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At least 595 records · Page 33Linked to original sources
PubMed1984

Effect of protein intake level on urinary energy/nitrogen ratio in Japanese.

Urinary energy/nitrogen ratios were determined in 179 female and 14 male subjects given protein from various sources and at various intake levels. The ratio decreased with increasing protein intake from zero to 1 g/kg/day but was constant when protein intake was between 1 to 1.8 g/kg/day. The ratio was not affected by the variety of protein source. There was no difference between the data for semisynthetic diet and conventional diet. Mean values and standard deviations of the ratio in men and women given the diet containing 1.0 to 1.8 g protein/kg/day were 9.06 +/- 0.56 (n = 14) and 8.19 +/- 0.81 (n = 37) kcal/kg N, respectively. The difference between two figures in men and women was significant (p less than 0.05). The mean values of urinary E/N ratio actually measured did not approach those of urea (5.34 kcal/g N), the principal nitrogenous compound in urine, the proportion of which increased at higher protein intake level. Characteristically high ratios were obtained in the ma-konbu (Laminaria japonica) and enokitake (Flammulina velutipes) diet groups. The results suggest that urinary energy originates not only from nitrogen-containing compounds but also from other organic compounds containing no nitrogen. Therefore, further investigation is necessary to evaluate the urinary E/N ratio applicable to the urinary loss of incompletely oxidized nitrogenous compounds.

Dietary Proteins↗
PubMed2002

Analyses of degradation products from lipid and protein hydrolyses in the small intestine of broiler chickens fed on maize-based diets containing guar gum, or wheat-based diets.

1. Three maize diets containing graded levels (0, 0.1, 0.3%) of guar gum and two wheat diets differing in their in vitro viscosities were fed to male broiler chickens (7 to 23 d) for measurements of growth performance and analyses of degradation products from lipid and protein hydrolyses in the small intestine of broiler chickens. Analyses of degradation products were conducted to define which step (hydrolysis or absorption) was most involved in the negative effects of the digesta viscosity on lipid and protein digestibilities. The experiment was also carried out to examine whether effects of wheats could be explained in terms of intestinal viscosity alone. 2. The intestinal viscosities with wheat diets were within the range of those observed with the three maize diets. The correlations between in vivo and in vitro viscosities were higher with real than with potential applied viscosity of diets, both in jejunum and ileum. 3. The mean gain:food ratio observed with wheat diets was lower (P<0.05) than with maize diets despite lower (P<0.05) mean intestinal viscosities in birds given the wheat than given the maize diets. This shows that factors different from intestinal viscosity were also involved in the negative effects of wheats. 4. Distributions of nitrogen compounds in digesta were characterised by low proportions of compounds with high molecular weight (>12,000). For all classes of nitrogen compounds, the contents measured in digesta dry matter did not differ between chickens fed with or without guar gum. 5. Distributions of lipid classes in both jejunum and ileum were characterised by a large proportion of free fatty acids (FFA) and very few triglycerides (TG). In the ileum, FFA and TG contents were both positively correlated with supernatant viscosity, but the slope for FFA content was 35 times higher than for TG. In these relationships, there was no difference between maize and wheat diets. 6. It is concluded that absorption was the main step involved in the lipid digestibility reduction due to intestinal viscosity. For proteins, the most important step (hydrolysis or absorption) involved in decreased digestibility due to intestinal viscosity was not clearly identified.

Animal Feed↗
PubMed1996

Nitric oxide, nitrite, and Fnr regulation of hmp (flavohemoglobin) gene expression in Escherichia coli K-12.

Escherichia coli possesses a soluble flavohemoglobin, with an unknown function, encoded by the hmp gene. A monolysogen containing an hmp-lacZ operon fusion was constructed to determine how the hmp promoter is regulated in response to heme ligands (O2, NO) or the presence of anaerobically utilized electron acceptors (nitrate, nitrite). Expression of the phi (hmp-lacZ)1 fusion was similar during aerobic growth in minimal medium containing glucose, glycerol, maltose, or sorbitol as a carbon source. Mutations in cya (encoding adenylate cyclase) or changes in medium pH between 5 and 9 were without effect on aerobic expression. Levels of aerobic and anaerobic expression in glucose-containing minimal media were similar; both were unaffected by an arcA mutation. Anaerobic, but not aerobic, expression of phi (hmp-lacZ)1 was stimulated three- to four-fold by an fnr mutation; an apparent Fnr-binding site is present in the hmp promoter. Iron depletion of rich broth medium by the chelator 2'2'-dipyridyl (0.1 mM) enhanced hmp expression 40-fold under anaerobic conditions, tentatively attributed to effects on Fnr. At a higher chelator concentration (0.4 mM), hmp expression was also stimulated aerobically. Anaerobic expression was stimulated 6-fold by the presence of nitrate and 25-fold by the presence of nitrite. Induction by nitrate or nitrite was unaffected by narL and/or narP mutations, demonstrating regulation of hmp by these ions via mechanisms alternative to those implicated in the regulation of other respiratory genes. Nitric oxide (10 to 20 microM) stimulated aerobic phi (hmp-lacZ)1 activity by up to 19-fold; soxS and soxR mutations only slightly reduced the NO effect. We conclude that hmp expression is negatively regulated by Fnr under anaerobic conditions and that additional regulatory mechanisms are involved in the responses to oxygen, nitrogen compounds, and iron availability. Hmp is implicated in reactions with small nitrogen compounds.

Aerobiosis↗
PubMed2002

Primary evaluation of methenamine as a NPN compound with probable effects on increasing ruminal escaped protein.

The effects of methenamine as a non-protein nitrogenous compound on protein and health status of feedlot lambs were studied in three groups of lambs receiving 5, 10, or 15 g of the substance daily in their feed for 100 days. The results were compared with data obtained from a control group receiving a diet low in crude protein without methenamine. Serum total protein, serum urea nitrogen and serum creatinine were measured every 10 days as indicators of protein metabolism and kidney function. Urine samples were also examined on the same days for possible side-effects of methenamine on the urinary tract. Following slaughter, various internal organs, including the brain and various parts of the gastrointestinal and urinary tracts, were examined both grossly and microscopically to detect any lesions. All groups receiving methenamine had serum total protein and serum urea nitrogen levels higher than those in the control group. The serum creatinine level was normal in all the groups throughout the experiment. No gross or microscopic lesion attributed to the toxic effects of methenamine was detected in any of the internal organs. Therefore, it is concluded that methenamine can be used as a non-protein nitrogenous compound without serious side-effects.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Treatment of coke-plant wastewater by biofilm systems for removal of organic compounds and nitrogen.

Coke-plant wastewater was treated by an anaerobic-anoxic-aerobic (A(1)-A(2)-O) biofilm system and an anoxic-aerobic (A/O) biofilm system, respectively. At same or similar levels of hydraulic retention time (HRT), the two systems had almost identical chemical oxygen demand (COD) and NH(3) removals, but a different organic-N removal. Set-up of an acidogenic stage benefited for the removal of organic-N and the A(1)-A(2)-O system was more useful for total nitrogen removal than the A-O system. HRT did not have a substantial effect on the COD and NH(3)-N removal efficiencies, but considerably influenced the organic-N removal and distribution of oxidized nitrogen in the final effluent. The GC/MS analysis demonstrated that some refractory compounds were decomposed at the acidogenic stage and resulted in the production of some intermediates, which were more readily degraded in the subsequent aerobic stage. Hence, the A(1)-A(2)-O system had better effluent quality than the A-O system in terms of effluent composition.

Bacteria, Aerobic↗
PubMed2004

Polaron transport mechanism in DNA.

A theory of polaron-hopping transport is studied in DNA in the presence of an electric field. The helix structure of DNA consists of a molecule of phosphoric acid, a molecule of sugar and a molecule of a nitrogen compound called a nitrogen base. The charge carriers are localized near the bases. Phonons are created due to internal motions such as changes in winding or the inclination angle of the helix. It is considered that, due to the interaction between a charge carrier and a phonon, a localized polaron is formed in the helix near a base. These internal motions also promote hopping of the localized polarons. By interacting with a phonon, the polaron undergoes a hopping process in the helix structure. We consider that the localized polaron sites are distributed randomly in both space and energy coordinates. A polaron hops from one site to another site in this space. Conduction is a result of many series of hops through this hopping space. This approach differs from the percolation method and others in the calculation of the conductivity. The present theory is used to explain the electric-field- and temperature-dependent conductivity experiments of DNA. A good agreement is found between theory and experiments.

DNA↗