Effects of diets containing tallow and soybean oil with and without cholesterol on hepatic metabolism of lipids and lipoproteins in the preruminant calf

The effects of long-chain fatty acids (230 g/kg of dietary DM) from tallow and from soybean oil, with or without cholesterol (10 g/kg of dietary DM), on hepatic lipid contents and on in vivo hepatic production rates of lipids and lipoproteins were investigated in 22 preruminant male calves fitted with chronic catheters and with electromagnetic blood flow probes implanted in the hepatic vessels. Diets containing soybean oil and soybean oil with cholesterol led to the development of triglyceride infiltration in the liver and to higher apparent hepatic secretion of very low density lipoproteins than did diets containing tallow or tallow with cholesterol. Addition of cholesterol to diets favored accumulation of low density lipoproteins in plasma and the net apparent secretion of these particles by the liver, especially for the diet containing soybean oil with cholesterol. Regardless of the diet, calf liver clearly removed large high density lipoproteins of type 1 that were rich in cholesteryl esters but secreted heavy high density lipoproteins that were rich in proteins. The intensity of removal of high density lipoproteins of type 1 by the liver depended on the plasma concentration of these particles, probably by mass action. This removal did not prevent the accumulation of high density lipoproteins of type 1 in plasma, such as it did in calves fed soybean oil.     

The impact of industrial factors of oil processing plant on serum lipoproteins

The study covered serum lipoproteins in workers engaged into production of higher fatty alcohols at oil-processing plant. The industrial factors appeared to induce changes in serum lipoproteins composition: lower share of High Density Lipoproteins and higher share of Very Low Density Lipoproteins. On the background of cardiovascular and gastrointestinal diseases, the occupational hazards may precipitate and aggravate alterations of serum lipoproteins composition in the workers.     

Oil blends containing partially hydrogenated or interesterified fats: differential effects on plasma lipids

The mechanism of adenosine-induced inhibition of ganglionic transmission was investigated in the isolated superior cervical ganglion (SCG) of the rat. The inhibitory effect of adenosine on the postganglionic compound action potential (CAP) was antagonized by pretreatment of ganglia with forskolin, isoproterenol (IPNE), arginine vasopressin (AVP), or papaverine, all of which are known to increase tissue cAMP level by different mechanisms. Furthermore, pretreatment of ganglia with the adenylate cyclase inhibitor SQ 22, 536, or the phosphodiesterase activator imidazole reversed the effects of IPNE and forskolin. Pretreatment with 8-bromo-cAMP, resulted in a marked antagonism of the adenosine-induced inhibition. By themselves, none of these drugs had any significant effect on the CAP. Adenosine slightly but significantly decreased the basal level of cAMP in untreated ganglia. Formation of cAMP induced by IPNE was markedly reduced by adenosine. This was largely reversed in the presence of the adenosine A1 receptor antagonist 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX) but not the A2 receptor antagonist 3, 7-dimethyl-1-propargylxanthine (DPMX). We conclude that the inhibition of ganglionic transmission by adenosine involves reduction of cAMP formation through activation of A1 receptors.     

Nutritional aspects of hydrogenated and regular soybean oil added to diets of broiler chickens

The objective of the present study was to evaluate the effect of degree of saturation of fat incorporated into broiler diets on performance and body fatty acid (FA) profile. The various degrees of saturation were achieved by using regular soybean oil (SO) and hydrogenated soybean oil (HSO), mixed at different proportions. The work was carried out on commercial broilers (Experiment 1) and on lines of chickens divergently selected for high (HF) or low (LF) abdominal fat (Experiment 2). Daily BW gain and gain:feed ratio increased and the amount of feed intake decreased as the dietary fat saturation decreased. Digestibility of total fat and of each of the FA was lowest in the HSO group and reached maximal values when 23% or more of the added oil was SO. The AMEn values of the diets were almost parallel to fat digestibility. The performance of the HF and LF chickens was affected by the degree of saturation similarly to that observed for the commercial stock. The degree of dietary fat saturation had very little effect on saturated FA (C16:0 and C18:0) in body lipids, reduced the level of monoenoic FA (C16:1 and C18:1), and raised that of polyunsaturated FA (PUFA) (C18:2, C18:3, and C20:4). Monoenoic FA were higher, whereas PUFA were lower in the HF than in the LF line. The improved AMEn in diets containing unsaturated fat is probably due to higher fat digestibility, direct deposition of PUFA in body lipids, and lower lipogenesis, associated with lower heat production.     

Acute and delayed effects of prolonged exercise on serum lipoproteins. II. Concentration and composition of low-density lipoprotein subfractions and very low-density lipoproteins

To investigate the effects of a single period of prolonged exercise on lipoprotein concentration and composition, 13 healthy endurance-trained men were examined before and after (1 h, 20 h) a cross-country run [30 km, time: 130 (SD 7.4) min]. The data show that following acute exercise, serum triglyceride (TG) concentration were reduced (36%) as a consequence of a reduced number (31%) of very low density lipoprotein (VLDL) particles. Changes in composition of VLDL were present but less evident. In contrast to this, acute exercise did not induce significant changes in the average concentration of individual low-density lipoprotein (LDL) subfractions. However, changes in dense LDL [density (d) > 1.044 g.ml-1] concentration were significantly correlated to changes in serum TG: a reduction of dense LDL occurred in subjects with large reductions in serum TG. In addition, LDL composition changed significantly. Immediately (1 h) after exercise the TG content of all LDL subfractions was reduced. These reductions were significant in large (d = 1.006-1.037 g.ml-1) and small LDL (1.044-1.063 g.ml-1). It can be concluded therefore from our study that acute exercise primarily altered the composition of LDL subfractions while their concentration remained stable.     

Studies on the apolipoproteins and lipoproteins of cord serum

Studies on the cord serum lipid transport system were initiated to determine whether there is a correlation between decreased cord serum lipid levels and the absence or diminished level of some or all of the human serum apolipoproteins. Immunologic studies indicated the presence of all the well-characterized apolipoproteins and provided evidence that these apolipoproteins occurred primarily as distinct lipoprotein species with a paucity of association complexes or what others have termed "triglyceride-rich" lipoproteins. Quantitation of the apolipoproteins present in cord serum by electroimmunoassay yielded the following mean levels: A-I = 73O mg/liter; A-II = 410 mg/liter; apolipoprotein B = 280 mg/liter; C-I = 59 mg/liter; C-II = 32 mg/liter; C-III = 65 mg/liter; apolipoprotein D = 37 mg/liter; and apolipoprotein E = 85 mg/liter. Levels of C-I, C-II, and apolipoprotein E approached adult levels (83 to 86% of the adult levels), whereas apolipoproteins B and D were most reduced when compared to the adult concentrations, 29 and 37%, respectively. The three other apolipoproteins were present at approximately one-half the levels found in adults.     

大豆酶解制油蛋白酶的筛选及工艺条件的研究

在以大豆乳液为水解底物进行酶水解来提取大豆油的工艺中,应用蛋白酶水解细胞壁中的蛋白成分使得脂蛋白复合体中的油脂得以释放,从而提高油脂的得油率,通过研究选出破壁能力较强的蛋白酶并优化其水解条件,最后得到最佳水解工艺.     

Effect of serum components from different species on destabilizing hydrogenated phosphatidylcholine-based liposomes

It is accepted that some serum components play important roles in enhancing liposome permeability and in facilitating rapid liposome uptake by the mononuclear phagocytic system. In this study we systematically investigated the influence of serum components from different species on complement-mediated immune damage to hydrogenated phosphatidylcholine (HEPC)-based liposomes. Our results demonstrated that when liposomes were incubated with fresh serum from rats or bovines, there was obvious leakage of 5(6)-carboxyfluorescein (CF) from the liposome. However, when liposomes were incubated with fresh serum from humans, rabbits, guinea pigs, mice, and dogs, almost no pronounced leakage from the liposome was observed. These results indicate that the variability of damage to a liposome corresponds to the variability of the animal species from which the serum comes. In addition, leakage of CF from liposomes was completely inhibited by heating at 56 degrees C for 30 min or by treatment with EDTA. However, such leakage was not blocked by treatment with EGTA/Mg2+, suggesting that the mechanism of lysis of liposomes is due to complement activation via the alternative pathway rather than via the classical pathway. Studies on reconstitution and compatibility further confirm that some serum factors (complement activating factors, CAFs) induce the activation of the complement system, ultimately leading to the lysis of the liposomes. However, CAF from different animal species exhibited corresponding species differences. Meanwhile, under the condition of heating and dialysis experiments, it is obvious that the CAF is susceptible to heat and the dialysed serum sustains biological activity to destabilize liposome following dialysis against a buffer with Ca2+ and Mg2+, indicating that the CAF is not a type of low-molecular weight material but a serum protein.     

Lipoprotein responses to fish, coconut and soybean oil diets with and without cholesterol in the Syrian hamster

Thirty-six young male Syrian hamsters were fed with test diets containing coconut oil, soybean oil or fish oil with and without 0.5% cholesterol for 6 weeks. Without dietary cholesterol supplementation, animals on the fish oil diet had significantly lower plasma total triglyceride (TG) and total cholesterol than those on the coconut oil or soybean oil diet. The decrease of TG was seen mainly in the very low density lipoprotein (VLDL) fraction. The degree of decrease in cholesterol was similar in all of the lipoprotein fractions. With 0.5% dietary cholesterol supplementation, there was no significant difference in plasma TG level among the three dietary groups. However, the fish oil group had significantly higher plasma cholesterol than the coconut oil and soybean oil groups. The increase of cholesterol was mainly in the VLDL and low density lipoprotein (LDL) fractions. In contrast to the plasma cholesterol level, the hepatic cholesteryl ester content was significantly lower in the cholesterol-supplemented fish oil group than in the coconut oil and soybean oil counterparts. The cholesterol-supplemented fish oil group showed higher liver microsomal acyl-coenzyme A:cholesterol acyltransferase activity than the other two groups, while there was no significant difference in the excretion of fecal neutral and acidic sterols among the three dietary groups.     

The significance of lipoproteins in serum binding variations of propofol

The protein binding of propofol was investigated in vitro in isolated lipoprotein fractions (very low-density lipoprotein [VLDL], low-density lipoprotein [LDL], and high-density lipoprotein [HDL]) and in serum samples from the following subjects: healthy normolipemic volunteers (n = 16), hyperlipidemic subjects diagnosed with familiar polygenic hypercholesterolemia (n = 26) showing high levels of cholesterol, and elderly subjects (n = 15). Protein binding was determined by using ultrafiltration, and the concentration of unbound propofol was measured by using liquid chromatography. Levels of total cholesterol, triglycerides, VLDL cholesterol, LDL cholesterol, HDL cholesterol, albumin, and alpha1-acid glycoprotein were also measured. Propofol was extensively bound to the three lipoprotein fractions (88%+/-2% to VLDL, 93%+/-1% to LDL, and 91%+/-4% to HDL). The percentage of unbound propofol was significantly decreased (P < 0.0001) in hyperlipidemic (0.88%+/-0.20%) individuals whose levels of cholesterol and triglycerides were increased versus healthy subjects (1.26%+/-0.22%), whereas no significant difference was found in the elderly group (1.12%+/-0.23%). A positive relationship was found between serum protein binding of propofol and lipid levels. Multiple regression analysis, including all subjects, showed that changes in the levels of total cholesterol and triglycerides explained approximately 62% of the variability in the serum protein binding of propofol. These results stress the importance of triglycerides and cholesterol in the serum protein binding of propofol. We therefore suggest that these variations in lipid levels, and consequently in protein binding, may influence anesthetic practice with propofol. IMPLICATIONS: We investigated the effect of serum lipids in the protein binding of propofol. We found that propofol binds extensively to all lipoprotein fractions. Propofol binding showed a significant relationship with the serum levels of cholesterol and triglycerides.     

Induction of P-selectin by oxidized lipoproteins. Separate effects on synthesis and surface expression

Leukocyte binding to the endothelium is one of the earliest events in the occurrence of atherosclerosis. Leukocyte adhesion molecules involved in this process have not been definitely identified. We have found that treatment of human aortic endothelial cells (HAECs) with minimally modified low-density lipoprotein (MM-LDL) for 24 hours caused a 2- to 3-fold increase of P-selectin protein, with little change in P-selectin surface expression. A 15-minute histamine treatment of cells exposed to MM-LDL caused a 50% to 100% increase in P-selectin surface expression compared with cells not treated with the lipoprotein. This increase resulted in a 2-fold increase in binding of leukocytes to the endothelium. Immunostaining of permeabilized HAECs after MM-LDL treatment also revealed a highly reproducible increase in intracellular P-selectin associated with rod-shaped structures, typical of Weibel-Palade bodies. Oxidized phospholipids were shown to be mainly responsible for the action of MM-LDL. This increased P-selectin expression was associated with MM-LDL-induced cAMP elevation. Like histamine, highly oxidized low-density lipoprotein, especially the oxidized fatty acids, caused immediate redistribution of P-selectin to the cell surface followed by reinternalization. Immunohistochemical staining showed that endothelial cells on human fatty streak lesions expressed increased levels of P-selectin compared with nonlesion areas. These studies suggest that P-selectin may play an important role in early recruitment of mononuclear cells to the subendothelium in human atherosclerosis and that oxidized lipoproteins may contribute to the increased expression of this molecule by increasing intracellular stores and causing redistribution to the cell surface.     

Influence of age and menopause on serum lipids and lipoproteins in healthy women

This study was carried out to investigate the effect of selenium supplementation at a therapeutic level on the isolated ileum contractions and the acetylcholine responses in New Zealand rabbits. While no difference with respect to the controls was found in the spontaneous ileum contraction frequencies a significant increase in the contraction amplitude was noted after 15 days of supplementation. Increasing concentrations of acetylcholine in the perfusion solution resulted in a significant increase of the contraction amplitudes in the supplemented animals as compared to controls. The tissue selenium levels and the gluthathione peroxidase activities were also found significantly higher than the controls. No difference was observed between the contraction numbers in the two groups. These findings indicate that selenium supplementation does not influence the smooth muscle resting potential.     

Effects of dietary coconut oil, butter and safflower oil on plasma lipids, lipoproteins and lathosterol levels

BACKGROUND: Complications that develop in groin hernias, such as irreducibility and obstruction, with or without strangulation may make an easily treatable condition a life-threatening one. Identification of risk factors that may predict development would help place the patient in a high-risk group. Priority admission and early elective surgery for such a patient would avoid significant mortality and morbidity. METHODS: This is a 10-year combined prospective and retrospective study of children and adults. Records of complicated groin hernias were identified from July 1985 to July 1995 from the outpatient department and available inpatient medical records. The same number of controls of simple uncomplicated hernias were then chosen using random number tables from among the large number belonging to the same time period. These two groups were then compared and analysed using statistical methods for age, sex, side of hernia, site of hernia (inguinal/femoral), duration of hernia, length of the waiting list for elective surgery, and contents of the hernial sac along with some other parameters to identify patients with high-risk factors. RESULTS: Age was found to be a significant risk factor and predicted complications in both elderly adults and very young children. Sex of the patient (male) and side of hernia (right) were significant risk factors in children only. Site of hernia was an important risk factor and adults with femoral hernia were most likely to experience complications. Duration of hernia for less than a year proved to be the most important risk factor for both children and adults. The majority of patients with complicated hernias had not presented earlier in the outpatient department, which implies that most hernias that become complicated do so within a very short time before patient referral. Mortality was high in patients with coexisting diseases, while morbidity was affected by viability of contents of the hernial sac which in turn was directly affected by duration of irreducibility or delay in presentation. CONCLUSIONS: The risk factors useful in predicting complications in an adult patient with groin hernia were age (older age group), duration of hernia (short duration), type of hernia (femoral more than inguinal) and coexisting medical illness. In children, the risk factors were age (very young), gender (male), short duration of hernia and side (right side).     

Selective effects of different antioxidants on oxidation of lipoproteins from rats

Constipation in childhood is often unrecognized and diagnosed upon manifestations such as pain and pseudo-diarrhoea reflecting of a fecalith. It is sometimes complicated with urinary infection and can be a factor favouring enuresis. In the absence of deterioration in the general condition, it reflects modification of the propulsive functions of the colon or of the reservoir function of the rectum. In a such context, no further explorations are required. Treatment involves dietary recommendations such as good nutritional balance and sufficient fibre intake as well as mineral-based laxatives (paraffin oil) or nonabsorbable osmotic sugars. Enemas and suppositories should be used in case of stool withholding. Sphincter reeducation by biofeedback is indicated in child over 8 years of age after failure of medical therapy.