A buckwheat protein product suppresses gallstone formation and plasma cholesterol more strongly than soy protein isolate in hamsters

This study was conducted to investigate the effects of a buckwheat protein product (BWP) on plasma cholesterol, gallbladder bile composition and fecal steroid excretion in hamsters fed diets with 5 g/kg cholesterol. Diets also contained 200 g/kg of casein, soy protein isolate (SPI) or BWP as protein sources. After 2 wk, plasma and liver concentrations of cholesterol in the hamsters fed BWP were significantly lower than those in the hamsters fed casein and SPI. The molar proportion of cholesterol in gallbladder bile was significantly lower in the BWP group than in the other groups, whereas that of bile acids was slightly higher in the BWP group (P 相似文献   

Dietary flaxseed meal is more protective than soy protein concentrate against hypertriglyceridemia and steatosis of the liver in an animal model of obesity

OBJECTIVE: Soy protein and flaxseed meal have been reported to have beneficial effects on many chronic diseases in humans and animals. The primary objective of the study was to evaluate the beneficial effects of soy protein and flaxseed meal on hypertriglyceridemia and liver steatosis associated with obesity and diabetes. We compared the effects of dietary soy protein and flaxseed meal with that of casein on plasma and liver lipids in a genetic model of obesity, type II diabetes and insulin resistance, namely the SHR/N-cp rat. METHODS: Lean and obese phenotypes of SHR/-cp rats were fed AIN 93 diets containing 20% of energy from casein (control), soy protein concentrate or flaxseed meal for six months. Plasma was analyzed for total cholesterol, LDL cholesterol, triglyceride and total protein. Liver was analyzed for steatosis by light microscopy after staining samples with Hematoxylin-Eosin and Oil-Red-O. RESULTS: In lean rats soy protein and flaxseed meal significantly decreased plasma total cholesterol (26.0% and 20.3% respectively) compared to casein. In obese rats flaxseed meal had significant cholesterol lowering effect compared to control rats (41%). Soy protein significantly lowered both plasma LDL-cholesterol and HDL-cholesterol in lean phenotypes while in obese phenotypes flaxseed meal significantly lowered LDL-cholesterol and HDL-cholesterol compared to casein-fed rats. Flaxseed meal also significantly lowered plasma triglyceride in both lean and obese rats compared to casein fed rats (33.7% and 37% respectively). There was significantly greater fat accumulation in livers of obese rats than lean rats (200%) regardless of dietary protein type. Flaxseed meal significantly lowered fat deposition in livers of both lean and obese rats compared to rats fed casein or soy protein. Dietary component(s) present in flaxseed meal or soy protein responsible for hypolipidemic effects is not clear. CONCLUSIONS: The marked hypotriglyceridemic and hypocholesterolemic effects of flaxseed meal may have important therapeutic implications in patients with hypertriglyceridemia and hypercholesterolemia and deserve further study in humans with these disorders. Flaxseed meal supplementation may provide a new therapeutic strategy to reduce hypertriglyceridemia and fatty liver.     

Dietary conjugated linoleic acids increase lean tissue and decrease fat deposition in growing pigs.

Conjugated linoleic acids (CLA) decrease the body fat content of rodents; the aim of this study was to determine whether dietary CLA altered carcass composition of pigs. Female Large White x Landrace pigs (n = 66) were used in this study. To obtain initial body composition, six pigs were slaughtered at 57 kg live weight, whereas the remaining pigs were allocated to one of six dietary treatments (0, 1.25, 2.5, 5.0, 7.5 and 10.0 g/kg CLA, containing 55% of CLA isomers). The diets, containing 14.3 MJ digestible energy (DE) and 9. 3 g available lysine per kg, were fed ad libitum for 8 wk. Dietary CLA had no significant effect on average daily gain (861 vs. 911 g/d for pigs fed diets with and without CLA, P = 0.15) or feed intake (2. 83 vs. 2.80 kg/d, P = 0.74). The gain to feed ratio was increased by dietary CLA by 6.3% (0.328 vs. 0.348, P = 0.009). Fat deposition decreased linearly (-8.2 +/- 2.09 g/d for each gram per kilogram increase in CLA concentration; P < 0.001) with increasing inclusion of CLA. At the highest level of CLA inclusion, fat deposition was decreased by 88 g/d (-31%). Similarly, the ratio of fat to lean tissue deposition decreased linearly (-0.093 +/- 0.0216 for each gram per kilogram increase in CLA concentration; P < 0.001) with increasing dietary CLA. The carcass lean tissue deposition response to dietary CLA was quadratic in nature and was maximized (+25%) at 5. 0 g/kg dietary CLA. Overall, dietary CLA increased the gain to feed ratio and lean tissue deposition and decreased fat deposition in finisher pigs.     

Dietary plasma protein reduces small intestinal growth and lamina propria cell density in early weaned pigs

ABSTRACT We quantified the effects of a diet containing animal plasma protein on small intestinal growth and mucosal morphology in early weaned pigs. Ninety-six pigs [14 d old, 4 kg body weight (BW)] were assigned in groups of 32 to three dietary treatments as follows: 1) free access to control diet (C), 2) free access to plasma protein diet (P), and 3) plasma protein, pair-fed to C (PPF). Eight pigs from each group were killed at 2, 4, 8 or 16 d. Over a 16-d period, weight gain in the P group was 43% greater (P < 0.05) than that in C pigs; weight gain was similar in C and PPF groups. Protein intake in the P group was 33% higher (P < 0.05) than that in the PPF group; no significant difference was observed between the C and P groups. Dietary protein conversion efficiencies in both the P and PPF groups were approximately 18% greater (P < 0.05) than those in the C group. Intestinal masses in the three groups did not differ at 2, 4 and 8 d. By 16 d, the jejunal and ileal protein and DNA masses (mg/kg BW) in both the P and PPF groups were lower than those in the C group (P < 0.05). Dietary plasma protein did not affect crypt cell proliferation, crypt depth or villous height in either the jejunum or ileum. However, the intravillous lamina propria cell density in the jejunum was significantly lower (P < 0.05) in P and PPF pigs than in C pigs. Plasma urea concentrations were also 40 and 42% lower (P < 0.05) in the P and PPF groups, respectively, than in the C group. Our results indicate that dietary plasma protein reduces the cellularity of the lamina propria, but not epithelial cell surface of the small intestine. Feeding plasma protein also increased the efficiency of dietary protein utilization, in part, by decreasing amino acid catabolism.     

Dietary protein intake is associated with lean body mass in community-dwelling older adults

Lean body mass (LBM) is important to maintain physical function during aging. We hypothesized that dietary protein intake and leisure-time physical activity are associated with LBM in community-dwelling older adults. To test the hypothesis, participants (n = 237; age, 65-92 years) did 3-day weighed food records and reported physical activity. Body composition was assessed using dual-energy x-ray absorptiometry. Protein intake was 0.98 ± 0.28 and 0.95 ± 0.29 g/kg body weight in male and female participants, respectively. Protein intake (in grams per kilogram of body weight) was associated with LBM (in kilograms); that is, the differences in LBM were 2.3 kg (P < .05) and 2.0 kg (P = .054) between the fourth vs the first and the fourth vs the second quartiles of protein intake, respectively. Only a minor part of this association was explained by increased energy intake, which follows an increased protein intake. Our study shows that dietary protein intake was positively associated with LBM in older adults with a mean protein intake higher than the current recommended daily allowance of 0.8 g/kg per day. Leisure-time physical activity, predominantly consisting of endurance type exercises, was not related to LBM in this group.     

Dietary soy protein is associated with reduced intestinal mucosal polyamine concentration in male Wistar rats

Quantitation of polyamine levels has been correlated with biomarkers of proliferation in the colon mucosa where dysregulated epithelial hyperproliferation is associated with colorectal cancer risk. This study was performed to assess the response of polyamine measurements to dietary factors in an animal model. Male Wistar rats were fed purified diet or diets substituted by 20% lard fat, 20% beet fiber and 20% soy protein. After 2 wk, mucosal polyamines were measured along intestinal tracts by HPLC. In rats fed the control diet (n = 10), mucosal polyamines were found at high levels in the duodenum, jejunum and ileum but at low levels in the cecum, colon and rectum. Compared with rats fed the control diet, those fed the 20% lard diet showed greater polyamine levels in the large intestine (P < 0.05, n = 10), but those fed the 20% fiber diet exhibited lower polyamine levels in the small intestine (P < 0.05, n = 9). However, rats fed the 20% soy protein diet had lower polyamine levels in both small and large intestines (P < 0.05, n = 15). Significant linear correlations were observed between rectal polyamine levels and the dietary energy intakes in these four diet groups (r = 0.972-0.991, P < 0.001). Supplementation of 0.1% soy isoflavones to the basal diet or 0.3% DL-methionine to the 20% soy protein diet for 4 wk did not affect polyamine levels. The results indicate that soy protein reduced mucosal polyamine levels, at least in part, through reduction of energy intakes. Further studies are warranted to verify that polyamine levels in intestinal mucosa are useful as an intermediate endpoint of the dietary risk factors.     

Dietary phosphate-dependent growth is not mediated by changes in plasma phosphate concentration

The present study was undertaken in order to assess the role of dietary phosphate in growth. A diet deficient in phosphate led to a suppression of growth in juvenile rats. The phenomenon is similar to that described for diets deficient in other essential single components such as Mg, Zn or K. However, unlike the other constituents, dietary phosphate restriction affected the growth rate much more than it altered the serum phosphate concentration; addition of phosphate to the drinking water of rats fed a low-phosphate diet restored the growth rate without a concomitant change in serum phosphate concentration. The suppression of growth rate by the deletion of phosphate was associated with a delayed decrease in food intake. This finding implies that the variation in appetite was secondary to the change in growth. The increase in body weight following phosphate supplementation was associated with a concomitant increment in food intake. The phosphate-dependent growth was, however, evident also in rats that were pair-fed with those that were not supplied with phosphate. It is concluded that dietary phosphate-dependent growth is not mediated by changes in phosphate concentrations in the extracellular fluid. It is plausible that signals arising from receptors for phosphate in the digestive system constitute part of the growth control apparatus in rats.     

Free amino acids are absorbed faster and assimilated more efficiently than protein in postlarval Senegal sole (Solea senegalensis)

To improve the formulation of diets for the early stages of marine fish, assimilation rates of free amino acids (FAA) and protein in postlarval Senegal sole (Solea senegalensis) were determined. Fish (2.45 +/- 0.87 mg dry weight) were tube fed 36 nL of a diet of FAA containing L-[(35)S] methionine (FAA diet) or bovine serum albumin, containing L-[methylated-(14)C]bovine serum albumin (Prot-diet), both at a concentration of 4.08 g/L. A time series was performed, and the amounts of label in incubation water, liver, gut and body carcass were quantified. The FAA diet was absorbed with a 3.5-times-higher transfer rate (P < 0.001) from the gut into the larval body tissues compared with the Prot-diet. The FAA diet also was assimilated with greater efficiency than the Prot-diet (80% versus 58%, P: = 0.001). If we assume that the label present in the gut represents amino acids incorporated into the intestinal tissue, the assimilation efficiencies for the two diets were 89 and 64%. Therefore, FAA seems to be superior to protein as a dietary source of amino acids in Senegal sole postlarvae. However, because the absorption dynamics of protein and FAA differ, care should be taken when using the sources together to avoid amino acid imbalance.     

Effects of dietary beef and soy protein on tissue composition and low density lipoprotein uptake in young pigs

To study effects of dietary protein source on plasma cholesterol homeostasis, six littermate pairs of 8-wk-old, castrated male pigs were assigned randomly to high fat diets containing either lean beef or soy protein isolate, with beef tallow as the major fat source in both diets. Diets were fed for 6 wk, with blood samples taken weekly and analyzed for lipid composition. At 6 wk, each pig was injected with [3H]cholesterol- and [14C]sucrose-labeled low density lipoproteins, and serial blood samples were taken. Pigs were then killed, and several tissues were sampled. Results show that dietary beef or soy protein, when fed with beef tallow as a fat source, has differential effects on rates of uptake of intact LDL by heart, M. sartorius muscle and subcutaneous adipose tissue, and on rates of uptake of LDL cholesterol by net free cholesterol exchange in subcutaneous and perirenal adipose tissues. Dietary protein source affected the composition of only two tissues analyzed. Pigs fed the beef-based diet had greater lipid concentrations in M. sartorius muscle, whereas pigs fed the soy protein-based diet had greater lipid concentrations in heart. Source of dietary protein did not influence in vivo kinetics of LDL cholesterol removal from blood plasma.     

Dietary conjugated linoleic acid consumption during pregnancy and lactation influences growth and tissue composition in weaned pigs

We evaluated the effects of conjugated linoleic acid (CLA) on growth performance, tissue fatty acid composition and ex vivo lipogenic enzyme activity in piglets (n = 40) reared on sows fed diets supplemented with CLA or linoleic acid (LA). Weaned offspring of both sow groups were offered either a CLA- or LA-enriched starter diet for 35 d. The starter diets were formulated to contain 2 g CLA (containing 58.9 g CLA/100 g total fatty acids) or LA per 100 g feed. All piglets were slaughtered at 70 d of age and tissue samples of the back fat, omental fat and longissimus dorsi were collected. Irrespective of the dietary fat supplied in the starter period, piglets reared on the CLA sows had greater final body and warm carcass weights (P: < 0.01), and greater feed intake (P: = 0.02) than piglets reared on the LA sows. The dietary effect on the fatty acid composition was similar for the adipose and muscle tissues. Compared with the LA-enriched diets, CLA increased the level of total saturated fatty acids (P: < 0.05), whereas that of monounsaturated fatty acids was decreased (P: < 0.05). Dietary CLA increased glucose-6-phosphate dehydrogenase (P: < 0.01) and malic enzyme activities (P: < 0.06) in the fat tissues, but did not affect fatty acid synthase activity. The shift toward a higher deposition of saturated fatty acids and a lower deposition of monounsaturated fatty acids is the result of down-regulation of Delta9-desaturase activity that was induced by CLA rather than an altered rate of de novo synthesis.     

Ovarian tissue vitrification is more efficient than slow freezing in protecting oocyte and granulosa cell DNA integrity

Abstract

Ovarian tissue cryopreservation is the primary treatment modality currently available to women at risk of losing their ovarian function due to cytotoxic therapy. However, the impact of these techniques on the oocyte DNA integrity is not elucidated. Here we have investigated the effect of vitrification and conventional slow freezing of eight week old Swiss albino mouse ovarian tissues on the oocyte and granulosa cell DNA integrity using the comet assay. The intracellular levels of reactive oxygen species in oocytes was measured by 2′,7′-dichlorodihydrofluorescein diacetate fluorescence. The cryopreservation of ovarian tissue by the slow freezing technique resulted in a significantly higher level of DNA fragmentation in oocytes in comparison to vitrification (p?<?0.05) whereas DNA fragmentation in granulosa cells was significantly higher than the control (p?<?0.01). Further, reactive oxygen species were significantly elevated in oocytes derived from slow freezing when compared to vitrification (p?<?0.05). Therefore, we conclude that the ovarian tissue slow freeze-thawing makes the oocyte and granulosa cells more vulnerable to DNA damage whereas vitrification appears to be a safer method than slow freezing for ovarian tissue cryopreservation.     

Muscle fractional protein synthesis is higher in Iberian than in Landrace growing pigs fed adequate or lysine-deficient diets

Protein deposition in Iberian pigs is low and the reasons for this are unknown. We investigated differences in protein synthesis rate in tissues of 30 Iberian and Landrace gilts fed 2 diets with adequate amino acid composition containing 160 or 120 g crude protein (CP)/kg, or a lysine-deficient diet (containing 120 or 160 g CP/kg for Iberian and Landrace pigs, respectively). Pigs were infused with a flooding dose of phenylalanine (15% as [(2)H(5)]-phenylalanine). Blood samples were taken from 12 to 40 min after the start of infusion, and samples from longissimus dorsi (ld), biceps femoris (bf), and semimembranosus (sm) muscles, liver, and duodenum were taken after slaughter. Body weights (BW) were 22.9 +/- 0.37 and 27.1 +/- 0.64 kg for Iberian and Landrace pigs, respectively. Iberian pigs fed the adequate diets had higher muscle fractional protein synthesis rates (FSR, %/d) than Landrace pigs. The FSR were 7.9 +/- 0.34 vs. 6.3 +/- 0.29%/d; 8.3 +/- 0.36 vs. 6.3 +/- 0.21%/d, and 7.7 +/- 0.23 vs. 6.4 +/- 0.36%/d for ld, bf, and sm muscles in Iberian and Landrace breeds, respectively (P < 0.01). However, muscles were between 20 and 32% smaller in the Iberian pigs (P < 0.01). Dietary protein level did not affect muscle FSR or size in either breed. Lysine deficiency reduced muscle FSR (46-49%, P < 0.001). Visceral tissues had greater relative weights in Iberian pigs (P < 0.001) with no breed differences in FSR. These findings might explain the low efficiency of protein and energy utilization by Iberian pigs compared with conventional pig breeds.     

Whey protein preloads are more beneficial than soy protein preloads in regulating appetite,calorie intake,anthropometry, and body composition of overweight and obese men

High-protein diets exert beneficial effects on appetite, anthropometry, and body composition; however, the effects of protein preloads depend on the amount, type, and time of consumption. Therefore, we hypothesized that long-term supplemental preloads of whey protein concentrate (WPC) and soy protein isolate (SPI) consumed 30 minutes before the largest meal would decrease appetite, calorie intake (CI), and anthropometry and improve body composition in overweight and obese men in free-living conditions. The subjects included 45 men with a body mass index between 25 and 40 kg/m² and who were randomly allocated to either the WPC (n = 26) or SPI (n = 19) groups. For 12 weeks, the subjects consumed 65 g WPC or 60 g SPI that was dissolved in 500 mL water 30 minutes before their ad libitum lunch. Appetite, CI, anthropometry, and body composition were assessed before and after the study and biweekly throughout. After 12 weeks, mean changes between the groups were significant for appetite (P = .032), CI (P = .045), anthropometry (body weight [P = .008], body mass index [P = .006], and waist circumference), and body composition (body fat mass and lean muscle [P < .001]). Relative to baseline, within-group mean changes from WPC were significant for appetite, CI, anthropometry, and body composition (P < .001). In the SPI group, mean changes were significant, relative to baseline, for all variables except lean muscle (P = .37). According to this 12-week study, WPC preloads conducted 30 minutes prior to the ad libitum main meal exerted stronger beneficial effects than did SPI preloads on appetite, CI, anthropometry, and body composition of free-living overweight and obese men.     

The clearance and metabolism of biotin administered intravenously to pigs in tracer and physiologic amounts is much more rapid than previously appreciated

Understanding of biotin pharmacokinetics and regulation of metabolism is essential for the determination of the biotin requirement for humans. Using Landrace-Cambrough pigs as a model, we initially demonstrated that biotin binding to protein accounts for only a small percentage of the total biotin in plasma. A physiologic amount of [14C]biotin was administered intravenously to three pigs; nine blood samples were collected over 48 h. Plasma concentrations of 14C-labeled metabolites were negligible for the first 2 h after biotin infusion. Disappearance curves of total 14C and of [14C]biotin were similar; both fit a triexponential function consistent with a three-compartment, open model. To characterize the rapid early phase of disappearance more precisely, a physiologic amount of [14C]biotin was administered intravenously to five pigs; eight blood samples were collected over the first hour and 16 total samples over 48 h. Again a triexponential function provided an excellent fit. The mean half-life values (+/- 1 SD) for the three phases were 0.11 +/- 0.07, 1.43 +/- 0.42 and 22 +/- 4 h. The [14C]biotin accumulated primarily in the liver, kidney and muscle. When administered intravenously at tracer doses to three pigs, [3H]biotin exhibited similar early pharmacokinetics; however, substantial quantities of a 3H-labeled metabolite appeared after 1 h. These studies provide evidence that egress of biotin from plasma is more rapid than previously appreciated. The slower second and third phases may represent transport into the cytosol, biotransformation into intermediates and covalent binding to intracellular proteins. Similar pharmacokinetics are likely to be seen in humans.     

Cats require more dietary phenylalanine or tyrosine for melanin deposition in hair than for maximal growth

In 1986, the NRC recommended a dietary concentration of 4.0 g/kg of phenylalanine and 8.5 g/kg of total aromatic amino acids for growing kittens on the basis of maximal growth rate and nitrogen balance. Black hair-coated cats were given purified diets containing the following phenylalanine + tyrosine (Phe + Tyr) concentrations (g/kg diet): 4 + 2, 4 + 4, 4 + 6, 4 + 8, 10 + 0, 10 + 2, 10 + 4, 10 + 6, 10 + 8, 10 + 10, 24 + 0 for at least 6 mo. All other amino acids were present at about twice the requirements. Total melanin and the oxidation product of eumelanin, pyrrole-2,3,5-tricarboxylic acid (PTCA) were measured in hair. There was a significant linear relationship between the concentrations of tyrosine in plasma and PTCA in hair. The relationship between PTCA concentration in hair and Phe + Tyr in the diet had a point of inflection at approximately 16 g/kg Phe + Tyr. Cats fed diets with <16 g Phe + Tyr developed "red hair." We confirmed the anecdotal reports that the black hair of cats can change from black to reddish brown. An aromatic amino acid concentration > or =18 g/kg is recommended for the prevention of visually discernible red hair in black-coated cats. Dietary concentrations >18 g total aromatic amino acids/kg diet promote a greater ratio of PTCA:total melanin in hair. We are unaware of a secondary nutrient requirement being so much greater than the requirement for growth.     

The live Mycobacterium tuberculosis phoP mutant strain is more attenuated than BCG and confers protective immunity against tuberculosis in mice and guinea pigs

The Mycobacterium tuberculosis phoP mutant strain SO2 has previously been shown to have reduced multiplication in mouse macrophages and in vivo using the mouse intravenous-infection model. In this study we demonstrate that the M. tuberculosis SO2 is highly attenuated when compared with the parental M. tuberculosis MT103 strain and also more attenuated than BCG in severe combined immunodeficiency disease (SCID) mice. Complementation of the M. tuberculosis SO2 with the wild-type phoP gene restored the virulence of the strain in the SCID mice, confirming that the attenuated phenotype is due to the phoP mutation. In Balb/c mice subcutaneously vaccinated with either M. tuberculosis SO2 or BCG, the proportions of CD4+ and CD8+ populations measured in the spleen were significantly higher in the M. tuberculosis SO2 vaccinated group. In addition, the proportion of antigen-stimulated CD4+/CD8+ cells expressing IFN-gamma was significantly higher in the M. tuberculosis SO2 vaccinated group when compared with the BCG group. Balb/c mice subcutaneously vaccinated with the M. tuberculosis SO2 strain were also protected against intra-venous challenge with M. tuberculosis H37Rv at levels comparable to mice vaccinated with BCG, as measured by reduced bacterial counts in lung and spleens. Guinea pigs subcutaneously vaccinated with the M. tuberculosis SO2 strain were protected against aerosol challenge with M. tuberculosis H37Rv delivered at different doses. A high dose aerosol challenge of M. tuberculosis SO2 vaccinated guinea pigs resulted in superior levels of protection when compared with BCG vaccination, as measured by guinea pig survival and reduction in disease severity in the lung.