Effect of curcumin and capsaicin on arachidonic acid metabolism and lysosomal enzyme secretion by rat peritoneal macrophages

The inflammatory mediators secreted by macrophages play an important role in autoimmune diseases. Spice components, such as curcumin from turmeric and capsaicin from red pepper, are shown to exhibit antiinflammatory properties. The influence of these spice components on arachidonic acid metabolism and secretion of lysosomal enzymes by macrophages was investigated. Rat peritoneal macrophages preincubated with 10 μM curcumin or capsaicin for 1 h inhibited the incorporation of arachidonic acid into membrane lipids by 82 and 76%: prostaglandin E₂ by 45 and 48%; leukotriene B₄ by 61 and 46%, and leukotriene C₄ by 34 and 48%, respectively, but did not affect the release of arachidonic acid from macrophages stimulated by phorbol myristate acetate. However, the secretion of 6-keto PG F_1α was enhanced by 40 and 29% from macrophages preincubated with 10 μM curcumin or capsaicin, respectively, as compared to those produced by control cells. Curcumin and capsaicin also inhibited the secretion of collagenase, elastase, and hyaluronidase to the maximum extent of 57, 61, 66%, and 46, 69, 67%, respectively. These results demonstrated that curcumin and capsaicin can control the release of inflammatory mediators such as eicosanoids and hydrolytic enzymes secreted by macrophages and thereby may exhibit antiinflammatory properties.     

显色底物磷脂酰肌醇的酶法制备及应用效果研究

磷脂酰肌醇(phosphatidylinositol,PI)可以作为特异性底物对单核细胞增生性李斯特菌(Listeria monocytogenes,LM)进行快速检测。传统的PI分离方法效率不高,难以得到单一磷脂。而利用磷脂酶D(phospholipase D)的磷脂转移特性,水解大豆磷脂中除PI以外的成分,可以得到高纯度PI。通过单因素和正交试验设计,优化phospholipase D水解大豆磷脂的条件。实验结果表明,在100 mg大豆粉末磷脂中加入phospholipase D(≥50,000 units/mL)2.0μL,在37℃下反应4 h得到纯度达到86.67%的PI。进一步将制备产物用于显色培养基,经细菌试验显示了对LM具有特异的显色效果,可以作为昂贵的进口底物的替代品应用。     

Effects of phorbol esters,A23187 and vasopressin on oleate metabolism in isolated rat hepatocytes

Studies were conducted to compare the metabolic effects of vasopressin, 4β-phorbol-12-myristate-13-acetate (PMA) and A23187 on ketogenesis and oleate metabolism in isolated hepatocytes from fed rats. Vasopressin inhibited the formation of acid-soluble products from [1-¹⁴C]oleate (0.25 mM, 0.5 mM and 1 mM), the inhibition being most marked at low (0.25 mM) concentration of oleate. Conversion of [1-¹⁴C]oleate into¹⁴CO₂ and esterified products was stimulated by vasopressin. The stimulatory effect of this hormone on¹⁴CO₂ production was most marked at high (1 mM) concentration of oleate, whereas that on [1-¹⁴C]-oleate esterification was most marked at low (0.25 mM) concentration of oleate. These vasopressin actions were abolished when hepatocytes were incubated in the absence of calcium in the medium. Our results strongly suggest that both increase in esterification and increase in oxidation to CO₂ contribute to the anti-ketogenic action of vasopressin when oleate is added as substrate, although the relative extent of their contribution varies according to the oleate concentration. The anti-ketogenic action of vasopressin was mimicked by PMA but not by A23187. PMA also caused a stimulation of [1-¹⁴C]oleate esterification although the effect was diminished at 1 mM [1-¹⁴C]oleate. A23187 failed to affect [1-¹⁴C]oleate esterification. The metabolic effects of PMA were elicited in the absence of extracellular calcium, too. Conversion of [1-¹⁴C]oleate into¹⁴CO₂ was only slightly increased by both PMA and A23187 when 1 mM [1-¹⁴C]oleate was added as substrate. The marked stimulatory effect of vasopressin on¹⁴CO₂ production from [1-¹⁴C]oleate was not reproduced even by the combination of PMA and A23187. The possible involvement of protein kinase C and calcium mobilization in the regulation of oleate metabolism is discussed.     

Regulation of lung surfactant cholesterol metabolism by serum lipoproteins

The isolated perfused rat lung was used as an experimental model in the study of the lipoprotein regulation of surfactant cholesterol metabolism. Addition of low density lipoproteins (LDL) to the perfusion medium at a cholesterol concentration of 0.5 mM had no inhibitory effect on [1-¹⁴C]-acetate incorporation into cholesterol of either the surfactant or residual fractions. Increasing the concentration of cholesterol in the medium to 2.5 mM resulted in significant inhibition of incorporation into cholesterol of both fractions. A similar inhibition resulted when lungs were perfused with 2.5 mM cholesterol in the form of high density lipoproteins (HDL). No inhibition of fatty acid synthesis, measured as incorporation into cholesteryl esters, was observed. The rate of uptake by perfused lung of cholesterol from both high and low density lipoproteins was similar. Competitive binding studies with¹²⁵I-labeled lipoproteins indicated the existence of lung receptors for both classes of lipoprotein. The rate of uptake of the apoprotein moiety of low density lipoproteins was significantly greater than that of high density lipoproteins. These data suggest that lung cholesterol metabolism may be subject to regulation by both low and high density serum lipoproteins.     

Metabolism of ceramide phosphorylethanolamine,phosphatidylinositol, phosphatidylserine and phosphatidylglycerol by housefly larvae

Microsome preparations (40,000–90,000 g sediment) fromMusca domestica, housefly, larvae convert exogenous³²P-labeled phosphatidylinositol, phosphatidylserine and phosphatidylglycerol to the respective lysoglycerophosphatides and, ultimately, to the glycerophosphoryl derivatives. These data, combined with previous results, demonstrate that housefly larvae can convert their normal diacylglycerophosphatides to the respective glycerophosphoryl derivatives. Experiments utilizing exogenous³H-labeled,³²P-labeled and¹⁴C-labeled ceramide phosphorylethanolamine demonstrate that particulate preparations from housefly larvae convert ceramide phosphorylethanolamine to ceramide, phosphorylethanolamine, sphingosine and fatty acid. The presence of ceramide phosphorylethanolamine phosphohydrolase and ceramidase activity in housefly larvae is consistent with the conclusion that ceramide phosphorylethanolamine is metabolized to ceramide and phosphorylethanolamine and the ceramide is then hydrolyzed to sphingosine and fatty acid. Thus, metabolism of ceramide phosphorylethanolamine by these insects is analogous to the metabolism of sphingomyelin by mammalian systems. Paper No. 5250 from the Michigan Experiment Station.     

Regulation of hepatic carbohydrate metabolism by FFA and acetyl-CoA: Sequential feedback inhibition

In recent years experiments in slices, perfused liver and in the whole animal demonstrated that liver carbohydrate metabolism can be controlled by free fatty acids (FFA). Our investigations suggest that FFA and acetyl-CoA might provide regulation of the rate and direction of opposing pathways of hepatic glycolysis and gluconeogenesis by controlling the activity of key enzyme systems. Long and short chain FFA were observed to selectively inhibit the key enzymes of glucose catabolism, glucokinase, hexokinase, phosphofructokinase and pyruvate kinase. The long chain FFA were inhibitors two magnitudes stronger than octanoate. The FFA were also able to inhibit lactate production in a fortified supernatant fluid system. Acetyl-CoA inhibited hepatic glucokinase and pyruvate kinase but did not affect liver hexokinase, phosphofructokinase, lactate dehydrogenase, glucose-6-phosphatase or fructose-1, 6-diphosphatase. The inhibition of glucokinase and pyruvate kinase was dependent on the dose and preincubation time with acetyl-CoA. The acetyl-CoA is the end product of the degradation of FFA which in turn is an end product of glucose catabolism; therefore, the inhibition of the three key glycolytic enzymes by FFA and the subsequent reinforcement of the inhibition of glucokinase and pyruvate kinase may be called sequential feedback inhibition. The regulatory role of phosphoenol-pyruvate, NADH, ATP, alanine and oxaloacetate in the control of hepatic carbohydrate metabolism is discussed.     

Differential alterations of ethanolamine and choline phosphoglyceride metabolism by clofibrate and retinoic acid in human fibroblasts are not mediated by phorbol ester-sensitive protein kinase C

Peroxisomal proliferators and retinoids have been reported to interact to regulate lipid metabolism, particularly β-oxidation of fatty acids. Based on postulated interactions of these agents at the levels of receptors and response elements, we examined whether interactions exist between the peroxisomal proliferator, clofibrate (CLF), and retinoic acid (RA) in modulation of phospholipid turnover in cultured human skin fibroblasts. Treatment of cultured cells with either 25 μM CLF or 1 μM RA alone decreased [¹⁴C]ethanolamine incorporation into ethanolamine phosphoglycerides (EPG) by 20–30%, and simultaneous exposure to both agents resulted in additive inhibition. By contrast, [³H]choline incorporation into phospholipid was stimulated 5–30% by incubation with either agent; when CLF and RA were administered together, the stimulatory effects were additive. Different types of pulse-chase studies examining effects on uptake, biosynthesis, and degradation of labelled phospholipids indicated stimulation of EPG degradation and inhibition of phosphatidylcholine degradation by CLF; no effect on catabolism of either phospholipid was observed with RA. Combinations of modifiers of protein kinase activity [4β-12-O-tetradecanoylphorbol-13-acetate (β-TPA), 1-(5-isoquino-linesulfonyl)-2-methylpiperazine dihydrochloride,N-(2′-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride,bis-indolylmaleimide, staurosporine] indicated that β-TPA-responsive protein kinases were not involved. Accordingly, CLF and RA regulate biosynthesis and degradation of ethanolamine and choline phosphoglycerides in cultured skin fibroblasts by different mechanisms that do not involve classical protein kinase C (PKC) isoforms, even though turnover of phospholipids generating lipid activators of PKC occurs.     

The capture of carbon dioxide by transition metal aluminates,calcium aluminate,calcium zirconate,calcium silicate and lithium zirconate

The capture of CO₂ by transition metal (Mn, Ni, Co and Zn) aluminates, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate was carried out at pre- and post-combustion temperatures. The prepared metal adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface area analysis and acidity/alkalinity measurements. The different experimental variables affecting the adsorbents ability to capture CO₂, such as the mol ratio of metal ions, the pressure of CO₂, the exposure time and the temperature of the adsorbent were also investigated. Calcium zirconate captured 13.85 wt-% CO₂ at 650°C and 2.5 atm and calcium silicate captured 14.31 wt-% at 650°C. Molecular sieves (13X) and carbon can only capture a negligible amount of CO₂ at high temperatures (300°C–650°C). However, the mixed metal oxides captured reasonable amount of CO₂ at these higher temperatures. In addition, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate adsorbents captured CO₂ at both pre and post-combustion temperatures. The trend for the amount of captured carbon dioxide over the adsorbents was calcium aluminate相似文献   

Regulation of HepG2 cell apolipoprotein B metabolism by the citrus flavanones hesperetin and naringenin

Our previous studies showed that replacing the drinking water of rabbits fed a casein-containing diet with either orange juice or grapefruit juice reduced serum low density lipoprotein cholesterol and hepatic cholesteryl ester concentrations. To determine whether the changes observed in rabbits were due to flavonoids present in the juices acting directly on the liver’ the effects of hesperetin and naringenin on net apolipoprotein B (apoB) secretion by HepG2 cells were investigated. These flavanones dose-dependently reduced net apoB secretion by up to 81% after a 24 h incubation’ while doses of 60 μg/mL reduced net apoB secretion by 50% after 4 h. Coincubation with the proteasome inhibitor’ MG-132’ did not alter the ability of the flavonoids to reduce net apoB secretion over 4 h’ suggesting that the flavonoid-induced changes in apoB metabolism were not due to a direct increase in proteasomal activity. However’ the flavonoids were unable to reduce net apoB secretion after 4 h in the presence of oleate’ suggesting that these compounds may interfere with the availability of neutral lipids for lipoprotein assembly. Furthermore’ our ¹⁴C-acetatelabeling studies showed a 50% reduction in cholesteryl ester synthesis in the presence of either flavonoid’ which could account for the reduction in net apoB secretion caused by incubation with these compounds. These in vitro studies suggest that hesperetin and naringenin may’ in part’ reduce net apoB secretion by HepG2 cells by inhibiting cholesteryl ester synthesis and that these compounds are good candidates for further in vivo studies to determine whether they are responsible for the cholesterol-lowering properties of dietary citrus juices.     

Effect of phagocytosis and lonophores on release and metabolism of arachidonic acid from human neutrophils

Challenge of human neutrophils prelabeled with [³H]arachidonate and [¹⁴C] palmitate or [¹⁴C]-stearate with opsonized zymosan or the Ca²⁺ ionophores A23187 or Ionomycin caused the release of [³H], but not [¹⁴C], fatty acid. With the ionophores, but not zymosan, considerable conversion of the [³H] arachidonate to hydroxyeicosatetraenoates occurred. Although various isomers were recovered, the 5-hydroxyeicosatetraenoate appeared to be the major product. In these experiments, no [¹⁴C] products were detected such as lysophospholipid, diglyceride or monoglyceride. Although no definitive statement can be made about the mechanism of release of arachidonate, our data are most easily interpreted as the result of the action of a phospholipase A₂.     

酶/MOFs复合材料催化性能调控及应用

金属有机框架（MOFs）具有比表面积大、设计性强和生物相容性好等优良特性，可以作为固定化酶的理想载体，从而提高游离酶的稳定性和催化性能，许多酶/MOFs复合材料也显示出比游离酶更好的催化性能。因此，酶/MOFs复合材料已应用于生物传感、检测、催化等领域，已成为传统催化剂的环保替代品。综述了酶在MOFs上的3种固定化方法（表面固定、孔封装和原位包埋法），重点介绍了4种影响酶/MOFs复合材料催化性能的因素及调控方法，对酶/MOFs复合材料在催化方面的应用也进行了总结，并对酶固定化的未来进行了展望。     

Regulation of adiponectin secretion and expression by insulin and β‐agonists in rat

The adipocytokines, including adiponectin, are important factors in the regulation of insulin sensitivity and carbohydrate and lipid metabolism. It is proved that concentrations of adiponectin are decreased in obesity, an insulin resistant state. The current study is to address potential mechanisms regulating adiponectin secretion and expression in vivo. To observe the regulation of adiponectin by fasting‐refeeding and β‐agonists, male Wistar rats were fasted for 18 h and allowed to refeed with/without a β3‐adrenergic receptor agonist infused into refeeding rats. We also investigated the effects of insulin clamp on adiponectin secretion and expression, including euglycemic–hyperinsulinemic clamp and hyperglycemic–hyperinsulinemic clamp. Plasma adiponectin levels were determined by radioimmunoassay. Using real‐time PCR assays, we analyzed the expression of adiponectin genes in rat primary adipocytes. Refeeding of 18‐h fasted rats increased plasma adiponectin concentration (～2‐fold) and adipose tissue adiponectin expression (～3‐fold), and these effects were mimicked by hyperinsulinemia in the absence of refeeding and completely blocked by administration of β‐agonists during refeeding. We conclude that (i) adiponectin secretion and expression are acutely regulated in vivo by nutritional status; (ii) in vivo, insulin and β‐agonists act directly at the adipocyte to regulate adiponectin secretion and expression.     

Modulation of phorbol ester-associated events in epidermal cells by linoleate and arachidonate

To elucidate the events elicited by the skin tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA), which are modulated by linoleic acid (LA) and arachidonic acid (AA), the activity of these fatty acids in cultured mouse epidermal cells was compared. Approximately 94% of either exogenous radiolabelled fatty acid was incorporated into the total phospholipid pool over 15 h. The relative distribution among the phospholipid classes differed, however, such that approximately 70% of phospholipid-associated [¹⁴C]-LA was found in phosphatidylcholine, compared to approximately 30% for [¹⁴C]AA. Phosphatidylethanolamine and phosphatidylinositol/phosphatidylserine contained 17 and 13% of the phospholipid [¹⁴C]LA, and 34 and 30% of [¹⁴C]AA, respectively. Prostaglandin (PG) E₂ production was low but similar in unstimulated cultures prelabelled with either [¹⁴C]LA or [¹⁴C]AA. However, in cultures treated with TPA (1.6 μM), [¹⁴C]AA-prelabelling resulted in approximately three times the amount of [¹⁴C]PGE₂ compared with cultures prelabelled with [¹⁴C]LA. Cultured cells were found to contain significant δ6 desaturase activity, which may enable conversion of LA to AA, and thus may account for the observed PGE₂ production from [¹⁴C]LA treated cells. AA-Supplemented (1.6 μM) cultures supported approximately twice the induction of ornithine decarboxylase activity by TPA compared with cultures treated with 1.8 μM LA. Activation of partially purified protein kinase C was similar for either fatty acid tested over a 10–300 μM dose range. Overall, the results suggest that LA does not have the same biological activity as AA with regard to several TPA-associated events known to be important in skin tumor promotion. This reduced biological activity of LA may be partly responsible for the known inhibition of mouse skin tumor promotion by high dietary levels of LA [Leyton, J., Lee, M.L., Locniskar, M.F., Belury, M.A., Slaga, T.J., Bechtel, D., and Fischer, S.M. (1991)Cancer Res. 51, 907–915].     

Novel synthesis,characterization and application of dibutyrate bis(2-hydroxyethyl) terephthalamide as a plasticizer in PVC compounding

This study focuses on the synthesis and application of dibutyrate of bis(2-hydroxyethyl) terephthalamide (DB-BHETA) as a plasticizer in poly(vinyl chloride) (PVC) compounding. DB-BHETA was synthesized from poly(ethylene terephthalate) bottle waste through aminolysis followed by condensation reaction with butyric acid. Synthesized DB-BHETA was characterized by FTIR, DSC and NMR. Plasticized PVC was prepared by melt blending of PVC in different ratios with DB-BHETA and the mechanical, thermal and rheological properties were investigated. The glass transition temperature (T _g) decreased with increasing concentration of DB-BHETA, confirming its plasticizing effect. The impact properties of PVC/DB-BHETA were maximum at weight ratio of 80/20. Shore hardness continuously reduced with increase in the concentration of DB-BHETA in PVC. Also, incorporation of DB-BHETA results in a gradual decrease in the loss modulus (viscous) and an increase in the storage modulus (elastic).     

电感耦合等离子体发射光谱法测定生物柴油中的K、Ca、Na、Mg

采用酸消解法对生物柴油样品进行前处理,使用电感耦合等离子体发射光谱仪测定生物柴油中K、Ca、Na、Mg的含量。实验结果表明该方法在0．05~2．0mg·L-1的浓度范围内呈现了良好的线性关系,相关系数均大于0．999,相对标准偏差4．54％-5．72％,加标回收率86．5％～109．0％。最终建立起了一种快速高效,能够同时分析生物柴油中K、ca、Na、Mg含量的方法。     

Studies of phospholipid metabolism, proliferation, and secretion of stably transfected insulinoma cells that overexpress group VIA phospholipase A2

A cytosolic 84 kDa Group VIA phospholipase A₂ (iPLA₂β) that does not require Ca²⁺ for catalysis was cloned from Chinese hamster ovary (CHO) cells, murine P388D1 cells, pancreatic islet β-cells, and other sources. Proposed iPLA₂β functions include participation in phosphatidylcholine (PC) homeostasis by degrading excess PC generated in CHO cells that overexpress CTP:phosphocholine cytidylyltransferase (CT), which catalyzes the rate-limiting step in PC biosynthesis; participation in biosynthesis of arachidonate-containing PC species in P388D1 cells by generating lysophosphatidylcholine (IPC) acceptors for arachidonate incorporation; and participation in signaling events in insulin secretion from islet β-cells. To further examine iPLA₂β functions in β-cells, we prepared stably transfected INS-1 insulinoma cell lines that overexpress iPLA₂β activity eightfold compared to parental INS-1 cells or to INS-1 cells transfected with an empty retroviral vector that did not contain iPIA₂β cDNA. The iPLA₂β-overexpressing cells exhibit a twofold increase in CT activity compared to parental cells but little change in rates of [³H] choline incorporation into or disappearance from PC. Electrospray ionization (ESI) tandem mass spectrometric measurements indicate that iPLA₂β-overexpressing cells have 1.5-fold higher LPC levels than parental INS-1 cells but do not exhibit increased rates of [³H]arachidonate incorporation into phospholipids, and incorporation is unaffected by a bromoenol lactone (BEL) suicide substrate inhibitor of iPLA₂β. The rate of appearance of arachidonate-containing phosphatidylethanolamine species visualized by ESI mass spectrometry is also similar in iPLA₂β-overexpressing and parental INS-1 cells incubated with supplemental arachidonic acid, and this process is unaffected by BEL. Compared to parental INS-1 cells, iPLA₂β-overexpressing cells proliferate more rapidly and exhibit amplified insulin secretory responses to a protein kinase C-activating phorbol ester, glucose, and a cAMP analog. These findings suggest that iPLA₂β plays a signaling role in β-cells that differs from housekeeping functions in PC biosynthesis and degradation in P388D1 and CHO cells.     

电位滴定法测定钙奶中钙含量

提出了以钙离子选择性电极为指示电极，甘汞电极为参比电极，EGTA标准溶液为滴定剂的电位滴定法测定钙奶中钙含量，滴定终点由电位突跃来判断，此法简便，灵敏，准确，相对标准偏差为0.16%。加标回收率为99.0%-100.%，可用于直接测定混浊或有色液体中钙含量。     

Regulation of very low density lipoprotein apo B metabolism by dietary fat saturation and chain length in the guinea pig

Studies investigated the effects of dietary fatty acid composition and saturation on the regulation of very low density lipoprotein (VLDL) apo B flux, clearance, and conversion to low density lipoprotein (LDL) in guinea pigs fed semipurified diets containing 15% (w/w) corn oil (CO), lard (LA), or palm kernel oil (PK). Plasma cholesterol levels were highest with dietary PK (3.1±1.0 mmol/L) followed by LA (2.4±0.4 mmol/L) and CO (1.6±0.4 mmol/L) intake. VLDL particles were larger (P<0.05) in the LA (78±7 nm) and PK (69±10 nm) groups compared to animals fed CO (49±5 nm). VLDL-apo B fractional catabolic rates (FCR) were highest in guinea pigs fed the LA diet (P<0.05) and VLDL apo B flux, estimated from VLDL ¹²⁵I-apo B turnover kinetics, were higher in LA compared to PK or CO fed guinea pigs. In the case of PK consumption, the kinetic estimates of VLDL apo B flux significantly underestimated rates compared to direct VLDL apo B secretion measurements and LDL turnover analyses. These data demonstrate that differences in the composition and amount of saturated fatty acids have differential effects on VLDL apo B flux, catabolism, and conversion to LDL which, together with changes in LDL receptor-mediated catabolism, determine plasma LDL cholesterol levels in guinea pigs. The data also indicate that kinetic analysis of VLDL metabolism in PK fed animals is inaccurate possibly due to the presence of a small, nonequilibrating pool of newly synthesized VLDL which is rapidly converted to LDL.     

Sphingolipid metabolism II. The biosynthesis of 3-keto-dihydrosphingosine by a partially-purified enzyme from rat brain

A condensation reaction between serine and palmitoyl CoA by a partially-purified enzyme from rat brain is described. The product of the reaction, 3-keto-dihydrosphingosine is characterized by the conversion to several derivatives. The addition of EDTA to the incubation mixture results in inhibition of the conversion of serine to phospholipid, with the result that 3-keto-dihydro-sphingosine is the sole product.     

还原-氧化-石灰法处理氯代硝基苯废水的研究

研究了硫化钠还原、Fenton试剂氧化、石灰脱色综合方法处理氯代硝基苯酸性废水。考察了溶液pH值及硫化钠、双氧水、硫酸亚铁、石灰用量等因素对CODCr去除率的影响。结果表明,用该方法处理氯代硝基苯酸性废水,CODCr去除率可达到94%以上。