Reduced and high molecular weight barley beta-glucans decrease plasma total and non-HDL-cholesterol in hypercholesterolemic Syrian golden hamsters

Consumption of concentrated barley beta-glucan lowers plasma cholesterol because of its soluble dietary fiber nature. The role of molecular weight (MW) in lowering serum cholesterol is not well established. Prior studies showed that enzymatic degradation of beta-glucan eliminates the cholesterol-lowering activity; however, these studies did not evaluate the MW of the beta-glucan. The current study was conducted to evaluate whether barley beta-glucan concentrates, partially hydrolyzed to reduce MW, possess cholesterol-lowering and antiatherogenic activities. The reduced MW fraction was compared with a high MW beta-glucan concentrate from the same barley flour. Concentrated beta-glucan preparations were evaluated in Syrian Golden F(1)B hamsters fed a hypercholesterolemic diet (HCD) with cholesterol, hydrogenated coconut oil, and cellulose. After 2 wk, hamsters were fed HCD or diets that contained high or reduced MW beta-glucan at a concentration of 8 g/100 g at the expense of cellulose. Decreases in plasma total cholesterol (TC) and non-HDL-cholesterol (non-HDL-C) concentrations occurred in the hamsters fed reduced MW and high MW beta-glucan diets. Plasma HDL-C concentrations did not differ. HCD-fed hamsters had higher plasma triglyceride concentrations. Liver TC, free cholesterol, and cholesterol ester concentrations did not differ. Aortic cholesterol ester concentrations were lower in the reduced MW beta-glucan-fed hamsters. Consumption of either high or reduced MW beta-glucan increased concentrations of fecal total neutral sterols and coprostanol, a cholesterol derivative. Fecal excretion of cholesterol was greater than in HCD-fed hamsters only in those fed the reduced MW beta-glucan. Study results demonstrate that the cholesterol-lowering activity of barley beta-glucan may occur at both lower and higher MW.     

Anthrax vaccine efficacy in golden Syrian hamsters

The efficacy of a licensed human anthrax vaccine (anthrax vaccine adsorbed, AVA) was tested in golden Syrian hamsters against a virulent Bacillus anthracis spore challenge. Groups of golden Syrian hamsters were vaccinated at either 0 and 4 weeks or 0, 4 and 8 weeks, then challenged subcutaneously (s.c.) at 10 weeks with spores of various B. anthracis isolates. Although ELISA and toxin neutralization assays demonstrated high titers, none of the AVA-vaccinated hamsters were protected from challenge or demonstrated a significantly extended time to death compared to that of control animals. The results of the study demonstrate that the golden Syrian hamster is not an appropriate model for investigating human anthrax vaccine efficacy.     

Phytosterols protect against diet-induced hypertriglyceridemia in Syrian golden hamsters

Background

In addition to lowering LDL-C, emerging data suggests that phytosterols (PS) may reduce blood triglycerides (TG), however, the underlying mechanisms are not known.

Methods

We examined the TG-lowering mechanisms of dietary PS in Syrian golden hamsters randomly assigned to a high fat (HF) diet or the HF diet supplemented with PS (2%) for 6 weeks (n?=?12/group). An additional subset of animals (n?=?12) was provided the HF diet supplemented with ezetimibe (EZ, 0.002%) as a positive control as it is a cholesterol-lowering agent with known TG-lowering properties.

Results

In confirmation of diet formulation and compound delivery, both the PS and EZ treatments lowered (p?<?0.05) intestinal cholesterol absorption (24 and 31%, respectively), blood non-HDL cholesterol (61 and 66%, respectively), and hepatic cholesterol (45 and 55%, respectively) compared with the HF-fed animals. Blood TG concentrations were lower (p?<?0.05) in the PS (49%) and EZ (68%)-treated animals compared with the HF group. The TG-lowering response in the PS-supplemented group was associated with reduced (p?<?0.05) intestinal SREBP1c mRNA (0.45 fold of HF), hepatic PPARα mRNA (0.73 fold of HF), hepatic FAS protein abundance (0.68 fold of HD), and de novo lipogenesis (44%) compared with the HF group. Similarly, lipogenesis was lower in the EZ-treated animals, albeit through a reduction in the hepatic protein abundance of ACC (0.47 fold of HF).

Conclusions

Study results suggest that dietary PS are protective against diet-induced hypertriglyceridemia, likely through multiple mechanisms that involve modulation of intestinal fatty acid metabolism and a reduction in hepatic lipogenesis.     

Red wine phenolic compounds reduce plasma lipids and apolipoprotein B and prevent early aortic atherosclerosis in hypercholesterolemic golden Syrian hamsters (Mesocricetus auratus)

The effects of a red wine phenolic extract (PE) on plasma lipoproteins and early atherosclerosis were studied in hamsters. Hamsters (n = 32) were divided into 4 groups of 8 and fed an atherogenic diet for 8 wk. They received by force- feeding 7.14 mL/(kg. d) PE in 2.6 mol/L ethanol (E + PE) or PE in water (W + PE), mimicking a moderate consumption of red wine or alcohol-free red wine [30.4 mg/(kg. d)], or 2.6 mol/L ethanol (E-PE) or water (W-PE) as their respective controls. Plasma cholesterol and triglyceride concentrations were lower in groups that consumed PE. The decrease in plasma apolipoprotein (Apo) B concentration was due mainly to PE and was significantly lower in Group E + PE than in Group E-PE (-7.5%) and in Group W + PE than in Group W-PE (-40%). Apo-A1 was not affected. PE significantly increased plasma antioxidant capacity by 9% in Group E + PE and 18% in Group W + PE compared with their respective controls. Liver glutathione peroxidase activity was 67% greater in the group receiving PE in water compared with the group given water; there was no effect when PE was given in ethanol relative to its control. Aortic fatty streak area (AFSA) was significantly reduced in the groups receiving PE in ethanol (-32%) or PE in water (-29%) in comparison with their respective controls. Ethanol significantly reduced AFSA by 60% (Group E-PE vs. Group W-PE) or 62% (Group E + PE vs. Group W + PE). These data suggest that ethanol is a complementary component of phenolics in the benefits of red wine for hamsters and that chronic ingestion of PE in ethanol prevents the development of atherosclerosis through several mechanisms. With moderate consumption of red wine, ethanol can improve the effects of phenolic compounds. However, alcohol-free red wine appears to be a very good alternative to red wine.     

Repeated exposure to acetaldehyde vapor. Studies in Syrian golden hamsters.

The subacute inhalation toxicity of acetaldehyde was examined with four groups of 20 hamsters each, exposed repeatedly to acetaldehyde vapor at concentrations of 0, 390, 1,340, and 4,560 ppm (six hr day, five days/week) for a 90-day period. The highest level induced growth retardation, ocular and nasal irritation, increased numbers of erythrocytes, increased weights of heart and kidneys, and severe histopathological changes in the respiratory tract that mainly consisted of necrosis, inflammatory changes, and hyper- and metaplasia of the epithelium. The upper segments of the respiratory tract were much more severely injured than the lower parts. At 1,340 ppm treatment-releated changes included increased kidney weights in males and slight hyper- and metaplastic changes of the tracheal epithelium; 390 ppm was considered a no toxic effect level.     

Involvement of prostaglandin A1 in interrupting early pregnancy in Syrian golden hamsters

The effects of a single administration of authentic prostaglandin A1 intravaginally in early pregnant hamsters were investigated. A single dose of 1 mcg/animal given on day 4 of pregnancy inhibited the appearance of embryonic swellings when observed on day 8 of pregnancy. A significant fall (p<0.01) in FSH with a rise (p<0.03) in prolactin concentration in the serum and no change in LH levels were observed. The pituitary content of prolactin showed a significant decrease (p<0.0006) with no change in FSH and LH contents.Progesterone concentration in the serum was markedly reduced (p<0.002), along with that of the ovaries (p<0.01). The decline in progesterone concentration coincided with the absence of corpora lutea and the embryos. However, no change in ovarian weights was observed. These results indicate the contragestive potential of prostaglandin A1. It appears to act as a luteolytic agent by disrupting the luteotropic complex (FSH:prolactin ratio).

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Resumen Se investigaron los efectos de una administración intravaginal de prostaglandina A1 en hamsters con embarazo temprano. Una sola dosis de 1 mcg/animal al 4° día del embarazo (P) inhibió la aparición de los edemas embriónicos cuando se los observó en el 8° día del embarazo. Se notó una caída significativa (p<0,01) en FSH con un aumento (p<0,03) en la concentración de prolactina y ningun cambio en los niveles de LH. E1 contenido de prolactina en la pituitaria mostró una disminución significativa (p<0,0006) sin cambios en los niveles de FSH y LH.La concentración de progesterona en suero estuvo notablemente reducida (p<0,002) asi como la de los ovarios (p<0,01). La disminución en la concentración de progesterona coincidió con la ausencia de cuerpo lúteo y de embriones. Sin embargo, no se observó cambio en el peso ovárico. Estos resultados indican el potencial antigestante de la prostaglandina A1. Esta parece actuar como agente luteolítico, interrumpiendo el complejo luteotrópico (relación FSH:prolactina).

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Resumé On a étudié les effets de l'administration par voie intravaginale d'une dose unique de prostaglandine A1 à des hamsters au début de la gestation. On a constaté au huitième jour qu'une dose unique de 1 mcg par animal, administrée au quatrième jour de gestation, avait inhibé l'apparition des grosseurs embryonnaires. On a constaté en outre une baisse significative (p<0,01) de l'HSF, avec une augmentation (p<0,03) de la concentration de prolactine sérique, mais aucun changement dans les niveaux de l'HL. La teneur en prolactine retrouvée dans l'hypophyse présentait une biasse significative (p<0,0006), sans qu'il y ait eu de changement dans la teneur en HSF et HL. En outre, la concentration de progestérone dans le sérum et dans les ovaires était sensiblement réduite (respectivementp<0,002 etp<0,01). La baisse de la concentration de progestérone concidait avec l'absence de corps jaune et d'embryon. Aucune modification du poids des ovaires n'a cependant été observée. Ces résultats font apparaitre le potentiel de la prostagladine A1 en tant qu'agent inhibiteur de la gestation. Son action semble être celle d'un agent lutéolytique qui perturbe le complexe lutéotrope. (HSF: proportion de prolactine)

     

Enhancement of BOP-induced pancreatic carcinogenesis in selenium-fed Syrian golden hamsters under specific dietary conditions

We measured the effects of dietary selenium (Se) on pancreatic cancer induced in Syrian golden hamsters by N-nitrosobis(2-oxopropyl)amine (BOP). The animals were fed six experimental diets that contained different combinations of the following: 0.1, 2.5, or 5.0 ppm Se from sodium selenite or 2.5 ppm Se from D,L-selenomethionine in either a low (6.0%)- or high (24.4%)-fat diet. Se treatment was begun four weeks before BOP treatment, and the high-fat diet was fed from one week after the last BOP treatment. No evidence for inhibition of pancreatic cancer by Se was observed; in fact, with some experimental conditions, high-Se diets increased the pancreatic carcinoma yield. However, the dietary conditions needed for enhancement differed between the sexes. The male hamsters that received the high-fat diet containing 2.5 ppm Se had more carcinomas than did males given the 0.1 ppm Se level. Carcinoma yields in females did not differ between these diets. Females that received 2.5 ppm Se from D,L-selenomethionine had a greater pancreatic carcinoma yield that did those given 0.1 ppm Se diet. However, carcinoma yields did not differ in males fed these diets. Acinar cell nodule yields were generally reduced in hamsters given the high-Se diets, especially when Se levels in the high-fat diets were compared. Prefeeding 0.1 or 2.5 ppm Se did not influence the elution constants of pancreatic DNA from ductal cells, indicating no effect of Se on the repair of BOP-induced, single-strand breaks in DNA from these cells. Measurements in acinar cells suggested a more rapid repair of single-strand breaks in hamsters prefed 2.5 ppm Se than in those prefed 0.1 ppm Se.     

High urinary isoflavone excretion phenotype decreases plasma cholesterol in golden Syrian hamsters fed soy protein

Apparent absorption of isoflavones varies greatly among individuals but is relatively stable within an individual. We hypothesized that high urinary isoflavone excreters would show less plasma non-HDL cholesterol (non-HDL-C) than low isoflavone excreters after soy protein feeding. Fifty Golden Syrian hamsters were fed a high-fat/casein diet (n = 10) or a high-fat/soy protein diet (n = 40) for 4 wk. We identified 2 distinct urinary isoflavone excretion phenotypes based upon HPLC analysis of urinary glycitein using a pairwise correlation plots analysis, or based upon total urinary isoflavone using a hierarchical cluster test. High isoflavone excreters showed greater urinary isoflavones (P < 0.05) than did low isoflavone excreters at wk 1 and 4. The low urinary glycitein excretion phenotype was more stable than the high urinary glycitein excretion phenotype by McNemar's test. High urinary isoflavone excreters had significantly less non-HDL-C than did the low isoflavone excreters or casein-fed controls (P < 0.05). Plasma total and non-HDL-C were negatively correlated with urinary daidzein, glycitein, and total isoflavone excretion (r = -0.45 to -0.58, P < 0.05). Urinary isoflavone excretion phenotypes predicted the cholesterol-lowering efficacy of soy protein. Isoflavone absorbability, probably due to gut microbial ecology, is an important controllable variable in studies of effects of soy protein on blood lipids.     

Hypoxia and induced mutations in Syrian (golden) hamsters. The origin and perpetuation of a species.

We were able to identify anomalous chromosome patterns-monosomy, trisomy, and polyploidy-in metaphase plates prepared from embryos of Syrian hamsters (Mesocricetus auratus) whose mothers had been exposed to low-pressure hypoxia during the hours after copulation. These females were exposed in a low-pressure chamber for 4 hours at pressures equivalent to 30,000 feet of altitude before (estimated) ovulation to create acid shifts of pH equilibrium in the milieu of newly released eggs during passage of sperm upward, during fertilization itself, and during early cleavage stages. The D group chromosomes were most frequently involved in both monosomy and hyperdiploidy. The easily identifiable X chromosome also appeared to be susceptible to aneuploid formation. Chromosomally abnormal patterns most frequently among sibling embryos conceived by aging mothers exposed to low-pressure hypoxia. The significance of induced mutations is discussed.     

The form of dietary conjugated linoleic acid does not influence plasma and liver triacylglycerol concentrations in Syrian golden hamsters

Several studies have shown that conjugated linoleic acid (CLA) supplementation can improve the plasma lipid profile and thereby probably decrease the risk for development of atherosclerosis. The aim of the present study was to compare the effects on plasma and organ lipids of different dietary forms of CLA: triacylglycerol (TAG), diacylglycerol (DAG), monoacylglycerol (MAG), and fatty acid ethyl esters (FAEEs). DAG-, MAG-, and FAEE-CLA were produced by enzymatic interesterifications and all supplements were composed of a 1:1 mixture of the 2 major CLA isomers: cis-9, trans-11 and trans-10, cis-12. Male Syrian Golden hamsters were fed mildly atherogenic diets (10 g butter/100 g, 0.1 g cholesterol/100 g) supplemented with 0.5 g CLA/100 g or without CLA (control) for 8 wk. Liver weights were greater in the TAG- and FAEE-CLA groups than in the control group. In general, the form of CLA did not differentially affect plasma or liver cholesterol or plasma lipoprotein cholesterol concentrations, but only the TAG-CLA group had a higher final plasma TAG concentration than the control group. Both CLA isomers were incorporated into plasma, livers, and spleens. The results of the present study suggest that the form in which CLA is supplemented in the diet does not affect hamster plasma and liver TAG concentrations. The TAG-CLA form, a frequently used form of supplemental CLA, increases plasma TAG concentrations. If similar effects occur in humans, supplemental TAG-CLA cannot be considered to be beneficial given the relation between plasma TAG and the development of atherosclerosis.     

Inhibition by selenium of intrahepatic cholangiocarcinoma induction in Syrian golden hamsters by N'-nitrosobis(2-oxopropyl)amine.

The effects of selenium supplementation on induction of cholangiocarcinomas and related precancerous lesions in female Syrian Golden hamsters by N'-nitrosobis(2-oxopropyl)amine (BOP) were investigated. Four-week-old animals were divided into two groups according to the selenium level contained in the drinking water (0.1 ppm or 4.0 ppm) and fed a purified diet containing less than 0.05 ppm of the trace element. Starting at Week 4 of the experiment, hamsters were administered 10 weekly injections of BOP (10 mg/kg body wt) and then killed 18 weeks after the last carcinogen administration. Animals receiving physiological saline alone served as controls. Cholangiocellular carcinomas tended to be reduced, and putative preneoplastic lesions of cholangiofibrosis were significantly decreased in the high-as opposed to the low-selenium groups in terms of both incidence rate and number per effective animal. The respective high and low selenium values for incidence and number were 24/38% and 0.34/0.66, respectively, for cholangiocarcinomas and 50/89% and 1.21/8.44, respectively, for cholangiofibroses. Proliferation of intrahepatic bile ducts was also significantly inhibited in the high-selenium group along with cyst formation. Biochemical investigation revealed both selenium level and glutathione peroxidase activity to be significantly greater in the high-than in the low-selenium group livers. The results thus suggest that selenium may inhibit BOP-induction of bile duct lesions, possibly via glutathione peroxidase-mediated alteration of carcinogenesis.     

Ethanol-extracted soy protein isolate does not modulate serum cholesterol in golden Syrian hamsters: a model of postmenopausal hypercholesterolemia

Soy protein consumption has been linked to reduction in hypercholesterolemia, a risk for coronary heart disease. However, to what extent soy protein itself or its non-nutritive components, e.g., isoflavones and saponins, exert this cholesterol-lowering effect requires further investigation. To evaluate the effect of the protein component alone on lipid variables, ethanol-extracted, isoflavone-depleted soy protein isolate (SPe) was studied in ovarian hormone-deficient hamsters. Forty-eight 6-month-old female Golden Syrian hamsters were either sham-operated or ovariectomized and fed casein-based or SPe-based diets for 70 d. Ovariectomy, but not protein source, significantly (P < 0.05) increased serum phospholipids and total, non-high density lipoprotein, free and esterified cholesterol concentrations. Serum HDL cholesterol concentrations were not altered with either treatment. No significant differences were observed in liver total lipids or liver total cholesterol among the groups. Soy protein isolate, however, lowered serum triglyceride concentrations in both sham-operated and ovariectomized hamsters. These findings confirm the ovariectomized hamster as a model of postmenopausal hypercholesterolemia. The results are consistent with earlier observations that isoflavones or other nonprotein components, perhaps in combination with soy protein, play an important role in exerting this hypocholesterolemic effect. Further studies are needed to investigate whether isolated nonprotein components of soy would be able to prevent the ovarian hormone deficiency-associated rise in serum cholesterol regardless of dietary protein source.     

Dietary fat type affects vitamins C and E and biomarkers of oxidative status in peripheral and brain tissues of golden Syrian hamsters

Oxidative stress is an important trigger in the complex chain of events leading to neurodegenerative diseases. On the other hand, dietary fatty acids play an essential role in brain function. The objectives of this study were to assess the effect of dietary fat type on vitamin C and vitamin E (alpha-and gamma-tocopherol) concentrations in peripheral and brain tissues and its effect on 8-epiPGF(2)alpha (F(2)-isoprostanes). Male Golden Syrian hamsters (n = 120, 8 wk old) were fed diets enriched in butter, hydrogenated fat (margarine), and canola and soybean oils. After 12 wk, hamsters were deprived of food, anesthetized with isoflurane, and killed via terminal exsanguination. Analyses of vitamins C, E, and 8-epiPGF(2)alpha were performed in peripheral tissues and brain. Hamsters consuming the margarine-enriched diet had lower (P < 0.05) vitamin C and alpha-tocopherol concentrations in liver, plasma, and brain, and higher (P < 0.02) plasma 8-epiPGF(2)alpha than groups fed the butter, and the canola and soybean oil diets. Liver and plasma gamma-tocopherol concentration was higher (P < 0.001) among the groups fed the soybean- and margarine-enriched diets compared with the other groups. alpha-Tocopherol was higher (P < 0.05) and 8-epiPGF(2)alpha lower (P < 0.01) among the groups fed the canola and soybean oil diets compared with the other groups. Across the groups, an inverse correlation between plasma levels of vitamin C and 8-epiPGF(2)alpha (r = -0.37, P = 0.03) and a positive correlation between plasma levels of vitamin C and alpha-tocopherol were observed (r = 0.341, P = 0.003). Hamsters fed the butter-enriched diet had a higher (P < 0.03) plasma uric acid concentration than the other groups. The results of this study provide new evidence concerning the effect of dietary fat on antioxidant status, which is important for the maintenance of good health.     

Dietary energy shortage and ethanol intake in golden hamsters

Adult male golden hamsters, which are avid consumers of ethanol solutions, were maintained on powdered Purina chow and tap water, and they were permitted continuous access to either a 15% or a 30% ethanol solution (v/v). In two experiments, the effect of chronic dietary energy shortage on ethanol consumption was examined. Energy shortage was produced either by food restriction (Experiment 1) or by dilution of the diet with nonnutritive cellulose (Experiment 2). Dietary energy shortage caused increases of up to 50% in ethanol consumption, and the energy derived from ethanol offset the short-fall in food-derived energy by up to 50%. When normal feeding conditions were reinstated, hamsters maintained their enhanced intake of ethanol solutions, consuming up to 15.4 g/kg/day of ethanol. Possible factors underlying the enhanced intake of ethanol solution both during and after dietary energy shortage are discussed.     

Dietary salt and voluntary ethanol consumption in golden hamsters

Adult male golden hamsters were maintained on powdered Purina chow and tap water, and were permitted continuous access to either a 15% or a 30% ethanol solution (v/v); after an initial 4–5 weeks of ethanol availability, hamsters had stabilized their intakes and were deriving an average of 1.25 and 1.96 g/day of absolute ethanol from the 15% and 30% solutions, respectively. When salt was added to the diet in increasing concentrations ranging from 4% to 10% over a period of 40 days, hamsters reduced chow-derived calories by up to 35%, increased tap water consumption by up to 50%, and increased consumption of ethanol solutions by up to 100%; when unadulterated Purina chow was reinstated, intakes of chow-derived calories, tap water, and ethanol solutions returned to baseline levels. Hamsters that were continuously maintained on unadulterated Purina chow, but with chow-derived calories matched to that of animals on the salt-adulterated diet, significantly increased their ethanol intake, but not their tap water intake; the increase in their ethanol intake was only about half as large as that of hamsters that had salt added to the diet, but the increase persisted even after ad lib feeding was reinstated. The results indicate that the addition of salt to the diet of hamsters produces large increases in ethanol consumption; furthermore, the increased ethanol intake is not simply the result either of a nonselective increase in fluid consumption or of the reduction in food intake that accompanies the addition of salt to the diet. Results are related to the possible role of the renin-angiotensin system in the control of ethanol consumption in the golden hamster.     

Dietary soy and soy isoflavones have gender-specific effects on plasma lipids and isoflavones in golden Syrian f(1)b hybrid hamsters

The specific components of soy responsible for its beneficial effects on plasma lipids are unknown. Golden Syrian F(1)B Hybrid hamsters (75 male, 74 female) were evaluated for the effect of dietary soy and soy isoflavones on plasma lipids. They were fed the following diets for 16 wk: casein/lactalbumin (C/L), soy protein with isoflavones [Soy(+)], soy protein with isoflavones removed [Soy(-)], Soy(-) plus isoflavone extract (IF), and C/L + IF. At necropsy, plasma total cholesterol, HDL cholesterol (HDLC), LDL + VLDL cholesterol (LDL + VLDLC), isoflavones, and uterine and accessory gland weights were measured. Male hamsters fed the three soy-containing diets had lower LDL + VLDLC concentrations than those fed the two C/L diets (P < 0.01), and those fed Soy(-) + IF did not differ from those fed Soy(+). In females, diet did not affect plasma LDL + VLDLC concentration. Females fed Soy(+) or Soy(-) had higher HDLC (P < 0.05) than those fed C/L. HDLC was not affected by diet in males. Due to higher equol production (P < 0.01), males had greater plasma isoflavone concentrations (P < 0.01) than females. There was a positive association between plasma total isoflavones and LDL + VLDLC (r = 0.65, P < 0.05) in females. These data suggest gender differences in plasma lipid and isoflavone responses to soy- based diets in Syrian F(1)B Hybrid hamsters, which offer an opportunity to explore effects of sex hormones on isoflavone metabolism and the effects of isoflavones on lipid metabolism.     

Diets containing barley significantly reduce lipids in mildly hypercholesterolemic men and women

BACKGROUND: Barley has high amounts of soluble fiber but is not extensively consumed in the US diet. OBJECTIVE: This study investigated whether consumption of barley would reduce cardiovascular disease risk factors comparably with that of other sources of soluble fiber. DESIGN: Mildly hypercholesterolemic subjects (9 postmenopausal women, 9 premenopausal women, and 7 men) consumed controlled American Heart Association Step 1 diets for 17 wk. After a 2-wk adaptation period, whole-grain foods containing 0, 3, or 6 g beta-glucan/d from barley were included in the Step 1 diet menus. Diets were consumed for 5 wk each and were fed in a Latin-square design. Fasting blood samples were collected twice weekly. RESULTS: Total cholesterol was significantly lower when the diet contained 3 or 6 g beta-glucan/d from barley than when it contained no beta-glucan; the greatest change occurred in the men and postmenopausal women. HDL and triacylglycerol concentrations did not differ with the 3 amounts of dietary beta-glucan. Large LDL and small VLDL fractions and mean LDL particle size significantly decreased when whole grains were incorporated into the 3 diets. Large LDL and large and intermediate HDL fractions were significantly higher, mean LDL particle size was significantly greater, and intermediate VLDL fractions were significantly lower in the postmenopausal women than in the other 2 groups. A group-by-diet interaction effect was observed on LDL fractions and small LDL particle size. CONCLUSION: The addition of barley to a healthy diet may be effective in lowering total and LDL cholesterol in both men and women.     

Cholesterol synthesis and esterification in hypercholesterolemic hamsters: Influence of a fruit-enriched diet

An experimental model consisting of hamsters which develop high levels of cholesterol in plasma and in the liver with age, was used to study the influence of a fruit-enriched diet on cholesterol metabolism: synthesis and esterification in the liver and in the ileum. After weaning, the animals received either a standard balanced diet or a combined diet: fruits (apples) in addition to the same standard diet. The diets were consumed ad libitum. The combined diet prevented the development of hypercholesterolemia and cholesterol ester storage in the liver. Cholesterol levels reached 170 17±in plasma and 1621±272 in the liver of animals fed the standard diet. They were only 109±8 and 312±7 respectively in animals fed the apple-enriched diet. This diet also stimulated the conversion of [2–14C]-acetate and [2–14C]-mevalonate into cholesterol in the liver. Moreover, the percentage radioactivity derived from mevalonate found in the esterified cholesterol was strongly reduced, 10% in contrast to 60% in the liver of hamsters fed the standard diet alone. Thus, the combined diet increased the capacity of the liver to synthesize cholesterol from acetate or mevalonate and decreased the esterification rate of the neoformed molecules. No marked alteration in the rate of synthesis or esterification of cholesterol was observed in the intestinal wall.