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Obesity is a public health concern resulting in a variety of health complications, including heart disease and insulin resistance. Estrogens have been associated with a reduced risk of obesity, but this relationship remains incompletely understood. We assessed the role of 17β-estradiol (E2) in mitigating complications associated with obesity by supplementing E2 in the diets of overfed zebrafish. We report that dietary E2 supplementation protects against weight gain and modulates de novo cholesterol synthesis in a sex-specific manner. Our studies lead us to propose a model in which E2 regulates hmgcr expression independently of unsaturated fat consumption. These data can be used to develop sex-specific treatments for obesity-related health conditions.

Metabolic dysfunction-associated steatotic liver disease (MASLD) comprises a spectrum of liver diseases, ranging from liver steatosis to metabolic dysfunction-associated steatohepatitis (MASH), increasing the risk of developing cirrhosis and hepatocellular carcinoma (HCC). Fibrosis within MASLD is critical for disease development; therefore, the identification of fibrosis-driving factors is indispensable. We analyzed the expression of interleukin 32 (IL-32) and chemokine CC ligand 20 (CCL20), which are known to be linked with inflammation and fibrosis, and for their expression in MASLD and hepatoma cells. RT-PCR, ELISA and Western blotting analyses were performed in both human liver samples and an in vitro steatosis model. IL-32 and CCL20 mRNA expression was increased in tissues of patients with NASH compared to normal liver tissue. Stratification for patatin-like phospholipase domain-containing protein 3 (PNPLA3) status revealed significance for IL-32 only in patients with I148M (rs738409, CG/GG) carrier status. Furthermore, a positive correlation was observed between IL-32 expression and steatosis grade, and between IL-32 as well as CCL20 expression and fibrosis grade. Treatment with the saturated fatty acid palmitic acid (PA) induced mRNA and protein expression of IL-32 and CCL20 in hepatoma cells. This induction was mitigated by the substitution of PA with monounsaturated oleic acid (OA), suggesting the involvement of oxidative stress. Consequently, analysis of stress-induced signaling pathways showed the activation of Erk1/2 and p38 MAPK, which led to an enhanced expression of IL-32 and CCL20. In conclusion, cellular stress in liver epithelial cells induced by PA enhances the expression of IL-32 and CCL20, both known to trigger inflammation and fibrosis.

Background: Partial hepatectomy is a preferred treatment option for many patients with hepatocellular carcinoma however, pre-existing pathological abnormalities originating from hepatic steatosis can alter the decision to perform surgery or postoperative outcomes as a consequence of the impact steatosis has on liver regeneration., Aim: The aim of this study was to investigate the role of a saturated or unsaturated high fat diet-mediated steatosis on liver regeneration following partial hepatectomy., Methods: Mice were fed a low-fat control diet (CD, 13% fat), lard-based unsaturated (LD, 60% fat) or milk-based saturated high fat diet (MD, 60% fat) for 16 weeks at which time partial hepatectomy (approx. 70% resection) was performed. At days-2 and 7 post hepatectomy, one hour prior to euthanization, mice were injected with 5-bromo-2'-deoxyuridine in order to monitor hepatic regeneration. Serum was collected and assessed for levels of ALT and AST. Resected and regenerated liver tissue were examined for inflammation-indicative markers employing RT-PCR, Western blots, and histological methods., Results: Mice fed LD or MD exhibited higher NAFLD scores, increased expression of inflammatory cytokines, neutrophil infiltration, macrophage accumulation, increased apoptosis, and elevated levels of serum ALT and AST activities, a decrease in the number of BrdU-incorporated-hepatocytes in the regenerated livers compared to the mice fed CD. Mice fed MD showed significantly lower percent of BrdU-incorporated hepatocytes and a higher trend of inflammation compared to the mice fed LD., Conclusion: A diet rich in saturated or unsaturated fat results in NASH with decreased hepatic regeneration however unsaturated fat diet cause lower inflammation and higher regeneration than the saturated fat diet following partial hepatectomy in mice., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Islam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The cell nucleus is surrounded by a double membrane. The lipid packing and viscosity of membranes is critical for their function and is tightly controlled by lipid saturation. Circuits regulating the lipid saturation of the outer nuclear membrane (ONM) and contiguous endoplasmic reticulum (ER) are known. However, how lipid saturation is controlled in the inner nuclear membrane (INM) has remained enigmatic. Using INM biosensors and targeted genetic manipulations, we show that increased lipid unsaturation causes a reprogramming of lipid storage metabolism across the nuclear envelope (NE). Cells induce lipid droplet (LD) formation specifically from the distant ONM/ER, whereas LD formation at the INM is suppressed. In doing so, unsaturated fatty acids are shifted away from the INM. We identify the transcription circuits that topologically reprogram LD synthesis and identify seipin and phosphatidic acid as critical effectors. Our study suggests a detoxification mechanism protecting the INM from excess lipid unsaturation., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Modifying dairy fat composition by increasing the MUFA content is a potential strategy to reduce dietary SFA intake for cardiovascular disease (CVD) prevention in the population., Objectives: To determine the effects of consuming SFA-reduced, MUFA-enriched (modified) dairy products, compared with conventional dairy products (control), on the fasting cholesterol profile (primary outcome), endothelial function assessed by flow-mediated dilatation (FMD; key secondary outcome), and other cardiometabolic risk markers., Methods: A double-blind, randomized, controlled crossover 12-wk intervention was conducted. Participants with a 1.5-fold higher (moderate) CVD risk than the population mean replaced habitual dairy products with study products (milk, cheese, and butter) to achieve a high-fat, high-dairy isoenergetic daily dietary exchange [38% of total energy intake (%TE) from fat: control (dietary target: 19%TE SFA; 11%TE MUFA) and modified (16%TE SFA; 14%TE MUFA) diet]., Results: Fifty-four participants (57.4% men; mean ± SEM age: 52 ± 3 y; BMI: 25.8 ± 0.5 kg/m2) completed the study. The modified diet attenuated the rise in fasting LDL cholesterol observed with the control diet (0.03 ± 0.06 mmol/L and 0.19 ± 0.05 mmol/L, respectively; P = 0.03). Relative to baseline, the %FMD response increased after the modified diet (0.35% ± 0.15%), whereas a decrease was observed after the control diet (-0.51% ± 0.15%; P< 0.0001). In addition, fasting plasma nitrite concentrations increased after the modified diet, yet decreased after the control diet (0.02 ± 0.01 μmol/L and -0.03 ± 0.02 μmol/L, respectively; P = 0.01)., Conclusions: In adults at moderate CVD risk, consumption of a high-fat diet containing SFA-reduced, MUFA-enriched dairy products for 12 wk showed beneficial effects on fasting LDL cholesterol and endothelial function compared with conventional dairy products. Our findings indicate that fatty acid modification of dairy products may have potential as a public health strategy aimed at CVD risk reduction. This trial was registered at clinicaltrials.gov as NCT02089035., (Copyright © The Author(s) 2020.)

Background: Short chain fatty acids (SCFAs; e.g., acetate, propionate, and butyrate) are produced by microbial fermentation of fiber in the colon. Evidence is lacking on how high-fiber diets that differ in macronutrient composition affect circulating SCFAs., Objectives: We aimed to compare the effects of 3 high-fiber isocaloric diets differing in %kcal of carbohydrate, protein, or unsaturated fat on circulating SCFAs. Based on previous literature, we hypothesized that serum acetate, the main SCFA in circulation, increases on all high-fiber diets, but differently by macronutrient composition of the diet., Methods: OmniHeart is a randomized crossover trial of 164 men and women (≥30 y old); 163 participants with SCFA data were included in this analysis. We provided participants 3 isocaloric high-fiber (∼30 g/2100 kcal) diets, each for 6 wk, in random order: a carbohydrate-rich (Carb) diet, a protein-rich (Prot) diet (protein predominantly from plant sources), and an unsaturated fat-rich (Unsat) diet. We used LC-MS to quantify SCFA concentrations in fasting serum, collected at baseline and the end of each diet period. We fitted linear regression models with generalized estimating equations to examine change in ln-transformed SCFAs from baseline to the end of each diet; differences between diets; and associations of changes in SCFAs with cardiometabolic parameters., Results: From baseline, serum acetate concentrations were increased by the Prot (β: 0.24; 95% CI: 0.12, 0.35), Unsat (β: 0.21; 95% CI: 0.10, 0.33), and Carb (β: 0.12; 95% CI: 0.01, 0.24) diets; between diets, only Prot compared with Carb was significant (P = 0.02). Propionate was decreased by the Carb (β: -0.10; 95% CI: -0.16, -0.03) and Unsat (β: -0.10; 95% CI: -0.16, -0.04) diets, not the Prot diet; between diet comparisons of Carb vs. Prot (P = 0.006) and Unsat vs. Prot (P = 0.002) were significant. The Prot diet increased butyrate (β: 0.05; 95% CI: 0.00, 0.09) compared with baseline, but not compared with the other diets. Increases in acetate were associated with decreases in insulin and glucose; increases in propionate with increases in leptin, LDL cholesterol, and blood pressure; and increases in butyrate with increases in insulin and glucose, and decreases in HDL cholesterol and ghrelin (Ps < 0.05)., Conclusions: Macronutrient composition of high-fiber diets affects circulating SCFAs, which are associated with measures of appetite and cardiometabolic health. This trial was registered at clinicaltrials.gov as NCT00051350., (Copyright © The Author(s) 2020.)

Several studies have demonstrated the relationship between bone marrow adiposity (BMAT) and bone mass. 1 H magnetic resonance spectroscopy is a noninvasive technique able to assess both BMAT quantity and quality. The aim of our study was to perform quantitative and qualitative analyses of BMAT and to investigate its association with bone mineral density (BMD) in healthy nonobese volunteers. Fifty-one healthy volunteers, 21 men and 30 women, underwent 1.5 T 1 H magnetic resonance spectroscopy of the lumbar spine. BMD was determined by dual-energy X-ray absorptiometry of the lumbar spine. Correlation analysis was performed to evaluate association among lipids fractions, BMD, and age. The female and male volunteers had similar body mass index and BMD (p > 0.05). Our data demonstrated an inverse correlation of BMD and BMAT with age, with a stronger correlation of saturated lipids (r = 0.701; p < 0.0001) compared with unsaturated lipids (UL) (r = 0.278; p = 0.004). Importantly, female subjects had the highest amount of UL (confidence interval: 0.685%-1.722%; p < 0.001). Our study reports that men and women with similar BMD and body mass index have striking differences in bone marrow lipids composition, namely women have higher UL than men. In addition, we believe that our study brings new insights to the complex network involving BMAT and other factors that influence bone integrity., (Copyright © 2016 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)

Purpose: To propose and optimize diffusion-weighted stimulated echo acquisition mode (DW-STEAM) for measuring fat unsaturation in the presence of a strong water signal by suppressing the water signal based on a shorter T2 and higher diffusivity of water relative to fat., Methods: A parameter study for point-resolved spectroscopy (PRESS) and STEAM using oil phantoms was performed and correlated with gas chromatography (GC). Simulations of muscle tissue signal behavior using DW-STEAM and long-echo time (TE) PRESS and a parameter optimization for DW-STEAM were conducted. DW-STEAM and long-TE PRESS were applied in the gastrocnemius muscles of nine healthy subjects., Results: STEAM with TE and mixing time (TM) up to 45 ms exhibited R(2) correlations above 0.98 with GC and little T2 -weighting and J-modulation for the quantified olefinic/methylene peak ratio. The optimal parameters for muscle tissue using DW-STEAM were b-value = 1800 s/mm(2), TE = 33 ms, TM = 30 ms, and repetition time = 2300 ms. In vivo measured mean olefinic signal-to-noise ratios were 72 and 40, mean apparent olefinic water fractions were 0.19 and 0.11 for DW-STEAM and long-TE PRESS, respectively., Conclusion: Optimized DW-STEAM MR spectroscopy is superior to long-TE PRESS for measuring fat unsaturation, if a strong water peak prevents the olefinic fat signal's quantification at shorter TEs and water's tissue specific ADC is substantially higher than fat., (© 2015 Wiley Periodicals, Inc.)

Objectives: To characterize via NMR spectroscopy the full spectrum of metabolic changes in umbilical vein blood plasma of newborns diagnosed with different clinical forms of intrauterine growth restriction (IUGR)., Methods: 23 early IUGR cases and matched 23 adequate-for-gestational-age (AGA) controls and 56 late IUGR cases with 56 matched AGAs were included in this study. Early IUGR was defined as a birth weight <10(th) centile, abnormal umbilical artery (UA) Doppler and delivery <35 weeks. Late IUGR was defined as a birth weight <10(th) centile with normal UA Doppler and delivery >35 weeks. This group was subdivided in 18 vasodilated (VD) and 38 non-VD late IUGR fetuses. All AGA patients had a birth weight >10(th) centile. (1)H nuclear magnetic resonance (NMR) metabolomics of the blood samples collected from the umbilical vein at delivery was obtained. Multivariate statistical analysis identified several metabolites that allowed the discrimination between the different IUGR subgroups, and their comparative levels were quantified from the NMR data., Results: The NMR-based analysis showed increased unsaturated lipids and VLDL levels in both early and late IUGR samples, decreased glucose and increased acetone levels in early IUGR. Non-significant trends for decreased glucose and increased acetone levels were present in late IUGR, which followed a severity gradient when the VD and non-VD subgroups were considered. Regarding amino acids and derivatives, early IUGR showed significantly increased glutamine and creatine levels, whereas the amounts of phenylalanine and tyrosine were decreased in early and late-VD IUGR samples. Valine and leucine were decreased in late IUGR samples. Choline levels were decreased in all clinical subforms of IUGR., Conclusions: IUGR is not associated with a unique metabolic profile, but important changes are present in different clinical subsets used in research and clinical practice. These results may help in characterizing comprehensively specific alterations underlying different IUGR subsets.

The effect of supplementing a basal diet with 1 of 3 plant oils on productive efficiency and milk fatty acid composition was studied in dairy goats. Sixteen Malagueña goats were used in a 4×4 Latin square experiment with 21-d periods and 4 goats per treatment. The basal diet comprised 30% alfalfa hay and 70% pelleted concentrate. Experimental treatments were control (basal diet without added oil) and the basal diet supplemented with 48g/d of high oleic sunflower oil (HOSFO), regular sunflower oil (RSFO), or linseed oil (LO). Dry matter intake and body weight were not affected by treatments. Milk production was higher in HOSFO treatment and milk fat content was higher in RSFO and LO treatments, although no differences in milk energy production or milk renneting properties were found. The RSFO and LO treatments increased the proportion of vaccenic acid in milk fat more so than the HOSFO diet, and rumenic acid followed the same pattern. The content of trans10-18:1 remained low in all experimental diets (<0.7% of total fatty acid methyl esters) although HOSFO and RSFO diets increased it. The variations in the fatty acid profiles observed with the 4 diets, mainly the unsaturated fatty acid isomer contents, are extensively discussed. Compared with that in the control diet, the n-6:n-3 fatty acid ratio in milk fat substantially decreased with the LO, increased with RSFO, and did not change with HOSFO. The addition of moderate amounts of LO to the diets of dairy goats has favorable effects on milk fatty acid composition from the point of view of the human consumer, without negative effects on animal performance., (Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Unsaturated lipids having various physiological roles are of significance in biochemistry, nutrition, medicine, and food. However, the susceptibility of lipids to oxidation is a major cause of quality deterioration in food emulsions. The reaction mechanism and factors that influence oxidation are appreciably different for emulsified lipids and bulk lipids. This article gives a brief overview of the current knowledge on autoxidation of oil-in-water food emulsions, especially those that contain unsaturated lipids, which are important in the food industry. Autoxidation of unsaturated lipids in oil-in-water emulsion is discussed, and so also their oxidation mechanism, the major factors influencing oxidation, determination measures, research status, and the problems encountered in recent years. Some effective strategies for controlling lipid oxidation in food emulsion have been presented in this review.

In contrast to the majority of the Order, the dampwood termites of the family Termopsidae found in colder regions can experience frost and snow, either in cool temperate areas at high latitudes (45 degrees ), or alpine areas at high elevations (>1000m). This suggests that dampwood termites are adapted to cold climates. We investigated this hypothesis in two dampwood termites, Porotermes adamsoni Froggatt and Stolotermes victoriensis Hill. We measured nest temperatures and atmospheric temperatures of their alpine habitat during winter, and measured survival and recovery at subzero temperatures. We also determined the minimum temperature at which these species remain active and the LT50 values. We used a novel gas chromatographic strategy to examine eight metabolites from individuals of both species collected in winter and summer to identify possible cryoprotectants. Both P. adamsoni and S. victoriensis had significantly higher levels of trehalose, a known cryoprotectant, in winter than in summer; in addition S. victoriensis also had higher levels of unsaturated fatty acid ligands in winter than in summer, consistent with patterns observed for cold adaptation in other organisms. These results are the first to reveal that dampwood termites are adapted to cold climates and use trehalose and unsaturated lipids as cryoprotectants.

Background: Prenatal hypoxia is an important cause of intrauterine growth retardation that affects fetal lung maturation, although previous studies have rendered conflicting results. The fetal chicken model allows the study of the isolated effects of hypoxia during development., Objectives: We hypothesized that prenatal hypoxia would differentially affect surfactant synthesis, depending on timing and duration of hypoxia. Pulmonary vascular endothelial growth factor (VEGF) expression was analyzed as a possible link between oxygen sensing and surfactant production., Methods: Fertilized White Leghorn eggs were incubated in normoxia, hyperoxia (60% O(2)) from day 15 or hypoxia (15% O(2)) from either day 6 or day 15 of incubation. Whole lung disaturated phospholipids (DSPL) and mRNA expression of VEGF isoforms were quantified at day 16 and 19., Results: Lung DSPL content increased approximately threefold between day 16 and 19 in control animals. Both hypoxia and hyperoxia from day 15 significantly increased DSPL content at day 19 versus control (103 +/- 22 and 116 +/- 18 vs. 81 +/- 15 microg/mg protein, p < 0.01 and p < 0.001, respectively), while long-term hypoxia tended to decrease DSPL content (65 +/- 17 microg/mg protein, p = 0.056). No differences in DSPL content were observed at day 16. Short-term hypoxia transiently up-regulated VEGF146 1.5-fold at day 16 (p < 0.05). A similar trend was observed for VEGF122 (p = 0.058) and VEGF190 (p = 0.08), while no differences were present at day 19., Conclusions: Both prenatal hypoxia and hyperoxia induced during critical windows of lung development differentially modulate surfactant synthesis. Our data support the concept that fetal oxygen tension is a key signal in the regulation of the surfactant system., (Copyright 2009 S. Karger AG, Basel.)

Background and Objective: Vasoactive substances such as histamine, acetylcholine or ATP increase the [Ca2+]i of endothelial cells, which leads to the activation of nitric oxide synthase (eNOS). The NO produced by this enzyme relaxes the underlying smooth muscle. Evidence suggests that eNOS activation is dependent on agonist-induced Ca2+ entry. Recently we have shown that in human endothelial cells (HUVEC), this Ca2+ entry is sensitive to isoflurane. The objective here was to study the mechanism by which volatile anaesthetics can depress the histamine-induced Ca2+ entry into HUVEC cells., Methods: HUVECs on coverslips were loaded with the Ca2+ indicator Fluo-3 and inserted in a gastight, temperature-controlled perfusion chamber. Excitation was at 488 nm and fluorescence signals were monitored with a confocal laser scanning microscope (MRC1024, Biorad). Direct measurement of the Ca2+ influx was with Mn2+ as surrogate for calcium at 360 nm in cells loaded with Fura-2., Results: Addition of histamine induces a biphasic [Ca2+]i increase consisting of Ca2+ release from internal stores and a Ca2+ influx from the external medium (plateau phase). The plateau phase was dose-dependently inhibited by enflurane and sevoflurane (13.7 resp. 21.9% inhibition by 1 MAC anaesthetic). Direct measurement of the Ca2+ influx using the Mn2+ quench of the Fura-2 fluorescence gave similar results. The inhibition of the anaesthetics was not reduced by inhibition of the cGMP pathway, inactivation of protein kinase C, depolarization of the cells or the presence of specific Ca2+-dependent K+ channel inhibitors. Interestingly, unsaturated fatty acids inhibit the histamine-induced Ca2+ influx in a similar way as the volatile anaesthetics., Conclusions: Volatile anaesthetics dose-dependently inhibit the histamine-induced Ca2+ influx in HUVECs by a mechanism that may involve unspecific perturbation of the lipid bilayer.

The possible roles of reduced glutathione (GSH) in chilling tolerance were studied in callus generated from a representative alpine plant, Chorispora bungeana Fisch. & C.A. Mey (C. bungeana). The callus grew well under low-temperature and chilling treatment led only to slight injury, as indicated by a low level of ion leakage (IL). Malondialdehyde measurements also were not elevated, however GSH was. Exogenously application of l-buthionine-(S R)-sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase (gamma-ECS), arrested the GSH accumulation induced by chilling and resulted in a significant decrease in cell growth and an increase in IL and malondialdehyde. These results implied that C. bungeana is a plant with a strong low-temperature tolerance mechanism, and the tolerance of C. bungeana may be associated with GSH accumulation. Under chilling treatment, the proportion of unsaturated fatty acid in the plasma membrane (PM) increased significantly in callus of C. bungeana mainly due to increases in C18:2 and C18:3, the membrane fluidity (indicated by DPH fluorescent polarization) however was maintained. High PM H(+)-ATPase activities were also induced by chilling. Exogenously application of BSO blocked the effects of chilling treatments on the changes of fatty acids and PM H(+)-ATPase activities, reducing the PM membrane fluidity. On the other hand, simultaneous application of GSH and BSO to callus under chilling treatments reversed the effects of BSO on the changes of fatty acids, PM fluidity and PM H(+)-ATPase activities. These results suggested that GSH induced by low-temperature treatments may confer chilling tolerance to C. bungeana, probably by increasing unsaturated fatty acid compositions and maintaining PM fluidity and high enzymatic activity.

Polyunsaturated fats have been linked to occurrences of sporadic colon cancer. One possible cause may be degradation of polyunsaturated fats during cooking, resulting in multiple reactive carbonyl species (RCS) that can damage nuclear DNA and proteins, particularly in rapidly dividing colon crypt cells. This study describes a novel antiserum against RCS-modified DNA, with apparent order of reactivity to DNA modified with 4-hydroxy-trans-2-nonenal > glyoxal > acrolein > crotonaldehyde > malondialdehyde; some reactivity was also observed against conjugated Schiff base-type structures. Anti-(RCS-DNA) antiserum was successfully utilised to demonstrate formation of RCS-DNA in a human colon cell model, exposed to RCS insult derived from endogenous and exogenous lipid peroxidation sources. Further utilisation of the antiserum for immunohistochemical analysis confirmed RCS-modified DNA in crypt areas of 'normal' colon tissue. These results fully support a potential role for dietary lipid peroxidation products in the development of sporadic colon cancer.

To improve hybrid tilapia (Oreochromis niloticusxO. aureus) survival under cold shock, the influence of diets containing various dietary lipids was investigated. Four different diets were used which consisted of 12% fish oil, 12% palmitoleic oil 12% coconut oil, and a mixture of fish oil (7%) and corn oil (5%). Our results showed that during cold shock, the proportion of saturated fatty acids in the fish steadily and significantly decreased for all of the diets, but the proportion of monounsaturated fatty acids increased. Proportions of polyenoic fatty acids initially increased then stabilized for the mixed, fish, and coconut oil diets, but did not significantly increase until day 4 for the palmitoleic oil diet. The stearoyl-CoA desaturase (SCD) activity was the lowest on day 0 and then gradually increased for all diets. At any point, the enzymatic activity of SCD was the highest for fish on the mixed and the coconut oil diet, followed by the palmitoleic oil diet, and was lowest for the fish oil diet. The expression of SCD mRNA steadily increased for all diets, but increased more substantially for the mixed diet. On day 6, the expression was the highest for fish on the mixed diet, followed by the coconut oil diet, with the lowest levels for those on the palmitoleic and fish oil diets. These results show that dietary lipids strongly affect the fatty acid composition and SCD expression in tilapia under cold shock, and cold tolerance of this species is also affected.

Insulin resistance occurs in 20%-25% of the human population, and the condition is a chief component of type 2 diabetes mellitus and a risk factor for cardiovascular disease and certain forms of cancer. Herein, we demonstrate that the sphingolipid ceramide is a common molecular intermediate linking several different pathological metabolic stresses (i.e., glucocorticoids and saturated fats, but not unsaturated fats) to the induction of insulin resistance. Moreover, inhibition of ceramide synthesis markedly improves glucose tolerance and prevents the onset of frank diabetes in obese rodents. Collectively, these data have two important implications. First, they indicate that different fatty acids induce insulin resistance by distinct mechanisms discerned by their reliance on sphingolipid synthesis. Second, they identify enzymes required for ceramide synthesis as therapeutic targets for combating insulin resistance caused by nutrient excess or glucocorticoid therapy.

Leaf membrane lipids of the Arabidopsis (Arabidopsis thaliana) fatty acid biosynthesis 1 (fab1) mutant contain a 35% to 40% increase in the predominant saturated fatty acid 16:0, relative to wild type. This increase in membrane saturation is associated with loss of photosynthetic function and death of mutant plants at low temperatures. We have initiated a suppressor screen for mutations that allow survival of fab1 plants at 2 degrees C. Five suppressor mutants identified in this screen all rescued the collapse of photosynthetic function observed in fab1 plants. While fab1 plants died after 5 to 7 weeks at 2 degrees C, the suppressors remained viable after 16 weeks in the cold, as judged by their ability to resume growth following a return to 22 degrees C and to subsequently produce viable seed. Three of the suppressors had changes in leaf fatty acid composition when compared to fab1, indicating that one mechanism of suppression may involve compensating changes in thylakoid lipid composition. Surprisingly, the suppressor phenotype in one line, S31, was associated with a further substantial increase in lipid saturation. The overall leaf fatty acid composition of S31 plants contained 31% 16:0 compared with 23% in fab1 and 17% in wild type. Biochemical and genetic analysis showed that S31 plants contain a new allele of fatty acid desaturation 5 (fad5), fad5-2, and are therefore partially deficient in activity of the chloroplast 16:0 Delta7 desaturase. A double mutant produced by crossing fab1 to the original fad5-1 allele also remained alive at 2 degrees C, indicating that the fad5-2 mutation is the suppressor in the S31 (fab1 fad5-2) line. Based on the biophysical characteristics of saturated and unsaturated fatty acids, the increased 16:0 in fab1 fad5-2 plants would be expected to exacerbate, rather than ameliorate, low-temperature damage. We propose instead that a change in shape of the major thylakoid lipid, monogalactosyldiacylglycerol, mediated by the fad5-2 mutation, may compensate for changes in lipid structure resulting from the original fab1 mutation. Our identification of mutants that suppress the low-temperature phenotype of fab1 provides new tools to understand the relationship between thylakoid lipid structure and photosynthetic function.

Purpose: To use proton magnetic resonance spectroscopy ((1)H-MRS) to evaluate vertebral marrow fat, and to determine whether bone density correlates with fat content and fat unsaturation levels in postmenopausal women., Materials and Methods: Fifty-three women (mean age = 70 years) underwent dual energy x-ray absorptiometry and (1)H-MRS, and 12 young female controls (mean age = 28 years) underwent (1)H-MRS of the lumber spine. Water and lipid peak amplitudes were measured to calculate fat content and fat unsaturation index. Spearman's correlation tests and a t-test comparison of means were applied., Results: (1)H-MRS was successful in 15 normal, 15 osteopenic, and 20 osteoporotic subjects, and in all controls. Marrow fat content was significantly elevated in osteoporotic (65.5% +/- 10%) and osteopenic (63.5% +/- 9.3%) subjects compared to normal subjects (56.3% +/- 11.2%) and young controls (29% +/- 9.6%). The fat unsaturation index was significantly decreased in osteoporotic (0.091 +/- 0.013) and osteopenic (0.097 +/- 0.014) subjects compared to normal subjects (0.114 +/- 0.016) and young controls (0.127 +/- 0.031). A good inverse correlation was observed between the fat content and the unsaturation index (r(s) = -0.53, P < 0.0001)., Conclusion: Osteoporosis is associated with increased marrow fat. As marrow fat increases, saturated lipids appear to increase preferentially to unsaturated lipids., ((c) 2005 Wiley-Liss, Inc.)

Single cell oils (SCOs) are now produced by various microorganisms as commercial sources of arachidonic acid (ARA) and docosahexaenoic acid (DHA). These oils are now used extensively as dietary supplements in infant formulas. An understanding of the underlying biochemistry and genetics of oil accumulation in such microorganisms is therefore essential if lipid yields are to be improved. Also an understanding of the biosynthetic pathways involved in the production of these polyunsaturated fatty acids (PUFAs) is also highly desirable as a prerequisite to increasing their content in the oils. An account is provided of the biosynthetic machinery that is necessary to achieve oil accumulation in an oleaginous species where it can account for lipid build up in excess of 70% of the cell biomass. Whilst PUFA production in most microorganisms uses a conventional fatty acid synthase (FAS) system followed by a series of desaturases and elongases, in Schizochytrium sp., and probably related thraustochytrid marine protists, PUFA synthesis now appears to be via a polyketide synthase (PKS) route. This route is discussed. It clearly represents a major departure from conventional fatty acid biosynthesis, possibly as a means of decreasing the amount of NADPH that is needed in the overall process.

Lipid analogs with dialkylindocarbocyanine (DiI) head groups and short or unsaturated hydrocarbon chains (e.g. DiIC(12) and FAST DiI) enter the endocytic recycling compartment efficiently, whereas lipid analogs with long, saturated tails (e.g. DiIC(16) and DiIC(18)) are sorted out of this pathway and targeted to the late endosomes/lysosomes (Mukherjee, S., Soe, T. T., and Maxfield, F. R. (1999) J. Cell Biol. 144, 1271-1284). This differential trafficking of lipid analogs with the same polar head group was interpreted to result from differential partitioning to different types of domains with varying membrane order and/or curvature. Here we investigate the system further by monitoring the trafficking behavior of these lipid analogs under conditions that alter domain properties. There was a marked effect of cholesterol depletion on the cell-surface distribution and degree of internalization of the lipid probes. Furthermore, instead of going to the late endosomes/lysosomes as in control cells, long chain DiI analogs, such as DiIC(16), were sorted to the recycling pathway in cholesterol-depleted cells. We confirmed that this difference was due to a change in overall membrane properties, and not cholesterol levels per se, by utilizing a Chinese hamster ovary cell line that overexpressed transfected stearoyl-CoA desaturase 1, a rate-limiting enzyme in the production of monounsaturated fatty acids. These cells have a decrease in membrane order because they contain a much larger fraction of unsaturated fatty acids. These cells showed alteration of DiI trafficking very similar to cholesterol-depleted cells. By using cold Triton X-100 extractability of different lipids as a criterion to determine the membrane properties of intracellular organelles, we found that the endocytic recycling compartment has abundant detergent-resistant membranes, in contrast to the late endosomes and lysosomes.

A major part of the palmitic acid (C16:0) generated by fatty acid synthase is converted into stearic acid (C18:0) via carbon chain elongation. Here, we describe the cloning and expression of a rat hepatic enzyme, rELO2, responsible for the elongation of C16:0, presumably at the condensing reaction. Heterologous expression experiments in a yeast, Saccharomyces cerevisiae, demonstrated the elongation activity of rELO2 on C16:0 and to a lesser extent, C18:0 and fatty acids with low desaturation degree. This was distinct from that rELO1, a rat homolog of HELO1, which preferably catalyzed the elongation of mono- and polyunsaturated fatty acids of C16-C20. The Northern analysis showed that the expression of rELO2, but not rELO1, in hepatocytes was activated by the cycles of fasting and refeeding rats on a fat-free diet. Under these conditions, the rELO1 was expressed constitutively in various tissues but the rELO2 transcripts were detected predominantly in liver.

This experiment was designed to evaluate the effects of dietary red wine phenolic compounds (WP) and cholesterol on lipid oxidation and transport in rats. For 5 wk, weanling rats were fed polyunsaturated fat diets (n-6/n-3 = 6.4) supplemented or not supplemented with either 3 g/kg diet of cholesterol, 5 g/kg diet of WP, or both. The concentrations of triacylglycerols (TAG, P < 0.01) and cholesterol (P < 0.0002) were reduced in fasting plasma of rats fed cholesterol despite the cholesterol enrichment of very low density lipoprotein + low density lipoprotein (VLDL + LDL). The response was due to the much lower plasma concentration of high density lipoprotein (HDL) (-35%, P < 0.0001). In contrast, TAG and cholesteryl ester (CE) accumulated in liver (+120 and +450%, respectively, P < 0.0001). However, the cholesterol content of liver microsomes was not affected. Dietary cholesterol altered the distribution of fatty acids mainly by reducing the ratio of arachidonic acid to linoleic acid (P < 0.0001) in plasma VLDL + LDL (-35%) and HDL (-42%) and in liver TAG (-42%), CE (-78%), and phospholipids (-28%). Dietary WP had little or no effect on these variables. On the other hand, dietary cholesterol lowered the alpha-tocopherol concentration in VLDL + LDL ( -40%, P < 0.003) and in microsomes (-60%, P < 0.0001). In contrast, dietary WP increased the concentration in microsomes (+21%, P < 0.0001), but had no effect on the concentration in VLDL + LDL. Cholesterol feeding decreased (P < 0.006) whereas WP feeding increased (P < 0.0001) the resistance of VLDL + LDL to copper-induced oxidation. The production of conjugated dienes after 25 h of oxidation ranged between 650 (WP without cholesterol) and 2,560 (cholesterol without WP) micromol/g VLDL + LDL protein. These findings show that dietary WP were absorbed at sufficient levels to contribute to the protection of polyunsaturated fatty acids in plasma and membranes. They could also reduce the consumption of alpha-tocopherol and endogenous antioxidants. The responses suggest that, in humans, these substances may be beneficial by reducing the deleterious effects of a dietary overload of cholesterol.

The consumption of fat-enriched diets may alter the uptake and metabolism of chylomicron remnant cholesterol by the liver. To test this hypothesis, [3H]cholesterol-labelled chylomicron remnants derived from different dietary fats were studied in perfused livers both from rats fed on diets enriched in the corresponding fats and from rats fed on a low-fat diet. Livers from rats fed on each of the fat-enriched diets removed similar amounts (34-40%) of the [3H]cholesterol-labelled remnants added, whereas livers from rats fed on the low-fat diet removed significantly more labelled fish-oil and butter-fat remnants than olive-, maize- or palm-oil remnants. Significantly more remnant [3H]cholesterol was secreted into the perfusate HDL by livers from rats fed on the olive-oil, fish-oil and butter-fat diets when compared with those from rats fed on the low-fat diet or the maize-oil diet. Furthermore, the excretion of remnant [3H]cholesterol via the bile acid was increased by the olive-, maize-, palm- or fish-oil diets, and decreased by the butter-fat diet when compared with the low-fat diet, although the [3H]bile acid excreted remained less on saturated fat diets. This investigation shows that the hepatic uptake and subsequent metabolism of cholesterol from chylomicron remnants is influenced by the type of fat in the diet as well as the fatty acid composition of the particles themselves, and may help to explain some of the hyper- and hypocholesterolaemic effects of saturated and unsaturated fatty acids.

The effect of variation of the degree of cis-unsaturation on cell membrane protein functioning was investigated using a model lipid bilayer system and protein kinase C (PKC). This protein is a key element of signal transduction. Furthermore it is representative of a class of extrinsic membrane proteins that show lipid dependent interactions with cell membranes. To test for dependence of activity on the phospholipid unsaturation, experiments were devised using a vesicle assay system consisting of phosphatidylcholine (PC) and phosphatidylserine (PS) in which the unsaturation was systematically varied. Highly purified PKC alpha and epsilon were obtained using the baculovirus-insect cell expression system. It was shown that increased PC unsaturation elevated the activity of PKC alpha. By contrast, increasing the unsaturation of PS decreased the activity of PKC alpha, and to a lesser extent PKC epsilon. This result immediately rules out any single lipid bilayer physical parameter, such as lipid order, underlying the effect. It is proposed that while PC unsaturation effects are explainable on the basis of a contribution to membrane surface curvature stress, the effects of PS unsaturation may be due to specific protein-lipid interactions. Overall, the results indicate that altered phospholipid unsaturation in cell membranes that occurs in certain disease states such as chronic alcoholism, or by dietary manipulations, are likely to have profound effects on signal transduction pathways involving PKC and similar proteins.

The effect of dosing vehicle on toxicity and metabolism of unsaturated aliphatic nitriles was investigated in male Sprague-Dawley rats. Five unsaturated aliphatic nitriles--acrylonitrile, methacrylonitrile, allylnitrile, crotononitrile and fumaronitrile--were prepared in five different dosing vehicles--saline, corn oil, safflower oil, mineral oil, olive oil and Tween-20. Groups of six male rats were given 0.5 LD50 doses of the nitriles by gavage and they were observed for 12 It for cholinomimetic and central nervous system effects. Cyanide and glutathione levels were determined in blood and various organs at 1, 3 and 6 h after nitrile administration and thiocyanate levels were determined at 6 h after nitrile administration. The results indicate that all the vehicles studied potentiated the toxicity of all the nitriles compared to nitriles administered in saline and significantly increased their metabolism to cyanide and thiocyanate and nitrile-induced depletion of glutathione in rats. This behavior of vehicles illustrates the difficulty of identifying suitable vehicles for administration of lipophilic compounds in toxicology studies.

It is a common belief among physicians that nutritional therapy in type II diabetic subjects is inefficient because the patients do not comply with the recommendations. Failure of a therapeutic response leads to feelings of guilt in patients, followed by frustration, and refusal of further treatment. The physician rapidly starts with drug or insulin therapy before the effects of diet treatment are assessable. Nutritional recommendations for diabetics are basically the same as for non-diabetics. Successful dietary treatment of obese type II diabetic subjects requires realistic goals regarding weight loss. Frequent mistakes are that an ideal body weight is aimed for, and that the patients are asked to omit only carbohydrates in the diet. Splitting of the meals, and distribution of carbohydrate-containing foods to individual meals during the day are important components of a meal plan. The patient should also be counciled how to avoid visible and invisible dietary fats. Exchange lists are frequently administered, but they fail, because they are too complicated. Only a part of decompensated type II diabetic subjects respond to weight loss. The response is evident already after a few [2.3 kg] weight loss. Other diabetic subjects fail to improve their glucose control after weight loss. These patients require an alternative treatment, i.e. oral antidiabetic agents or insulin. Frequently behavior therapy is of advantage in obese type II diabetic subjects, in addition to longterm dietary treatment. Dieticians should be involved in all difficult cases since they have the necessary experience to perform this longterm treatment.

This study has investigated the influence of dietary fatty acid composition on mammary tumour incidence in N-ethyl-N-nitrosourea (ENU)-treated rats and has compared the susceptibility to dietary fatty acid modification of the membrane phospholipids phosphatidylinositol (PI) and phosphatidylethanolamine (PE) from normal and tumour tissue of rat mammary gland. The incidence of mammary tumours was significantly lower in fish oil--(29%), compared with olive oil--(75%; P < 0.04) but not maize oil--(63%; P < 0.1) fed animals. No differences in PI fatty acid composition were found in normal or tumour tissue between rats fed on maize oil, olive oil or fish oil in diets from weaning. When normal and tumour tissue PI fatty acids were compared, significantly higher amounts of stearic acid (18:0) were found in tumour than normal tissue in rats given olive oil (P < 0.05). A similar trend was found in animals fed on maize oil, although differences between normal and tumour tissue did not reach a level of statistical significance (P < 0.1). In mammary PE, maize oil-fed control animals had significantly higher levels of linoleic acid (18:2n-6) than either olive oil- or fish oil-fed animals (P < 0.05, both cases) and levels of arachidonic acid were also higher in maize oil- compared with fish oil-fed animals (P < 0.05). In tumour-bearing animals no differences in PE fatty acid composition were found between the three dietary groups. When normal and tumour tissue PE fatty acids were compared, significantly lower amounts of linoleic acid (18:2n-6; P < 0.01) and significantly greater amounts of arachidonic acid (20:4n-6; P < 0.05) were found in tumour than normal tissue of rats fed on maize oil. The present study shows that the fatty acid composition of PI from both normal and tumour tissue of the mammary gland is resistant to dietary fatty acid modification. The PE fraction is more susceptible to dietary modification and in this fraction there is evidence of increased conversion of linoleic acid to arachidonic acid in tumour compared with normal tissue. Lower tumour incidence rates in rats given fish oils may in part be due to alteration in prostanoid metabolism secondary to displacement of arachidonic acid by eicosapentaenoic acid, but PE rather than PI would appear to be the most likely locus for diet-induced alteration in prostanoid synthesis in this tissue. Effects of dietary fatty acids other than on the balance of n-6 and n-3 fatty acids, and on prostanoid metabolism, should also be considered. The significance of increased stearic acid content of PI in tumours of olive oil-fed animals and the possible influence of dietary fatty acids on the capacity for stearic acid accumulation requires further study.

We tested the hypothesis that plasma thyroid hormone levels in infant baboons are differentially affected by breast-feeding and nursery rearing. Infant baboons were breast-fed (n = 17), or fed formulas with a high polyunsaturated to saturated fat ratio (P/S) (n = 13), or a low P/S formula (n = 14). Plasma total triiodothyronine (T3) and free T3 (fT3) concentrations increased from 4 to 14 weeks of age in infants fed either formula, but decreased in breast-fed infants. At 9 and 14 weeks of age, infants fed the formulas averaged 31% higher T3 and 53% higher fT3 concentrations compared with breast-fed infants. Although T3 concentrations of the high P/S formula group compared with the low P/S formula group were not different at any single age, from 4 to 14 weeks the T3 averaged 19% higher in the high P/S formula group. Plasma total thyroxine (T4) or free T4 (fT4) concentrations were not significantly different among the diet groups during the preweaning period. In summary, formula-fed infants maintained higher plasma T3 and fT3 levels compared with breast-fed infants in the late preweaning period.

Natural-abundance 13C magnetic resonance spectroscopy was used for determining noninvasively the relative concentration of mono- and polyunsaturated fatty acids of adipose tissue in two groups of volunteers. The first consisted of subjects who had followed a fat-reduced diet for at least half a year before the 13C measurements. The second were control subjects who were on a usual high-fat diet. The ratio of unsaturated to total fatty acids in adipose tissue determined by 13C MRS correlated significantly with the same ratio in fat of the diet composition estimated by a dietician according to food records. The results indicate that 13C MRS is capable of assessing the degree of unsaturation of dietary fatty acids consumed during the preceding months.

The relationship between plasma levels of Lp[a] and LDL was examined using dietary regimens. In 81 normolipidemic male outpatients, dietary cholesterol was increased by consuming six eggs per day from a mean (SD) level of 311 (162) to 1430 (198) mg per day. Mean (SD) LDL-cholesterol levels increased from 102 (26) mg/dl to 120 (33) mg/dl (P less than 0.001), while mean (SD) Lp[a] levels were 5.5 (6.1) mg/dl on the basal diet and 5.6 (6.4) mg/dl on the cholesterol-rich diet. No significant correlation was observed between increases in either LDL-cholesterol or apolipoprotein B to Lp[a], nor was there any relationship between individual baseline levels of Lp[a] and dietary-induced changes of Lp[a]. Fourteen of the 81 participants were reexamined under strict nutritional control. Four diets with 40% of calories as fat, but differing in the type of fat and the amount of cholesterol, were administered sequentially to all subjects. As expected, mean (SD) LDL-cholesterol and apolipoprotein B levels were highest on the saturated fat, high cholesterol diet (112 (32) mg/dl and 79 (22) mg/dl) and lowest on the polyunsaturated fat, low cholesterol diet (77 (27) mg/dl and 53 (18) mg/dl). In contrast, mean Lp[a] levels did not significantly change among the four diets (range 4.2-4.9 mg/dl). No correlation of Lp[a] responses with changes in plasma lipids, apolipoproteins, or lipoproteins was observed on any diet. These data suggest that determinants of plasma Lp[a] levels are distinctly different from the determinants of plasma LDL levels in normolipidemic males.

1. The specific activity of hepatic and renal peroxisomal D-amino acid oxidase (D-AAOX) was measured in rats fed diets containing various quantities of vegetable oil. 2. Increasing the amount of dietary sunflower seed oil (SSO) from 10 to 25% (w/w) reduced the specific activity of hepatic D-AAOX by up to 30% after 10 days. 3. In both tissues, the enzyme activity was moderately decreased during the first two-day period after administration of the 25% SSO diet was begun. Unlike hepatic D-AAOX, renal D-AAOX returned to its baseline level in the kidney after the third day. 4. In contrast to SSO, hydrogenated coconut oil (HCO) did not evoke alterations of D-AAOX activity. 5. The activity levels of another peroxisomal enzyme, L-2-hydroxy acid oxidase (L-HAOX), in the liver of rats fed the high-SSO diet vs those fed the control diet were similar. 6. The subcellular distribution of D-AAOX and L-HAOX was not altered in the liver of rats fed the 25% SSO diet during the 10-day period.

We have studied the generation of volatile hydrocarbons by fatty acid-modified L1210 leukemia cells in tissue culture as a measure of lipid peroxidation. There was considerable generation of ethane, and this was dependent on cell number and Fe2+ concentration; it was eliminated by antioxidants and augmented by ascorbic acid. The assay was sensitive and reproducible; ethane was detected when as little as 0.03% of the cellular n-3 (omega-3) fatty acids were peroxidized. To gain further understanding we used a lipid modification model that allows study of cells enriched with fatty acids of different degrees of unsaturation. The quantity of ethane generated was greatest by cells modified with fatty acids of the n-3 family, and there was a high direct correlation of percentage of n-3 fatty acids contained in cellular lipids with peroxidation as measured by ethane generation. Ethane generation was more sensitive in detecting peroxidation than loss of polyunsaturated fatty acids. We conclude that lipid-supplemented leukemic cells produce ethane, and that the rate of generation is a sensitive, quantitative, and highly useful measure of lipid peroxidation when small amounts of iron are present.

High-fat, high-cholesterol diets have been linked to colon cancer in both epidemiological and animal studies. Saturated and N-6 polyunsaturated fats have both been implicated as playing causative roles. Epidemiological studies have shown a reduced colon cancer incidence in populations consuming a large quantity of N-3 polyunsaturated fat. This study asked whether N-3 polyunsaturated fat found in fish oil would also be associated with reduced colon cancer in animal studies. 1,2-Dimethylhydrazine was used to induce colon cancer in mice fed three high-fat, high-cholesterol diets (beef tallow, safflower oil, and fish oil) and one low-fat, cholesterol-free diet (soybean oil). Colon adenocarcinomas developed in 55% of mice fed tallow, 48% of those fed low-fat diets, 33% of those fed safflower oil, and 18% of those fed fish oil (p less than 0.05). Tumors per animal were also greatest in mice fed tallow and fewest in those fed fish oil (p less than 0.05). Plasma cholesterol levels were significantly higher in mice fed tallow than in mice fed fish oil, but this did not show any association with tumors. Plasma triglyceride levels were not significantly different among groups but were strongly correlated with colon cancers (r = 0.90, p less than 0.025). In both plasma and colon mucosa cells, saturated fat levels were similar. Monounsaturated fat was highest in plasma of mice fed tallow and correlated strongly with colon cancers (r = 0.84, p less than 0.005). N-6 polyunsaturated fat was highest in plasma and colon mucosa cells of both mice fed safflower oil and those fed low-fat (soybean oil) diet, but there was no association with tumors. N-3 polyunsaturated fat was highest in plasma and colon mucosa cells of mice fed fish oil and showed a negative association with tumors (r = -0.57, p less than 0.05). Thus, in this model of colon cancer, a diet high in fish oil was associated with less colon cancer. Monounsaturated fat was most strongly correlated with tumors. This study suggests monounsaturated fat promotes colon tumors and N-3 polyunsaturated fat inhibits colon tumors.

Early weaning of piglets induces a rapid decrease in the concentration of all plasma lipoproteins within 2 d. The decline was more progressive when 20% saturated fatty acid (lard) (SF) was added to the diet; saturated fatty acid was more effective than unsaturated fatty acid (sunflower oil) (UF). Medium-chain triglycerides had no protective effect. Intestinal synthesis of apoprotein AI was twofold higher in preweaning piglets than in adults (12.9% of total synthesis vs 5.9%, p less than 0.01) when measured in intestinal mucosa. On day 4 of weaning, synthesis was still at the preweaning level in all groups but on day 7 was maintained only by the SF diet (11.7%). We conclude that long-chain lipids, particularly saturated fatty acids, prevent a decrease in lipoproteins at weaning, mainly by maintaining intestinal apo AI synthesis at a high level.

Official methods were used to analyze composite samples of milk collected during the first 15 wk of lactation from 21 Holstein cows fed a milled ration containing 0 (basal), 15% (medium, or 30% (high) protected-tallow supplement (seven cows per treatment). Protein fractions and amino acid composition of the total proteins were determined from samples of individual milking. Melting characteristics of pooled samples were determined by nuclear magnetic resonance. Milk yield was similar for the three treatments, but percent fat and fat yield were higher for cows fed protected tallow. Percentages and yields of protein and solids-not-fat were decreased on the protected tallow treatments, especially for high tallow. The decrease in protein was in the casein fraction. Amino acid composition of the total proteins was similar for the three treatments. Feeding protected tallow caused decreases in all fatty acids except 4:0, 16:1, 18:0, and 18:1 which increased. Nuclear magnetic resonance indicated that butter from the basal group would be harder than that from cows fed protected tallow.

Previous studies have shown that polyunsaturated ruminant fats in the diets of human subjects cause an increase in cholesterol and bile acid excretion during the first 3 weeks of such diets. The present studies were designed to compare the effects of polyunsaturated (P) and conventional (S) ruminant fats at two levels of dietary cholesterol intake: a higher (HC) and lower (LC). Four study periods, each of about 3 weeks' duration, were conducted in 5 healthy subjects providing these dietary combinations: HCS, HCP, LCS, LCP. Neutral sterols and bile acids were measured in the feces, and sterol balances were calculated. Plasma cholesterol levels were significantly lower with P than with S diets at both HC and LC intakes. Changes attributable to differences in fatty acids and to differences in cholesterol intake appeared to exert independent effects. The major changes occurred in lipoproteins with density 1.019-1.045. Cholesterol absorption expressed as a percentage of the dietary intake was not significantly different with the four diets. Neutral sterol excretion of probable endogenous origin and bile acid excretion were significantly higher during the HCP than during the HCS periods, but the difference between LCP and LCS periods was less marked. Net sterol excretion was therefore significantly greater with HCP and LCP than with HCS and LCS diets, the differences being greater at HC than at LC intakes. Comparisons of diets with similar fatty acid but differing cholesterol intakes showed lower net sterol excretion with HCS than with LCS diets (presumably due to suppression by HC by cholesterol synthesis), but this difference was not seen between HCP and LCP diets. This finding, together with greater sterol excretion with HCP than with HCS diets, showed that enhanced sterol excretion with polyunsaturated fat was potentiated with higher cholesterol intake. This enhanced excretion was generally greater during the first than during the second 3-week period of polyunsaturated fat.

The effect of ethanol on human blood platelet aggregation is generally inhibitory, but aggregation caused by arachidonic acid is either unaffected or potentiated by ethanol. Of the other aggregatory agents tested, the calcium ionophore A23187, collagen, and thrombin were most inhibited by ethanol. These results suggest that in the case of collagen and ionophore A23187 ethanol may act to inhibit aggregation at some point between the rise in cytosolic calcium and the cleavage of membrane phospholipids associated with the platelet release reaction. A similar spectrum of inhibition was produced by the incorporation of unsaturated fats into the platelet or by reduction of divalent cations by addition of EDTA to the external medium. Platelets in which unsaturated fats were incorporated were less susceptible to inhibition by ethanol than those into which saturated fats had been incorporated.

Hepatic cholesterol synthesis was studied in rats after consuming diets of varying neutral lipid and cholesterol content. Cholesterol synthesis was evaluated by measuring 3-hydroxy-3-methylglutaryl-CoA reductase and by determining the rate of 3H-labeled sterol production from [3H]mevalonate. Results were correlated with sterol balance data and hepatic lipid content. Hepatic cholesterol synthesis was relatively great when cholesterol was excluded from the diet. The source of neutral dietary lipids, saturated vs. unsaturated, produced no change in hepatic sterol synthesis. Values for fecal sterol outputs and hepatic cholesterol levels were also similar in rats consuming either saturated or unsaturated fats. When 1% cholesterol was added to the diet, hepatic cholesterol synthesis was suppressed but the degree of suppression was greater in rats consuming unsaturated vs. saturated fats. This was associated with greater accumulation of cholesterol in livers from rats consuming unsaturates and a reduction in fecal neutral sterol output in this group as opposed to results from rats on saturated fats. Cholesterol consumption also altered the fatty acid composition of hepatic phospholipids producing decreases in the percentages of essential polyunsaturated fatty acids. It is concluded that dietary cholesterol alters cholesterol and fatty acid metabolism in the liver and that this effect is enhanced by dietary unsaturated fats.

Adipose tissue in man is a major site for cholesterol storage. In obesity over half of total body cholesterol may reside within this tissue; however, relatively little attention has been directed toward understanding the cholesterol metabolism and its relationship to whole body cholesterol homeostasis in this tissue. In this review the factors which influence cholesterol storage are discussed, with particular emphasis on the effects of diet and drug treatment in both animals and man. The uptake, synthesis, and mobilization of adipose tissue cholesterol appears to be mediated and/or regulated, as in other tissues, by the plasma lipoproteins, and these processes are examined with regard to both normal and pathologic states.

Studies were carried out to examine the effects of dietary fat and cholesterol on cholesterol homeostasis in man. 75 12-wk studies were carried out during intake of 35% of calories as either saturated or polyunsaturated fat, first low and then high in dietary cholesterol. Dietary fat and cholesterol intakes, plasma lipid and lipoprotein levels, cholesterol absorption and sterol synthesis in isolated blood mononuclear leukocytes were measured during each diet period. In 69% of the studies the subjects compensated for the increased cholesterol intake by decreasing cholesterol fractional absorption and/or endogenous cholesterol synthesis. When an increase in plasma cholesterol levels was observed there was a failure to suppress endogenous cholesterol synthesis. Plasma cholesterol levels were more sensitive to dietary fat quality than to cholesterol quantity. The results demonstrate that the responses to dietary cholesterol and fat are highly individualized and that most individuals have effective feedback control mechanisms.

Collagen-induced arthritis (CIA) in rodents is an experimental animal model that shares many clinical and pathologic findings with rheumatoid arthritis in man. Our previous findings suggested that the amelioration of CIA in mice by a fish oil diet was associated with macrophage accumulation and metabolism of eicosapentaenoic acid and a subsequently altered prostaglandin (PG) profile. In these experiments, we examined the role of gender and found that macrophages from female arthritis-susceptible B10.RIII or B10.G mice synthesized more PG and thromboxane than macrophages isolated from the males. Compared with males, female mice had higher circulating anti-type II collagen antibodies but were less likely to develop CIA. Females, especially those on a fish oil diet, developed a much less severe disease than the males. This supports our hypothesis that the type and/or amount of eicosanoid produced from the macrophage may alter the course of experimentally induced arthritis.