The molecular organization of nerve membranes

Summary The lipid content and composition from an axolemma-rich preparation isolated from squid retinal axons was analyzed.The lipids, which accounted for 45.5% of the dry weight of this membrane, were composed of 22% cholesterol, 66.7% phospholipids and 5.2% free fatty acids. The negatively charged species phosphatidyl ethanolamine (37%), phosphatidyl serine (10%) and lysophosphatidyl ethanolamine (4%) made up 51% of the phospholipids. The amphoteric phosphatidyl choline and sphingomyelin accounted for 39% and 4%, respectively.The relative distribution of fatty acids in each of the isolated phospholipids was studied. The most remarkable feature of these phospholipids was the large proportion of long-chain polyunsaturated fatty acids. The 226 acyl chain accounted for 37% in phosphatidyl ethanolamine, 21.7% in phosphatidyl choline, 17.5% on phosphatidyl serine and 20.3% in sphingomyelin (all expressed as area %).The molar fraction of unsaturated fatty acids reached 65% in phosphatidyl ethanolamine and 42.0 and 44.8% in phosphatidyl choline and phosphatidyl serine, respectively. The double bond index in these species varied between 1.0 and 2.6.The lipid composition of the axolemma-rich preparation isolated from squid retinal axons appears to be similar to other excitable plasma membranes in two important features: (a) a low cholesterol/phospholipid molar ratio of 0.61; and (b) the polyunsaturated nature of the fatty acid of their phospholipids.This particular chemical composition may contribute a great deal to the molecular unstability of excitable membranes.The preceding papers of this series were published inArchives of Biochemistry and Biophysics.     

Disposition and hepatoprotection by phosphatidyl choline liposomes in mouse liver

Small unilamellar liposomes with an average diameter of 80 nm were prepared from phosphatidyl choline of various sources using the dialysis method with cholate as a detergent. When 14C-labeled soybean liposomes were intravenously injected into male NMRI mice, up to 10% of the total label was found in the liver lipid. The uptake was dose-dependent and reached an apparent saturation 4 h after injection. The liver maintained a constant radioactivity corresponding to 1.9 +/- 0.13 mg phospholipid/g liver until ten hours after injection of 850 mg labeled phosphatidyl choline/kg body wt. Little radioactivity was taken up by the spleen. Analogous doses of liposomes prepared from egg yolk phosphatidyl choline led to a radioactivity corresponding to 1.3 +/- 0.4 mg lipid/g liver 4 h after injection. Liposomes with a similar size were prepared from hydrated, i.e., saturated phosphatidyl choline. After intravenous administration of these liposomes, an amount of 5.3 +/- 0.5 mg labeled lipid was found per g liver after 4 h. In contrast to unsaturated liposomes, 5.8 +/- 0.8 mg lipid per gram spleen was trapped by the spleen. The pharmacodynamic effect of these different liposomes was studied in benzo[a]pyrene-pretreated mice intoxicated with 400 mg/kg paracetamol. Animals which received paracetamol exhibited serum alanine aminotransferase activities of 4220 +/- 1140 units/l after 4 h and exhaled 120 +/- 19 nmol ethane kg-1 h-1. When pretreated with 850 mg soybean phosphatidyl choline/kg body wt. (i.v.) 2 h prior to paracetamol, the increase in serum transaminase activity was reduced to 117 +/- 104 units/l and ethane exhalation amounted to 18 +/- 8 nmol kg-1 h-1. In contrast, similar pretreatment with egg yolk phosphatidyl choline or hydrated phosphatidyl choline failed to protect against paracetamol-induced hepatotoxicity. The different pharmacodynamic effects of the two phosphatidyl cholines of plant or animal origin cannot be explained on the basis of their different pharmacokinetics. In the case of soybean phosphatidyl choline liposomes, the amount of radioactive lipid found in the liver correlated with the hepatoprotective potency.     

The Electrical Capacitance of Phospholipid Membranes

As one of the methods of finding out the structural change of lipid bilayers due to change of environmental solution, the capacitances of phosphatidyl choline (egg lecithin) and phosphatidyl serine (bovine brain) bilayer membranes in solutions of various pH and salt contents were measured. It was found that the capacitance of the bilayer depended upon pH and salt content. The capacitance had a minimum value around pH 4 for phosphatidyl choline and around pH 3-4 for phosphatidyl serine bilayers, respectively. The value of the capacitance increased as the pH of the solution became lower or higher. As the concentration of cholesterol in the phosphatidyl choline bilayer increased, the capacitance increased and reached a saturation value. A DC voltage across the phosphatidyl choline bilayer did not affect the value of the capacitance practically.     

Effects of orally administered cytidine 5'-diphosphate choline on brain phospholipid content

Cytidine, as cytidine 5'-diphosphate choline (CDP-choline), is important for the synthesis of phosphatidylcholine in cell membranes. To investigate whether exogenous CDP-choline could affect brain phospholipid composition, we supplemented the diet of mice with this drug (500 mg/kg/day) for 27 months in 3-month-old mice and for 90, 42, and 3 days in 12-month-old mice, and measured their levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and the content of phosphatidylinositol plus phosphatidic acid in the cerebral cortex. After 27 months of treatment, PC and PE increased significantly by 19% (P < 0.05) and by 20% (P < 0.01), respectively. PS levels increased by 18% (not statistically significant). Similar elevations in PC and PE levels were obtained when older mice were treated for only 3 months (P < 0.05). No changes were observed with shorter treatment periods. These results suggest that chronic administration of CDP-choline can have effects on brain phospholipid composition that may underlie its reported utility in various neurologic disorders.     

Silicon bioavailability studies in young rapidly growing rats and turkeys fed semipurified diets

Two experiments were conducted using completely randomized designs to study the bioavailability of Si from three sources to growing rats and turkeys fed semipurified diets. The basal diets were dextrose-egg albumin for rats and dextrose-casein for turkeys. The Si sources were tetraethylorthosilicate (TES), sodium silicate (NaSil), and sodium zeolite A (NaZA). Rats and turkeys were supplemented at 500 and 270 ppm Si, respectively, from each source. A control group of unsupplemented rats and turkeys was included in each experiment. In general, irrespective of Si source, Si supplementation slowed (p < 0.05 orp < 0.01) growth rates in both rats and turkeys. Although dietary Si supplementation reduced (p < 0.05) plasma Mg levels and liver Zn concentrations in rats, it increased (p < 0.05) plasma P and reduced (p < 0.05) plasma Cu levels in turkeys. Rats on TES had significantly slower (p < 0.05 orp < 0.01) growth rates (5–10%) than those on NaSil or NaZA. In rats, NaZA and TES reduced (p < 0.05) hemoglobin concentrations and plasma Zn, respectively. However, plasma Mg levels were higher (p < 0.05) in TES than NaSil-or NaZA-fed rats. The source of the dietary Si did not affect (p < 0.05) the organ weights of rats and their mineral concentrations. Turkeys on TES diets grew at a significantly faster (p < 0.05) rate (15%) than those on NaSil or NaZA diets during the first 2 wk of experimentation. However, after 4 wk, there were no significant (p > 0.05) differences in growth between the Si sources. In turkeys, NaZA increased (p < 0.05) hematocrit levels and plasma Mg levels. Turkeys on NaZA diets had larger (p < 0.05) hearts and livers than those on NaSil but not TES. Liver Mn content was higher (p < 0.05) in turkeys on NaSil than TES or NaZA. Heart Zn was lower (p < 0.05) in turkeys on NaSil than TES, but not NaZA.     

Characterization of gastric mucosal membranes: lipid composition of purified gastric microsomes from pig, rabbit, and frog

The lipid compositions of the gradient-purified gastric microsomal membranes from the fundic mucosa of pig, rabbit, and frog were determined. The total lipid content varied widely. Compared to the rabbit (21.6 ± 0.6 mg/100 mg protein), the pig had about twice as much and the frog about three times as much lipid. The levels of cholesterol were higher in both mammalian species (about 32% of the lipid) compared to frog (23%). Phospholipids accounted for about 45, 54, and 52% of the total microsomal lipids from pig, rabbit, and frog and the molar ratios of cholesterol to phospholipid in the three species were 1.95, 1.6, and 1.17, respectively. Phosphatidyl choline and phosphatidyl ethanolamine together constituted about 75% of the total phospholipids in pig and frog and 93% in rabbit gastric microsomes. Sphingomyelin comprised 19.3, 3.2, and 1.5% in pig, rabbit, and frog, respectively. Phosphatidyl inositol constituted 5, 2.7, and 23.6% in pig, rabbit, and frog, respectively. The ratios of phosphatidyl ethanolamine to phosphatidyl choline were 1.17, 1.1, and 0.85 in pig, rabbit, and frog, respectively. The saturated fatty acids 16:0 and 18:0 and the unsaturated fatty acid 18:1 and 18:2 were the predominant fatty acids in all phospholipids. The ratios of saturated to unsaturated fatty acids were between 0.8 and 0.9 in phosphatidyl choline and 0.27 and 0.5 in phosphatidyl ethanolamine from all three species. The contributions by saturated fatty acids were much more in phosphatidyl inositol and sphingomyelin than in phosphatidyl choline and phosphatidyl ethanolamine from all species. Position 1 of phosphatidyl choline had 63% saturated and 37% unsaturated fatty acids; while the reverse was true for position 2. Phosphatidyl ethanolamine, however, had 85% saturated fatty acids in position 1 compared to only 25% in position 2. Arachidonic acid (20:4) was present in significant amounts in all species located exclusively at position 2 of both phosphatidyl choline and phosphatidyl ethanolamine.     

Role of Choline Deficiency in the Fatty Liver?Phenotype of Mice Fed a Low Protein,Very Low Carbohydrate Ketogenic Diet

Though widely employed for clinical intervention in obesity, metabolic syndrome, seizure disorders and other neurodegenerative diseases, the mechanisms through which low carbohydrate ketogenic diets exert their ameliorative effects still remain to be elucidated. Rodent models have been used to identify the metabolic and physiologic alterations provoked by ketogenic diets. A commonly used rodent ketogenic diet (Bio-Serv F3666) that is very high in fat (~94% kcal), very low in carbohydrate (~1% kcal), low in protein (~5% kcal), and choline restricted (~300 mg/kg) provokes robust ketosis and weight loss in mice, but through unknown mechanisms, also causes significant hepatic steatosis, inflammation, and cellular injury. To understand the independent and synergistic roles of protein restriction and choline deficiency on the pleiotropic effects of rodent ketogenic diets, we studied four custom diets that differ only in protein (5% kcal vs. 10% kcal) and choline contents (300 mg/kg vs. 5 g/kg). C57BL/6J mice maintained on the two 5% kcal protein diets induced the most significant ketoses, which was only partially diminished by choline replacement. Choline restriction in the setting of 10% kcal protein also caused moderate ketosis and hepatic fat accumulation, which were again attenuated when choline was replete. Key effects of the 5% kcal protein diet – weight loss, hepatic fat accumulation, and mitochondrial ultrastructural disarray and bioenergetic dysfunction – were mitigated by choline repletion. These studies indicate that synergistic effects of protein restriction and choline deficiency influence integrated metabolism and hepatic pathology in mice when nutritional fat content is very high, and support the consideration of dietary choline content in ketogenic diet studies in rodents to limit hepatic mitochondrial dysfunction and fat accumulation.     

Hypolipidemic and antioxidant properties of <Emphasis Type="Italic">Ganoderma lucidum</Emphasis> (Leyss:Fr) Karst used as a dietary supplement

In this study, the hypolipidemic and antioxidant properties of Ganoderma lucidum CG 144, a medicinal mushroom cultivated on wet wheat grains by solid-state fermentation, were investigated followed dietary supplementation. Basal chow was supplemented with 85, 50, or 10% of G. lucidum CG 144 dried spawn, resulting in G85, G50, and G10 diets, respectively, and fed to normocholesterolemic and induced-hypercholesterolemic mice. The G85 diet triggered significant loss of body weight compared with the G50 and G10 diets (P < 0.01). In the normocholesterolemic mice, regular consumption of high concentrations (G85 and G50 diets) of dried spawn led to significant changes in the plasma lipid concentrations (P < 0.05). Although there were no significant changes in the plasma cholesterol concentrations, the G85 and G50 diets decreased the low-density-lipoprotein (LDL) cholesterol levels by 71 and 98%, respectively, and increased the high-density-lipoprotein (HDL) cholesterol levels by 80 and 86%, respectively. Further, the plasma triacylglycerol levels decreased by 32.5 and 42% with the G85 and G50 diets, respectively. The G10 diet did not alter the plasma lipid profile in the normocholesterolemic mice (P > 0.05) but significantly decreased the cholesterol concentrations (P < 0.001) in the induced-hypercholesterolemic mice. Peritoneal macrophages from the induced-hypercholesterolemic mice fed the G10 diet produced lower nitric oxide than the controls (P < 0.05).     

Effects of feed form and energy levels on growth performance,carcass yield and nutrient digestibility in broilers

Feed form is well recognized to improve broiler performance, specially by increasing feed intake (FI). However, when different diet energy levels are used, the results differ in the literature. Therefore, this experiment was conducted to evaluate the influence of feed form and dietary metabolizable energy (ME) levels on broiler performance, carcass yield and on the digestibility of DM, CP, starch and gross energy. In total, 1152 male Cobb 500 broilers were evaluated between 35 and 47 days. The birds were distributed according to a completely randomized design in a 2 × 4 factorial arrangement, consisting of two feed forms (mash or pellet) and four ME levels (12.73, 13.06, 13.40 or 13.73 MJ/kg), totaling eight treatments with eight replicates of 18 birds. Broilers fed the lowest ME level presented the lowest weight gain (WG) and worst feed per unit gain (P < 0.01). Metabolizable energy intake increased (P < 0.01) with progressive increments of ME, which, however, did not affect caloric conversion (CC, P > 0.05). Pelleted diets promoted higher FI, WG, ME intake (P < 0.01) and better feed per unit gain and CC (P < 0.05) compared with mash. In mash diets, increasing dietary ME levels promoted a linear increase in WG (P < 0.01) and reduced feed per unit gain (P ≤ 0.05), but did not affect FI (P > 0.05). In pelleted diets, on the other hand, increasing ME levels linearly reduced FI (P < 0.05) and feed per unit gain (P < 0.01). Broilers fed pelleted diets presented higher abdominal fat deposition than those fed mash (P < 0.05). Increasing ME levels reduced the coefficients of ileal apparent digestibility of DM (P < 0.01) and total starch (P < 0.05) but did not affect the digestibility of other evaluated nutrients. The digestibility of all nutrients was lower when pelleted diets were fed compared with mash. Increasing inert material inclusion in the diets at the expense of soybean oil to reduce dietary ME levels promoted higher pellet durability index values (P < 0.05) and the percentage of fines (P < 0.01). Overall, the results suggest that pelleted diets promote better broiler performance because they increase FI, since the digestibility of dietary fractions is reduced. Chickens consuming low-energy pelleted diets may increase FI to compensate for energy deficit. In contrast, broilers fed mash diets may have reached their maximum intake capacity and did not regulate FI by changing feed energy density. When feeding pelleted diets, dietary energy reduction should be considered to reduce feed costs and to improve the carcass quality of broilers.     

Effect of acute hypobaric hypoxia on 32-P incorporation into phospholipids of alveolar surfactant, lung, liver and plasma of rat.

Exposure of adult rats to hypobaric hypoxia caused hypolipidemia, hypotriglyceridemia and hypophospholipidemia. Hypobaric hypoxia produced an increase in liver triglyceride and cholesterol levels and a decrease in lung triglyceride, total phospholipid and phosphatidyl choline. The proportion of phosphatidyl choline in the pulmonary surfactant fraction I phospholipids (responsible for reducing surface tension) decreased (55.2% as compared to 80.4% in control animals). Incorporation of 32-P into liver phosphatidyl ethanolamine was significantly increased, incorporation into lung phosphatidyl choline and phosphatidyl ethanolamine was increased whereas a decreased incorporation into plasma phosphatidyl choline was observed. The data suggest an enhanced lipid synthesis in liver with a probable impairment of mobilization into plasma.     

Hepatic Subcellular Fractions Lipids in Rats Fed Millet (Sorghum vulgarie) at Different Protein Levels

Effect of feeding defatted millet (Sorghum vulgarie) flour at 5, 10 and 14.5% protein levels respectively for six weeks has been studied on rat liver mitochondrial, microsomal and supernatant fractions total lipids, cholesterol, triglycerides, total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine. The results have been compared with rats fed casein at 10% level for the same period. The metabolism of liver subcellular fractions lipids of millet diet and casein diet fed rats has been studied by the incorporation of acetate-1-¹⁴C and . A significant increase in mitochondrial triglycerides of rats fed millet diet at 5 and 10% protein level, in microsomes of rats fed millet diet at 5, 10 and 15% protein levels and in supernatant fractions of rats fed millet diet at 5 and 15% protein levels was observed. A significant increase in total cholesterol in mitochondria and microsomes and a significant decrease in supernatant fraction of rats fed millet diet at 10% protein level was observed. A significant increase in mitochondrial total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine in rats fed millet diet at 10% protein level and a decrease in these in rats fed millet diet at 5 per cent protein level was observed. In microsomes total phospholipids were increased in rats millet diet at 10% protein level and phosphatidyl choline was increased in rats fed millet diet at 15% protein level. Total phospholipids, phosphatidyl choline and phosphatidyl ethanolamine were significantly reduced in the supernatant fraction of rats fed millet at 10% protein level.

Incorporation of acetate-1-¹⁴C into nonsaponifiable fraction of mitochondria, microsomes and supernatant fractions of rats fed millet diet at 5 and 15 % protein levels was significantly greater, and in saponifiable fractions of the above subcellular fractions was greater in rats fed millet diet at 5 per cent protein level. The specific activity (counts/min/mg) of free cholesterol in mitochondria, microsomes and supernatant fractions of millet diet fed rats was significantly greater, whereas the specific activity of triglycerides was not significantly different from the controls. The acetate-1-¹⁴C specific activity of phosphatidyl choline and phosphatidyl ethanolamine was significantly greater in all the above subcellular fractions of millet diet fed rats (except of phosphatidyl choline in rats fed millet diet at 5 % protein level). The specific activities of phosphatidyl choline were significantly greater in mitochondria of rats fed millet diet at 5 % protein level and of phosphatidyl choline and phosphatidyl ethanolamine in microsomes and supernatant fractions of rats fed millet diet at 5 and 15% protein levels. The specific activities of phosphatidyl choline were significantly decreased in mitochondria and microsomes of rats fed millet diet at 10% protein level. The total acetate-1-¹⁴C activities (counts/min/g equivalent wet liver) of free and esterified cholesterol triglycerides, phosphatidyl choline and phosphatidyl ethanolamine showed that their synthesis from acetate-1-¹⁴C was either enhanced in millet diet fed rats or was comparable to the controls. The total activity of (counts/min/g equivalent wet liver) into phosphatidyl choline and phosphatidyl ethanolamine showed that their synthesis was decreased in microsomes of rats fed millet diet at 10% protein level, increased in rats fed millet diet at 5 and 15% protein levels.     

Effects of semi-purified diet on depressive behaviors in aged mice

Diet is a key modifiable factor influencing the composition of gut microbiota. There are two types of commercially available diets for experimental animals: non-purified and semi-purified diets. Non-purified diets are composed of complex ingredients from multiple sources, while semi-purified diets are formulated with refined ingredients. Accumulating evidence has demonstrated a link between the gut microbiota and depression, and feed ingredients may influence depressive physiology and behaviors. To test this hypothesis, we examined how chronic non-purified (CRF-1) and semi-purified (AIN-93G) diets affected phenotypes, including depressive behaviors, plasma corticosterone levels, and small-intestine microbiota in young (2 months old) and aged (22 months old) inbred C57BL/JJcl mice. In young mice, similar phenotypes were associated with non-purified and semi-purified diets. However, in aged mice, semi-purified diets increased depressive behaviors in the tail suspension (P < 0.05) and forced swimming tests (P < 0.01). The corticosterone levels were similar between the two diets under normal rearing conditions. However, immediately after exposure to the stressful conditions of the forced swimming test, the corticosterone levels in the aged mice fed the semi-purified diet were higher than those of mice fed the non-purified diet (P < 0.05). There were fewer Lactobacillales in the small intestines of aged mice fed the semi-purified diet compared to those fed the non-purified diet (P < 0.01). Further, α-diversity was lower in aged mice fed the semi-purified versus non-purified diet (P < 0.01). Our results indicate that host physiology and gut microbiota differed according to whether the aged mice were fed a non-purified or semi-purified diet. Specifically, those fed the semi-purified diet were more vulnerable to stress than age-matched mice fed the non-purified diet. Our findings indicate that researchers should consider the effects of feed ingredients on depressive physiology and behaviors, and select diets that are appropriate for their particular research design. Further, identification of the ingredients in non-purified diets could facilitate examination of the mechanisms by which gut microbiota composition might increase resistance to stress and depression.     

Effects of oleamide on choline acetyltransferase and cognitive activities

We screened 50 Korean traditional natural plants to measure the activation effect on choline acetyltransferase and attenuation of scopolamine-induced amnesia. The methanolic extracts from Zizyphus jujuba among the tested 50 plants, showed the highest activatory effect (34.1%) on choline acetyltransferase in vitro. By sequential fractionation of Zizyphus jujuba, the active component was finally identified as cis-9-octadecenoamide (oleamide). After isolation, oleamide showed a 65% activation effect. Administration of oleamide (0.32%) to mice significantly reversed the scopolamine-induced memory and/or cognitive impairment in the passive avoidance test and Y-maze test. Injection of scopolamine to mice impaired performance on the passive avoidance test (31% decrease in step-through latency), and on the Y-maze test (16% decrease in alternation behavior). In contrast, mice treated with oleamide before scopolamine injection were protected from these changes (12-25% decrease in step-through latency; 1-10% decrease in alternation behavior). These results suggest that oleamide should be a useful chemo-preventive agent against Alzheimer's disease.     

Lipids from nerve tissues of the horseshoe crab, Limulus polyphemus.

1. The predominant lipids of nerve cords, ganglion and brain from horseshoe crabs were cholesterol (11% of lipid) and phospholipid (81% of lipid). 2. Major phospholipids were phosphatidyl ethanolamine and phosphatidyl choline with lesser amounts of phosphatidyl serine and phosphatidyl inositol and sphingomyelin. 3. The phospholipid fraction was characterized by a high content of plasmalogen, i.e. alk-1-enyl acyl phosphatides, so that 42% of the ethanolamine phosphatides were the plasmalogen, phosphatidal ethanolamine. 4. Phosphatidyl choline and phosphatidyl ethanolamine were high in polyunsaturation with 20:4 and 20:5 major fatty acids. Sphingomyelin had predominantly long chain saturated fatty acids. 5. Cerebrosides and gangliosides, which are associated with vertebrate nerve tissues, were absent from nerves of horseshoe crabs.     

The utilisation of yolk phosphoglycerides by the alligator during embryonic development

Summary A study was made of the concentrations and fatty acid compositions of the major phosphoglycerides in the yolk of the alligator egg on the 8th and 75th days of incubation. The major phosphoglycerides were phosphatidyl choline and phosphatidyl ethanolamine which at the start of incubation accounted for 72 and 18%, respectively, of total phosphoglyceride. Phosphoglycerides were characterised by low levels of linoleic acid but extremely high levels of C20 and C22 polyunsaturates. The extensive absorption of phosphoglyceride over the incubation period was accompanied by a reduction in percentage of phosphoglyceride within the residual yolk lipid, a reduction in the proportion of phosphatidyl choline within the total phosphoglyceride, and increases in the proportions of phosphatidyl ethanolamine and lyso-phosphatidyl choline. There were small but wide-spread changes in the fatty acid composition of the phosphatidyl choline during incubation. Within the phosphatidyl ethanolamine and phosphatidyl serine fractions there were very large reductions in the C20 and C22 polyunsaturated fatty acid levels. The phosphoglyceride changes are discussed with respect to the unique role of yolk lipid absorption in the nutrition of the developing embryo.     

1-Kestose consumption during pregnancy and lactation increases the levels of IgA in the milk of lactating mice

To examine the effect of dietary supplementation with 1-kestose on the IgA levels in milk, BALB/c mice were fed diets with or without 5% 1-kestose during pregnancy and lactation. The total and specific IgA levels in the milk were measured at 7 and 14?days after delivery. A two-way ANOVA with repeated measures resulted in a significant effect of 1-kestose-supplementation on total IgA concentrations (p?<?0.05) and the level of anti-Bacteroides IgA (p?<?0.05). A significant positive correlation was found between the mean count of Bacteroides spp. in maternal feces and the total IgA concentration in maternal milk (r?=?0.55, p?<?0.05), suggesting a potential link between the gut and mammary gland immune system. In conclusion, this study demonstrated the effects of dietary prebiotics on milk IgA production.     

Proteoglycan 4 deficiency protects against glucose intolerance and fatty liver disease in diet-induced obese mice

Objective

Proteoglycan 4 (Prg4) has emerged from human association studies as a possible factor contributing to weight gain, dyslipidemia and insulin resistance. In the current study, we investigated the causal role of Prg4 in controlling lipid and glucose metabolism in mice.

Dietary n-9, n-6, and n-3 fatty acids modify linoleic acid more than arachidonic acid levels in plasma and platelet lipids and minimally affect platelet thromboxane formation in the rabbit

We have studied the effects of semisynthetic diets containing 5% by weight (12% of the energy) of either olive oil (70% oleic acid, OA) or corn oil (58% linoleic acid), or fish oil (Max EPA, containing about 30% eicosapentaenoic, EPA C 20:5 n-3, plus docosahexaenoic, DHA C 22:6 n-3, acids, and less than 2% linoleic acid), fed to male rabbits for a period of five weeks, on plasma and platelet fatty acids and platelet thromboxane formation. Aim of the study was to quantitate the absolute changes of n-6 and n-3 fatty acid levels in plasma and platelet lipid pools after dietary manipulations and to correlate the effects on eicosanoid-precursor fatty acids with those on platelet thromboxane formation. The major differences were found when comparing the group fed fish oil and depleted linoleic acid vs the other groups. The accumulation of n-3 fatty acids in various lipid classes was associated with modifications in the distribution of linoleic acid and arachidonic acid in different lipid pools. In platelets maximal incorporation of n-3 fatty acids occurred in phosphatidyl ethanolamine, which also participated in most of the total arachidonic acid reduction occurring in platelets, and linoleic acid, more than archidonic acid, was replaced by n-3 fatty acids in various phospholipids. The archidonic acid content of phosphatidyl choline was unaffected and that of phosphatidyl inositol only marginally reduced. Thromboxane formation by thrombin stimulated platelets did not differ among the three groups, and this may be related to the minimal changes of arachidonic acid in phosphatidyl choline and phosphatidyl inositol.     

Biochemical changes accompanying apoptotic cell death in retinoblastoma cancer cells treated with lipogenic enzyme inhibitors

Retinoblastoma (RB) is a malignant intra-ocular neoplasm that affects children (usually below the age of 5 years). In addition to conventional chemotherapy, novel therapeutic strategies that target metabolic pathways such as glycolysis and lipid metabolism are emerging. Fatty acid synthase (FASN), a lipogenic multi-enzyme complex, is over-expressed in retinoblastoma cancer. The present study evaluated the biochemical basis of FASN inhibition induced apoptosis in cultured Y79 RB cells. FASN inhibitors (cerulenin, triclosan and orlistat) significantly inhibited FASN enzyme activity (P < 0.05) in Y79 RB cells. This was accompanied by a decrease in palmitate synthesis (end-product depletion), and increased malonyl CoA levels (substrate accumulation). Differential lipid profile was biochemically estimated in neoplastic (Y79 RB) and non-neoplastic (3T3) cells subjected to FASN inhibition. The relative proportion of phosphatidyl choline to neutral lipids (triglyceride + total cholesterol) in Y79 RB cancer cells was found to be higher than the non-neoplastic cells, indicative of altered lipid distribution and utilization in tumor cells. FASN inhibitor treated Y79 RB and fibroblast cells showed decrease in the cellular lipids (triglyceride, cholesterol and phosphatidyl choline) levels. Apoptotic DNA damage induced by FASN inhibitors was accompanied by enhanced lipid peroxidation.     

Phosphatidyl choline and the growth in serum-free medium of vascular endothelial and smooth muscle cells,and corneal endothelial cells

Liposomes made by sonication of egg yolk phosphatidyl choline support the proliferation of low-density bovine vascular and corneal endothelial cells, and vascular smooth muscle cells maintained on basement laminacoated dishes and exposed to a defined medium supplemented with transferrin. The optimal growth-promoting effect of phosphatidyl choline was observed at concentrations of 25 μg/ml for low-density cultures of vascular smooth muscle cells, and 100 μg/ml for vascular and corneal endothelial cells. The growth rate and final cell density of vascular endothelial cells exposed to a synthetic medium supplemented with transferrin and either high-density lipoproteins or phosphatidyl choline has been compared. Although cultures exposed to phosphatidyl choline reached a final cell density similar to that of cultures exposed to high-density lipoproteins, they had a longer average doubling time (17 h vs. 12 h) during their logarithmic growth phase and a shorter lifespan (17 generations vs. 30 generations). Similar observations were made in the case of vascular smooth muscle cells or bovine corneal endothelial cells maintained in medium supplemented with transferrin, fibroblast growth factor (FGF) or epidermal growth factor (EGF), and insulin and exposed to either high-density lipoproteins or phosphatidyl choline. Since phosphatidyl choline can, for the most part, replace highdensity lipoproteins in supporting the proliferation of various cell types, it is likely that the growth stimulating signal conveyed by high-density lipoproteins is associated with its polar lipid fraction, which is composed mostly of phosphatidyl cholines.