Separation of Lipoproteins for Quantitative Analysis of 14C-Labeled Lipid-Soluble Compounds by Accelerator Mass Spectrometry

To date, 14C tracer studies using accelerator mass spectrometry (AMS) have not yet resolved lipid-soluble analytes into individual lipoprotein density subclasses. The objective of this work was to develop a reliable method for lipoprotein separation and quantitative recovery for biokinetic modeling purposes. The novel method developed provides the means for use of small volumes (10-200 µL) of frozen plasma as a starting material for continuous isopycnic lipoprotein separation within a carbon- and pH-stable analyte matrix, which, following post-separation fraction clean up, created samples suitable for highly accurate 14C/12C isotope ratio determinations by AMS. Manual aspiration achieved 99.2 ± 0.41% recovery of [5-14CH3]-(2R, 4'R, 8'R)-α-tocopherol contained within 25 µL plasma recovered in triacylglycerol rich lipoproteins (TRL = Chylomicrons + VLDL), LDL, HDL, and infranatant (INF) from each of 10 different sampling times for one male and one female subject, n = 20 total samples. Small sample volumes of previously frozen plasma and high analyte recoveries make this an attractive method for AMS studies using newer, smaller footprint AMS equipment to develop genuine tracer analyses of lipophilic nutrients or compounds in all human age ranges.

Fitm2 is required for ER homeostasis and normal function of murine liver

The endoplasmic reticulum (ER)-resident protein fat storage-inducing transmembrane protein 2 (FIT2) catalyzes acyl-CoA cleavage in vitro and is required for ER homeostasis and normal lipid storage in cells. The gene encoding FIT2 is essential for the viability of mice and worms. Whether FIT2 acts as an acyl-CoA diphosphatase in vivo and how this activity affects the liver, where the protein was discovered, are unknown. Here, we report that hepatocyte-specific Fitm2 knockout (FIT2-LKO) mice fed a chow diet exhibited elevated acyl-CoA levels, ER stress, and signs of liver injury. These mice also had more triglycerides in their livers than control littermates due, in part, to impaired secretion of triglyceride-rich lipoproteins and reduced capacity for fatty acid oxidation. We found that challenging FIT2-LKO mice with a high-fat diet worsened hepatic ER stress and liver injury but unexpectedly reversed the steatosis phenotype, similar to what is observed in FIT2-deficient cells loaded with fatty acids. Our findings support the model that FIT2 acts as an acyl-CoA diphosphatase in vivo and is crucial for normal hepatocyte function and ER homeostasis in the murine liver.

Consuming High-Fat and Low-Fat Ground Beef Depresses High-Density and Low-Density Lipoprotein Cholesterol Concentrations, and Reduces Small, Dense Low-Density Lipoprotein Particle Abundance

We hypothesized that consumption of high-fat (HF) ground beef (24% fat) would not affect plasma concentrations of high-density lipoprotein cholesterol (HDL-C) or low-density lipoprotein (LDL-C), whereas low-fat (LF) ground beef (5% fat) would decrease HDL-C and LDL-C concentrations. In a randomized 2-period crossover, controlled feeding trial, 25 men (mean age and body mass index, 40 years and 31.2) consumed 115-g HF or LF patties, 5/week for 5 weeks with a 4-week washout. The HF treatment increased % energy from fat (p = 0.006) and saturated fat (p = 0.004) and tended (p = 0.060) to depress % energy from carbohydrates. The HF and LF treatments decreased the plasma concentrations of HDL-C (p = 0.001) and LDL-C (p = 0.011). Both ground beef treatments decreased the abundance of HDL_3a and increased the abundance of HDL₃ (p ≤ 0.003); the LF treatment also decreased the abundance of HDL_2b and HDL_2a (p ≤ 0.012). The HF and LF treatments decreased the abundance of LDL₃ and LDL₄ (p ≤ 0.024) and the HF treatment also decreased LDL₅ (p = 0.041). Contrary to our hypothesis, the HF treatment decreased plasma HDL-C and LDL-C concentrations despite increased saturated fat intake, and both treatments decreased the abundance of smaller, denser LDL subfractions.

Baseline Insulin Resistance Is a Determinant of the Small, Dense Low-Density Lipoprotein Response to Diets Differing in Saturated Fat, Protein, and Carbohydrate Contents

Individual responses to diet vary but causes other than genetics are poorly understood. This study sought to determine whether baseline values of homeostasis model assessment (HOMA-IR) was related to changes in small, dense low-density lipoprotein (sdLDL, i.e., LDL₄, d = 1.044–1.063 g/mL) amounts quantified by isopycnic density profiling, in mildly hypercholesterolemic subjects (n = 27) consuming one of three low saturated fatty acid (SFA) diets: Dietary Approaches to Stop Hypertension (DASH), Beef in an Optimal Lean Diet (BOLD) and BOLD plus extra protein (BOLD+) when compared to a higher-SFA healthy American diet (HAD). The diets were consumed in random order for 5 wk, with 1 wk between diets. BOLD+ reduced fractional abundance (%) LDL₄ (p < 0.05) relative to HAD, DASH and BOLD, and reductions in % LDL₄ correlated with reductions in triglycerides (p = 0.044), total cholesterol (p = 0.014), LDL cholesterol (p = 0.004) and apolipoprotein B (p < 0.001). Responses to the four diets were similar (~12% decrease in % LDL₄, p = 0.890) in the lower (<2.73 median) HOMA-IR subgroup but differed across diet conditions in the higher HOMA-IR subgroup (p = 0.013), in which % LDL₄ was reduced with BOLD+ (−11%), was unchanged in BOLD and increased with the HAD (8%) and DASH (6%) diets (p < 0.05 for BOLD+ vs. HAD). Individual responses to diet interventions are influenced by presence and degree of insulin resistance as measured by HOMA-IR.

Differential Modulation of 25-hydroxycholecalciferol on Innate Immunity of Broiler Breeder Hens

Simple Summary

No predominant changes between R- vs. Ad-feed intake on leukocyte defense against pathogens were observed in broiler breeder hens despite some differences in inflammatory and respiratory burst responses. Overall, supplemental 25-OH-D₃ had more pronounced effects on the innate immunity of Ad-hens. In vitro studies confirmed the differential effects of 25-OH-D₃ to rescue immune functions altered by glucose and/or palmitic acid exposure.

Abstract

Past immunological studies in broilers focused on juveniles within the rapid pre-slaughter growth period and may not reflect adult immune responses, particularly in breeders managed with chronic feed restriction (R). The study aimed to assess innate immune cell functions in respect to R vs. ad libitum (Ad) feed intake in breeder hens with and without dietary 25-hydroxycholecalciferol (25-OH-D₃) supplementation. Ad-feed intake consistently suppressed IL-1β secretion, respiratory burst, and cell livability in peripheral heterophils and/or monocytes along the feeding trial from the age of 51 to 68 weeks. Supplemental 25-OH-D₃ repressed IL-1β secretion and respiratory burst of both cells mostly in R-hens, but promoted monocyte phagocytosis, chemotaxis, and bacterial killing activity in Ad-hens in accompany with relieved hyperglycemia, hyperlipidemia, and systemic inflammation. Overnight cultures with leukocytes from R-hens confirmed the differential effects of 25-OH-D₃ to rescue immune functions altered by glucose and/or palmitic acid exposure. Studies with specific inhibitors further manifested the operative mechanisms via glucolipotoxicity in a cell type- and function-dependent manner. The results concluded no predominant changes between R- vs. Ad-feed intake on leukocyte defense against pathogens despite some differential differences, but supplemental 25-OH-D₃ exerts more pronounced effects in Ad-hens.

Whole and Isolated Protein Fractions Differentially Affect Gastrointestinal Integrity Markers in C57Bl/6 Mice Fed Diets with a Moderate-Fat Content

Various proteins or protein fractions reportedly positively affect gastrointestinal integrity and inflammation in diets providing >45% energy as fat. This study tested whether benefits were seen in diets providing 30% of energy as fat. Purified diets (PD) with isolated soy protein (ISP), dried whole milk powder (DWMP), milk fat globule membrane (MFGM), or milk protein concentrate (MPC) as protein sources were fed to C57BL/6J mice (n = 15/diet group) for 13 weeks. MFGM-fed mice were heaviest (p < 0.005) but remained within breeder norms. Growth rates and gut motility were similar for all PD-fed mice. FITC-dextran assessed gut permeability was lowest in DWMP and MFGM (p = 0.054); overall, plasma endotoxin and unprovoked circulating cytokines indicated a non-inflammatory state for all PD-fed mice. Despite differences in cecal butyrate and intestinal gene expression, all PDs supported gastrointestinal health. Whole milk provided more positive effects compared to its fractions. However, ISP-fed mice showed a >370%, (p < 0.006) increase in colonic myeloperoxidase activity indicative of tissue neutrophil infiltration. Surprisingly, FITC-dextran and endotoxin outcomes were many folds better in PD-fed mice than mice (strain, vendor, age and sex matched) fed a “chow-type” nutritionally adequate non-PD. Additional variables within a diet’s matrix appear to affect routine indicators or gastrointestinal health.

Unrestricted Feed Intake Induces β-Cell Death and Impairs Insulin Secretion in Broiler Breeder Hens

Simple Summary

Ad-feed intake caused transient hyperinsulinemia, but ultimately impaired insulin secretion and glucose clearance leading to hyperglycemia in broiler breeder hens. The impairments were operated at insulin gene expression and at pyruvate anaplerosis for ATP supply for insulin release. Lipotoxicity, inflammation, and cell apoptosis in the β-islets contributed to impaired insulin secretion in Ad-hens.

Abstract

Past studies regarding to insulin secretion and glucose disposal in chickens were focused on rapidly growing juvenile broilers and may not reflect glucose/insulin physiology in adulthood. The study aimed to assess insulin secretion and glucose disposal in respect to restricted (R) vs. ad libitum (Ad) feed intake for obesity development in broiler breeder hens. Hens at age of 26 weeks were continued on R rations, or allowed Ad-feed intake up to 45 weeks. Results from prandial changes and glucose tolerance test suggested that Ad-feed intake to 45 weeks impaired insulin secretion and glucose clearance, and, thus, caused hyperglycemia in accompany with transient hyperinsulinemia at age of 33 weeks (p < 0.05). The alterations were shown operating at both transcript and protein level of insulin gene expression per se and at ATP supply for insulin release as evidenced by consistent changes of enzyme expression and activity in pyruvate anaplerosis in the β-islets (p < 0.05). Ad-feed intake also increased β-islet triacylglycerol and ceramide accumulation and provoked interleukin-1β (IL-1β) production (p < 0.05), which were further manifested by a detrimental increase of caspase 3/7 activity and cell apoptosis (p < 0.05). Results support the conclusion that release to Ad-feed intake in broiler breeder hens transiently induced hyperinsulinemia along rapid bodyweight gain and adiposity, but later provoked lipotoxicity and inflammation leading to β-cell apoptosis and ultimately impaired insulin secretion and glucose disposal.

Effect of a low-fat diet on serum triglyceride and cholesterol concentrations and lipoprotein profiles in Miniature Schnauzers with hypertriglyceridemia

Background

Hypertriglyceridemia is common in Miniature Schnauzer (MS). Dietary management of hypertriglyceridemia is important, but no studies are available.

Hypothesis/Objectives

To evaluate the effect of a commercially available low‐fat diet on serum triglyceride and cholesterol concentrations and lipoprotein profiles in MS with hypertriglyceridemia.

Animals

Sixteen MS with hypertriglyceridemia and 28 MS without hypertriglyceridemia.

Methods

Prospective clinical trial. Four blood samples (1‐2 months before and 1 day before diet change and 2 and 3 months after the dogs were fed the low‐fat diet) were collected from the MS with hypertriglyceridemia.

Results

Serum triglyceride concentrations for the 2 samples after the diet change (median of sample 3 = 177 mg/dL; range, 48‐498; median of sample 4 = 168 mg/dL; range, 77‐745) were significantly lower than the 2 samples before the diet change (median of sample 1 = 480 mg/dL; range, 181‐1320; median of sample 2 = 493 mg/dL; range, 114‐1395; P < .001). Serum cholesterol concentrations for the 2 samples after the diet change (mean for sample 3 = 257 mg/dL, SD = 82.2; mean for sample 4 = 178 mg/dL, SD = 87.4) were also significantly lower than the 2 samples before the diet change (mean for sample 1 = 381 mg/dL, SD = 146.1; mean for sample 2 = 380 mg/dL, SD = 134.7; P < .001). Before the diet change, 15/16 (94%) of hyperlipidemic MS were classified as hyperlipidemic based on their lipoprotein profiles alone. After the diet change, significantly fewer MS (7/16; 44%; odds ratio = 19.3; 95% CI = 2.0‐184.0; P = .006) were classified as hyperlipidemic based on lipoprotein profile analysis.

Conclusions and Clinical Importance

The study diet was effective in reducing serum triglyceride and cholesterol concentrations and correcting lipoprotein profiles in MS with hypertriglyceridemia.

Dietary supplementation of 25-hydroxycholecalciferol improves cardiac function and livability in broiler breeder hens-amelioration of blood pressure and vascular remodeling

A supplement of 69 μg 25-hydroxycholecalciferol (25-OH-D3)/kg feed suppressed the mortality in feed-restricted broiler breeder hens and in hens allowed ad libitum feed intake (Ad-hens) in a feeding trial from age 26 to 60 wk. Outcomes for the mechanisms found that 25-OH-D3 relieved systemic hypoxia, pathological cardiac remodeling and arrhythmias, and hepatopathology to improve hens' livability. In the study, we further evaluated the effect of 25-OH-D3 on blood pressure and vascular remodeling relative to cardiac pathogenesis of sudden death (SD). Ad libitum feed intake increased mechanical loading and contributed to maladaptive cardiac hypertrophy as evidenced by consistently elevated peripheral arterial blood pressure in Ad-hens before SD (P < 0.05). In planned longitudinal measurements, Ad-hens also showed higher right ventricle systolic pressure and right ventricle diastolic pressure (RVDP) (P < 0.05). Supplemental 25-OH-D3 relieved peripheral hypertension and prevented time-dependent increases of RVDP in Ad-hens through the renin-angiotensin system and circulating nitric oxide availability and by regulating vascular remodeling including elastin/collagen ratio and smooth muscle cell proliferation in the pulmonary artery for improved elasticity/stiffness (P < 0.05). The antihypertensive effect via the renin-angiotensin system and nitric oxide regulation in respect to heart rate and arrhythmias by 25-OH-D3 were further confirmed in 51 week-old feed-restricted broiler breeder hens challenged with salt loading for 5 wk. Despite feed restriction, the most feed-efficient hens of feed-restricted groups also exhibited cardiac pathological hypertrophy, in conjunction with higher right ventricle systolic pressure, RVDP, plasma nitric oxide levels, and more dramatic arterial remodeling (P < 0.05). These results suggest that peripheral and pulmonary hypertension are the key drivers of SD and that 25-OH-D3 is an effective antihypertensive supplement to alleviate cardiac pathogenesis and improve livability in broiler breeder hens.

A novel NanoBiT-based assay monitors the interaction between lipoprotein lipase and GPIHBP1 in real time

The hydrolysis of triglycerides in triglyceride-rich lipoproteins by LPL is critical for the delivery of triglyceride-derived fatty acids to tissues, including heart, skeletal muscle, and adipose tissues. Physiologically active LPL is normally bound to the endothelial cell protein glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1), which transports LPL across endothelial cells, anchors LPL to the vascular wall, and stabilizes LPL activity. Disruption of LPL-GPIHBP1 binding significantly alters triglyceride metabolism and lipid partitioning. In this study, we modified the NanoLuc® Binary Technology split-luciferase system to develop a novel assay that monitors the binding of LPL to GPIHBP1 on endothelial cells in real time. We validated the specificity and sensitivity of the assay using endothelial lipase and a mutant version of LPL and found that this assay reliably and specifically detected the interaction between LPL and GPIHBP1. We then interrogated various endogenous and exogenous inhibitors of LPL-mediated lipolysis for their ability to disrupt the binding of LPL to GPIHBP1. We found that angiopoietin-like (ANGPTL)4 and ANGPTL3-ANGPTL8 complexes disrupted the interactions of LPL and GPIHBP1, whereas the exogenous LPL blockers we tested (tyloxapol, poloxamer-407, and tetrahydrolipstatin) did not. We also found that chylomicrons could dissociate LPL from GPIHBP1 and found evidence that this dissociation was mediated in part by the fatty acids produced by lipolysis. These results demonstrate the ability of this assay to monitor LPL-GPIHBP1 binding and to probe how various agents influence this important complex.

Serum triglyceride and cholesterol concentrations and lipoprotein profiles in dogs with naturally occurring pancreatitis and healthy control dogs

BACKGROUND

Previous studies have reported an association between hyperlipidemia and pancreatitis in dogs, but details of this association remain poorly defined.

HYPOTHESIS/OBJECTIVES

To compare serum triglyceride and cholesterol concentrations and lipoprotein profiles between dogs with naturally occurring pancreatitis and healthy dogs.

ANIMALS

Seventeen dogs with a clinical diagnosis of pancreatitis (Group 1) and 53 healthy control dogs (Group 2).

METHODS

Prospective case-control study.

RESULTS

In Group 1, 3/17 dogs (18%) had hypertriglyceridemia whereas in Group 2, 4/53 dogs (7.5%) had hypertriglyceridemia (odds ratio [OR], 2.63; 95% confidence interval [CI], 0.52-13.14; P = .35). A significant difference was found in serum triglyceride concentrations between Group 1 (median, 67 mg/dL) and Group 2 (median, 54 mg/dL; P = .002). In Group 1, 4/17 dogs (24%) had hypercholesterolemia, whereas 1/53 (1.9%) dogs in Group 2 had hypercholesterolemia (OR, 16; 95% CI, 1.64-155.5; P = .01). No significant difference was found in serum cholesterol concentrations between Group 1 (median, 209 mg/dL) and Group 2 (median, 227 mg/dL; P = .56). Lipoprotein profiles were significantly different between Group 1 and Group 2 dogs (Eigenvalues, 0.6719; R² = 1.0; P = .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Most dogs with pancreatitis (>70%) had serum triglyceride and cholesterol concentrations within reference intervals. In the small percentage of dogs that had hypertriglyceridemia, hypercholesterolemia, or both, increases were mild. Important differences were identified in lipoprotein profiles between dogs with pancreatitis and healthy control dogs. Dogs with pancreatitis had higher low-density lipoprotein fractions and lower triglyceride-rich lipoprotein and high-density lipoprotein fractions than healthy dogs.

Dietary supplementation of 25-hydroxycholecalciferol improves livability in broiler breeder hens

The study aimed to examine the effects of 25-hydroxycholecalciferol (25-OH-D3) on reproductive performance and livability in broiler breeder hens. Hens at age of 26 wk were continued on restricted rations (R) or allowed ad libitum feeding (Ad) to 60 wk of age. Ad-feed intake greatly impaired egg production and hens' livability. The survival rate in both R- and Ad-hens was improved (86.7 vs.78.9% and 48.2 vs.29.1%, respectively) as was egg production in R-hens (P < 0.05) by inclusion of 69 μg 25-OH-D3/kg feedin the basal diet. Sudden death (SD) was the cause of hen mortality; hens died earlier with heavier BW and greater absolute and relative abdominal fat weights than surviving hens. Interestingly, feed intake of SD hens became less than that of surviving hens after 37 and 42 wk in Ad- and R-groups, respectively, and led to a progressive decline in SD hen BW with a ratio (relative to surviving hens of the same age) equaled 1 around 34 to 38 wk in Ad-groups and 52 to 53 wk in R-groups. Supplementation of 25-OH-D3 ameliorated untoward changes of heart and respiratory rate of Ad-survivors after 29 wk (P < 0.05), but had no significant effects on SD AD-hens. In contrast to the surviving counterparts, all SD hens experienced persistently higher respiratory rates in conjunction with declining heart rates (P < 0.05), suggesting compromised cardiac function as the cause of SD, in which hens increased heart and respiratory rate for more blood and oxygen supply to meet the need for rapid BW gain and/or adiposity in response to Ad-feed intake or due to genetically better feed efficiency even under R-feed intake. As the cardiorespiratory derangements advanced, compromised cardiac function ultimately led to heart failure and sudden death despite spontaneous reductions in feed intake and BW loss in all SD hens. Provision of 69 μg 25-OH-D3/kg feed is an effective and practical method to improve livability in broiler breeder hens.

Effects of 1 year of exercise training versus combined exercise training and weight loss on body composition, low-grade inflammation and lipids in overweight patients with coronary artery disease: a randomized trial

Background

Dyslipidaemia and low-grade inflammation are central in atherogenesis and linked to overweight and physical inactivity. Lifestyle changes are important in secondary prevention of coronary artery disease (CAD). We compared the effects of combined weight loss and interval training with interval training alone on physical fitness, body composition, dyslipidaemia and low-grade inflammation in overweight, sedentary participants with CAD.

Methods

Seventy CAD patients, BMI 28–40 kg/m² and age 45–75 years were randomised to (1) 12 weeks’ aerobic interval training (AIT) at 90% of peak heart rate three times/week followed by 40 weeks’ AIT twice weekly or (2) a low energy diet (LED) (800–1000 kcal/day) for 8–10 weeks followed by 40 weeks’ weight maintenance including AIT twice weekly and a high-protein/low-glycaemic load diet. Effects of the intervention were evaluated by physical fitness, body weight and composition. Dyslipidaemia was described using both biochemical analysis of lipid concentrations and lipoprotein particle subclass distribution determined by density profiling. Low-grade inflammation was determined by C-reactive protein, soluble urokinase-type plasminogen activator receptor and tumour necrosis factor α. Effects on continuous outcomes were tested by mixed-models analysis.

Results

Twenty-six (74%) AIT and 29 (83%) LED + AIT participants completed the study. At baseline subject included 43 (78%) men; subjects averages were: age 63 years (6.2), body weight 95.9 kg (12.2) and VO₂peak 20.7 mL O₂/kg/min (4.9). Forty-six (84%) had pre-diabetes (i.e. impaired fasting glucose and/or impaired glucose tolerance). LED + AIT reduced body weight by 7.2 kg (− 8.4; − 6.1) and waist circumference by 6.6 cm (− 7.7; − 5.5) compared to 1.7 kg (− 0.7; − 2.6) and 3.3 cm (− 5.1; − 1.5) after AIT (within-group p < 0.001, between-group p < 0.001 and p = 0.018, respectively). Treatments caused similar changes in VO₂peak and lowering of total cholesterol, triglycerides, non-HDL cholesterol and low-grade inflammation. A shift toward larger HDL particles was seen following LED + AIT while AIT elicited no change.

Conclusions

Both interventions were feasible. Both groups obtained improvements in VO₂peak, serum-lipids and inflammation with superior weight loss and greater central fat loss following LED + AIT. Combined LED induced weight loss and exercise can be recommended to CAD patients.

Trial registration NCT01724567, November 12, 2012, retrospectively registered (enrolment ended in April 2013).

Liraglutide in combination with metformin may improve the atherogenic lipid profile and decrease C-reactive protein level in statin treated obese patients with coronary artery disease and newly diagnosed type 2 diabetes: A randomized trial

BACKGROUND AND AIMS

Atherosclerosis in obesity and type 2 diabetes (T2DM) is associated with low-grade inflammation (LGI) and dyslipidemia, where especially small, dense lipoprotein particles are atherogenic. The glucagon-like peptide-1 receptor agonist, liraglutide, reduces cardiovascular events by poorly understood mechanisms. We investigated the effect of liraglutide combined with metformin on LGI and lipoprotein density profiles in patients with stable coronary artery disease (CAD) and newly diagnosed T2DM.

METHODS

We conducted a randomized, double-blind, placebo-controlled, cross-over trial over a 12 + 12-week period, with ≥2-week wash-out.

INTERVENTION

liraglutide/metformin vs. placebo/metformin. Lipoproteins were separated by continuous density gradient ultracentrifugation, and LDL divided into five subfractions between 226 and 270 Å, considering particle size ≤255 Å as the atherogenic pattern. Plasma C-reactive protein and tumor necrosis factor-α were assessed by the enzyme-linked immunosorbent-assay.

RESULTS

28 out of 41 randomized patients completed all visits. Intention-to-treat analysis was performed but one patient had statin dosage and was excluded from the analysis. 95% of the patients were on statin therapy. Overall, liraglutide did not affect lipid subfractions or markers of LGI compared to placebo. The combination of liraglutide and metformin reduced the total LDL subfractions, primarily by reducing the most atherogenic subfraction LDL₅, and reduced CRP but not TNF-α. Explorative analyses suggested that the subfraction LDL₅ during the wash-out period rebounded significantly at least in a per-protocol analysis of the sub-group of patients starting the liraglutide therapy.

CONCLUSIONS

In patients with CAD and newly diagnosed T2DM on stable statin therapy, liraglutide combined with metformin may improve the atherogenic LDL lipid profile and CRP.

Novel lipoprotein density profiling in laminitic, obese, and healthy horses

Lipoproteins are water-miscible macromolecules enabling the transport of lipids in blood. In humans, altered proportions of lipoproteins are used to detect and classify metabolic diseases. Obesity and obesity-related comorbidities are common in horses. The pathophysiology of obesity is poorly understood and likely multifactorial. Development of new diagnostic tests to identify horses at risk of developing obesity to implement preventative measures is critical; however, a necessary first step to accomplish this goal is to improve our understanding of the pathophysiology of disease. Thus, the objective of this study was to characterize and compare lipoprotein profiles of horses with normal and excess body conditions, with and without laminitis using a novel method of continuous lipoprotein density profiling (CLPDP). Comparisons were made between 4 groups of horses: (1) laminitic, obese horses (n = 66); (2) laminitic, nonobese horses (n = 35); (3) nonlaminitic, obese horses (n = 41); and (4) nonlaminitic, nonobese horses (n = 95). Lipoprotein profiling, including evaluation of triglyceride-rich lipoprotein (TRL), low-density lipoproteins (LDLs), and high-density lipoproteins (HDLs) was performed using CLPDP, and all 4 groups were compared. A significant difference was observed among groups for the subfractions TRL, LDL1, LDL2, HDL2b, HDL2a, HDL3a, HDL3b, HDL3c, and total HDL. This is the first known description of CLPDP to characterize equine lipid profiles and holds promise as a useful method for lipid characterization of horses.

Evaluation of density gradient ultracentrifugation serum lipoprotein profiles in healthy dogs and dogs with exocrine pancreatic insufficiency

Changes in proportions of lipoprotein classes have been described in disease states in humans. In veterinary medicine, hyperlipidemia can cause complications, such as cutaneous xanthomas, liver disease, cholelithiasis, pancreatitis, glomerular disease, lipemia retinalis, or peripheral neuropathy, but there are few reports regarding lipoproteins in diseased animals. For canine serum, we partially validated continuous lipoprotein density profiling (CLPDP), a novel density gradient ultracentrifugation technique. We examined canine lipoproteins separated by CLPDP by transmission electron microscopy (TEM). We compared lipoprotein profiles between healthy control dogs ( n = 29) and dogs with exocrine pancreatic insufficiency (EPI; n = 28) using CLPDP. Dogs with EPI included those untreated (EPI-NT; n = 6) and those treated with enzyme supplementation (EPI-T; n = 22). Our preliminary assay validation showed that CLPDP was repeatable (CV = 11.2%) and reproducible (CV = 10.6%) in canine serum. The diameters of lipoproteins analyzed by TEM were similar to those reported previously. Dogs in the EPI-NT group had more severe dyslipidemia than dogs in the EPI-T group. Dogs in the EPI-T group had lipoprotein profiles similar to healthy control dogs. CLPDP might be a useful tool for evaluating dyslipidemia in dogs.

Altered lipoprotein profiles in cats with hepatic lipidosis

OBJECTIVES

The aim of this study was to assess serum lipoprotein profiles using rapid single-spin continuous lipoprotein density profiling (CLPDP) in healthy control cats and cats with hepatic lipidosis (HL).

METHODS

Analysis of serum lipoprotein profiles using the CLPDP was performed in 23 cats with HL and 20 healthy control cats. The area under the curve for each lipoprotein fraction, triglyceride (TG)-rich lipoproteins (TRLs), low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs), was calculated. Serum cholesterol and TG concentrations were measured using a clinical chemistry analyzer.

RESULTS

Serum cholesterol and TG concentrations were not significantly different between healthy control cats and cats with HL ( P = 0.5075 and P = 0.2541, respectively). LDL content was significantly higher in cats with HL than in healthy control cats ( P = 0.0001), while HDL content was significantly lower in cats with HL than in healthy control cats ( P = 0.0032). TRL content was not significantly different between the two groups ( P = 0.0699). The specific fraction (1.037-1.043 g/ml) within nominal LDL in serum distinguished healthy control cats from cats with HL with a sensitivity of 87% and a specificity of 90%.

CONCLUSIONS AND RELEVANCE

Serum lipoprotein profiles were altered in cats with HL, even though serum cholesterol and TG concentrations were not significantly different compared with healthy control cats. The CLPDP might be a useful tool for assessing lipid metabolism in cats with HL.

Obesity-associated cardiac pathogenesis in broiler breeder hens: Development of metabolic cardiomyopathy

Feed intake is typically restricted (R) in broiler hens to avoid obesity and improve egg production and livability. To determine whether improved heart health contributes to improved livability, fully adult 45-week-old R hens were allowed to consume feed to appetite (ad libitum; AL) up to 10 wk (70 d). Mortality, contractile functions, and morphology at 70 d, and measurements of cardiac hypertrophic remodeling at 7 d and 21 d were made and compared between R and AL hens. Outcomes for cardiac electrophysiology and mortality, reported separately, found increased mortality in AL hens in association with cardiac pathological hypertrophy and contractile dysfunction. The present study aimed to delineate metabolic cardiomyopathies underlying the etiology of obesity-associated cardiac pathology. Metabolic measurements were made in hens continued on R rations or assigned to AL feeding after 7 d and 21 days. AL feeding increased plasma insulin, glucose, and non-esterified fatty acid (NEFA) concentrations by 21 d (P < 0.05). Metabolic cardiomyopathy in AL-hens was confirmed by cardiac triacylglycerol (TG) and ceramide accumulation consistent with up-regulation of related enzyme gene expressions, and by increased indices of oxidation stress (P < 0.05). In contrast to R hens, cardiac pyruvate dehydrogenase (PDH) activity and glucose transporter (GLUT) gene expressions increased progressively while carnitine palmitoyltransferase-1 (CPT-1) transcript levels in AL hens declined from 7 d to 21 d (P < 0.05), reflecting a shift from an oxidative to a more glycolytic metabolism, a typical metabolic derangement associated with cardiac hypertrophic remodeling. Cardiac pathogenesis in AL hens was further indicated by increased leukocyte infiltrates, interleukin-1β (IL-1β) and IL-6 production, cellular apoptosis, interstitial fibrosis, and expression of the heart failure marker myosin heavy chain (MHC-β; cardiac muscle beta) (P < 0.05). Results support the conclusion that diabetic conditions, cardiac inflammation and lipotoxic metabolic derangements act as pathological cues to trigger pathogenic changes along cardiac hypertrophy in AL hens.

Obesity-associated cardiac pathogenesis in broiler breeder hens: Pathological adaption of cardiac hypertrophy

Broiler hens consuming feed to appetite (ad libitum; AL) show increased mortality. Feed restriction (R) typically improves reproductive performance and livability of hens. Rapidly growing broilers can exhibit increased mortality due to cardiac insufficiency but it is unknown whether the increased mortality of non-R broiler hens is also due to cardiac compromise. To assess cardiac growth and physiology in fully mature birds, 45-week-old hens were either continued on R rations or assigned to AL feeding for 7 or 21 days. AL hens exhibited increased bodyweight, adiposity, absolute and relative heart weight, ventricular hypertrophy, and cardiac protein/DNA ratio by d 21 (P < 0.05). Increased heart weights due to hypertrophic growth was attributed to enhanced IGF-1-Akt-FoxO1 signaling and its downstream target, translation initiation factor 4E-BP1 in conjunction with down-regulation of ubiquitin ligase atrogin-1/MAFbx (P < 0.05). Reduced activation of cardiac AMPK and downstream activation of ACC-1 in parallel with increased cardiac nitric oxide levels, calcineurin activity, and MAPK activation in AL hens (P < 0.05) suggested that metabolic derangement develops along the cardiovascular remodeling. These indictors of cardiac maladaptive hypertrophic growth were further supported by uregulation of heart failure markers, BNP and MHC-β (P < 0.05). Hens allowed AL feeding for 70 d exhibited a higher incidence of mortality (40% vs. 10%) in association with ascites, pericardial effusion, and ventricle dilation. A higher incidence of irregular ECG patterns and rhythmicity consistent with persistently elevated systolic blood pressure and ventricle fibrosis were observed in AL hens (P < 0.05). These observations support the conclusion that AL feeding in broiler hens results in maladaptive cardiac hypertrophy that progresses to overt pathogenesis in contractility and thereby increases mortality. Feed restriction provides clear physiological benefit to heart function of adult broiler hens.

Phenamil, an amiloride derivative, restricts long bone growth and alters keeled-sternum bone architecture in growing chickens

"Broiler-type" chickens are fast-grow-ing, heavy-bodied birds with high demands on bone quality. Phenamil increased mineralization in cultured murine mesenchymal stem cells. Phenamil effects were tested in 2 groups of weight and gender matched day-old broiler chickens (n = 13). Oral administration of 30 mg phenamil/kg body weight d 1 to 13 reduced growth of chicks d 5 to 14 (P = 0.002); with phenamil-treated (PT) chick body weight being 84% of vehicle-treated (VT) chicks' body weight on d 14. Tissues collected on d 15 showed that femur lengths and widths did not differ, but tibias from PT chicks were 6% shorter (P = 0.002) and 13% narrower (P = 0.012) with 18% thinner tibial cross-sections (P < 0.008) than in VT chicks. Angles of the caudal aspect of the anterior surface of keeled-sternums were 166° in PT chicks, flatter than the 148° found in VT chicks (P = 0.000). Total mineral content of both tibia and femur were lower in PT chicks (P = 0.005 for both). Bone Ca, P, and Mg (ppm) in ash were similar, but Ca:P was lower (1.70 vs 1.75) in PT versus VT chicks (P < 0.05). Osteocalcin was ∼20% lower (P = 0.020), PINP was ∼45% higher (P = 0.000) in PT chicks. Carboxy-terminal telopeptide type I collagen (ICTP) and cross-linked N-telopeptide of type I collagen (NTX1) were similar in the 2 groups. Phenamil had unexpected and detrimental effects on bone formation in growing broiler chicks, reducing linear skeletal growth and markedly changing bone architecture.

Impaired thermogenesis and sharp increases in plasma triglyceride levels in GPIHBP1-deficient mice during cold exposure

Glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1 (GPIHBP1), an endothelial cell protein, binds LPL in the subendothelial spaces and transports it to the capillary lumen. In Gpihbp1^-/- mice, LPL remains stranded in the subendothelial spaces, causing hypertriglyceridemia, but how Gpihbp1^-/- mice respond to metabolic stress (e.g., cold exposure) has never been studied. In wild-type mice, cold exposure increases LPL-mediated processing of triglyceride-rich lipoproteins (TRLs) in brown adipose tissue (BAT), providing fuel for thermogenesis and leading to lower plasma triglyceride levels. We suspected that defective TRL processing in Gpihbp1^-/- mice might impair thermogenesis and blunt the fall in plasma triglyceride levels. Indeed, Gpihbp1^-/- mice exhibited cold intolerance, but the effects on plasma triglyceride levels were paradoxical. Rather than falling, the plasma triglyceride levels increased sharply (from ∼4,000 to ∼15,000 mg/dl), likely because fatty acid release by peripheral tissues drives hepatic production of TRLs that cannot be processed. We predicted that the sharp increase in plasma triglyceride levels would not occur in Gpihbp1^-/-Angptl4^-/- mice, where LPL activity is higher and baseline plasma triglyceride levels are lower. Indeed, the plasma triglyceride levels in Gpihbp1^-/-Angptl4^-/- mice fell during cold exposure. Metabolic studies revealed increased levels of TRL processing in the BAT of Gpihbp1^-/-Angptl4^-/- mice.

Lipoprotein lipase reaches the capillary lumen in chickens despite an apparent absence of GPIHBP1

In mammals, GPIHBP1 is absolutely essential for transporting lipoprotein lipase (LPL) to the lumen of capillaries, where it hydrolyzes the triglycerides in triglyceride-rich lipoproteins. In all lower vertebrate species (e.g., birds, amphibians, reptiles, fish), a gene for LPL can be found easily, but a gene for GPIHBP1 has never been found. The obvious question is whether the LPL in lower vertebrates is able to reach the capillary lumen. Using purified antibodies against chicken LPL, we showed that LPL is present on capillary endothelial cells of chicken heart and adipose tissue, colocalizing with von Willebrand factor. When the antibodies against chicken LPL were injected intravenously into chickens, they bound to LPL on the luminal surface of capillaries in heart and adipose tissue. LPL was released rapidly from chicken hearts with an infusion of heparin, consistent with LPL being located inside blood vessels. Remarkably, chicken LPL bound in a specific fashion to mammalian GPIHBP1. However, we could not identify a gene for GPIHBP1 in the chicken genome, nor could we identify a transcript for GPIHBP1 in a large chicken RNA-seq data set. We conclude that LPL reaches the capillary lumen in chickens - as it does in mammals - despite an apparent absence of GPIHBP1.

Feed restriction ameliorates metabolic dysregulation and improves reproductive performance of meat-type country chickens

Restricted feed intake improves egg production in Cornish×Plymouth Rock (broiler) hens. Red-feather (RF) and Black-feather (BF) chickens are 2 local strains of non-broiler meat-type chickens whose egg production has declined with continued selection for meat yield, and which are unstudied regarding restricted feeding and egg-laying improvement. Sixteen week old RF and BF pullets were either fed ad libitum (AL) or restricted to 85% AL intake (R). At 35wk and 50wk R-hens showed improved egg production and less abnormal ovarian morphology than AL-hens. Obesity, hepatic steatosis, lipotoxic change to plasma lipids, and systemic inflammation induced by AL feeding in RF and BF hens were similar to those observed previously in AL-broiler hens. Egg production was negatively correlated to body weight, fractional abdominal fat weight and plasma NEFA concentrations in AL hens (P<0.05). AL-hen hierarchical follicles accumulated ceramide and increased interleukin-1β production (P<0.05) in conjunction with increased granulosa cell apoptosis, follicle atresia, ovarian regression, and reduced plasma 17β-estradiol concentrations (P<0.05). The present outcomes from non-broiler but nevertheless meat-type country chicken strains indicate that selection for rapid growth and increased meat yield fundamentally changes energy metabolism in a way that renders hens highly susceptible to reproductive impairment from lipid dysregulation and pro-inflammatory signaling rather than impaired resource allocation per se.

Incorporation of therapeutically modified bacteria into gut microbiota inhibits obesity

Metabolic disorders, including obesity, diabetes, and cardiovascular disease, are widespread in Westernized nations. Gut microbiota composition is a contributing factor to the susceptibility of an individual to the development of these disorders; therefore, altering a person's microbiota may ameliorate disease. One potential microbiome-altering strategy is the incorporation of modified bacteria that express therapeutic factors into the gut microbiota. For example, N-acylphosphatidylethanolamines (NAPEs) are precursors to the N-acylethanolamide (NAE) family of lipids, which are synthesized in the small intestine in response to feeding and reduce food intake and obesity. Here, we demonstrated that administration of engineered NAPE-expressing E. coli Nissle 1917 bacteria in drinking water for 8 weeks reduced the levels of obesity in mice fed a high-fat diet. Mice that received modified bacteria had dramatically lower food intake, adiposity, insulin resistance, and hepatosteatosis compared with mice receiving standard water or control bacteria. The protective effects conferred by NAPE-expressing bacteria persisted for at least 4 weeks after their removal from the drinking water. Moreover, administration of NAPE-expressing bacteria to TallyHo mice, a polygenic mouse model of obesity, inhibited weight gain. Our results demonstrate that incorporation of appropriately modified bacteria into the gut microbiota has potential as an effective strategy to inhibit the development of metabolic disorders.

Feed intake alters immune cell functions and ovarian infiltration in broiler hens: implications for reproductive performance

Leukocytes are known to participate in ovarian activities in several species, but there is a surprising lack of information for the common chicken. Broiler hens consuming feed ad libitum (AL) exhibit a number of ovarian irregularities, but leukocyte functions are unstudied. In contrast to feed-restricted (R) hens, AL feeding for 7 wk significantly reduced egg production and clutch length while increasing pause length and atretic follicle numbers (P < 0.05). Granulosa cells from F1 follicles of AL hens contained less progesterone, and follicle walls were thicker with loose fibrous morphology and had less collagenase-3-like gelatinolytic activity but more IL-1beta (P < 0.05) production, suggestive of slower maturation in ovulatory process and inflamed necrosis. Interestingly, while highly infiltrated with immune cells, particularly heterophils, IL-1beta, MMP-22-like, and gelatinase A activities were reduced in AL hen peripheral heterophils and monocytes (P < 0.05); however, AL monocytes showed an increase in phagocytosis rate (P < 0.05). Generation of reactive oxygen intermediates was also suppressed in AL heterophils but increased in AL monocytes (P < 0.05). In contrast to leukocyte-free control, both AL and R heterophils and monocytes suppressed progesterone production and increased cell death in a dose-dependent manner when coincubated with granulosa cells at different ratios (P < 0.05). AL monocytes suppressed progesterone production more, but AL heterophils were less proapoptotic when compared to their R counterparts (P < 0.05). Alterations of cellular ceramide content (P < 0.05) corresponded to the discrepancy between heterophil and monocyte functionality. In conclusion, leukocyte dysfunction contributes to impaired ovarian activities of overfed broiler hens.

Obesity-induced dysfunctions in female reproduction: lessons from birds and mammals

Follicle wall rupture and ovum release, i.e., ovulation, has been described as a controlled inflammatory event. The process involves tissue remodeling achieved through leukocyte-mediated proteolysis. In birds, ovulation is the first step in the energy-intensive process of egg formation, yet hens that consume energy in excess of productive requirements experience impaired egg-laying ability. Broiler chickens, selected for rapid lean muscle gain, and coincidentally hyperphagia, develop adult obesity when given free access to feed. Obese broiler hens experience elevated circulating concentrations of insulin and leptin, changes in lipid and lipoprotein metabolism similar to those of human metabolic syndrome, as well as increased systemic inflammation. Overall, the manifestations in poultry are similar to those of women with polycystic ovary syndrome. It was shown recently that, in hens, as in mammals, changes in lipid synthesis and metabolism cause granulosa cell apoptosis and altered immune function and hormone production, further compromising ovarian function. To date, there is insufficient information on the means used by the ovary to direct leukocyte function toward successful ovulation. More information is needed regarding the control of proteolytic actions by leukocytes with regards to the roles of specific enzymes in both ovulation and atresia. The broiler hen has provided unique insight into the interrelations of energy intake, obesity, leukocyte function, and reproduction. Additional work with this model can serve the dual purposes of improving avian reproduction and providing novel insights into polycystic ovary syndrome in women.

Identification of important regressor groups, subgroups and individuals via regularization methods: application to gut microbiome data

MOTIVATION

Gut microbiota can be classified at multiple taxonomy levels. Strategies to use changes in microbiota composition to effect health improvements require knowing at which taxonomy level interventions should be aimed. Identifying these important levels is difficult, however, because most statistical methods only consider when the microbiota are classified at one taxonomy level, not multiple.

RESULTS

Using L1 and L2 regularizations, we developed a new variable selection method that identifies important features at multiple taxonomy levels. The regularization parameters are chosen by a new, data-adaptive, repeated cross-validation approach, which performed well. In simulation studies, our method outperformed competing methods: it more often selected significant variables, and had small false discovery rates and acceptable false-positive rates. Applying our method to gut microbiota data, we found which taxonomic levels were most altered by specific interventions or physiological status.

AVAILABILITY

The new approach is implemented in an R package, which is freely available from the corresponding author.

CONTACT

tpgarcia@srph.tamhsc.edu

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Structured variable selection with q-values

When some of the regressors can act on both the response and other explanatory variables, the already challenging problem of selecting variables when the number of covariates exceeds the sample size becomes more difficult. A motivating example is a metabolic study in mice that has diet groups and gut microbial percentages that may affect changes in multiple phenotypes related to body weight regulation. The data have more variables than observations and diet is known to act directly on the phenotypes as well as on some or potentially all of the microbial percentages. Interest lies in determining which gut microflora influence the phenotypes while accounting for the direct relationship between diet and the other variables A new methodology for variable selection in this context is presented that links the concept of q-values from multiple hypothesis testing to the recently developed weighted Lasso.

Novel lipoprotein density profiling in healthy dogs of various breeds, healthy Miniature Schnauzers, and Miniature Schnauzers with hyperlipidemia

BACKGROUND

Despite the importance of abnormalities in lipoprotein metabolism in clinical canine medicine, the fact that most previously used methods for lipoprotein profiling are rather laborious and time-consuming has been a major obstacle to the wide clinical application and use of lipoprotein profiling in this species. The aim of the present study was to assess the feasibility of a continuous lipoprotein density profile (CLPDP) generated within a bismuth sodium ethylenediaminetetraacetic acid (NaBiEDTA) density gradient to characterize and compare the lipoprotein profiles of healthy dogs of various breeds, healthy Miniature Schnauzers, and Miniature Schnauzers with primary hypertriacylglycerolemia. A total of 35 healthy dogs of various breeds with serum triacylglycerol (TAG) and cholesterol concentrations within their respective reference intervals were selected for use as a reference population. Thirty-one Miniature Schnauzers with serum TAG and cholesterol concentrations within their respective reference intervals and 31 Miniature Schnauzers with hypertriacylglyceridemia were also included in the study.

RESULTS

The results suggest that CLPDP using NaBiEDTA provides unique diagnostic information in addition to measurements of serum TAG and cholesterol concentrations and that it is a useful screening method for dogs with suspected lipoprotein metabolism disorders. Using the detailed and continuous density distribution information provided by the CLPDP, important differences in lipoprotein profiles can be detected even among dogs that have serum TAG and cholesterol concentrations within the reference interval. Miniature Schnauzers with serum TAG and cholesterol concentrations within the reference interval had significantly different lipoprotein profiles than dogs of various other breeds. In addition, it was further established that specific lipoprotein fractions are associated with hypertriacylglyceridemia in Miniature Schnauzers.

CONCLUSIONS

The results of the present study suggest that density gradient ultracentrifugation using NaBiEDTA is a useful screening method for the study of lipoprotein profiles in dogs. Therefore, this method could potentially be used for diagnostic purposes for the separation of dogs suspected of having lipoprotein abnormalities from healthy dogs.

Mobilization of ectopic yolk in Gallus domesticus: a novel reverse lipid transport process

In many oviparous animals, bursting type atresia of ovarian follicles occurs during the reproductive cycle resulting in the escape of yolk into the extracellular compartment. In birds, this ectopic yolk is rapidly cleared by an unknown process that involves the appearance of yolk-engorged macrophage-like cells. To study this unique type of lipid transport, we injected young male chickens intra-abdominally with egg yolk. Absorption of egg yolk from the body cavity markedly increased the triacylglyceride-rich fraction (TRL) of plasma lipoproteins and was coincident with increased levels of plasma triacylglycerides (TAG) but not non-esterified fatty acids (NEFA). Thus, the transport of yolk lipids from the abdominal cavity appears to occur in lipoproteins and be more similar to the transport of hepatic TAG to the periphery via lipoproteins than to transport of adipose TAG to the periphery via NEFA released by the action of lipases. When macrophages were exposed to yolk in vitro, they quickly phagocytized yolk; however, it is unclear if this level of phagocytosis contributes significantly to total yolk clearance. Instead, the chicken macrophage may function more as a facilitator of yolk clearance through modification of yolk lipoproteins and the regulation of the local and systemic immune response to ectopic yolk. Yolk appears to be anti-inflammatory in nature. Yolk did not increase inflammatory cytokines IL-1, IL-6 and IFNγ either in vivo or in vitro; in fact, yolk dampened many inflammatory changes caused by lipopolysaccharide (LPS). Conversely, LPS-induced inflammation retarded yolk clearance from the abdominal cavity and plasma TAG levels.

Palmitic acid in chicken granulosa cell death-lipotoxic mechanisms mediate reproductive inefficacy of broiler breeder hens

In vivo and in vitro approaches were used to elucidate mechanisms of palmitate-induced cytotoxicity of follicle granulosa cells in fuel-overloaded broiler hens. In contrast to their energy-restricted counterparts, broiler breeder hens fed ad libitum for 2 wk had dyslipidemia, atresia within hierarchical ovarian follicles, and a 34% reduction in egg production (P < 0.05). Based on vital staining of freshly isolated granulosa cells with annexin V/propidium iodide, there were increases in apoptosis consistent with suppressed Akt activation (P < 0.05). Supplementing primary granulosa cell cultures with 0.5 mM palmitate for 48 or 96 h increased apoptosis (P < 0.05). Palmitate-induced cell death was accompanied by increased acyl-CoA oxidase, carnitine palmitoyl transferase-1, serine palmitoyl transferase, and sphingomyelinase transcripts and increased concentrations of proinflammatory interleukin-1β (P < 0.05). Triacsin-C inhibition of fatty acyl-CoA synthesis blunted interleukin-1β production and rescued granulosa cultures from palmitate-induced cell death. That there was partial to complete prevention of cell death with addition of the free radical scavenger pyrrolidine dithiocarbamate, the sphingomyelinase inhibitor imipramine, or the de novo ceramide synthesis inhibitor fumonisin B1, supported the notion that palmitate-induced granulosa cell cytotoxicity operated through a palmitate-derived metabolite. Palmitoyl-CoA may be channeled into β-oxidation and/or into bioactive metabolites that increase free radical generation, an inflammatory response, and ceramide production. In conclusion, palmitate-derived metabolites activated apoptotic machinery in avian granulosa cells, which caused ovarian follicular atresia and reduced egg production in fuel-overloaded broiler breeder hens.

Palmitoleate induces hepatic steatosis but suppresses liver inflammatory response in mice

The interaction between fat deposition and inflammation during obesity contributes to the development of non-alcoholic fatty liver disease (NAFLD). The present study examined the effects of palmitoleate, a monounsaturated fatty acid (16∶1n7), on liver metabolic and inflammatory responses, and investigated the mechanisms by which palmitoleate increases hepatocyte fatty acid synthase (FAS) expression. Male wild-type C57BL/6J mice were supplemented with palmitoleate and subjected to the assays to analyze hepatic steatosis and liver inflammatory response. Additionally, mouse primary hepatocytes were treated with palmitoleate and used to analyze fat deposition, the inflammatory response, and sterol regulatory element-binding protein 1c (SREBP1c) activation. Compared with controls, palmitoleate supplementation increased the circulating levels of palmitoleate and improved systemic insulin sensitivity. Locally, hepatic fat deposition and SREBP1c and FAS expression were significantly increased in palmitoleate-supplemented mice. These pro-lipogenic events were accompanied by improvement of liver insulin signaling. In addition, palmitoleate supplementation reduced the numbers of macrophages/Kupffer cells in livers of the treated mice. Consistently, supplementation of palmitoleate decreased the phosphorylation of nuclear factor kappa B (NF-κB, p65) and the expression of proinflammatory cytokines. These results were recapitulated in primary mouse hepatocytes. In terms of regulating FAS expression, treatment of palmitoleate increased the transcription activity of SREBP1c and enhanced the binding of SREBP1c to FAS promoter. Palmitoleate also decreased the phosphorylation of NF-κB p65 and the expression of proinflammatory cytokines in cultured macrophages. Together, these results suggest that palmitoleate acts through dissociating liver inflammatory response from hepatic steatosis to play a unique role in NAFLD.

Effect of dietary omega-3 fatty acids on red blood cell lipid composition and plasma metabolites in the cockatiel, Nymphicus hollandicus

Although dietary n-3 fatty acids have been extensively studied in poultry, they have not yet been prospectively investigated in psittacines, despite potential benefits for preventing and treating atherosclerosis, osteoarthritis, and other chronic disease processes. The objectives of this study were to investigate the incorporation of dietary n-3 fatty acids into red blood cells (RBC) and to determine the effects of supplementation of psittacine diets with fish or flax oil on plasma lipids and lipoproteins in the cockatiel. Adult cockatiels were fed a custom-formulated diet containing either 4% (wt/wt, as-fed) beef tallow (CON), 3% fish oil + 1% tallow (FSH), or 3.5% flax oil + 0.5% tallow (FLX; n = 20 per diet group). Baseline measurements were obtained for RBC fatty acid composition, triacylglycerides (TAG), and cholesterol. After 8 to 13 wk on the study diets, plasma chemistry profiles, lipoprotein density profiles, and RBC fatty acid composition were determined. At 8 wk, total plasma cholesterol was least in FSH birds (P < 0.05) and TAG concentrations were less in FSH birds than FLX birds (P < 0.05). Total n-3 fatty acids, docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid were markedly greater in the RBC of FSH birds than FLX or CON birds (P < 0.05). Alpha linolenic acid was greatest in FLX (P < 0.05). Initial and final BW, and nonlipid plasma chemistry values did not differ among diet groups. No adverse effects of dietary supplementation of cockatiels with 3.5% flax oil or 3% fish oil were observed during the 13-wk feeding period. Although fish and flax oils provided similar total n-3 PUFA to the diets, fish oil caused greater reductions in cholesterol and TAG, and greater total RBC n-3 incorporation. Thus, dietary modification of psittacine diets with long chain n-3 PUFA from fish oil appears safe and may be beneficial to these long-lived companion birds.

Ceramide accumulation and up-regulation of proinflammatory interleukin-1β exemplify lipotoxicity to mediate declines of reproductive efficacy of broiler hens

The study was conducted to delineate fundamental mechanisms that initiate the deleterious effect of fuel overloading on reproductive efficacy of broiler breeder hens. Sixty hens at age 26 wk were fed recommended amounts of feed (160 g/d per hen) or allowed voluntary feeding (approximately 30% more than restriction). At age 35 and 50 wk, hens were sampled for further analyzes. Voluntary feeding resulted in poor egg production, high rate of mortality, and abnormal ovarian structure (mainly overt hierarchical follicle atresia at age 35 wk and ovarian involution at age 50 wk). In contrast to feed-restricted hens, voluntary feeding also induced metabolic dysregulations that comprised enhanced adiposity; hepatic triacylglycerol accumulation; and elevated concentrations of plasma glucose, NEFAs, very low density lipoprotein, triacylglycerol, phospholipids, and sphingomyelin (P < 0.05). Furthermore, hepatic and circulating ceramide and sphingomyelin accumulation, and up-regulation of proinflammatory IL-1β expression in liver and adipose tissues (P < 0.05) systemically manifested the development of lipotoxicity in feed-satiated hens. Lipotoxicity leading to impaired ovarian dysfunctions, including follicle atresia, ovarian regression, and a decline of circulating estradiol levels (P < 0.05) in feed-satiated hens, was further exemplified by ceramide accumulation and up-regulation of IL-1β, serine palmitoyltransferase, and sphingomyelinase transcript abundance, but suppressed protein kinase Akt activation (P < 0.1 to 0.05) within the hierarchical follicles. This study provides the first in vivo evidence of the actions of ceramide and IL-1β in mediating overfeeding-induced follicle atresia and progression of ovarian involution in broiler hens.

Consumption of high-oleic acid ground beef increases HDL-cholesterol concentration but both high- and low-oleic acid ground beef decrease HDL particle diameter in normocholesterolemic men

On the basis of previous results from this laboratory, this study tested the hypothesis that ground beef high in MUFA and low in SFA would increase the HDL-cholesterol (HDL-C) concentration and LDL particle diameter. In a crossover dietary intervention, 27 free-living normocholesterolemic men completed treatments in which five 114-g ground beef patties/wk were consumed for 5 wk with an intervening 4-wk washout period. Patties contained 24% total fat with a MUFA:SFA ratio of either 0.71 (low MUFA, from pasture-fed cattle) or 1.10 (high MUFA, from grain-fed cattle). High-MUFA ground beef provided 3.21 g more 18:1(n-9), 1.26 g less 18:0, 0.89 g less 16:0, and 0.36 g less 18:1(trans) fatty acids per patty than did the low-MUFA ground beef. Both ground beef interventions decreased plasma insulin and HDL(2) and HDL(3) particle diameters and increased plasma 18:0 and 20:4(n-6) (all P ≤ 0.05) relative to baseline values. Only the high-MUFA ground beef intervention increased the HDL-C concentration from baseline (P = 0.02). The plasma TG concentration was positively correlated with the plasma insulin concentration (r = 0.40; P < 0.001) and negatively correlated with HDL-C (r = -0.47; P < 0.001) and plasma 18:0 (r = -0.24; P < 0.01). Plasma insulin and HDL diameters were not correlated (r = 0.01; P > 0.50), indicating that reductions in these measures were not coordinately regulated. The data indicate that dietary beef interventions have effects on risk factors for cardiovascular disease that are independent (insulin, HDL diameters) and dependent (HDL-C) on beef fatty acid composition.

Copper and zinc balance in exercising horses fed 2 forms of mineral supplements

Studies comparing the absorption and retention of various forms of trace minerals in horses have yielded mixed results. The objective of this study was to compare Cu and Zn absorption and retention in exercising horses where the mineral was supplemented in the sulfate or organic chelate form. Nine mature horses were used in a modified switchback design experiment consisting of seven 28-d periods. Horses were fed a diet consisting of 50% concentrate and 50% hay that was balanced to meet the energy, protein, Ca, and P requirements for horses performing moderate-intensity exercise. Horses were subjected to a controlled mineral repletion-depletion diet sequence before feeding the experimental diet to standardize mineral status across horses. The experimental diet was designed to provide 90% of the 1989 NRC for Cu and Zn, with supplemental mineral provided in the inorganic sulfate form (CuSO(4) and ZnSO(4)) or the organic chelate form (Cu-Lys and Zn-Met). Feed, fecal, urine, and water samples collected during a total collection during the last 4 d of the experimental diet periods were analyzed to determine apparent absorption and retention of Cu and Zn from the 2 mineral forms. A formulation error caused horses receiving the organic chelate diet to consume about 3 times the amount of Cu and Zn compared with those fed the sulfate-supplemented diet. Copper and Zn intake and fecal excretion were greater (P < 0.05) for horses consuming the organic chelate-supplemented diet. Apparent absorption values for all horses were negative. Apparent Cu absorption and retention as a percentage of intake were greater for horses fed the organic chelate diet (P < 0.05). It is unknown why excretion of Cu and Zn by the horses during the total collection exceeded the mineral intake. Although Cu-Lys seemed to be better absorbed than CuSO(4) and absorption of Zn-Met and ZnSO(4) were not different, these results are tempered by the observation of abnormally high fecal and urinary excretion values for Cu and Zn in the present study.

Cholesterol intake modulates plasma triglyceride levels in glycosylphosphatidylinositol HDL-binding protein 1-deficient mice

OBJECTIVE

To determine whether plasma triglyceride levels in adult Glycosylphosphatidylinositol HDL-binding protein 1 (GPIHBP1)-deficient (Gpihbp1(-/-)) mice would be sensitive to cholesterol intake.

METHODS AND RESULTS

Gpihbp1(-/-) mice were fed a Western diet containing 0.15% cholesterol. After 4 to 8 weeks, their plasma triglyceride levels were 113 to 135 mmol/L. When 0.005% ezetimibe was added to the diet to block cholesterol absorption, Lpl expression in the liver was reduced significantly, and the plasma triglyceride levels were significantly higher (>170 mmol/L). We also assessed plasma triglyceride levels in Gpihbp1(-/-) mice fed Western diets containing either high (1.3%) or low (0.05%) amounts of cholesterol. The high-cholesterol diet significantly increased Lpl expression in the liver and lowered plasma triglyceride levels.

CONCLUSIONS

Treatment of Gpihbp1(-/-) mice with ezetimibe lowers Lpl expression in the liver and increases plasma triglyceride levels. A high-cholesterol diet had the opposite effects. Thus, cholesterol intake modulates plasma triglyceride levels in Gpihbp1(-/-) mice.

Chylomicronemia elicits atherosclerosis in mice--brief report

OBJECTIVE

The risk of atherosclerosis in the setting of chylomicronemia has been a topic of debate. In this study, we examined susceptibility to atherosclerosis in Gpihbp1-deficient mice (Gpihbp1(-/-)), which manifest severe chylomicronemia as a result of defective lipolysis.

METHODS AND RESULTS

Gpihbp1(-/-) mice on a chow diet have plasma triglyceride and cholesterol levels of 2812+/-209 and 319+/-27 mg/dL, respectively. Even though nearly all of the lipids were contained in large lipoproteins (50 to 135 nm), the mice developed progressive aortic atherosclerosis. In other experiments, we found that both Gpihbp1-deficient "apo-B48-only" mice and Gpihbp1-deficient "apo-B100-only" mice manifest severe chylomicronemia. Thus, GPIHBP1 is required for the processing of both apo-B48- and apo-B100-containing lipoproteins.

CONCLUSIONS

Chylomicronemia causes atherosclerosis in mice. Also, we found that GPIHBP1 is required for the lipolytic processing of both apo-B48- and apo-B100-containing lipoproteins.