFO), which is high in eicosapentaenoic (20∶5n−3) and docosahexaenoic (22∶6n−3) acids, or safflower oil (SAF), which is high in linoleic acid (18∶2n−6).In vivo- orin vitro-activated macrophages were assessed for select functions. As expected, macrophages from mice fed LIN and MFO produced significantly lower levels of both prostaglandins and leukotriene C₄ when compared with macrophages from mice fed SAF. In addition, LIN and MFO macrophages were able to synthesize leuko-triene C₅, which could not be produced by macrophages from mice fed SAF. The effects of LIN, however, were not as pronounced as those of MFO. With respect to specific functions, macrophages from mice fed LIN did not have altered cytolytic capacity when compared with macrophages from mice fed SAF and activatedin vitro with either lipopolysaccharide (LPS) alone for 24 h or with LPS plus interferon gamma (IFNγ) for 5 h. Diet did not significantly alter tumoricidal capacity of macrophages activated completelyin vivo either. Specific binding of macrophages to tumor targets, nitric oxide production and the production of tumor necrosis factor alpha were found to be unaltered by LIN when compared with SAF. The results are not consistent with a general n−3 effect, as LIN could not effect the functions comparable to MFO. The results also suggest that a change in eicosanoid production may not be sufficient to modulate tumoricidal activity in macrophages.     

渣油加氢催化剂孔结构对反应活性的影响

在3L中型加氢试验装置上考察了渣油加氢脱硫催化剂孔结构对反应活性的影响，试验结果表明，当孔结构发生变化时，催化剂的脱硫、脱氮、脱残炭及脱金属反应活性呈现不同的变化规律。     

Effect of surface structure on cell growth prepared by the terminal immobilization method

Substrate effects of surface morphology and chemical structure for cell cultures prepared by molecular terminal immobilization method were studied. When we focused attention on a phenyl group as a functional moiety, the cell growth on the surface prepared by the immobilization method showed a better proliferation rate than that of a substrate prepared by the casting method. Further, from the results of mouse fibroblast L929 cell (L‐cell) growth on poly(amino acid)‐immobilized surfaces in Dulbecco's minimal essential medium containing 10% FBS, it was indicated that the amino group was more effective than the phenyl group, and that a slight difference of chemical structure had a substantial influence on cell growth. In addition, mouse bone marrow–derived Sp2/0‐Ag14 cell (Sp2/0 cell) culture in ASF‐104 serum‐free medium, poly(amino acid)‐immobilized substrates showed an almost equal proliferation rate to that in a serum‐containing medium. These results showed that effective cell growth can occur on immobilized surfaces, and that detection of a weak interaction depends on the functional groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3001–3008, 2004     

1,25-dihydroxyvitamin D3 increases the activity of the intestinal phosphatidylcholine deacylation-reacylation cycle

The activity of the intestinal phosphatidylcholine deacylation-reacylation cycle has been found to be stimulated by 1,25-dihydroxy-vitamin D₃. The stimulation of this cycle thus provides a possible mechanism for the reported retailoring of the fatty acid composition of phosphatidylcholine in intestinal cell membranes by 1,25-dihydroxy-vitamin D₃ and its analogue, 1α-hydroxyvitamin D₃.     

酚酸结构对酚酸-g-聚甘露糖醛酸抗氧化性能的影响

以海藻酸钠水解产物聚甘露糖醛酸(PM)为原料,通过聚甘露糖醛酸-乙二胺(PM-EDA)中间体与酚酸接枝共聚,制备了8种PM的酚酸(PA)接枝共聚物酚酸-g-聚甘露糖醛酸(PA-g-PM),并探究了PA结构对8种PA-g-PM抗氧化活性的影响。在n_PM:n_EDA=1:1.5,PM与两种活化剂碳二亚胺(EDC)、N-羟基琥珀酰亚胺(NHS)的摩尔比1:2:1,活化0 h,pH 8.0条件下,反应24 h,获得最高取代度(17.27%)的PM-EDA。PM的PA-g-PM接枝率在4.171±0.16 ~ 8.880±0.32 mg GA/g之间。UV-vis、FT-IR、XRD表征证实酚酸已成功接枝到PM上获得PA-g-PM。相比PM,8种PA-g-PM的对DPPH的清除率和对铁的还原力均显著提升。PA-g-PM的抗氧化性能与其中的酚羟基个数呈正相关关系,对位酚羟基PA-g-PM的抗氧化性能优于邻位酚羟基PA-g-PM的抗氧化性能,PA-g-PM中的酚羟基被甲氧基取代其抗氧化性能减弱。以期本研究结果为海藻酸钠在食品、化妆品、医药等行业高值开发利用奠定理论基础。     

碳化条件对碳微球结构的影响及其性能评价

以葡萄糖为碳源,直接水热合成法制备碳微球。利用扫描电镜(SEM)和傅里叶变换红外(FT-IR)光谱仪对碳微球进行表征,探究碳化条件对碳微球结构的影响。结果表明,葡萄糖经过碳化由棒状变成球状,碳化温度180℃和碳化时间7 h条件下制备的碳微球结构较均匀,并且含有—OH及—COOH官能团,将制备的催化剂用于纤维素水解时,水解率最高达46. 22%。     

Effect of clay dispersion on the cell structure of LDPE/clay nanocomposite foams

In this study, the effect of clay and its dispersion state on the cell morphology and foaming behavior of chemically crosslinked polyethylene (PE) foams were examined. In addition, the effect of foaming process on the clay morphology was also considered. It was shown that the morphology of the clay before the foaming process and its compatibility with PE matrix play a major role in determining the final foam properties. A PE‐g‐MA compatibilizer was used to increase the melt intercalation of PE onto the clay galleries and to improve clay dispersion in the PE matrix. The uniform dispersion of clay provided greater and well‐ dispersed nucleation sites. This led to smaller cell size, narrower cell size distribution, and higher cell density, and lower foam density. During the foaming process, intercalated clays were delaminated due to the rapid polymer melt expansion that inhibited gas release and increased foam expansion ratio. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

(3H)Forskolin- and (3H)dihydroalprenolol-binding sites and adenylate cyclase activity in heart of rats fed diets containing different oils

The characteristics of the cardiac adenylate cyclase system were studied in rats fed diets containing fish oil (menhaden oil) and other oils. Adenylate cyclase activity generally was higher in cardiac homogenates and membranes of rats fed diet containing 10% menhaden oil than in the other oils. The increase in enzyme activity, especially in forskolin-stimulated activity, was associated with an increase in the concentration of the [³H]forskolin-binding sites in cardiac membranes of rats fed menhaden oil. The β-adrenergic receptor concentration was not significantly altered although the affinity for [³H]dihydroalprenolol-binding was lower in membranes of rats fed menhaden oil than those fed the other oils. ω-3 fatty acids from menhaden oil were incorporated into the cardiac membrane phospholipids. The results suggest that the observed increase in myocardial adenylate cyclase activity of rats fed menhaden oil may be due to an increase in the number of the catalytic subunits of the enzyme or due to a greater availability of the forskolin-binding sites.     

Efficient production of cyclic adenosine monophosphate from adenosine triphosphate by the N-terminal half of adenylate cyclase from Escherichia coli

In this study, we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate(c AMP) from adenosine triphosphate(ATP). First, adenylate cyclase from Escherichia coli MG1655(EAC) and Bordetella Pertussis(BAC) were expressed in E. coli BL21(DE3) and comparatively analyzed for their activities. As a result, EAC from E. coli MG1655 exhibited a higher activity. However, amount of EAC were obtained in an insoluble form. Therefore, we expressed the first 446 amino acids of EAC(EAC446) to avoid the inclusion body. The effects of induction temperature, incubation time, and incubation p H were further evaluated to improve the expression of EAC446. Subsequently, the reaction process for the production of c AMP with ATP as a starting material was investigated. As none of c AMP was detected in the whole-cell based biocatalytic process, the reaction catalyzed by the crude enzyme was determined for c AMP production. What's more,the reaction temperature, reaction p H, metal ion additives and substrate concentration was optimized, and the maximum c AMP production of 18.45 g·L~(-1) was achieved with a yield of 95.4% after bioconversion of 6 h.     

Efficient production of cyclic adenosine monophosphate from adenosine triphosphate by the N-terminal half of adenylate cyclase from Escherichia coli

In this study, we aimed at developing an efficient biocatalytic process for bio-production of cyclic adenosine monophosphate (cAMP) from adenosine triphosphate (ATP). First, adenylate cyclase from Escherichia coli MG1655 (EAC) and Bordetella Pertussis (BAC) were expressed in E. coli BL21 (DE3) and comparatively analyzed for their activities. As a result, EAC from E. coli MG1655 exhibited a higher activity. However, amount of EAC were obtained in an insoluble form. Therefore, we expressed the first 446 amino acids of EAC (EAC446) to avoid the inclusion body. The effects of induction temperature, incubation time, and incubation pH were further evaluated to improve the expression of EAC446. Subsequently, the reaction process for the production of cAMP with ATP as a starting material was investigated. As none of cAMP was detected in the whole-cell based biocatalytic process, the reaction catalyzed by the crude enzyme was determined for cAMP production. What's more, the reaction temperature, reaction pH, metal ion additives and substrate concentration was optimized, and the maximum cAMP production of 18.45 g·L^-1 was achieved with a yield of 95.4% after bioconversion of 6 h.