Functional diversity and nutritional content in a deep-sea faunal assemblage through total lipid, lipid class, and fatty acid analyses

Lipids are key compounds in marine ecosystems being involved in organism growth, reproduction, and survival. Despite their biological significance and ease of measurement, the use of lipids in deep-sea studies is limited, as is our understanding of energy and nutrient flows in the deep ocean. Here, a comprehensive analysis of total lipid content, and lipid class and fatty acid composition, was used to explore functional diversity and nutritional content within a deep-sea faunal assemblage comprising 139 species from 8 phyla, including the Chordata, Arthropoda, and Cnidaria. A wide range of total lipid content and lipid class composition suggested a diversified set of energy allocation strategies across taxa. Overall, phospholipid was the dominant lipid class. While triacylglycerol was present in most taxa as the main form of energy storage, a few crustaceans, fish, jellyfishes, and corals had higher levels of wax esters/steryl esters instead. Type and amount of energy reserves may reflect dietary sources and environmental conditions for certain deep-sea taxa. Conversely, the composition of fatty acids was less diverse than that of lipid class composition, and large proportions of unsaturated fatty acids were detected, consistent with the growing literature on cold-water species. In addition, levels of unsaturation increased with depth, likely suggesting an adaptive strategy to maintain normal membrane structure and function in species found in deeper waters. Although proportions of n-3 fatty acids were high across all phyla, representatives of the Chordata and Arthropoda were the main reservoirs of these essential nutrients, thus suggesting health benefits to their consumers.

The association of the lipidomic profile with features of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects up to 18% of reproductive-aged women with reproductive and metabolic complications. While lipidomics can identify associations between lipid species and metabolic diseases, no research has examined the association of lipid species with the pathophysiological features of PCOS. The aim of this study was to examine the lipidomic profile in women with and without PCOS. This study was a cross-sectional study in 156 age-matched pre-menopausal women (18-45 years, BMI >20 kg/m²; n = 92 with PCOS, n = 64 without PCOS). Outcomes included the association between the plasma lipidomic profile (325 lipid species (24 classes) using liquid chromatography mass spectrometry) and PCOS, adiposity, homeostasis assessment of insulin resistance (HOMA), sex hormone-binding globulin (SHBG) and free androgen index (FAI). There were no associations of the lipidomic profile with PCOS or testosterone. HOMA was positively associated with 2 classes (dihydroceramide and triacylglycerol), SHBG was inversely associated with 2 classes (diacylglycerol and triacylglycerol), FAI was positively associated with 8 classes (ceramide, phosphatidylcholine, lysophosphatidylcholine, phosphatidylethanolamine, lysophosphatidylethanolamine, phosphatidylinositol, diacylglycerol and triacylglycerol) and waist circumference was associated with 8 classes (4 positively (dihydroceramide, phosphatidylglycerol, diacylglycerol and triacylglycerol) and 4 inversely (trihexosylceramide, G_M3 ganglioside, alkenylphosphatidylcholine and alkylphosphatidylethanolamine)). The lipidomic profile was primarily related to central adiposity and FAI in women with or without PCOS. This supports prior findings that adiposity is a key driver of dyslipidaemia in PCOS and highlights the need for weight management through lifestyle interventions.

Comprehensive analysis of phospholipids and glycolipids in the opportunistic pathogen Enterococcus faecalis

Enterococcus faecalis is a Gram-positive, opportunistic, pathogenic bacterium that causes a significant number of antibiotic-resistant infections in hospitalized patients. The development of antibiotic resistance in hospital-associated pathogens is a formidable public health threat. In E. faecalis and other Gram-positive pathogens, correlations exist between lipid composition and antibiotic resistance. Resistance to the last-resort antibiotic daptomycin is accompanied by a decrease in phosphatidylglycerol (PG) levels, whereas multiple peptide resistance factor (MprF) converts anionic PG into cationic lysyl-PG via a trans-esterification reaction, providing resistance to cationic antimicrobial peptides. Unlike previous studies that relied on thin layer chromatography and spectrophotometry, we have performed liquid chromatography-tandem mass spectrometry (LC-MS/MS) directly on lipids extracted from E. faecalis, and quantified the phospholipids through multiple reaction monitoring (MRM). In the daptomycin-sensitive E. faecalis strain OG1RF, we have identified 17 PGs, 8 lysyl-PGs (LPGs), 23 cardiolipins (CL), 3 glycerophospho-diglucosyl-diacylglycerols (GPDGDAG), 5 diglucosyl-diacylglycerols (DGDAG), 3 diacylglycerols (DAGs), and 4 triacylglycerols (TAGs). We have quantified PG and shown that PG levels vary during growth of E. faecalis in vitro. We also show that two daptomycin-resistant (DapR) strains of E. faecalis have substantially lower levels of PG and LPG levels. Since LPG levels in these strains are lower, daptomycin resistance is likely due to the reduction in PG. This lipidome map is the first comprehensive analysis of membrane phospholipids and glycolipids in the important human pathogen E. faecalis, for which antimicrobial resistance and altered lipid homeostasis have been intimately linked.

Increased T cell immunoglobulin and mucin domain containing 4 (TIM-4) is negatively correlated with serum concentrations of interleukin-1β in type 2 diabetes

BACKGROUND

T cell immunoglobulin and mucin domain containing 4 (TIM-4), a novel immune regulator, is selectively expressed on antigen-presenting cells, especially macrophages and mature dendritic cells. Although TIM-4 plays key roles in mutiple immune diseases, whether it is involved in type 2 diabetes mellitus (T2D) remains unknown. The aim of the present study was to investigate the expression of TIM-4 in T2D and determine its significance in disease progression.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from T2D patients and healthy controls to measure TIM-4 mRNA expression by real-time polymerase chain reaction (PCR), and sera were collected to determine interleukin (IL)-1β concentrations and other clinical indicators (high-sensitivity C-reactive protein [hsCRP], total cholesterol, low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol, triglyceride, fasting glucose, HbA1c, aspartate aminotransferase, and alanine aminotransferase).

RESULTS

Expression of TIM-4 mRNA was increased significantly in PBMCs from T2D patients compared with healthy controls. There was a positive correlation between TIM-4 mRNA expression and serum concentrations of hsCRP. However, there was a negative correlation between TIM-4 mRNA expression and IL-1β concentrations, indicating the potential role for TIM-4 to negatively regulate IL-1β production. In addition, TIM-4 mRNA expression was negatively correlated with lowLDL-C, and there was a tendency for a negative relationship between TIM-4 mRNA expression and HbA1c.

CONCLUSIONS

The results of the present study indicate that TIM-4 contributes, at least in part, to the pathogenesis of T2D, possibly by regulating IL-1β.

[Effect of sacha inchi oil (plukenetia volúbilis l) on the lipid profile of patients with hyperlipoproteinemia]

We performed a pilot, experimental, open study in order to know the effect, effective dosage and secondary effects of sacha inchi´s (Plukenetia Huallabamba) [corrected] oil on the lipid profiles of patients with hypercholesterolemia. We included 24 patients of ages 35 to 75, to whom we measured total cholesterol (TC), HDL, triglycerides (Tg), glucose (G), non-esterified fatty acids (NEFA) and insulin (I) levels in blood, then we randomized them to receive sacha inchi oil orally 5 ml or 10 ml of a suspension of sacha inchi oil (2gr/5ml) for four months. The oil intake produced a decrease in the mean values of TC, and NEFA, and a rise in HDL in both subgroups. The subgroup receiving 10 ml was associated to an increase in the insulin levels. Sacha inchi oil appears to have beneficial effects on the lipid profile of patients with dyslipidemia, but their efficacy and security should be evaluated in randomized clinical trials.

[Body mass index influence on aortic valve stenosis]

AIM

The 12 months' observation of body mass index (BMI) influence on natural course of aortic valve stenosis (AVS).

PATIENTS

60 AVS patients who did not agree for operational treatment were divided into group A (n = 15) with BMI 20-25, group B (n = 27) with BMI 25,01-30 and group C BMI > 30.

METHODS

Plasma Lp(a), total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides and C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor (TNF-alpha) as well as titers of immunoglobulin (Ig) class G, A, M against chlamydia pneumoniae were measured every 12 months. Echo-cardiographic evaluation of aortic valve was also done every 12 months.

RESULTS

Means serum CRP at 12 month was the highest in group C. No differences in mean serum TNF-alpha and IL-6 levels as well as in Ig titers between groups A, B, C were found. At 12 month of observation HDL/total cholesterol ratio as well as HDL/LDL-cholesterol ratio were the lowest in group B. Left atrium diameter and right ventricle diameter were bigger in groups B and C compared to group A at the visit I and after 12 months of observation. Systolic intraventricular septum (IVS syst) thickness was the highest in group C at visit I. Diastolic left ventricle posterior wall thickness (LVPW) was the highest in group C during 12 months of observation.

CONCLUSION

The increase in fat tissue mass may lead to increase in inflammatory process and cardiac muscle remodeling in AVS patients.

A 24-month dietary carcinogenicity study of DAG (diacylglycerol) in rats

Toxicologic and carcinogenic effects of DAG (diacylglycerol) oil, administered in diet for 24 months to Crl:CD((R))(SD)-IGS BR rats, were evaluated using diet-restricted and ad libitum-fed groups. All dietary fat (consistently 5.5%) was provided by DAG and/or the control article, TG (triacylglycerol) oil. Dietary concentrations (% DAG/% TG) were 0%/5.5%, 1%/4.5%, 2.75%/2.75% and 5.5%/0%. Separate groups were fed the 0%/5.5% and 5.5%/0% diets ad libitum. Another group received the standard rodent diet (fat content 4.5%) on the restricted feeding regimen. Clinical condition, ophthalmic findings, palpable mass occurrence, body composition, clinical pathology parameters and incidence of neoplastic lesions were unaffected by DAG in comparison to TG. Groups fed the 5.5% (DAG and/or TG) fat diet when compared to the 4.5% fat diet group displayed lower survival, higher body weights, organ weights, percent body fat, higher fat-related serum chemistry parameters, incidence of microscopic changes in the heart, kidneys, liver, bone marrow, spleen, and incidences of pituitary and mammary gland neoplasms. Parameters more affected in all the ad libitum groups than in the restricted diet groups (regardless of test article) fed the same diet included survival, body weights, body fat, fat-related serum chemistry parameters, and incidences of heart, kidney and liver microscopic changes. However, the DAG and TG ad libitum-fed groups were not different from one another. Thus, DAG-treated animals had no higher risk of carcinogenic effects than rats fed on similar feeding regimens with a diet in which all dietary fat came from TG.

A 24-month dietary carcinogenicity study of DAG in mice

This study evaluated the possible carcinogenic effects of DAG (diacylglycerol) oil when given in the diet at levels up to 6.0% for 24 months to mice. Dietary fat was provided by DAG and/or the control article, TG (triacylglycerol oil). Dietary concentrations (% DAG/% TG) were 0%/6.0% (TG control), 1.5%/4.5%, 3.0%/3.0%, and 6.0%/0%. An additional control group received the standard rodent diet (fat content 4.5%). The clinical condition of the animals, ophthalmic findings, palpable mass occurrence, body weights and gross and histopathologic findings were unaffected by DAG in comparison to TG. The findings in DAG-treated groups were no different than those observed in the TG control group. The standard basal diet had 4.5% fat content. Both TG and/or DAG, when presented separately or together in the diet at a total fat level of 6.0%, resulted in some differences relative to the basal diet control (lower survival, higher body weights, lower food consumption, and higher incidences of macroscopic and microscopic findings), presumably related to the higher dietary fat content and/or the semi-purified diet. However, these parameters were similar in groups fed a diet with 6.0% dietary fat that was either DAG or TG. Thus, DAG at dietary concentrations up to 6.0% for 24 months produced no signs of systemic toxicity and had no effect on the incidence of neoplastic findings.

The Influence of Water Content of Triglyceride Oils on the Solubility of Steroids

PURPOSE

To determine if hydration of long- and medium-chain triglyceride oils (long = soybean and olive, medium = Miglyol 812) has a significant effect on the ability to solubize the model hydrophobic compounds progesterone, estradiol, and testosterone.

METHODS

Soybean, olive, and Miglyol 812 oils were treated in one of two ways: hydrated or desiccated (hydrated, then dried). Solubility of (3)H-labeled progesterone, estradiol, and testosterone in the triglycerides was measured by liquid scintillation counting.

RESULTS

Both hydration state and chain length of the triglycerides were shown to have a significant influence on the solubility of steroids. Solubility of estradiol hemihydrate and testosterone monohydrate in hydrated triglycerides is decreased by about 30%-40% compared with desiccated oils. The solubility of anhydrous testosterone was decreased by hydration of the oils due to conversion to the monohydrate crystalline form. In contrast, the solubility of progesterone was insensitive to the state of hydration of all oils.

CONCLUSIONS

Hydration of triglyceride oils caused a significant decrease in the solubility of steroids, which may form hydrates or hemihydrates. Results suggest the need for knowledge of the hydration state of triglyceride oils to be used as pharmaceutical excipients.

Substituting abacavir for hyperlipidemia-associated protease inhibitors in HAART regimens improves fasting lipid profiles, maintains virologic suppression, and simplifies treatment

Background

Hyperlipidemia secondary to protease inhibitors (PI) may abate by switching to anti-HIV medications without lipid effects.

Method

An open-label, randomized pilot study compared changes in fasting lipids and HIV-1 RNA in 104 HIV-infected adults with PI-associated hyperlipidemia (fasting serum total cholesterol >200 mg/dL) who were randomized either to a regimen in which their PI was replaced by abacavir 300 mg twice daily (n = 52) or a regimen in which their PI was continued (n = 52) for 28 weeks. All patients had undetectable viral loads (HIV-1 RNA <50 copies/mL) at baseline and were naïve to abacavir and non-nucleoside reverse transcriptase inhibitors.

Results

At baseline, the mean total cholesterol was 243 mg/dL, low density lipoprotein (LDL)-cholesterol 149 mg/dL, high density lipoprotein (HDL)-cholesterol 41 mg/dL, and triglycerides 310 mg/dL. Mean CD4+ cell counts were 551 and 531 cells/mm³ in the abacavir-switch and PI-continuation arms, respectively. At week 28, the abacavir-switch arm had significantly greater least square mean reduction from baseline in total cholesterol (-42 vs -10 mg/dL, P < 0.001), LDL-cholesterol (-14 vs +5 mg/dL, P = 0.016), and triglycerides (-134 vs -36 mg/dL, P = 0.019) than the PI-continuation arm, with no differences in HDL-cholesterol (+0.2 vs +1.3 mg/dL, P = 0.583). A higher proportion of patients in the abacavir-switch arm had decreases in protocol-defined total cholesterol and triglyceride toxicity grades, whereas a smaller proportion had increases in these toxicity grades. At week 28, an intent-to treat: missing = failure analysis showed that the abacavir-switch and PI-continuation arms did not differ significantly with respect to proportion of patients maintaining HIV-1 RNA <400 or <50 copies/mL or adjusted mean change from baseline in CD4+ cell count. Two possible abacavir-related hypersensitivity reactions were reported. No significant changes in glucose, insulin, insulin resistance, C-peptide, or waist-to-hip ratios were observed in either treatment arm, nor were differences in these parameters noted between treatments.

Conclusion

In hyperlipidemic, antiretroviral-experienced patients with HIV-1 RNA levels <50 copies/mL and CD4+ cell counts >500 cells/mm³, substituting abacavir for hyperlipidemia-associated PIs in combination antiretroviral regimens improves lipid profiles and maintains virologic suppression over a 28-week period, and it simplifies treatment.

Triacylglycerol molecular species are depleted to different extents in the myocardium of spontaneously hypertensive rats fed two oleic acid-rich oils

BACKGROUND

During the development of hypertension, glucose replaces triacylglycerols (TG) as the main energy source for the myocardium. However, there are no available studies investigating the TG molecular species composition of the myocardium in the spontaneously hypertensive rat (SHR). The objective of this study was to evaluate the effect of two dietary oils (virgin olive oil [VOO] and high-oleic sunflower oil [HOSO]) with a similar oleic acid content but different TG moieties on lipid composition and especially on TG molecular species, and also the effect of on lipoprotein lipase (LPL) activity, on the SHR myocardium.

METHODS

Wistar-Kyoto (WKY) rats and SHR were fed a baseline diet (BD) or a diet enriched by VOO or HOSO. Lipid classes, fatty acids of phospholipids (PL), TG, TG molecular species, and LPL were determined in the rat myocardium.

RESULTS

We found a depletion of the TG pool in the myocardium of SHR, which was comcomitant with cardiac hypertrophy. The loss of this lipid class was not corrected by dietary administration and was due to a nonspecific reduction in the fatty acid content and a specific lowering of dilinoleoyl-acyl-glycerol and di-and tri-saturated TG species. In addition, we observed an increased accumulation of arachidonic acid (20:4, n-6) in the PL of the SHR group fed BD or HOSO but not in that fed VOO, as compared with the corresponding WKY.

CONCLUSIONS

These results suggest that the depletion of TG in the heart of SHR is selective and is not reflected in the fatty acid profile. Although administration of either VOO or HOSO did not protect the heart against TG depletion, SHR fed VOO showed a more favorable PL compsition against changes caused by cardiac hypertrophy.

Triglyceride and coronary heart disease mortality in a 24-year follow-up study in Xi'an, China

PURPOSE

To study whether serum triglyceride (TG) was associated with coronary heart disease (CHD) mortality.

METHODS

A cohort analytic study carried out in a machinery factory in Xi'an, China on 1696 subjects aged 35 years or above (1124 men and 572 women) examined in 1976 and followed up till 2000.

RESULTS

At baseline, the mean serum total cholesterol (TC) and triglyceride (TG) was 4.64 and 1.16 mmol/L in men, 4.62 and 1.10 mmol/L in women, respectively. Three hundred six (239 men, 67 women) had died within 37,781 person-years of follow-up, with 49 CHD deaths (36 male, 13 female). The relative risk (95% confidence interval) of CHD mortality per mmol/L increase in TG was 2.13 (1.46-3.17) after adjusting for age, marital status, occupation, education, systolic blood pressure and TC. Dose-response relationship between TG levels by tertiles and CHD risk was found. Stratified analyses showed TG was an independent predictor for CHD mortality in subjects with lower or higher TC.

CONCLUSIONS

Chinese had lower levels of TC and TG than Western populations. This study provides new evidence that TG is an independent risk factor of CHD in subjects with lower or higher TC levels, and supports the lowering of cut-off value for elevated triglyceride.

Kefir consumption does not alter plasma lipid levels or cholesterol fractional synthesis rates relative to milk in hyperlipidemic men: a randomized controlled trial [ISRCTN10820810]

BACKGROUND

Fermented milk products have been shown to affect serum cholesterol concentrations in humans. Kefir, a fermented milk product, has been traditionally consumed for its potential health benefits but has to date not been studied for its hypocholesterolemic properties.

METHODS

Thirteen healthy mildly hypercholesterolemic male subjects consumed a dairy supplement in randomized crossover trial for 2 periods of 4 wk each. Subjects were blinded to the dairy supplement consumed. Blood samples were collected at baseline and after 4 wk of supplementation for measurement of plasma total, low-density lipoprotein, and high-density lipoprotein cholesterol and triglyceride concentrations, as well as fatty acid profile and cholesterol synthesis rate. Fecal samples were collected at baseline and after 2 and 4 wk of supplementation for determination of fecal short chain fatty acid level and bacterial content.

RESULTS

Kefir had no effect on total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol or triglyceride concentrations nor on cholesterol fractional synthesis rates after 4 wk of supplementation. No significant change on plasma fatty acid levels was observed with diet. However, both kefir and milk increased (p < 0.05) fecal isobutyric, isovaleric and propionic acids as well as the total amount of fecal short chain fatty acids. Kefir supplementation resulted in increased fecal bacterial content in the majority of the subjects.

CONCLUSIONS

Since kefir consumption did not result in lowered plasma lipid concentrations, the results of this study do not support consumption of kefir as a cholesterol-lowering agent.

Hyperreactive onchocerciasis exhibits reduced arachidonate and linoleate levels in serum triglycerides

The mechanism by which the minority of patients with onchocerciasis exhibiting the hyperreactive (sowda) form of the disease may be able to kill the microfilariae of Onchocerca volvulus is still poorly understood. In this study, the relative amounts of arachidonate and linoleate in serum phospholipids and triglycerides were investigated by gas chromatography both in patients infected with O. volvulus who exhibited either a hyperreactive or a generalized form of onchocerciasis and in persons with no filarial infections. Remarkable differences were observed in the serum triglycerides but not in the phospholipids. In comparison to persons without any filarial infection, significantly lower relative amounts of arachidonate--indicated by elevated triene-tetraene ratios--and of linoleate--indicated by lower diene + tetraene - triene values--were detected in patients with hyperreactive onchocerciasis, and less pronounced differences were found in persons with generalized onchocerciasis. The relationship between reduced amounts of arachidonate and linoleate in serum triglycerides and possible implications on the eicosanoid production in the host-parasite relationship leading to parasite elimination are discussed.

Depletion of linoleate induced by weight cycling is independent of extent of calorie restriction

Recent epidemiological studies have suggested that weight cycling induced by repeated dieting over time may increase the risk of cardiovascular disease. It is speculated that the increased mortality from coronary heart disease for people with a history of excessive weight cycling could be attributed to change in lipid metabolism. Previous studies have demonstrated that repeated cycling of 100% food restriction followed by ad libitum refeeding caused a depletion of linoleate and alpha-linolenate in rats. The objective of the present study was to test the hypothesis that the weight cycling-induced reduction in linoleate and alpha-linolenate is independent of extent of calorie restriction. Two consecutive weight cycles in three experiments were induced by 100% calorie restriction, 60% calorie restriction, and 36% calorie restriction, respectively, followed by ad libitum refeeding. As the consequence of the two weight cycles, linoleate and linolenate were decreased, whereas myristate, palmitate, and palmitoleate were proportionally increased in carcass and adipose tissue lipids. The results of all three experiments showed a preferential depletion of linoleate and alpha-linolenate without changes in final body weight, total body fat, and adipose tissue pads in the weight-cycled rats. In addition, the triacylglycerol species profile in the adipose tissue of weight-cycled rats was significantly remodeled, with a proportional depletion of linoleate-enriched triacylglycerol species (LLL, LLO, and LLP, where L, O, and P are linoleic, oleic, and palmitic acid, respectively) and a proportional accumulation of palmitate-enriched triacylglycerol species (OPPo, PPPo, and PPP, where Po is palmitoleic acid). We conclude that weight cycling changes the ratio of polyunsaturated fatty acids to saturated fatty acids and remodels the adipose tissue triacylglycerol species profile in rats.

The lipid, lipoprotein, and apolipoprotein effects of hydroxychloroquine in patients with systemic lupus erythematosus

Lipid, lipoprotein, and apolipoprotein effects of hydroxychloroquine were studied in 18 female patients with systemic lupus erythematosus (SLE) with mild or inactive disease. Patients were case matched (200-400 mg hydroxychloroquine daily vs no hydroxychloroquine) on several factors including daily corticosteroid dose in this cross sectional study. All had normal menstrual cycles; none smoked, used alcohol, were taking lipid altering medications or had other concurrent diseases. Patients taking hydroxychloroquine had 35-54% lower total triglyceride, VLDL-triglyceride, LDL-triglyceride, HDL-triglyceride, VLDL-cholesterol, and apolipoprotein CIII levels (p < 0.03). These results are encouraging in that hydroxychloroquine, in addition to being useful for alleviating the primary symptoms of SLE, may also be useful for ameliorating the adverse effects of corticosteroid therapy on triglyceride-rich lipoprotein metabolism.

Urinary organic acid excretion during feeding of medium-chain or long-chain triglyceride diets in patients with non-insulin-dependent diabetes mellitus

Medium-chain triglycerides (MCTs) are absorbed and metabolized differently from long-chain triglycerides (LCTs). Recent data indicate that MCTs may be useful as a dietary substitute in a variety of clinical disorders. The current studies were undertaken to characterize urinary organic acid excretion in patients with non-insulin-dependent diabetes mellitus during 4 d of an LCT or MCT diet. Urinary excretion of the dicarboxylic acids adipic, suberic, and 3-hydroxysebacic and the (omega-1) hydroxylation products 5-hydroxyhexanoic acid and 7-hydroxyoctanoic acid, was increased during MCT feeding as compared with LCT feeding. Urinary suberic and 7-hydroxyoctanoic acid excretions were increased 55- and 30-fold, respectively, during the MCT-substituted diet. Urinary organic acid profiles provide information on the fate of lipids during MCT feeding and may also be useful in assessing complicance during clinical trials employing MCT-substituted diets.

Plasma and white adipose tissue lipid composition in marmots

White adipose tissue biopsies and plasma samples were obtained from hibernating yellow-bellied marmots (Marmota flaviventris) maintained in the laboratory. In addition, biopsies and plasma samples were obtained from normothermic animals in the field and laboratory. Measurement of plasma free fatty acid (FA) levels indicated that winter laboratory animals exhibited increased lipolysis. Additionally, analysis of white adipose tissue triacylglycerol revealed that the FA composition of the storage fat in animals maintained on the standard laboratory diet is remarkably simple and uniform between different adipose depots in the same animal. Three FAs (palmitic, oleic, and linoleic acids) made up greater than 95% of the total. Triene (alpha-linolenate) was found in newly captured animals, but the percentage of this FA decreased rapidly when the animals were maintained on the standard laboratory diet. Throughout the hibernation season (October to April), white adipose tissue-saturated FA percentage decreased, monoene percentage remained constant, and diene percentage increased. Analysis of plasma FA composition suggested that these animals tended to metabolize saturated FAs from stored lipid during hibernation and that dienes were mobilized briefly after the last arousal from hibernation in spring. From these observations, we hypothesize that marmots preferentially metabolize saturated fats during the hibernation period and that essential FAs of the omega 6 series tend to be metabolized more slowly than other FAs. These characteristics suggest that marmots are a valuable animal model in which to study lipid metabolism.

Lipids of chicken epidermis

The lipids from chicken epidermis were analyzed by a combination of quantitative thin-layer and gas-liquid chromatography and by chemical and spectroscopic methods. The lipid groups present included wax diesters (34%), triglycerides (32%), sterols (11%), phospholipids (11%), nonphosphorus-containing sphingolipids (3%), beta-D-glucosylsterols (3%), 6-O-acyl-beta-D-glucosylsterols (2%), steryl esters (1%), cholesteryl sulfate (1%), and free fatty acids (1%). The major phospholipids were phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin, and the sphingolipids included ceramides, glucosylceramides, O-acylceramides, and O-acylglucosylceramides. Glucosylsterols and acylglucosylsterols have not been found in mammalian skin, and may be relevant to the evolutionary history of the epidermal water barrier. The wax diesters contained mainly 16-, 18-, and 20-carbon saturated fatty acids esterified to 20- through 24-carbon threo and erythro 2,3-diols, while the chicken epidermal triglycerides contained some very long-chain (26-40 carbon) saturated fatty acids. These wax diesters and unusual triglycerides may be of significance in human health.

Comparison of glucose, LCT, and LCT plus MCT as calorie sources for parenterally nourished rats

Protein and fat metabolism were studied in fed and protein-depleted rats. The rats were given one of three isocaloric, isonitrogenous nutrient mixes parenterally. The nutritional regimens differed in the source of nonprotein calories: i) glucose, ii) an emulsion containing long-chain fatty acid triglyceride esters (LCT), and iii) an emulsion containing both LCTs and medium-chain fatty acid triglycerides (MCT). Nitrogen balance, protein synthesis and breakdown, fat deposition in the liver, and the periuterine fat pads were measured using [15N]glycine as the tracer for the protein metabolism and deuterium for the lipid studies. Results are as follows. i) Nitrogen retention and protein synthesis were greater in the fed rats treated with glucose than with LCT. ii) Nitrogen fluxes were lower with LCT than with glucose. iii) Extensive lipogenesis in the liver was only found with the glucose-treated rats. iv) None of the caloric regimens promoted lipogenesis in the periuterine fat pads. v) With the two lipid-containing regimens there was a relative depletion of the depot fat in the periuterine fat pads relative to their glucose-treated counterparts. v) Although the MCT-containing emulsion did not cause hepatomegaly, its apparent caloric effectiveness was lower than that of either glucose or LCT. vi) Chain elongation is not a major pathway for MCT metabolism in parenterally nourished rats.

[Value of LDL-cholesterol determination in hyperlipoproteinemias]

Serum LDL-cholesterol concentrations were measured after precipitation in various forms of dyslipidaemia. LDL-cholesterol values were increased in hypercholesterolaemia and decreased in hypertriglyceridaemia. The LDL-cholesterol/total cholesterol ratio decreased with the presence of triglycerides. These data have prompted the authors to propose a classification of dyslipidaemia into hyper-and hypoLDLaemia. Such a classification would be helpful in the prevention, diagnosis and therapeutic surveillance of these diseases.