摘要:

Little is known about the mechanisms as to how nutrients affect plasma corticosteroids in cold-stressed and starved animals. Therefore, cold-stressed rats (maintained at 7 °C) were fasted (control) or fed a balanced diet (casein 20wt%, fat 5 wt%, starch 70 wt% and vitamin-mineral premix 5 wt%) or the following dietary nutrients for 72 h: casein, lard, starch, glycerol, stearic acid, leucine or glutamic acid. The animals were then killed and plasma corticosteroid concentrations (PCC) were determined. PCC were significantly reduced (p < 0.05) in cold-stressed animals fed a balanced diet (16.95 µg/100 ml plasma) compared to the fasted cold-stressed controls (FCSC) (24.16µg/100ml plasma). Additionally, corticosteroid concentrations (µg/100 ml plasma) of animals fed the following specific nutrients were also significantly lower than the FCSC values: starch (15.53), lard (12.01), stearic acid (12.74), glycerol (13.32) and leucine (16.03). Casein and glutamic acid did not significantly alter plasma corticosteroid levels relative to the FCSC concentration. It is concluded that certain specific building blocks of nutrient classes, i.e. stearic acid or glycerol, can alter PCC to the same extent as the parent compound (lard), however the individual components of casein, a complex nutrient, i.e. leucine, a ketogenic amino acid, versus glutamic acid, a glycogenic amino acid, may elicit a different PCC eff

ISSN:0250-6807    

DOI:10.1159/000177750

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

We report an impressive decline in plasma lipid resistance to oxidation during Triton-WR-1339-induced hyperlipidemia in rats. This decline is associated with a modification in the balances between α-tocopherol and lipids and α-tocopherol and ascorbate. These results are consistent with a weak resistance of accumulated native lipoproteins in plasma to oxidation, during a 6-hour time course, and they suggest a misunderstood role of lipoprotein catabolic enzymes: to improve this characteristic. Conclusively, the results lead us to propound Triton-induced hyperlipidemia as an original model for studying the balance impairment between antioxidants and oxidizable substrates.

ISSN:0250-6807    

DOI:10.1159/000177751

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Gastrointestinal injury involves oxidative damage as the result of oxygen-derived free radicals which are formed during the inflammatory reactions. Chylomicrons which are synthesized by the intestine can thus be exposed to lipid peroxidation in celiac disease. Similarly, low-density lipoprotein (LDL) propensity to oxidation may be enhanced as a result of a direct or indirect effect of the oxidative process. To resolve these possibilities, plasma chylomicrons and LDL were isolated from a patient with celiac disease and from a control healthy subject before and 3 h after a fat-rich meal, and their propensity to copper-induced lipid peroxidation was then analyzed. The patient’s chylomicrons, its LDL that was obtained before the fat-rich meal and its LDL that was obtained after the meal demonstrated 220, 39 and 48% elevation in their content of thiobarbituric-acid-reactive substances in comparison with the control lipoproteins. After a complete recovery of the patient’s intestine, the susceptibility of the patient lipoproteins to in vitro oxidation returned toward normal levels. In the patient LDL fraction (obtained either before or after the fat-rich meal), but not in the patient’s chylomicrons, the carotenoid content was reduced by 70%, vitamin E by 45%, and the LDL content of arachidonic acid was increased by 70% in comparison with the control lipoproteins. On recovery of the patient and return of the intestine to its normal morphology, normalization of all of these constituents was ach

ISSN:0250-6807    

DOI:10.1159/000177752

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Low-density lipoprotein (LDL) oxidation and macrophage cholesterol accumulation are both involved in atherogenesis. Recently it was shown that feeding rabbits or humans with an oleic-acid-rich diet reduced the susceptibility of their LDL to in vitro oxidation. Since olive oil is highly enriched with oleic acid, we tested the effect of olive oil supplementation (50 g/day) to the diet of 10 healthy male subjects, during a 2-week period, on macrophage uptake of their LDL and on the propensity of their LDL to oxidation (with copper ions). Olive oil supplementation to the diet resulted in LDL enrichment with oleic acid (C18:l) and sitosterol. No effect on plasma cholesterol levels was found, but the LDL cholesteryl ester content was reduced (16%) whereas its unesterified cholesterol was increased (41 %). Even after 1 week of the olive oil diet, the LDL susceptibility to in vitro oxidation was significantly reduced (p < 0.01). Macrophage uptake of LDL was studied by analysis of cellular cholesterol content and by analysis of the macrophage cholesterol esterification rates. LDL obtained after 1 and 2 weeks of the olive oil diet demonstrated reduced cellular uptake in comparison with LDL obtained before the supplementation of olive oil, by 50 and 61 %, respectively. The LDL resistance to oxidation was shown by a reduction in its peroxide, malondialdehyde and conjugated diene content by 73, 28 and 32%, respectively. LDL incubation with oleic acid for the period of its oxidation with copper ions demonstrated a dose-dependent inhibition of lipoprotein oxidation by up to 72% as opposed to linoleic and arachidonic acids (50 µM) which increased LDL oxidation by 22 and 72%, respectively. Sitosterol, in a similar incubation system, inhibited LDL oxidation by up to 26%. We conclude that olive oil supplementation to the diet modifies LDL lipid composition and enriches the lipoprotein with oleic acid and sitosterol. The antiatherogenic properties of this modified lipoprotein may be related to its resistance to in vitro peroxidation and its reduced uptake by macrophages

ISSN:0250-6807    

DOI:10.1159/000177753

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The influence of right hemicolectomy (RH) on fecal nitrogen excretion was determined with selected protein levels up to 25%. The endogenous fecal N was determined by extrapolating protein intake to zero. Fecal N was higher in RH than in control rats at all protein levels used. However, the slope of regression curves describing fecal nitrogen excretion was greater for RH compared with the control group. The endogenous fecal nitrogen was not significantly different between the two groups of rats. The feces from rats fed with 25% of protein were partitioned into individual fractions by physical separation and a study was made of the distribution of nitrogen in the bacterial, soluble and fiber fractions of the stool. RH decreased the N excreted in the bacterial fraction by 33% (from 1.71 ± 0.32 to 1.15 ± 0.18 mmol/day) and increased the N excreted in the soluble fraction by 280% (from 1.60 ± 0.30 to 6.08 ± 1.16 mmol/day). These results show that the RH increased the fecal N excretion and that this N is mainly in the soluble fract

ISSN:0250-6807    

DOI:10.1159/000177754

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The overall vegetable and animal protein combinations of the diet in Northern Mexico were determined through a dietary population survey. Vegetable sources made up 45% and animal protein was 55% (45V/55A). Further combinations of up to 100% vegetable protein dietary mixtures (100V) were studied to test the sensibility of the variations on protein requirements of pre-school, school children and adults. Diets were analyzed for amino acid composition and in vivo protein digestibility in rats to estimate true protein requirements according to FAO/WHO/UNU (1985). The effect on the preschool group showed the widest variation with 1.46 g/kg/day in the 45V/55A to 2.63 in the 100V. For the school-aged children and adults the variations were 1.15-1.79 and 0.94-0.84 g/kg/day respectively.

ISSN:0250-6807    

DOI:10.1159/000177755

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0250-6807    

DOI:10.1159/000177756

出版商:S. Karger AG    

年代:1993

数据来源: Karger