Tetsuya Kishi

Nutritional Responses of Tumor-bearing Rats to Oral or Intravenous Feeding

Two experiments were conducted with male rats weighing 170 to 190 grams. In experiment 1, some nutritional parameters were determined in tumor-bearing (TB) (Walker 256 carcinosarcoma) rats fed a 23.6% casein diet for 4 weeks after the tumor inoculation. Cumulative weight gain and food intake were less in TB rats than in nontumor-bearing (NTB) rats. At 3 and 4 weeks after the tumor inoculation, plasma histidine, alanine, and glycine levels were higher in TB rats than in NTB animals. The arginine level was lower in the plasma of TB rats at 4 weeks after the inoculation. The significance of decrease in plasma arginine with regard to tumor growth is discussed. In experiment 2, the effects of total parenteral nutrition (TPN) on TB rats were evaluated as compared with those of 5% glucose (Glc) solution. Body weights of TPN rats were maintained and their nitrogen (N) balances were positive during a 7-day experimental period, while 5% Glc animals showed severe body weight loss and apparent negative N balance. After the end of infusion, the plasma urea level of the TPN group was within normal range, whereas that of 5% Glc group showed a markedly high value. The plasma albumin level was higher in the TPN group. Liver and spleen weights were increased in TPN rats. Absolute tumor weight was somewhat greater in TPN rats than in 5% Glc rats, but the difference in tumor weight:body weight ratios became more slight. These results indicate that TPN was effective for maintaining the nutritional status of TB host without significant acceleration in tumor growth.

Optimal Ratio of Individual Branched-Chain Amino Acids in Total Parenteral Nutrition of Injured Rats

In this study, we investigated the optimal ratio of individual branched-chain amino acids (BCAA) in a balanced amino acid infusion in laparotomized rats. The total BCAA contents of four amino acid infusions were fixed at 31% of total amino acids. The weight ratios of individual BCAA (isoleucine:leucine:valine) in the solutions were 1:0.5:1, 1:1:1, 1:2:1, and 1:4:1, respectively. The laparotomized rats were infused with about 140 mg (experiment 1) and 100 mg (experiment 2) of nitrogen and 10 g of glucose daily for 7 days. In both experiments, no marked difference was observed in the mean cumulative 7-day nitrogen balance and the urinary 3-methyl-histidine levels of all the groups. The BCAA concentrations and the molar ratios of individual BCAA in plasma were disarranged by the infusion of the 1:0.5:1 and 1:4:1 solutions. The infusion of the 1:1:1 and 1:2:1 solutions tended, however, to allow the values to approach the preinfusion values. These results suggest that the optimal ratio of individual BCAA in an amino acid infusion lies between 1:1:1 and 1:2:1 for this injured rat model in total parenteral nutrition.

Amino acid levels in plasma and muscle of rats after intravenous administration of different amino acid infusions.

Studies were conducted on the participation of specific amino acids in the alterations of their levels in plasma and muscle of rats after short term intravenous infusion. Sufficient amounts of amino acids and glucose were used as a basal solution, and the levels in plasma and muscle were determined 30 min after the end of infusion. When an infusion solution devoid of one of the essential amino acids from the basal solution, -Leu, -Ile, -Lys or -Thr, was administered, the plasma and muscle levels of the deleted amino acids decreased in different degrees. With infusion of the deficient solutions except for the -Leu, no significant changes were observed in amino acids other than those deleted, although occasional changes were noted. On the other hand, the infusion of the -Leu resulted in significant increase of isoleucine and valine levels, and a moderate increase of many other amino acids both in plasma and in muscle. In contrast, when leucine was administered singly in an amount equivalent to that in the basal solution, isoleucine and valine decreased significantly. Most of the other amino acids also decreased markedly after the infusion of leucine alone. These results suggest that, in intravenous infusion, leucine plays a specific role on amino acid levels in plasma and muscle of rats.

Effect of Laparotomy and/or Starvation on the Plasma Rapid-turnover Protein Level in Rats

Plasma transferrin (Tf), transthyretin (TTR), and retinol-binding protein (RBP) have been proposed to be sensitive nutritional parameters. We investigated the effect of laparotomy and/or starvation on these plasma protein levels in rats. Starvation decreased the Tf, TTR, and RBP levels to 62.2%, 41.2%, and 52.0% of the initial values, respectively, until day 3, but then sustained the day-3 levels on day 4. In the starved and laparotomized rats, the TTR level on day 1 and the RBP level on day 2 were more decreased than those in the only-laparotomized rats. Recovery of the TTR and RBP levels in the laparotomized rats fed on a stock diet ad libitum was very slow. In conclusion, the plasma Tf, TTR, and RBP levels showed different responses according to the metabolic phase of starvation. Laparotomy affected differently each of these levels, but the decrease in these protein levels was mainly dependent on the nutritional condition of the laparotomized rats.

Nutritional effects of branched-chain amino acids on injured rats in total parenteral nutrition.

In this study, we investigated the optimal contents of branched-chain amino acids (BCAA) in a balanced amino acid infusion in laparotomized rats. The BCAA contents of four infusion solutions used were prepared to 22, 31, 40, and 49% of total amino acids, respectively. The amounts of essential amino acids except for BCAA were equal in all the solutions. Rats weighing about 240 g were infused with about 200 mg of nitrogen and 10 g of glucose daily for 7 days and evaluated for body weight change, nitrogen balance, plasma and urinary amino acid levels, and plasma constituent levels. The body weights of all the groups were approximately maintained during the infusion period. The nitrogen balance of the BCAA-31 group was more positive than that of the BCAA-22 group and was not different from those of the BCAA-40 and BCAA-49 groups. Plasma total-protein level of the BCAA-31 group was higher than that of the BCAA-22 group and was equal to those of the BCAA-40 and BCAA-49 groups. Even when the BCAA content in an amino acid infusion was increased, no abnormal elevation was observed in plasma BCAA levels. There were no differences in the other nutritional parameters among the four infusion groups. These results suggest that the BCAA contents in an amino acid infusion are enough at 31% of total amino acids for this injured rat model.

Nutritional Effects of Intravenous Infusion Solutions on Normal Rats: Effects of Increased Energy Level and Deletion of Acidic Amino Acids

Nutritional effects of intravenous infusion of an amino acid (AA) mixture enriched with the branched chain AA were previously evaluated at a daily level of 45 kcal and 200 mg N using male rats weighing approximately 200 g. The present study was conducted with male rats weighing approximately 200 g to evaluate the nutritional effects of 1) an AA infusion solution at further increased energy level, and 2) an AA solution devoid of aspartic and glutamic acids. By increasing daily energy input from 45 to 55 kcal/rat, the body weight gain of rat was markedly increased and more positive nitrogen balance was observed. Glucose, albumin, and free AA levels were unchanged in plasma of rats after the infusion period, while plasma urea level was somewhat lowered. Organ weights and liver lipid content were also unchanged. The administration of an infusion solution devoid of aspartic and glutamic acids resulted in little alteration in the amounts of urinary excretion and plasma levels of these acidic AA. Furthermore, other parameters measured showed no significant effect of the deletion of the AA. These results indicate that no advantage is expected in the use of acidic AA for parenteral nutrition.

Sandwich Enzyme Immunoassay for Rat Retinol-Binding Protein Using Antibody against Recombinant Antigen and Its Application

The development of a sandwich enzyme immunoassay for rat retinol-binding protein using molecular biological techniques was described. Rat retinol-binding protein gene cloned by the PCR method was expressed by a fusion vector pEZZ18 in Escherichia coli strain HB101. A recombinant retinol-binding protein fused with IgG-binding domain ZZ of protein A was purified with IgG-Sepharose. Antibody against the recombinant protein was found to be specific to rat retinol-binding protein in plasma by immunoblot analysis. Affinity-purified anti-recombinant protein IgG was biotinylated and used for the sandwich enzyme immunoassay. In this assay, the measurable range is 1.9-60 ng/ml and the coefficients of variation within and between the assay series (assay range: 4-30 ng/ml) are 4.30 +/- 4.33 and 5.32 +/- 1.45%, respectively. Cross-reactivity of the immunoassay was examined using bovine, human, and mouse serum. There was a cross-reaction only with mouse serum. In an in vitro experiment, retinol-binding protein produced by rat hepatocytes could be measured by the sandwich enzyme immunoassay.