Roles of nucleosides and nucleotide mixture in small bowel transplantation

Sublingual nucleotides prolong run time to exhaustion in young physically active men

Although dietary nucleotides have been determined to be required for normal immune function, there is limited direct interventional evidence confirming performance-enhancing effects of sublingual nucleotides in humans. A double-blind, placebo-controlled, randomized trial was conducted to evaluate the effect of sublingual nucleotides (50 mg/day) administered for 14 days in thirty young healthy physically active males, on endurance performance and immune responses. Fasting white blood cell count, natural killer cells (NKC) number, NKC cytotoxic activity, and serum immunoglobulin (IgA, IgM, IgG), and time to exhaustion, peak rate of perceived exertion, peak heart rate, and peak running speed during the exercise test were measured at baseline (day 0) and post-intervention (day 14). Time to exhaustion, as well as serum immunoglobulin A and NKC cytotoxic activity, were significantly higher at day 14 (p < 0.05) in participants supplemented with nucleotides compared with those who consumed placebo. No significant differences in other parameters were observed between groups at post-intervention. No volunteers withdrew before the end of the study nor reported any vexatious side effects of supplementation. The results of the present study suggest that sublingual nucleotides may provide pertinent benefit as both an ergogenic and immunostimulatory additive in active males.

The role of nucleotides in the immune and gastrointestinal systems: potential clinical applications

Nucleotides are low molecular weight biological molecules key to biochemical processes. Sources include de novo synthesis, recovery via salvage mechanisms, and dietary intakes. Although endogenous production serves as the main nucleotide source, evidence suggests that exogenous sources are essential to immune competence, intestinal development, and recovery. Dietary nucleotides serve a marked role in rapidly proliferating cells where they are necessary for optimal function. Accordingly, dietary nucleotides are deemed conditionally essential in the presence of various physiological stresses, including growth and development, recovery from injury, infection, and certain disease states. Clinical studies that evaluated nutrition formulations of nucleotides in combination with other specific nutrient substances demonstrated improved clinical outcomes in patients characterized as critically ill, injured, immune suppressed, or with chronic gastrointestinal conditions. However, conclusions regarding specific benefits of nucleotides are limited. Scientific substantiation of nucleotide supplementation in infant formula has been reported to improve the maturation and development of the intestinal tract as well as immune function. All medical nutrition products except for one immune-modulating formulation are devoid of nucleotides. In an effort to build on this, the current review presents the data to support potential clinical applications for nucleotides in enteral nutrition that may contribute to improved outcomes in physiologically stressed patients.

The nucleoside and nucleotide mixture (OG-VI) rescues intestinal-like epithelial cells from the cytotoxicity of chemotherapeutic agents

Immune cells and cells undergoing rapid turn-over can obtain exogenous nucleotides via salvage synthesis. We evaluated whether or not the balanced nucleoside and nucleotide mixture OG-VI, could rescue intestinal epithelial-like Caco-2 cells from the cytotoxic effects of several chemotherapeutic agents, in the presence and absence of glutamine (Gln). Cells were exposed to 5-fluorouracil (5FU), methotrexate (MTX) or 6-mercaptopurine (6MP), after which proliferation and cell cycle analyses were performed. Following exposure to the chemotherapeutic agents, we observed that cells treated with OG-VI proliferated well, whereas those without the supplement did not proliferate. Furthermore, following treatment with either 5FU or MTX, we observed that the number of cells in the G0/G1 phase decreased and those in the S phases increased. However, these cell cycle alterations were prevented by the addition of OG-VI. With the exception of 6MP-treated cells, we did not observe any effects on proliferation or cell cycle regulation that could be ascribed to the presence of Gln. Thus, we have demonstrated that OG-VI rescues cells from the cytotoxic effects of several chemotherapeutic agents.

The effect of a valine-rich diet on intestinal adaptation to massive small bowel resection in the rat

BACKGROUND/PURPOSE

Recently, valine, which is one of the branched chain amino acids, has been reported to enhance liver regeneration after hepatectomy in the rat. The aim of this study was to investigate the effect of enteral valine supplementation on intestinal adaptation.

MATERIALS/METHODS

Seven-week-old male Lewis rats underwent a 90% small bowel resection. The rats were randomly divided into two groups: group V (valine-rich diet) and group S (standard rat chow), according to the diet. The rats were sacrificed at the operation day and on postoperative days (POD) 7, 14, 30, and 60. The metrics were body weight (BW), blood amino acids, urine organic acids, and morphology of the residual small intestine.

RESULTS

The BW and the intestinal wet weight, jejunal crypt depth, and proliferating cell nuclear antigen-positive cells in group V at POD 7 were significantly higher than those values in group S, while those in group V at POD 30 and 60 were smaller than those in group S. The urine methylmalonic acid (MMA) level in group V at POD 30 and 60 was much higher than in group S.

CONCLUSION

Valine enhanced intestinal adaptation after massive small bowel resection in the acute phase. However, the long-term supplementation disturbed intestinal adaptation, which might be due to the high production of MMA.

Effect of a valine-rich diet on a rat model of short bowel syndrome

It has been recently reported that valine, which was one of the branched chain amino acids, enhanced liver regeneration after a hepatectomy in rats. The aim of this study is to investigate the effect of enteral valine supplementation on the intestinal adaptation of short bowel syndrome using a rat model. Seven-week-old male Lewis rats underwent a 90% small bowel resection. The rats were randomly divided into two groups; Group V (valine-rich diet which contains valine, five times as the normal amount of valine as that found in standard rat chow) and Group S (standard rat chow), according to the diet each group received. The rats were killed and evaluated at the operative day, and postoperative days (POD) 7, 14, 30, and 60, respectively. The parameters of estimation were body weight (BW), a blood amino acids analysis, a urine organic acids analysis and a morphological examination of the residual small intestines. The BW and the intestinal wet weight, jejunal crypt depth and proliferating cell nuclear antigen positive cells in Group V at POD 7 were significantly higher than in Group S, while those in the Group V at POD 30 and 60 were smaller than in Group S. The urine methylmalonic acid (MMA) level in Group V at POD 30 and 60 was much higher than in Group S. The valine-rich diet was thus found to enhance intestinal regeneration after a small bowel resection in the acute phase. However, the long-term valine-rich diet supplementation was found to disturb the intestinal adaptation, which might be caused by the high production of MMA due to the valine-rich diet. This is the first report in which valine was used as a promoter of intestinal adaptation.

Effect of a nucleoside/nucleotide-free diet in rat allogenic small intestinal transplantation

The aim of this study is to estimate the effect of nucleoside (NS) and nucleotide (NT) on the recipient and graft immune response after rat allogenic small intestinal transplantation. Seven-week-old Lewis rats were randomly assigned to two groups, including the NS/NT free group ( n=6) and the NS/NT supplemented group ( n=6), according to the diet received. The recipient Lewis rats were each given diet for 12 days, and then, on the nineteenth day of gestation, a 2 cm jejunum from the donor fetal Fischer rat was transplanted into the abdominal wall of the recipient rats using a non-vascular anastomotic technique. The recipient rats were killed on day 2 after transplantation, and then the recipient plasma interleukin-2 (IL-2) level was measured. In addition, the histological findings of the graft were analyzed. The IL-2 level of the NS/NT free group was significantly lower than that of the NS/NT supplemented group. In order to determine the grade of rejection, the morphological findings were blindly graded on a scale of 0-4. The mean grade of the NS/NT free group was also significantly lower than that of the NS/NT supplemented group. The NS/NT free diet is therefore considered to have an immunosuppressive effect on rat allogenic small intestinal transplantation based on the recipient plasma IL-2 levels and the histological findings of the grafts.