Consumption of a controlled low-fat diet containing olestra for 9 months improves health risk factors in conjunction with weight loss in obese men: the Ole' Study.

OBJECTIVE: To compare the effects of a standard American diet, a traditional low-fat diet, and a low-fat diet containing the fat substitute olestra on risk factors for heart disease and diabetes. DESIGN: A 9-month, double-blind, randomized, parallel-arm, feeding study comparing three diets: (1). control (33% fat), (2). fat-reduced (FR; 25% fat), and (3). fat-substituted (FS) where olestra replaced 1/3 of dietary fat (33% lipid and 25% digestible fat). Subjects were allowed to adjust their total energy intake as desired, allowing weight to fluctuate. SUBJECTS: A total of 37 healthy, obese men (age 36.7+/-1.3 y; body mass index 30.8+/-0.4 kg/m(2)). MEASUREMENTS: Body weight and composition by dual-energy X-ray absorptiometry, blood pressure, serum lipids, lipoproteins, hemostatic factors, glucose, insulin, and leptin at baseline and every 3 months. RESULTS: The FS group lost 6.27 kg of body weight by 9 months vs 4.0 kg in the control and 1.79 kg in the FR groups. There was a significant diet main effect on cholesterol (P=0.002), low-density lipoprotein cholesterol (P=0.003), and triglycerides (P=0.01), all of which decreased in the FS group but not the other groups by 9 months. Apolipoprotein B (ApoB) increased in the FR and control groups but was unchanged in the FS group (diet main effect P=0.04). High-density lipoprotein (HDL) cholesterol increased in all groups over 9 months (time main effect P=0.0001). Time main effects were also observed for cholesterol, ApoA1, ApoB, Factor VII, diastolic blood pressure, and glucose. After adjustment for % fat loss at 9 months, the effects of diet on change in risk factors remained significant only for triglycerides. DISCUSSION: Consumption of a low-fat diet containing olestra for 9 months produced significant improvement in cardiovascular risk factors, an effect largely explained by weight loss. Long-term low-fat diet consumption with or without olestra does not decrease HDL cholesterol.

Relationship of dietary fat and serum cholesterol ester and phospholipid fatty acids to markers of insulin resistance in men and women with a range of glucose tolerance.

High-fat diets are associated with insulin resistance, however, this effect may vary depending on the type of fat consumed. The purpose of this study was to determine the relationship between intakes of specific dietary fatty acids (assessed by 3-day diet records and fatty acid composition of serum cholesterol esters [CEs] and phospholipids [PLs]) and glucose and insulin concentrations during an oral glucose tolerance test (OGTT). Nineteen men and 19 women completed the study. Nine subjects had type 2 diabetes or impaired glucose tolerance. Fasting insulin correlated with reported intakes of total fat (r = .50, P < .01), monounsaturated fat (r = .44, P < .01), and saturated fat (r = .49, P < .01), but not with trans fatty acid intake (r = .11, not significant [NS]). Fasting glucose also correlated with total (r = .39, P < .05) and monounsaturated fat intakes (r = .37, P < .05). In multivariate analysis, both total and saturated fat intake were strong single predictors of fasting insulin (R2 approximately .25), and a model combining dietary and anthropometric measures accounted for 47% of the variance in fasting insulin. Significant relationships were observed between fasting insulin and the serum CE enrichments of myristic (C14:0), palmitoleic (C16:1), and dihomo-gamma-linolenic (C20:3n-6) acids. In multivariate analysis, a model containing CE 14:0 and percent body fat explained 45% of the variance in fasting insulin, and C14:0 and age explained 30% of the variance in fasting glucose. PL C20:3n-6 explained 30% of the variance in fasting insulin, and a model including PL C18:1n-11 cis, C20:3n-6, age and body fat had an R2 of .58. In conclusion, self-reported intake of saturated and monounsaturated fats, but not trans fatty acids, are associated with markers of insulin resistance. Furthermore, enhancement of dihomo-gamma-linolenic and myristic acids in serum CE and PL, presumably markers for dietary intake, predicted insulin resistance.

Effects of gestational alcohol exposure on the fatty acid composition of umbilical cord serum in humans.

This study examined the effects of maternal periconceptional alcohol intake on polyunsaturated fatty acid (PUFA) concentrations in human neonates. The area percentage of each fatty acid in cord blood serum from 12 infants born to control women (who consumed <2 mL absolute ethanol/d) was compared with that of 9 infants born to women whose periconceptional alcohol intake averaged > or = 30mL absolute ethanol/d. Periconceptional alcohol use was associated with a 30% increase in the proportion of docosahexaenoic acid (22:6n-3) in cord blood (3.0% of total lipid in control infants compared with 3.9% in alcohol-exposed infants; P < 0.01). The rise in the proportion of 22:6n-3 was responsible for increases in the ratio of n-3 to n-6 fatty acids and the ratio of long-chain n-3 to n-6 fatty acids (P < 0.055). Examination of the lipid-class fatty acid profile indicated that serum lipid alterations were localized to the cholesterol esters; 22:6n-3 in the cholesterol esters of alcohol-exposed infants increased 54% (P < 0.011) and arachidonic acid increased 55% (P < 0. 005). The relative fatty acyl composition of maternal serum showed a significant increase in 18:0 fatty acids in the alcohol-exposed group (25%, P < 0.005) but there were no changes in the other fatty acids. The increase in the proportion of 22:6n-3 was unexpected but is consistent with the hypothesis that this essential lipid may be conserved selectively. These results imply that the lifelong neurobehavioral and sensory dysfunction in fetal alcohol syndrome and other alcohol-related neurodevelopmental disorders may be due in part to PUFA dysregulation.

Retinal and brain accretion of long-chain polyunsaturated fatty acids in developing felines: the effects of corn oil-based maternal diets.

A study was carried out in domestic felines to determine whether corn oil-based maternal diets are an adequate source of essential fatty acids to support normal accumulation of long-chain polyunsaturated fatty acids in the brains and retinas of offspring and whether these diets have any subsequent effect on visual function. Female domestic felines were acclimated to one of six different defined diets 1 mo before mating and maintained on the diets throughout pregnancy and lactation. Four diets contained only corn and hydrogenated coconut oils as their source of fat in ratios of 1:9, 3:7, 6:4, and 9:1, respectively. Two reference diets also contained the long-chain polyunsaturated fatty acids arachidonate (20:4n-6) and docosahexaenoate (22:6n-3). When the offspring were 8 wk old, electroretinograms were obtained and the a- and b-wave implicit times were determined. The results showed that animals raised in litters in which the maternal diets were devoid of 20:4n-6 and 22:6n-3 had an increase in a- and b-wave implicit times compared with the controls. In the rod outer segments and brains of these animals, there were lower amounts of 22:6n-3 and higher amounts of long-chain n-6 polyunsaturated fatty acids compared with control animals. These findings showed that although corn oil-based diets were capable of maintaining 20:4n-6 concentrations in the developing brain and retina, only those diets containing 22:6n-3 could support a high accumulation of docosahexaenoic acid in these tissues. Moreover, low amounts of 22:5n-6 in the brains of animals in all of the corn oil-diet groups suggested that young felines have a low biosynthetic capacity to produce this fatty acid or 22:6n-3. These findings suggest that in juvenile felines, maintenance of 22:6n-3 status in the nervous system is important for optimal retinal function.

Effect of UV irradiation on lethal infection of mice with Candida albicans.

Exposure of mice to UV radiation inhibits the induction and elicitation of the delayed-type hypersensitivity (DTH) response to Candida albicans. To determine whether UV irradiation also affects the pathogenesis of systemic C. albicans infection, C3H mice were exposed to a single dose of 48 kJ/m2 UV-B radiation from FS40 sunlamps 5 days before or 5 days after sensitization with formalin-fixed C. albicans and challenged intravenously (i.v.) with a lethal dose of viable fungi 6 days after sensitization (11 or 1 days after UV irradiation). Exposing unsensitized mice to UV radiation 11 days before lethal challenge had no effect on survival, but the survival time of mice exposed to UV radiation 1 day before challenge was reduced by more than 50%. In the latter group, decreased survival time correlated with persistence of C. albicans in the brain and progressive growth of C. albicans in the kidneys. Sensitization of unirradiated mice with formalin-fixed C. albicans extended their survival time following lethal i.v. challenge with viable C. albicans. Exposing the mice to UV radiation 5 days before sensitization did not abrogate this beneficial effect of sensitization on survival, even though it significantly reduced the DTH response. Thus, immunity to systemic infection did not depend on the ability of the mice to exhibit a DTH response to C. albicans. The beneficial effect of sensitization on survival after lethal infection was abrogated, however, in mice exposed to UV radiation 1 day before lethal challenge with C. albicans. Furthermore, these mice were unable to contain the progressive growth of C. albicans in the kidneys, in contrast to sensitized, unirradiated mice.

The deleterious effect of macrophage colony-stimulating factor (CSF-1) on the pathology of experimental candidiasis in mice.

Mice infected with Candida albicans albicans intravenously were treated before or after infection with macrophage colony-stimulating factor (CSF-1) to elevate their circulating monocyte and tissue macrophage counts. Both treatments exacerbated the disease, causing a doubling of the rate of weight loss and leading to significantly earlier death. The results suggest that macrophages play a major role in the pathology of the disease.

Optimization of the liposomes encapsulating a new lipopeptide CGP 31362 for efficient activation of tumoricidal properties in monocytes and macrophages.

The purpose of this study was to optimize a suitable liposomal carrier for CGP 31362, a new synthetic lipopeptide analogue of gram-negative bacterial cell walls. CGP 31362 was inserted into the membranes of different liposomes with different phospholipid composition. We determined the ability of these liposomes to activate tumoricidal properties in mouse peritoneal and bone marrow macrophages, and in human monocytes. The ideal liposome carrier for CGP 31362 consisted of phosphatidylcholine and phosphatidylserine in a 7:3 molar ratio. Subsequent to efficient binding and endocytosis, CGP 31362 in liposomes of this composition rendered mouse macrophages and human monocytes highly tumoricidal. Moreover, even in the absence of interferon-gamma, human monocytes released significant levels of tumor necrosis factor and interleukin-1. These data show that in a suitable liposomal carrier, the new synthetic lipopeptide in liposomes is a potent activator of tumoricidal properties in macrophages.

Comparative efficacy of liposomes containing synthetic bacterial cell wall analogues for tumoricidal activation of monocytes and macrophages.

We examined the activation to the tumoricidal state of normal mouse peritoneal exudate macrophages, bone marrow macrophages, and human blood monocytes by liposomes containing either lipophilic muramyl tripeptide (CGP 19,835) or a new synthetic analogue of lipoprotein from gram-negative bacteria outer wall, CGP 31,362, or combinations of the two. The superiority of liposomes containing the synthetic lipopeptide over liposomes containing lipophilic muramyl tripeptide for in vitro activation of monocytes and macrophages was demonstrated in several experiments. First, liposome-CGP-19,835 activated monocytes only in the presence of interferon-gamma, whereas activation with liposome-CGP 31,362 was interferon-independent. Second, activation of both mouse macrophages and human blood monocytes by liposome-CGP 31,362 occurred at a lower liposomal concentration than that by liposome-CGP 19,835. Third, monocytes incubated with liposome-CGP 31,362 released both tumor necrosis factor (TNF) and interleukin-1 activities, whereas monocytes treated with liposome-CGP 19,835 (in the absence of interferon-gamma) released only TNF activity. These data suggest that liposomes containing the synthetic lipopeptide CGP 31,362 are superior to liposomes containing CGP 19,835 for systemic activation of macrophages.

Activation of macrophages to express cytocidal activity correlates with inhibition of their responsiveness to macrophage colony-stimulating factor (CSF-1): involvement of a pertussis toxin-sensitive reaction.

Bone marrow-derived murine macrophages were used to study the relationship between the proliferative response of macrophages to macrophage colony-stimulating factor (CSF-1) and their activation for cytocidal activity against tumour cells. Macrophage activation required two sequential signals. Lymphokines (gamma interferon, interleukin-4) provided the first (priming) signal; bacterial products (lipopolysaccharide, lipophilic muramyl tripeptide, lipopeptide 31362, pertussis toxin) provided the second (triggering) signal. Both priming and triggering agents inhibited [3H]-thymidine uptake by macrophages stimulated with CSF-1. The antiproliferative activity of priming and triggering stimuli was synergistic. Pretreatment with triggering stimuli at 37 degrees C caused a rapid reduction of the subsequent binding of [125I]-CSF-1 to the cell surface at 4 degrees C, whereas priming agents had relatively little effect. Growth inhibition by both priming and triggering agents was largely reversible by washing the cells, and occurred even when they were added as long as 24 h after the growth factor. The ability of pertussis toxin to both inhibit CSF-1-induced proliferation and trigger cytotoxicity in macrophages suggests the involvement of a regulatory GTP-binding protein (G protein) in both processes.

Exposure of mice to UV-B radiation suppresses delayed hypersensitivity to Candida albicans.

Groups of mice were exposed to a single dose of UV radiation before or after immunization with Candida albicans. The delayed type hypersensitivity (DTH) response was markedly depressed in all UV-irradiated groups. Exposure of mice to UV radiation before sensitization induced splenic suppressor cells that, upon transfer to normal recipients, impaired the induction of DTH to Candida. In contrast, exposure of mice to UV radiation after sensitization interfered with elicitation of the DTH response, but this suppression was not transferable. These studies demonstrate that immunity to Candida albicans in mice is impaired by exposure to UV radiation and that two separate mechanisms may be involved.

Mechanisms of combined effects of gamma-interferon and 5-fluorouracil on human colon cancers implanted into nude mice.

The purpose of these studies was to determine the possible mechanisms responsible for the therapeutic effects of systemic administration of 5-fluorouracil (FUra) and gamma-interferon on disseminated human colon cancer. We used several human carcinoma cell lines that were established from different surgical specimens. Some lines were selected in nude mice for increased metastatic potential, and one line was selected in vitro for resistance to human recombinant gamma-interferon (r-IFN-gamma). In initial in vitro studies, FUra was cytostatic against all the human cell lines but did not produce cytolysis in any of the lines tested. The two r-IFN-gamma were species specific for both antitumor and immunomodulatory effects. Human r-IFN-gamma produced cytostatic and cytolytic effects against sensitive human colon carcinoma cells but did not activate tumoricidal properties in mouse macrophages. In contrast, mouse r-IFN-gamma had no direct cytotoxic effects against any of the human colon carcinoma lines but did activate tumoricidal properties in mouse macrophages. Human colon carcinoma cells (sensitive or resistant to human r-IFN-gamma) were implanted into the spleens of nude mice. Three days later, we began treatments with FUra and human or mouse r-IFN-gamma. In all experiments, the combination of FUra with mouse r-IFN-gamma produced the best therapeutic effects against growth of the cells in the spleen and in the liver. Because the mouse r-IFN-gamma is devoid of direct antitumor effects (against human tumor cells) but is a potent macrophage activator, these results suggest that the antitumor effects were due to direct antitumor effects of FUra and to activation of host defense mechanisms by the r-IFN-gamma.

Phosphatidylserine decarboxylase: generation of asymmetric vesicles and determination of the transbilayer distribution of fluorescent phosphatidylserine in model membrane systems.

Large unilamellar vesicles (LUV) that contained a fluorescent analog of phosphatidylserine (NBD-PS) were used in model systems to determine the feasibility of employing phosphatidylserine decarboxylase (PS-decarboxylase) to generate asymmetric vesicles and to determine the transbilayer distribution of PS. PS-decarboxylase prepared by sonication of Escherichia coli JA 200 pLC 8-47 was found to be stable in detergent-free buffers and catalyzed the conversion of NBD-PS to NBD-phosphatidylethanolamine (NBD-PE). PS-decarboxylase was capable of decarboxylating virtually all of the NBD-PS present in the outer leaflet of LUV containing a symmetric or asymmetric (outside only) distribution of NBD-PS, but not NBD-PS present in the inner leaflet of the vesicles. The ability of PS-decarboxylase to decarboxylate only NBD-PS located in the outer leaflet of the vesicles was independently verified by resonance energy transfer (between NBD-PS and (lissamine) rhodamine B-labeled phosphatidylethanolamine) and by derivatization with trinitrobenzenesulfonic acid (TNBS). These techniques revealed that the exchangeable pool (the fraction of NBD-PS on the outer leaflet) and the respective fraction of Tnp-(NBD-PS) formed were equivalent to the extent of PS-decarboxylase-mediated decarboxylation of NBD-PS to NBD-PE. These results show that PS-decarboxylase can be used to generate asymmetric vesicles (i.e., PS inside, PE outside) and determine the intrabilayer distribution of PS in model membranes.