Effect of oxidation on chemical spectral and immunochemical properties of egg yolk lipoprotein

Studies are reported on the changes in the chemical, spectral, and immunochemical properties of the low density lipoprotein fraction of hen's egg yolk during oxidation. Sonication for 15 min at 15–20 C in the presence or absence of iron gave an increase in thiobarbituric value and UV absorption but did not influence the fluorescence. Storage at 50 C in the absence of iron after sonication for 15 min at 15–20 C produced increases in absorptivity in the fluorescence and UV spectra, as well as thiobarbituric values. Similar changes were produced without sonication in the presence of iron in ca. 8 days storage at 50 C. Ethylenediaminetetraacetic acid completely inhibited the effect of copper, as well as iron, under these conditions. Immunoelectrophoresis pattern was effected by oxidation under conditions that gave an increase in absorptivity in the fluorescence spectra. The first change appeared to involve a minor fast moving component which decreased even when oxidation was inhibited by ethylenediaminetetraacetic acid. As the oxidation proceeded, the mobility of the major component in the immunoelectrophoresis analysis was altered. The major reaction affecting the immunochemical properties appeared to be between the product of lipid oxidation and the protein moiety.     

Effect of nicotine on lipoprotein metabolism in rats

Nicotine, a major component of cigarette smoke, plays an important role in the development of cardiovascular disease and lung cancer in smokers. The effect of nicotine on lipoprotein metabolism was studied using rats as the experimental animal. There was a significant increase in the total cholesterol, phospholipids, and triglycerides as well as the amount of lipids associated with very low density lipoprotein (VLDL) and low density lipoprotein (LDL) in sera of nicotine-treated rats. The incorporation of ³H labeled leucine into the apo B was found to be increased both in the medium and associated cells in the hepatocytes isolated from nicotine-treated rats indicating an increased synthesis and secretion of the apo B containing lipoproteins. This was further confirmed by the higher incorporation of ¹⁴C acetate into total and individual lipids of LDL and VLDL secreted into the medium as well as that associated with different lipids in the cell layer. The activity of lipoprotein lipase in extrahepatic tissues and plasma lecithin cholesterol acyltransferase activity were significantly lower in nicotine-treated rats. These results indicate that nicotine exerts hyperlipidemic effects particularly by increasing the synthesis and secretion of triglyceride-rich lipoproteins. Since nicotine is one of the major hazardous components present in cigarette smoke and tobacco, one can extrapolate that the deleterious effect exerted by nicotine on rats extends to cigarette smokers and those who use other forms of tobacco.     

Impaired lipoprotein metabolism in obese offspring of streptozotocin-induced diabetic rats

The time course of changes in lipoprotein metabolism of obese offspring of mildly diabetic rats was studied with respect to serum lipoprotein composition as well as LCAT and tissue lipoprotein lipase (LPL) activities. Mild hyperglycemia in pregnant rats was induced by intraperitoneal injection of streptozotocin on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, obese pups had higher serum glucose, insulin, and lipoprotein (VLDL, LDL-HDL₁, HDL_2–3) levels than control pups. After 1 mon of life, all of these parameters in obese rats became similar to those of controls. However, LCAT, adipose tissue LPL, and hepatic triacylglycerol lipase activities were high. At 2 mon of age, VLDL-TAG levels were higher in obese females than in controls. By the age of 3 mon, obese offspring had developed insulin resistance with hyperglycemia, hyperinsulinemia, and higher serum lipoprotein concentrations. Indeed, qualitative abnormalities of lipoproteins were seen and were typical of obese and diabetic human beings. Fetal hyperinsulinemia should be considered as a risk factor for later metabolic diseases, including dyslipoproteinemia.     

乙烯装置复杂控制系统与应用

从介绍基础控制环境入手,着重探讨了以DCS为核心的裂解炉、压缩机复杂控制系统在乙烯装置的应用情况。     

Metabolic behavior in rats of a nonprotein microemulsion resembling low-density lipoprotein

A protein-free microemulsion (LDE) with a lipid composition resembling that of low-density lipoprotein (LDL) was used in metabolic studies in rats to compare LDE with the native lipoprotein. LDE labeled with radioactive lipids was injected into the bloodstream of male Wistar rats, and plasma kinetics of the labeled lipids were followed on plasma samples collected at regular intervals for 12 h after injection. The 24-h LDE uptake by different tissues was also measured in tissue samples excised after the animals had been sacrificed. We found that LDE plasma kinetics were similar to those described for native LDL [fractional clearance rate (FCR) of cholesteryl ester, 0.42±0.11 h⁻¹]. The major site for LDE uptake was the liver, and the tissue distribution of the LDE injected radioactivity was as one would expect for LDL. To test whether LDE was taken up by the specific LDL receptors, the LDE emulsion was injected into rats treated with 17α-ethinylestradiol, which is known to increase the activity of these receptors; as expected, removal of LDE from the bloodstream increased (FCR=0.90±0.35 h⁻¹). On the other hand, saturation of the receptors that remove remnants by prior infusion of massive amounts of lymph chylomicrons did not change LDE plasma kinetics. These results indicate that LDE is cleared from plasma by B,E receptors and not by the E receptors that remove remnants. Incorporation of free cholesterol into LDE increased LDE plasma clearance. Incubation studies also showed that LDE incorporates a variety of apolipoproteins, including apo E, a ligand for recognition of lipoproteins by specific receptors. Our data suggest that LDE can be a useful tool to test LDL metabolism and B,E receptor function.     

Quantitative determination of heparin released lipoprotein lipase activity in human plasma

A method for quantitative determination of heparin released lipoprotein lipase (LPL) activity has been developed. The importance of standardization of substrate and albumin in the assay system has been investigated. Determination of glycerol release in the assay system has been shown to have advantages compared with titration of fatty acids released. Enzyme plasma samples frozen for four months decreased in activity. The method seemed to be specific for emulsified triglycerides and the LPL activity was 98% inhibited by 1 M NaCl. However, there was a lack of reproducibility of the substrate when different lots were used. Analytical error of the method was approximately 5% and there was good reproducibility. Presented in part at the AOCS-AACC Joint Meeting, Washington, D.C., April, 1968.     

Cholesterol-lowering effect of dextro-thyroxine in patients with hypercholesterolemia and coronary diseasel

Sixty-three patients with hypercholesterolemia and coronary disease were treated with d-thyroxine for an average period of 16 months. D-thyroxine decreased serum cholesterol without increasing the metabolic rate significantly when amt ranging from 4–8 mg/day were used. In 56 patients with essential hypercholesterolemia d-thyroxine lowered the serum cholesterol in a little over half of the patients. In five patients with hypothyroidism and hypercholesterolemia treated with thyroid extract, the addition of d-thyroxine resulted in marked and sustained lowering of serum cholesterol without causing hypermetabolism. In two patients with diabetes mellitus and hypercholesterolemia d-thyroxine lowered the serum cholesterol without significantly affecting the diabetic state and the insulin requirement. Increase in angina was seen in 13% of the patients. In man, d-thyroxine lowers the serum cholesterol by increasing the degradation and excretion of cholesterol. Supported by grants from the USPHS (6361) and the American Heart Association.     

Nonalcoholic components in wine reduce low density lipoprotein cholesterol in normocholesterolemic rats

Using an experimental model that enables the effects of alcohol to be distinguished from the effects of the nonalcoholic components present in wine, we determined whether wine has effects other than those of alcohol on the metabolism of cholesterol. Male rats were fed a standard diet and had free access to water and either wine or an equivalent alcohol solution for 45 d or 6 mon. Alcohol intake was similar in the two groups of animals. Consumption of the alcohol solution or wine did not influence plasma cholesterol or high density lipoprotein-cholesterol. At 45 d, the consumption both of wine and of alcohol solution reduced low density lipoprotein (LDL)-cholesterol and very low density lipoprotein cholesterol. At 6 mon, only the rats that consumed wine had reduced LDL-cholesterol. After 45 d of consuming alcohol solution, total cholesterol in the aorta was significantly increased mainly as a result of the rise in free cholesterol. In the aorta, the effect of wine consumption was similar to the effect of alcohol solution consumption, although it was less intense. The only clear effect that could be ascribed to the nonalcoholic components in wine was that the LDL-cholesterol was reduced in the long term, although aortic cholesterol was not.     

Antioxidant activity of thiocholesterol on copper-induced oxidation of low-density lipoprotein

The effect of thiocholesterol (SH-Chol) on the copper-inducedin vitro oxidation of low-density lipoprotein (LDL; 1.019<d<1.063) was investigated. Among the antioxidants tested, including cysteine, glutathione, 2-mercaptoethanol, dithiothreitol, probucol, thiopalmitic acid,. and SH-Chol, SH-Chol was the most effective antioxidant in copper-induced LDL oxidation. Also, SH-Chol completely inhibited the formation oxysterols i.e., 7-hydroxycholesterol and 7-ketocholesterol, in LDL particles and reduced 1,1-diphenyl-2-picrylhydrazyl used as stable free-radical model. Moreover, SH-Chol suppressed the degradation of endogenous α-tocopherol in LDL particles. These findings indicate that SH-Chol acts as antioxidant in the oxidative damage of LDLin vitro and as a free-radical scavenger in lipid peroxidation.     

国内首套IGCC汽电联产装置:中国石化建造

经过3年的不懈努力,中国石化在福建炼油乙烯一体化项目中成功建成国内首套IGCC多联产装置,于2009年7月实现了全流程贯通。通过一丰的运转考验,该装置的可靠性得到了验证,各种能量得到了最大可能的回收,装置的各种消耗明显降低,流程设置的潜能得到了较好发挥。该装置的顺利建成及平稳运行为中国绿色能源产业树立了一个成功的典范,并为国际炼油化工领域提供了一条完整的一体化联合循环装置的解决方案。     

Changes in the activities of lipoprotein lipase and the lipogenic enzymes in tumor-bearing rats

The effects of tumor growth on lipid metabolism were investigated by evaluating serum lipids, lipoprotein lipase activity (LPLA), the lipogenic enzymes, urinary catecholamines along with serum insulin and glucagon levels. We injected 1.5×10⁶ cells of rat mammary tumor, AC33, and killed the rats on the 18th day. Serum triglycerides and free fatty acids of the tumor-bearing (TB) rats increased 4 and 5 times, respectively, more than the control (C) rats. Total liver lipids were not significantly different between the two groups. Tumor growth produced a 70% decrease in total epididymal fat pad LPLA; there were no changes in soleus muscle LPLA. Serum insulin levels of the TB rats were 49% less than the C rats. The TB rats had significantly lighter epididymal fat pads and lower activities of adipose fatty acid synthetase and citrate cleavage enzyme. Urinary catecholamines of the TB rats were reduced over 30% compared with the C rats. These results show that the hypertriglyceridemia of the TB rats may be due, in part, to a deficiency of adipose tissue LPLA. The data also suggest that the effects of the tumor on lipid metabolism may be mediated through insulin.     

Effects of dietary peanut oil on serum lipoprotein patterns of rats

Oils prepared from two varieties of peanuts and from a hybrid corn having linoleic acid concentrations substantially different from the respective commercial oils were compared with commercial oils for their effects on serum lipids of weanling female rats. In the first experiment, serum lipid patterns appeared to reflect linoleic acid content of the dietary oil. However, with a longer feeding period in the second experiment, serum lipid patterns were determined by the plant source of the dietary oil rather than its linoleic acid content; all peanut oils differed from both corn oils in their physiological effects. Diets containing triglyceride, hydrocarbon and sterol fractions obtained by liquid chromatography of peanut and corn oils were fed to female rats. The data provide no evidence that the hydrocarbon or sterol fractions of peanut oil are responsible for its unusual atherogenicity when fed as the sole fat source or that similar fractions from corn oil are protective against the effects of peanut oil.     

电厂锅炉复合有机酸化学清洗探析

根据某电厂运行锅炉的特点和对其管样进行的小型清洗试验结果,确定了本次化学清洗工艺为复合有机酸酸洗,柠檬酸漂洗,双氧水钝化。复合酸质量分数：4％～6％,柠檬酸质量分数：0．2％～0．5％,双氧水质量分数：0．1％--0．2％。化学清洗结束后,汽包、水冷壁管均已清洗干净;根据清洗管样和腐蚀指示片的测定结果,除垢率为98．1％,腐蚀速率为1．01g/（m2·h）,腐蚀总量为16．2g／m2,各项指标均达到了《火力发电厂锅炉化学清洗导则》（DIMT794—2001）中规定的优良标准。金属表面形成完整的、呈均匀深灰色的钝化膜。     

Effects of ethanol intake on lipoprotein lipase activity in adipose tissue of fasting subjects

Ethanol (ca. 1 g/kg body weight) was given alone or together with glucose or lipid (mixed triglycerides) perorally to young, fasting subjects. The changes with time (0–6 hr) of lipoprotein lipase activity (LLA) in adipose tissue, plasma glycerol, triglyceride, insulin, blood glucose, and alcohol concentrations were followed. A maximal mean blood alcohol concentration of 0.09% (w/v) was obtained 1 hr after ingestion with no apparent intoxicating effects. Ethanol intake prevented the previously observed [Nilsson-Ehle, P., S. Carlström and P. Belfrage,Scand. J. Clin. Lab. Invest. 35∶373 (1975)] glucose-induced rapid elevation of adipose tissue LLA but had small effects on this enzymatic activity when given alone or together with lipid. Confirming results by others, ethanol intake decreased plasma glycerol concentration and increased plasma triglycerides, especially after intake of lipid. It is suggested that ethanol intake interferes with the normal carbohydrate-induced elevation of adipose tissue LLA after a mixed meal, thereby decreasing the removal capacity for circulating dietary lipid and causing enhanced and prolonged alimentary hyperlipemia.     

Screening of crude plant extracts with anti-obesity activity

Obesity is a global health problem. It is also known to be a risk factor for the development of metabolic disorders, type 2 diabetes, systemic hypertension, cardiovascular disease, dyslipidemia, and atherosclerosis. In this study, we screened crude extracts from 400 plants to test their anti-obesity activity using porcine pancreatic lipase assay (PPL; triacylglycerol lipase, EC 3.1.1.3) in vitro activity. Among the 400 plants species examined, 44 extracts from plants, showed high anti-lipase activity using 2,4-dinitrophenylbutyrate as a substrate in porcine pancreatic lipase assay. Furthermore, 44 plant extracts were investigated for their inhibition of lipid accumulation in 3T3-L1 cells. Among these 44 extracts examined, crude extracts from 4 natural plant species were active. Salicis Radicis Cortex had the highest fat inhibitory activity, whereas Rubi Fructus, Corni Fructus, and Geranium nepalense exhibited fat inhibitory capacity higher than 30% at 100 μg/mL in 3T3-L1 adipocytes, suggesting anti-obesity activity. These results suggest that four potent plant extracts might be of therapeutic interest with respect to the treatment of obesity.     

Cholesterol-lowering effects of guar gum: Changes in bile acid pools and intestinal reabsorption

Soluble fibers such as guar gum (GG) may exert cholesterol-lowering effects. It is generally accepted that bile acid (BA) reabsorption in portal blood is reduced, thus limiting the capacity of BA to down-regulate liver cholesterol 7α-hydroxylase, the rate-limiting enzyme of BA synthesis. In the present work, rats were adapted to fiber-free (FF) or 5% GG diets (supplemented or not with 0.25% cholesterol), to investigate various aspects of enterohepatic BA cycling. GG in the diet at a level of 5% elicited a significant lowering of plasma cholesterol during the absorptive period, in cholesterol-free (−13%) or 0.25% cholesterol (−20%) diet conditions. In rats adapted to the GG diets, the small intestinal and cecal BA pools and the ileal vein-artery difference for BA were markedly enhanced; reabsorption in the cecal vein was also enhanced in these rats. [¹⁴C]Taurocholate absorption, determined in perfused ileal segments, was not significantly different in rats adapted to the FF or GG diet, suggesting that a greater flux of BA in the ileum might support a greater ileal BA reabsorption in rats adapted to the GG diet. In contrast, capacities for [¹⁴C]cholate absorption from the cecum at pH 6.5 were higher in rats adapted to the GG diet than to the FF diet. Acidification of the bulk medium in isolated cecum (from pH 7.1 down to pH 6.5 or 5.8) or addition of 100 mM volatile fatty acids was also found to stimulate cecal [¹⁴C]cholate absorption. These factors could contribute to accelerated cecal BA absorption in rats fed the GG diet. The effects of GG on steroid fecal excretion thus appear to accompany a greater intestinal BA absorption and portal flux to the liver. These results suggest that some mechanisms invoked to explain cholesterol-lowering effect of fibers should be reconsidered.     

Cholesterol-lowering ability of a phytostanol softgel supplement in adults with mild to moderate hypercholesterolemia

Plant sterols, incorporated into spreads and other food sources, have been shown to lower serum cholesterol concentrations. The effect of phytostanol supplementation in softgel form has not been assessed. Our objective was to examine the effects of sitostanol as sitostanol ester in softgel form on serum lipid concentrations in hypercholesterolemic individuals. Thirty hypercholesterolemic adults were supplemented with 1.6 g of free phytostanol equivalents as phytostanol ester (2.7 g stanol esters) or placebo per day for 28 d in a randomized, double-blind, parallel study design. Phytostanol supplementation resulted in a significant decrease in total cholesterol (TC) (−8%) and LDL-cholesterol (−9%). There were no alterations in concentrations of HDL-cholesterol or TG. Nor were the ratios of LDL/HDL or TC/HDL altered significantly. Thus, use of phytostanol ester softgel supplements improved serum total and LDL-cholesterol concentrations in hypercholesterolemic individuals.     

蛋黄磷脂的提纯

利用蛋白质不溶或微溶于某些溶剂的特点,用混合溶剂萃取粗蛋黄磷脂制备精蛋黄磷脂的工艺,该工艺易于实现工业化生产,磷脂纯度可达98%以上。     

Purification of the human anionic polypeptide fraction of the apo-bile lipoprotein complex by zonal ultracentrifugation

The two main proteic constituents of the human Apo-bile lipoprotein complex (BLC), i.e., the anionic polypeptide fraction (APF) and the IgA fragments, were separated by preparative zonal ultracentrifugation using a sucrose gradient containing 1.5 mM glycodesoxycholate. The purification of the APF was verified by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis and immunology, and its amino acid composition then was determined. This procedure was used to obtain a polyclonal antiserum directed solely against the APF.     

降血脂药物阿托伐他汀光谱性质的密度泛函研究

采用密度泛函理论的DFT/B3LYP/6-31+G(d,p)方法和基组,对阿托伐他汀药物分子的紫外-可见(UV-Vis)吸收光谱,红外(IR)吸收光谱,拉曼(Raman)吸收光谱,核磁共振(1HNMR)吸收光谱和分子荧光发射光谱等谱学性质,进行了模拟和归属分析,所得模拟结果基本与实验数据相吻合。