Modeling in nutrition and metabolism

Fundamentals of modeling of in vivo nutritional and metabolic systems are discussed. Emphasis is placed upon the potential usefulness of models, and the relationship between utility and model complexity. With the glucose regulating system used as a metaphoric example, the balance between available data and model simplification is drawn, with the goal of obtaining a representation of optimal complexity. From such an optimization procedure, it is argued that the maximum usefulness of models can be obtained with respect to the testing of specific physiological hypotheses, and the estimation of unmeasurable parameters or variables. The view is expressed that only with careful modeling procedures, in which principles of optimal complexity are applied, will the impact of models of nutritional systems be significant.     

膳食营养与宿主遗传通过肠道菌群调节能量代谢研究进展

文章从膳食营养、宿主遗传两方面阐述了肠道菌群对宿主能量代谢的调节作用,着重叙述了肠道菌群代谢产物调节宿主代谢的机制,并对今后的研究方向进行了展望。     

Role of food fiber in nutrition

Numerous experiments indicate that in the pathogenesis of so-called civilization diseases, low consumption of dietary fibers seems to be one of etiological factors. Therefore, it is not surprising that dietary fibers play an ever increasing role both in prevention and dietetic management of the diseases. Among these fibers wheat bran containing about 50% of dietary fibers has the most beneficial physiological effect. Besides, wheat bran is fit very well for production of different foodstuffs. Data are reported on the content of crude and dietary fibers in cabbage, radish, carrot, wheat bran and brown bread.     

Role of glutamine in enteral nutrition in intestinal insufficiency

In this review the role of glutamine in enteral nutrition in intestinal insufficiency is shown. It is emphasized, that glutamine plays an important role in preservation of structure and function of intestines in normal state and under stressful condition.     

Prepartal plane of nutrition, regardless of dietary energy source, affects periparturient metabolism and dry matter intake in Holstein cows

Previous research in our laboratory showed that dietary fat supplementation during the dry period was associated with decreased peripartum hepatic lipid accumulation. However, fat supplementation decreased dry matter (DM) intake and thereby confounded results. Consequently, 47 Holstein cows with body condition scores (BCS) ≤ 3.5 at dry-off were used to determine whether source or amount of energy fed to dry cows was responsible for the decreased hepatic lipid content. Moderate grain- or fat-supplemented diets [1.50 Mcal of net energy for lactation (NE_L)/kg] were fed from dry-off (60 d before expected parturition) to calving at either ad libitum (160% of NE_L requirement) or restricted (80% of NE_L requirement) intakes. Postpartum, cows were fed a single lactation diet for ad libitum intake and performance was measured for 105 d. Prepartum intakes of DM and NE_L were significantly lower for feed-restricted cows as designed. During the first 21 d postpartum, previously restricted cows had higher intakes of DM and NE_L. Body weights and BCS were lower prepartum for restricted cows but groups converged to similar nadirs postpartum. Restricted-fed cows had lower concentrations of glucose and insulin and increased concentrations of NEFA in plasma during the dry period. Peripartum NEFA rose markedly for all treatments but were higher postpartum for cows previously fed ad libitum. Plasma concentrations of NEFA and BHBA remained lower in cows restricted-during the dry period. Postpartum concentrations of total lipid and triglyceride in liver were lower in cows previously feed-restricted. Across dietary treatments, activity of carnitine palmitoyltransferase (CPT) in hepatic mitochondria was lowest at − 21 d, highest at 1 d, and decreased at 21 and 65 d relative to parturition. The activity of CPT at d 1 tended to be higher for previously feed-restricted cows; thereafter, CPT activity declined more rapidly than in cows fed ad libitum. Nutrient intake during the dry period had more pronounced effects on peripartal lipid metabolism and DMI than did composition of the prepartum diet.     

Effects of nutrition characteristics on oxidative metabolism in electric welders

Analysis of actual feeding and of oxidative metabolism in electric welders of enterprises was carried out. On the basis of obtained data the hypothesis concerning mechanism of oxidative metabolism violation developing in these conditions (oxidative stress) and its consequences for health is offered. The findings of investigation can be used of in development of products of a treatment-and-prophylactic feeding with antioxidative direction.     

The effect of nutrition on the metabolism of glycine

It can be concluded on the base of data from literature and of our own results, that the metabolism of glycine is localized mainly in liver tissue. The main catabolic pathway of nutritional glycine proceeds via the glycine-cleavage enzyme, serinehydroxymethyltransferase and serinedehydratase or serine-pyruvate aminotransferase and via serine and pyruvate. The physiological significance of this metabolic pathway is estimated. The catabolism via the C1-pool is limited by the regeneration rate of tetrahydrofolic acid. Other pathways (via glyoxylate, SHEMIN-cycle, aminoacetone cycle) are only of minor significance for the catabolism of glycine originating from food.     

Role of mineral nutrition in minimizing cadmium accumulation by plants

Cadmium (Cd) is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of great concern regarding its entry into the food chain. Cadmium enters into the soil–plant environment mainly through anthropogenic activities. Compounds of Cd are more soluble than other heavy metals, so it is more available and readily taken up by plants and accumulates in different edible plant parts through which it enters the food chain. A number of approaches are being used to minimize the entry of Cd into the food chain. Proper plant nutrition is one of the good strategies to alleviate the damaging effects of Cd on plants and to avoid its entry into the food chain. Plant nutrients play a very important role in developing plant tolerance to Cd toxicity and thus, low Cd accumulation in different plant parts. In this report, the role of some macronutrients (nitrogen, phosphorus, sulfur and calcium), micronutrients (zinc, iron and manganese), and silicon (a beneficial nutrient) has been discussed in detail as to how these nutrients play their role in decreasing Cd uptake and accumulation in crop plants. Copyright © 2010 Society of Chemical Industry     

Short-chain fatty acids in control of energy metabolism

Short-chain fatty acids (SCFAs), especially acetate, propionate and butyrate, are the end products from the intestinal microbial fermentation of dietary fibers and resistant starch. It has been well documented that plasma and colonic SCFAs are associated with metabolic syndromes. Recently, the involvement of SCFAs in energy homeostasis regulation has been extensively studied. The importance of SCFAs on energy metabolism has highlighted the potential of modulating SCFAs as a nutritional target to prevent and counteract metabolism disorders and its associated diseases such as obesity and type 2 diabetes. Here, we summarize the current knowledge about the biological properties of SCFAs with their impact on the energy homeostasis.