Lipid composition of cultured B16 melanoma cell variants with different lung-colonizing potential

Lipid components influence several cell surface properties that are critical in different stages of the metastatic process. In this study, we examined whether the different lung-colonizing potential of B16-F1 and B16-F10 melanoma cells could be related to a characteristic lipid profile. The lipid analyses, carried out on the same cell cultures used for the assay of lung-colonizing potential, revealed characteristics in the lipid composition of both B16-F1 and B16-F10 melanoma cells that are common to other systems of malignant cells: a high level of 18∶1 associated with low proportions of polyunsaturated fatty acids in phospholipids, accumulation of ether-linked lipids and absence of complex gangliosides. The two B16 melanoma variants differed significantly only with respect to ether-linked lipids, due to a higher level of alkyl-PC in B16-F10 than in B16-F1.     

柯里拉京对B16细胞增殖及酪氨酸酶活性的抑制作用

采用体外培养B16细胞,在柯里拉京作用不同时间后,用MTT(四甲基偶氮唑蓝)法检测柯里拉京对B16细胞生长的影响;用多巴氧化法检测柯里拉京对B16细胞中酪氨酸酶活性的抑制作用;用形态学和Hoechst33258染色法观察柯里拉京对B16细胞生长形态的影响。结果表明,柯里拉京对B16细胞增殖的抑制作用明显,其作用12,24和48 h的IC_(50)分别是35.63,25.78和20.94 mg/L;对作用于B16细胞中酪氨酸酶12,24和48 h时的IC_(50)分别是16.38,14.00和13.85 mg/L;形态学观察表明,当ρ(柯里拉京)16 mg/L作用24 h时,B16细胞损伤明显;Hoechst33258染色显示,当ρ(柯里拉京)≤16 mg/L作用24 h时,B16细胞呈现凋亡形态。     

Prevention of melanin formation by yeast cerebroside in B16 mouse melanoma cells

The effects of plant and yeast cerebrosides on melanin formation were examined in B16 mouse melanoma cells. Addition of yeast cerebroside significantly reduced melanin content to the same level as that of arbutin in control cells, although there was no suppression by plant cerebrosides and bovine brain cerebroside up-regulated melanin formation. None of the bovine brain cerebrosides examined had any effect on tyrosinase activity, but yeast cerebroside reduced the contents of tyrosinase. The results of the present study clearly showed that melanin formation is regulated by several different cerebrosides via tyrosinase. In addition, the findings presented here suggest that cerebrosides containing a 9-methyl type sphingoid base, such as yeast cerebroside, may be useful as skincare products for suppressing melanin formation.     

Effect of surface properties of silica nanoparticles on their cytotoxicity and cellular distribution in murine macrophages

In this study, complexes composed of poly-l-tyrosine (pLT) and single-walled carbon nanotubes (SWCNTs) were produced and the dispersibility of the pLT/SWCNT complexes in water by measuring the ζ potential of the complexes and the turbidity of the solution were investigated. It is found that the absolute value of the ζ potential of the pLT/SWCNT complexes is as high as that of SWCNTs modified with double-stranded DNA (dsDNA) and that the complexes remain stably dispersed in the water at least for two weeks. Thermogravimetry analysis (TGA) and visualization of the surface structures of pLT/SWCNT complexes using an atomic force microscope (AFM) were also carried out.     

Effect of surface properties of silica nanoparticles on their cytotoxicity and cellular distribution in murine macrophages

Surface properties are often hypothesized to be important factors in the development of safer forms of nanomaterials (NMs). However, the results obtained from studying the cellular responses to NMs are often contradictory. Hence, the aim of this study was to investigate the relationship between the surface properties of silica nanoparticles and their cytotoxicity against a murine macrophage cell line (RAW264.7). The surface of the silica nanoparticles was either unmodified (nSP70) or modified with amine (nSP70-N) or carboxyl groups (nSP70-C). First, the properties of the silica nanoparticles were characterized. RAW264.7 cells were then exposed to nSP70, nSP70-N, or nSP70-C, and any cytotoxic effects were monitored by analyzing DNA synthesis. The results of this study show that nSP70-N and nSP70-C have a smaller effect on DNA synthesis activity by comparison to unmodified nSP70. Analysis of the intracellular localization of the silica nanoparticles revealed that nSP70 had penetrated into the nucleus, whereas nSP70-N and nSP70-C showed no nuclear localization. These results suggest that intracellular localization is a critical factor underlying the cytotoxicity of these silica nanoparticles. Thus, the surface properties of silica nanoparticles play an important role in determining their safety. Our results suggest that optimization of the surface characteristics of silica nanoparticles will contribute to the development of safer forms of NMs.     

Effect of dihydroxydiphenyl ether on poly(ether ether ketone)

A series of modified poly(ether ether ketone) (PEEK) polymers were synthesized by introduction of addition ether groups from dihydroxydiphenyl ether (DHDE) into the PEEK structure. The inherent viscosity of the DHDE-modified PEEK increased with reaction time at 320 °C. DSC thermograms showed the melting points of the obtained PEEK decreased with the increase of the DHDE content in the backbone. The degradation temperature (T_d) was slightly decreased by the introduction of DHDE. The crystallinity as measured via the X-ray diffraction (XRD) increases with the introduction of DHDE into the modified PEEK. The crystalline structure was identified as an orthorhombic structure with lattice constants a = 7.72 Å, b = 5.86 Å, and c = 10.24 Å. Due to the glass transition temperature (T_g) and the melting temperature (T_m) decreasing with the increase of the DHDE content in the reaction system. the processability of the resultant PEEK could be improved through this DHDE modification.     

The ether lipid inositol-C2-PAF is a potent inhibitor of cell proliferation in HaCaT cells

The search for specific anticancer drugs that do not interfere with DNA synthesis or influence the cytoskeleton has led to the development of modified phospholipids with antiproliferative properties. These compounds cause remodeling of the structure and function of plasma membranes. Recently, we described novel compounds, the glycosidated phospholipids, that surprisingly inhibit cell proliferation. These compounds contain alpha-D-glucose in the sn-2 position of the glycerol backbone of phosphatidylcholine (PC) and platelet-activating factor (PAF), which gives rise to 2-glucophosphatidylcholine (Glc-PC) and 1-O-octadecyl-2-O-alpha-d-glucopyranosyl-sn-2-glycero-3-phosphatidylcholine (Glc-PAF), respectively. Glc-PC and Glc-PAF inhibit the growth of HaCaT cells at nontoxic concentrations. Here we report the introduction of myo-inositol, in place of alpha-D-glucose, in the sn-2 position of the glycerol backbone; this leads to two diastereomeric 1-O-octadecyl-2-O-(2-(myo-inositolyl)-ethyl)-sn-glycero-3-(R/S)-phosphatidylcholines (Ino-C2-PAF). The inositol-containing PAF enhances the antiproliferative capacity (IC(50)=1.8 microM) and reduces the cytotoxicity relative to Glc-PAF (LC(50)=15 microM). Through biological assays, we showed that, in HaCaT cells, Ino-C2-PAF causes upregulation of the keratinocyte-specific differentiation marker involucrin, increases the activity of the differentiation marker transglutaminase, and induces apoptosis at nontoxic concentrations. Ino-C2-PAF therefore seems to be a promising candidate for development as an antiproliferative drug for the treatment of hyperproliferative diseases of the skin.     

一种含有拟冠醚结构双子型肽脂质的合成改进

针对以2,5,8,11-四氧十二烷二酰基(TEO)连接的含有组氨酸残基的双子型肽脂质化合物N2,N2-2,5,8,11-四氧十二烷二酰-双(N,N-双十六烷基-L-组氨酰胺)合成收率低的问题进行了改进.首先去掉双十六烷基-L-组氨酰胺上伯胺基和咪唑基团上叔丁氧羰基(Boc)或对甲苯磺酰基(Tos)的保护,然后与TEO再进行反应,反应后的产物分离纯化容易,收率可达58%.     

The effect of culture medium composition on ether lipid cytotoxic activity

The effect of a serum-free medium (TNB-100), compared to RPMI 1640 containing 10% fetal bovine serum (FBS), on the lipid composition of HL60 and K562 leukemic cells was investigated. The 10% FBS RPMI medium contained approximately three times more phospholipids (PL), about three times more protein and eight times more cholesterol (CHOL) than did the TNB-100 medium. Cells cultured in TNB-100 medium, referred to as HL60-TNB and K562-TNB cells, were significantly lower in PL and CHOL than 10% FBS RPMI cells, with about a threefold higher PL-to-CHOL ratio; however, these cells were significantly higher in protein content. Cells grown in TNB-100 were also significantly more fluid than 10% FBS RPMI cells and were more sensitive to the fluidizing action of the ether lipid 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine. The 50% inhibitory dose of the drug was about 50% lower in TNB-grown cells than in 10% FBS RPMI cells.     

Melanogenesis inhibitory activity of two generic drugs: cinnarizine and trazodone in mouse B16 melanoma cells

More than 200 generic drugs were screened to identify the inhibitory activity on melanogenesis in mouse B16 melanoma cells. Cinnarizine and trazodone were identified as melanogenesis inhibitors. The inhibitory effects of the two drugs on cell survival, melanogenesis, and tyrosinase activity were investigated. The results showed that both cinnarizine and trazodone inhibited melanogenesis in B16 cells by a dose-dependent manner at the non-cytotoxic concentrations. Based on the results of the present study, seeking new melanogenesis inhibitors from generic drugs is an alternative approach to developing new depigmenting agents in cosmeceuticals. Moreover, cinnarizine and trazodone were proven to be good candidates as skin-whitening agents for treatment of skin hyperpigmentation.     

Inhibition of melanogenesis by Erigeron canadensis via down-regulating melanogenic enzymes in B16F10 melanoma cells

The effects of Erigeron canadensis extract on melanogenesis and cell toxicity in cultured B16F10 mouse melanoma cells were investigated. E. canadensis extract down regulated melanin synthesis effectively at a non-toxic concentration. Its extract was fractionated by using a recycling HPLC with GS310 column (21.5×500 mm, 10–15 μM) into five fractions. The fraction 1 showed melanin inhibition by 48.0% at 100 mg/ml which was 2.5 times more efficient than the depigmenting effect of commercial arbutin (17.5%) and also did not show cell toxicity. To elucidate the depigmenting mechanism of fraction 1, in vitro and cellular tyrosinase activity, antioxidant activity, and protein level of the main melanogenic enzymes, such as tyrosinase, TRP-1 and TRP-2 were evaluated. Fraction 1 inhibited melanin synthesis in B16F10 melanoma cells by decreasing protein levels of melanogenic enzymes, especially tyrosinase. In conclusion, we suggest that this fraction may be a safe and effective depigmentation agent.     

Effect of flow characteristics on the diffusion-limited current density in an electrodeposition cell

The main parameters characterizing the effect of the turbulent flow of an electrolyte between two planar electrodes, one of which may be in motion, are demonstrated by means of numerical and experimental studies. The analysis is carried out for the case of zinc electrodeposition. A model is proposed, which takes into account the production of hydrogen, to represent the variation of the diffusion limited current density as a function of the flow characteristics and of the solution composition.     

Effect of annealing on the properties of poly(ether ether ketone)

The effect of annealing on the properties of poly(ether ether ketone) has been studied by changing annealing temperature and time. Crystallinity increases with annealing temperature, but is little affected by annealing time. Annealing time results suggest an improved crystalline perfection as annealing time increases. Higher crystallinity levels cause an increase in stress-related properties and a decrease in strain-related properties. Crystalline perfection, however, seems to produce an increase in stress-related properties, but it does not affect strain-related properties. Consideration has also been given to the effect of other possible parameters different from crystalline structure, such as crosslinking, on the variation of properties.     

Effect of different cell disruption methods on lipid yield of Schizochytrium sp.

In this study, it was investigated to increase the lipid yield of the microalgae Schizochytrium sp., by applying different cell disruption methods; acid treatment with HCl, osmotic shock, enzyme applications and ultrasonic homogenizer were combined with the Bligh and Dyer or Soxhlet methods. In the Soxhlet method, the lipid and fatty acid yields decreased due to the inability of the method to break down the lipid cells sufficiently and the high temperature application. Enzyme application (hemicellulase treatment at 55°C for 2 days) prior to Bligh and Dyer method (BDE) was found more efficient in terms of lipid and DHA yield compared to other methods. BDE process increased the lipid yield to 21.72 ± 0.74% and DHA content to 19.25 ± 0.09% from lipid yield of 18.87 ± 0.4% and DHA content of 18.41 ± 0.20% by the Bligh and Dyer control (BDC). Major saturated fatty acids were 14:0, 16:0, 18:0, 24:0 and the highest saturated fatty acid was 16:0 (palmitic acid). Lipid health indices such as n-6/n-3, PUFA/SFA, atherogenicity index, thrombogenicity index and hypocholesterolemic/hypercholesterolemic ratios were almost favorable. With this study, appropriate lipid extraction methods were studied to provide an economical and environmental friendly suggestion for future studies to be used in areas such as food, feed and cosmetics grade. It was concluded that the most convenient method among the cell disruption methods was BDE owing to lipid and fatty acid yield.     

聚苯酯对聚醚醚酮结晶行为的影响

用模压法制备了聚苯酯(Ekonol)／聚醚醚酮(PEEK)复合材料，通过X射线衍射(XRD)、差示扫描量热分析(DSC)考察了PEEK的结晶行为，并测定了复合材料的熔点、结晶温度和玻璃化转变温度。结果表明：Ekonol含量的大小对PEEK的结晶行为产生了直接影响，PEEK的相对结晶度随着Ekonol含量的增加而提高；Ekonol含量小于30％时，对复合材料的熔点、结晶温度和玻璃化转变温度影响不大，但含量大于30％时，材料的结晶温度、熔融温度下降，玻璃化转变温度提高。     

Effect of lipid derivatives on invasion in vitro and on surface glycoproteins of three rodent cell types

The antiinvasive activity on MO₄ mouse cells of the following lipid derivatives was tested in vitro: an alkyllysophospholipid derivative (BM 41.440), an alkyl-linked lipoidal amine (CP-46,665) and a naturally occurring ester-linked phospholipid (2-LPC). In this test, BM 41.440 had the same antiinvasive potency as ET-18-OCH₃, whereas CP-46,665 and 2-LPC had no effect on invasion. Comparison of the antiinvasive effect of ET-18-OCH₃ on three types of cells showed the following ranking: 12R1C-RK rat kidney adenovirus type 12 transfected cells>MO₄ mouse cells>LLC-H61 Lewis lung carcinoma cells. This ranking was not reflected in ET-18-OCH₃-induced changes of cell surface exposed glycopeptides derived from the three types of cells metabolically labeled with radioactive fucose. The present and previous experiments suggested that changes in invasion caused by lipid derivatives depended upon relative cell surface fucosylglycopeptide alterations in both the invasive cells and the normal tissue.     

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.     

Characterization of an HL-60 cell variant resistant to the antineoplastic ether lipid 1-O-octadecyl-2-o-methyl-rac-glycero-3-phosphocholine

A resistant cell line (HL-60R) was selected by incubating HL-60 cells with increasing concentrations of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH₃) and used to examine the mechanism of resistance to the antineoplastic ether-linked lipid. The HL-60R cells exhibited a>10-fold increase in resistance when measured by [³H]-thymidine incorporation in comparison to the HL-60 cell line. ET-18-OCH₃ binding occurred at 4°C and was not saturable at the concentrations tested (1–100 μM), indicating that the binding was receptor-independent. At 4°C, association of ET-18-OCH₃ was low for each cell line. At 37°C, uptake in the HL-60 cells was approximately 5-fold greater in comparison to HL-60R cells at each concentration tested. However, when the cellular content of ET-18-OCH₃ was equal, both cell lines experienced similar declines in cell growth. Cellular incorporation of ether lipid was determined using serum-free media and in the presence of serum albumin or lipoproteins. Reduced uptake by the resistant cell line was observed only in the presence of albumin. A greater proportion of ether lipid could be removed from prelabeled HL-60R cells than from HL-60 cells, by an albumin wash procedure, indicating an increased rate of internalization and retention by the sensitive cell line. ET-18-OCH₃ uptake in the HL-60 cell line was also more sensitive to treatment with endocytic (chloroquine, monensin) or metabolic (NaF, KCN) inhibitors. These results suggest that uptake is the principal determinant influencing sensitivity of the resistant cell line and consists of receptor-independent binding followed by internalization. Differential uptake requires the presence of serum albumin and is dependent on the energy-dependent endocytosis of the ether lipid.     

Effect of the temperature on the drawing behavior of poly(ether ether ketone)

This study examines the drawing behavior of amorphous films of poly(ether ether ketone) (PEEK) and the effect of the drawing and the drawing temperature on some physical properties of the drawn samples. The thermal analysis shows that the amorphous films drawn at 200% of deformation and at temperatures of 80, 120, and 140°C crystallize by heating and the crystallization occurs at lower temperature with a lower crystallization enthalpy. The first effect can be related to the influence of orientation on the crystallization rate and the second to strain-induced crystallization. The dynamic—mechanical behavior of the drawn samples is in good agreement with the thermal analysis and confirms the presence of strain-induced crystallization at drawing temperatures well below 180°C. © 1992 John Wiley & Sons, Inc.     

Effect of phosphatidylcholine structure on the adenylate cyclase activity of a murine fibroblast cell line

To determine which structural characteristics of membrane phospholipids influence adenylate cyclase activity, we measured basal and sodium fluoride- or forskolin-stimulated activity in a murine fibroblast cell line,i.e., Balb/c3T3 cells grown in media supplemented with fetal calf serum (FCS), lipid-depleted FCS (LD-FCS) or LD-FCS complexed with different phosphatidylcholine (PC) molecular species. Cells grown in the presence of LD-FCS showed a substantial decrease in their basal and NaF-stimulated adenylate cyclase activities; however, their forskolin-stimulated activity was not altered, suggesting that the enzyme's catalytic site is not affected by changes in membrane lipids. Media supplemented with different LD-FCS/PC complexes were shown to prevent the LD-FCS-mediated reduction of basal and NaF-stimulated adenylate cyclase activity to different extents. Addition ofcis-9-16∶1/cis-9-16∶1,cis-9-18∶1/cis-9-18∶1 orcis-9-18∶1/cis-9,12-18∶2sn-glycerophosphocholine (GPC) completely restored adenylate cyclase activity, whilecis-11-18∶1/cis-11-18∶1 GPC was not effective and only a partial recovery was observed with 16∶0/16∶0, 16∶0/cis-9-18∶1 andtrans-9-18∶1 GPC. Considering the structural features of these seven PC molecular species, the findings suggest that an optimal lipid environment is conferred to the enzyme by the presence of thecis double bonds, each located in Δ9 position of the PC acyl chains. The limited effect ofcis-9-16∶1/cis-9-18∶1 GPC andcis-9-18∶1/cis-9-16∶1 GPC suggests that an equal length of the terminal hydrocarbon chains extending bevond the Δ9 double bonds is also important. Moreover, complete restoration of adenylate cyclase activity in cells exposed to 16∶0/cis-9,12-18∶2 GPC suggests that twocis-9,12 double bonds located on the same chain are as effective as twocis-9 double bonds each located on two different chains of PC. As the four double bonds of 16∶0/cis-5,8,11,14-20∶4 GPC had no effect, a mere increase in the number of double bonds seems insufficient to build an optimal lipid microenvironment for the enzyme.