An elemental diet, commercially named Elementalio, contains an amino acid mixture and many other essential nutrients. The amino acid mixture is prepared from hydrolysis of swine blood and supplemented with certain crystalline L-amino acid. The animal experiments suggest that it has a better nutritional effect than other domestic elemental diets in terms of body weight gain, nitrogen balance and correction of hypoproteinemia.

In the present study, an amino acid mixture had been prepared from whole swine blood by acid hydrolysis, ion-exchange separation and adequate supplementation of L-Trp, L-Met, and L-Ile. The content of essential amino acid, chemical score and essential amino acid index of the product were 49.33, 63.77, and 92.38% respectively and its essential amino acid pattern was closely similar to casein or whole egg protein with sulfur-containing amino acid as its first limiting amino acid. In the rat growth experiment, its nutritional value had been proved to be comparable with casein and better than swine blood powder itself in terms of weight gain, PER, and NPR. Therefore, this amino acid mixture can be considered as an ideal food additive and nitrogen source for elemental diet and this is an important way in the utilization of swine blood.

Objective: To investigate the dynamic changes of plasma and erythrocyte riboflavin and its derivatives concentrations after riboflavin deficiency and so as to provide theoretic basis for their application in riboflavin status assessment. Methods: The riboflavin deficiency was induced in rats by feeding a riboflavin deficient diet. The plasma and erythrocyte riboflavin and its derivatives (FMN and FAD) were analysed with HPLC method. The blood glutathione reductase activity coefficient (BGRAC), erythrocyte GSH concentration and urinary riboflavin excretion were also measured. Results: The plasma riboflavin concentration as well as the urinary riboflavin excretion were decreased rapidly early after riboflavin deficiency and followed by plasma riboflavin derivatives. The erythrocyte riboflavin and its derivatives and GSH concentrations were decreased significantly later. On the other hand, the BGRAC was increased significantly in the early period of riboflavin deficiency and the change, however, was limited in a narrow range. Conclusion: The plasma and erythrocyte riboflavin concentration can be applied as a marker in riboflavin status assessment but human studies are necessary for further research.

Objective: To develop a high performance liquid chromatographic (HPLC) method for determination of riboflavin, FMN, and FAD in human plasma and erythrocytes. Method: Waters 600 model HPLC pump and an Atlantis TM C18 column (150 mm?4.6 mm i.d. 5 ?m) were used. The mobile phase consisted of 35% methanol and 65% 5 mmol/L ammonium acetate solution. The flow rate was 1.0ml/min. The spectro-photofluorimeter was set at wavelength of 450 nm for excitation and 520 nm for emission. Plasma and erythrocyte hemolyzed samples were treated with acetonitrile and chloroform. and the supernatant was analyzed. Results: A good linear correlation existed between riboflavin, FMN and FAD concentration (from 1 to 400 nmol/L) and fluorescence intensity. The detection limits were 2.0 nmol/L, 2.5nmol/L and 2.5nmol/L at a signal to noise ratio of 3, respectively. The intra-assay and inter-assay relative standard deviations were in the range of 1.3% to 3.7%. The recoveries for riboflavin, FMN and FAD in both plasma and erythrocytes were satisfactory. Conclusion:This method for determination of riboflavin,FMN, and FAD in human plasma and erythrocytes is sensitive, rapid and accurate.

The effects of high concentrations (1-5mmol/L) of different amino acids in Hanks solution on the proliferation of Ehrlich ascites tumor cells and Walker 256 carcinosarcoma cells were examined. In order to demonstrate the inhibitory effect of some amino acids at high concentration level, the further studies were conducted on Ehrlich ascites tumor cells, human hepatoma cells and lung cancer cells, using Eagle's MEM as culture medium. The possible toxicity of the high concentrations of single amino acids to normal tissue cells was tested on mouse bone marrow cells. Although some amino acids exhibited a significant inhibitory effect, the responses of different tumor cells to the high concentrations of different amino acids were not entirely similar. Moreover, the effects presented by some amino acids on Ehrlich ascites tumor cells in Hanks solution could be diminished or eliminated in Eagle's MEM. Among the aromatic and basic amino acids, only the tryptophan was found to be inhibitory to the multiplication of mouse bone marrow cells at high concentration levels in vitro.

Objectives:In this study,the effects of glutamine(Gln) and branched chain amino acids(BCAA) enriched formulas on free radical metabolism and immunity in traumatized rats were investigated. Methods:After injury,twenty one male Wistar rats were randomly divided into three groups,and fed with rations containing casein,a commercial amino acids(17AA),and a new amino acids formula(20 AA) respectively.The rations were isonitrogenous and isocaloric.Before operation and on days 3,7,14 postoperation,body weight,dietary intake,the concentrations of MDA,the activities of SOD in plasma were measured.At last,the animals were killed,the hydroyproline and spleen lymphocyte blastogenesis were determined. Results:①After injury,body weight of rats were reduced significantly,the concentrations of MDA in plasma were increased,while the SOD activities were decreased. ②Compared with 17AA group, the levels of hydroyproline in sponge were increased in 20AA group.③There were better effects of reducing plasma MDA levels and enhancing plasma antioxidase activities in 20 AA group than 17 AA group.④The weight of thymus and spleen and spleen lymphocyte blastogenesis were more obviously increased in 20AA group than in 17AA group. Conclusions:The new amino acids preparations can increase the antioxidase activities,enhance immunity and promote wound healing.

To improve tryptophan production in Escherichia coli, key genes in the tryptophan biosynthesis pathway -aroG, trpED, trpR and tnaA were manipulated. TrpR gene was knocked out to eliminate the repression on the key genes controlling tryptophan biosynthesis and transportation on bacteria chromosome, and the tryptophan degradation was blocked by tnaA gene knockout. Then the bottleneck in tryptophan biosynthesis pathway was removed by co-expressing aroGfbr gene and trpEDfbr gene. Compared with the MG1655, the tryptophan production of trpR knockout and double-genes knockout strains was improved 10-folds and about 20-folds, respectively. After the trpEDfbr was expressed, the tryptophan production increased to 168 mg/L, and when the aroGfbr and trpEDfbr were co-expressed, the tryptophan production increased to 820 mg/L. This work laid the foundation for further construction of higher-efficient engineered strain for tryptophan production.
3-Deoxy-7-Phosphoheptulonate Synthase ; metabolism ; Amino Acid Transport Systems ; genetics ; Bacterial Proteins ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; Escherichia coli Proteins ; genetics ; Gene Knockout Techniques ; Genetic Engineering ; Repressor Proteins ; genetics ; Tryptophan ; biosynthesis